# Rb26 Head Flow Figures



## DrGtr (Jul 18, 2009)

I was wondering what would it be the best cfm of an rb26 head, some people say 300 int and 200+ ex.

What are your thoughts, opinions, results .


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## R.I.P.S NZ (May 7, 2004)

Kind of like a dyno, every result is going to be different unless compared on the same machine under the same conditions and its best to use a flow bench to measure gains as a % rather than putting an absolute value on it.

With NOS my exhaust flows HEAPS more than 200, lol.


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## MMT (Nov 10, 2010)

DrGtr said:


> I was wondering what would it be the best cfm of an rb26 head, some people say 300 int and 200+ ex.
> 
> What are your thoughts, opinions, results .


You could PM [email protected] engines, he eats, drinks and sleeps RB heads.


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## bigmikespec (Sep 5, 2008)

^^^ would never know never seen pictures of any


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## R.I.P.S NZ (May 7, 2004)

^^^x2 lol


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## MMT (Nov 10, 2010)

Yea I know but, I could give you a list of members on this board that actually know Andy and have seen the evidence.
You know there are lots of different types of people. Some will shout from the roof top and post pictures every time they make a modification, no matter how significant and some don't. 
I'm an engineer and I'm really interested to see his work on RB heads. I've seen the graphs on his flow bench showing the cfm at standard and what benefits can be gained through loads of different modifications. His quality of work and standards are impeccable I've seen some real POS heads land in his workshop and be amazed when he's finished them as they look brand new.
But maybe you're right guys, maybe he should promote himself a bit more by posting a few pics of his work, I don't know and its not my choice.
Back to the OP, PM [email protected] engines. :thumbsup:


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## R.I.P.S NZ (May 7, 2004)

MMT, its a location joke, Andy will know what we mean.

I'm sure he's doing great work, we just wanna see results!!


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## MMT (Nov 10, 2010)

R.I.P.S NZ said:


> MMT, its a location joke, Andy will know what we mean.
> 
> I'm sure he's doing great work, we just wanna see results!!


Ok :thumbsup:


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## bigmikespec (Sep 5, 2008)

Yeah definitely keen to see a result! C


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## DrGtr (Jul 18, 2009)

The reason why i ask is because i have opened quite a bit more than normal the exhaust ports , and due to the fact that i am going to bench flow it soon i would like to see if i get some good or bad results. hope i could get around 240 from the exhaust and 300 from the intake. I wish i could sent it to Andy from the begin. damn travel costs.


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## rb30r34 (Jun 30, 2008)

DrGtr said:


> The reason why i ask is because i have opened quite a bit more than normal the exhaust ports , and due to the fact that i am going to bench flow it soon i would like to see if i get some good or bad results. hope i could get around 240 from the exhaust and 300 from the intake. I wish i could sent it to Andy from the begin. damn travel costs.


Can anyone link me to some engines that andy has built that have these awesome heads on them.


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## Heat Treatments (Jan 11, 2009)

With NOS my exhaust flows HEAPS more than 200, lol.[/QUOTE]

Nos works good as you said Rob, also 60psi boost helps with flow figures:runaway:

HTL Racing


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## scoooby slayer (Jun 13, 2009)

bigmikespec said:


> ^^^ would never know never seen pictures of any


not rb but ive just got this 2jz head from andy fully worked.
he has all the gear diamond tip head skimmer, iirc superflow cfm machine, lathes and mills and a valve cutting machine lots of ££££ worth in his workshop.


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## rb30r34 (Jun 30, 2008)

Looks pretty tidy, hurry up and get it on your engine so we can see the results!


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## scoooby slayer (Jun 13, 2009)

rb30r34 said:


> Looks pretty tidy, hurry up and get it on your engine so we can see the results!


im in no hurry engine is running sweet and making 760 rwhp.


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## DrGtr (Jul 18, 2009)

It looks nice what cfm did you get from this?


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## scoooby slayer (Jun 13, 2009)

DrGtr said:


> It looks nice what cfm did you get from this?


im sure andy mentioned 176cfm but its all dependant on the vacuum pressure run as to what it flows. max that he knows recorded on my spec head is iirc 1300 hp. im sure he will comment once he sees this thread.


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## R.I.P.S NZ (May 7, 2004)

The sign of a good head is X amount of power at the lowest possible boost, let us know how you get on, if you get 1200whp+ at under 2 bar on petrol with a GT45 sized turbo your on the right track.


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## bigmikespec (Sep 5, 2008)

Jokes aside I would really love to see some results from Andy's work. I don't mind having to send a bare head over there and let him work his "magic" but no magin to speak of.

Anyone had an engine or head built by him that cares to share?


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## blue32 (Jan 3, 2007)

Iv'e had an engine built by Andy,










Had it dry sumped, all designed by AMT nothing 'off the shelf' with exception to the pump and had no problems what so ever - last night i went round to his house at 8-9pm my fuel pressure reg had broke (nothing to do with AMT - more like old age and abuse lol ) Andy no hesitation set up my new reg, checked all fuel pressure - not many tuners would do that on a Saturday night.

I've seen quite a few trick mods by Andy on other engines / heads hes done;



















.... and never known anyone so OCD about clean! lol :thumbsup:










Top bloke, good company with a good rep thats ever increasing. Would recommend his work, i'll try ang get some more photos next time im round as the things there involved with at the moments, including Andys own build are some very good projects.

If your wanting a new build engine done i would PM [email protected] - and his speciality is Cylinder head work. They have all the tools / machinery in house and nothing is subbed out, you won't be disappointed.


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## blue32 (Jan 3, 2007)

Some more work;



















This is part of the development work for Andys own engine... nice small turbo :runaway:

Andy designed and build the manifold himself ... designed around some massive lift cams he's also designed... but details surrounding that are at Andys Discrepancy


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## rb30r34 (Jun 30, 2008)

How much power at what boost does you engine make mate? And with what turbos


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## Corsa1 (Sep 8, 2003)

The trouble has been not been able to get the right size seat insert for the 37mm valves so we have now bought some material called Trojan as we can't buy copper beryllium any more because of the hazard's that go with the machining of it, so we are in the process of making the inserts up at the moment.


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## MMT (Nov 10, 2010)

[email protected] said:


> The trouble has been not been able to get the right size seat insert for the 37mm valves so we have now bought some material called Trojan as we can't buy copper beryllium any more because of the hazard's that go with the machining of it, so we are in the process of making the inserts up at the moment.


You're a teaser Andy. Take a few pics of the real goodies. :thumbsup:


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## DrGtr (Jul 18, 2009)

Andy what are you cfm figures normally with your flow bench / up to what hp.
let say with tomei 270 in/ex 10.8 lift and 260 in/ex 9.1 what you would expect from those to give you?


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## Corsa1 (Sep 8, 2003)

It depends on what spec head we see around 160+ cfm @10 on a road head thats on a 86mm bore.


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## R.I.P.S NZ (May 7, 2004)

[email protected] said:


> It depends on what spec head we see around 160+ cfm @10 on a road head thats on a 86mm bore.


Would it be fair to say you use the flow bench for comparison to quantify improvement rather than worrying about absolute figures much the same as a dyno operator would?

ie, what does a stock ex port flow on your machine, then under the same conditions what have you got them to flow after the work is done.

P.S. That supra head looks nice BTW.


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## DrGtr (Jul 18, 2009)

in the Australian forum i have notice that they speak a lot about having ex cfm more than 200 up to 240 and intake 300+ for a head to be good why is that? is the difference with flow benches so much?
one flow bench showing 160 and an othe one with same head 200?

In my case i will be using 270 tomei 10.80 lift and supertech 1mm oversize valves 3 angle cut for example and i have ported the head quite extensively i hope not too much its been my first rb26 head porting ( probably not doing it again next time is a flight ticket and going to Andy), what would a good race porting cfm should i expect at 10.80 in/ex if everything went perfectly ?


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## bigmikespec (Sep 5, 2008)

[email protected] said:


> The trouble has been not been able to get the right size seat insert for the 37mm valves so we have now bought some material called Trojan as we can't buy copper beryllium any more because of the hazard's that go with the machining of it, so we are in the process of making the inserts up at the moment.


Andy, I have looked into seat and guide material a fair bit and Trojan is a pretty good replacement for CuBe. AMPCO45 is also a replacement material which is a Ni-Al bronze alloy. 

What material are the valves? I would not think CuBe is necessary unless you have titanium valves.


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## rb30r34 (Jun 30, 2008)

DrGtr said:


> in the Australian forum i have notice that they speak a lot about having ex cfm more than 200 up to 240 and intake 300+ for a head to be good why is that? is the difference with flow benches so much?
> one flow bench showing 160 and an othe one with same head 200?
> 
> In my case i will be using 270 tomei 10.80 lift and supertech 1mm oversize valves 3 angle cut for example and i have ported the head quite extensively i hope not too much its been my first rb26 head porting ( probably not doing it again next time is a flight ticket and going to Andy), what would a good race porting cfm should i expect at 10.80 in/ex if everything went perfectly ?


Did you do your porting yourself?


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## DrGtr (Jul 18, 2009)

rb30r34 said:


> Did you do your porting yourself?


is that a bad thing to do?
did i destroyed my head?


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## rb30r34 (Jun 30, 2008)

DrGtr said:


> is that a bad thing to do?
> did i destroyed my head?


Obviously i cant say whether or not you have made it better or worse without you running it but you can defiantly make a head worse if you port the wrong places.
Its normally quite a specialized task that requires a lot of skill and practice as well as an in depth understanding of flow characteristics etc.

I hope your porting has been successful for your sake. The best thing you could do is try and see what the guys who make the most power at the least boost have done and try replicate that. Dont worry about cfm so much as a flow bench is best used to measure the gain from a known base line (eg a stock head) and the final numbers will vary from one machine to the next so cant really be used as a measure of how good a head is unless a before and after graph can be shown.


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## DrGtr (Jul 18, 2009)

I will do in few days i am going back in Cyprus hopefully the machine shop will finish the 3 angle cut so we could flow bench the head and i will let you know how it did go.


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## Corsa1 (Sep 8, 2003)

DrGtr said:


> in the Australian forum i have notice that they speak a lot about having ex cfm more than 200 up to 240 and intake 300+ for a head to be good why is that? is the difference with flow benches so much?
> one flow bench showing 160 and an othe one with same head 200?
> 
> In my case i will be using 270 tomei 10.80 lift and supertech 1mm oversize valves 3 angle cut for example and i have ported the head quite extensively i hope not too much its been my first rb26 head porting ( probably not doing it again next time is a flight ticket and going to Andy), what would a good race porting cfm should i expect at 10.80 in/ex if everything went perfectly ?


All our testing is done @10``of water but you will find that with the bigger flowbenchs they do it @28``of water and that is why you see number of 200+ CFM we have the software to convert it.


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## DrGtr (Jul 18, 2009)

[email protected] said:


> All our testing is done @10``of water but you will find that with the bigger flowbenchs they do it @28``of water and that is why you see number of 200+ CFM we have the software to convert it.


i have no idea what flowbench it is i will let you know in a week when i go back.


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## wax (Nov 21, 2010)

I hate flow benches they tell only half the story. Want to make it flow big numbers then make the port massive. Want the engine to make good power make the port flow and keep the speed up and the flow between the intake and the exhaust at the right ratio


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## Corsa1 (Sep 8, 2003)

They are a development tool as you can test different valve seat angles air speed cam lift, the only people who slag them off are the ones who don't own one who wants to build an engine to keep taking the head off to try different things on the ports but ever one to there own


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## GT-R Glenn (Nov 9, 2002)

Doc
Flow Bench
Read


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## wax (Nov 21, 2010)

[email protected] said:


> They are a development tool as you can test different valve seat angles air speed cam lift, the only people who slag them off are the ones who don't own one who wants to build an engine to keep taking the head off to try different things on the ports but ever one to there own


Im struggling to understand what you have written. However I think your trying to say I am slagging them because I dont own one, and I wish I did so I could so I could attempt different port shapes and valve angle to increase flow??
Actually your right I dont own one anymore, But let me rephrase what I said in the first place.
I hate it when people just talk flow figures and flow bench race. Flow bench figure's on there own do not show the full story. Is that better ??


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## R.I.P.S NZ (May 7, 2004)

Andy.........Would it be fair to say you use the flow bench for comparison to quantify improvement rather than neccessarily worrying about absolute figures?


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## R.I.P.S NZ (May 7, 2004)

wax said:


> Flow bench figure's on there own do not show the full story.


:thumbsup:


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## GT-R Glenn (Nov 9, 2002)

Its not rocket science 
Get a standard head, measure the flow at given valve lift, usually in 1mm increments
Alter the port shape, stick back on flowbench and measure airflow at the same increments.
Then after several years of experimenting, you can make the airflow characteristics change.

Some people , can even just look at a port and see exactly where the least amount of metal removal will gain the largest increase, quite often opening up the area that shrouds the valve.

You can without a doubt, get an increase in a standard head without flow testing it....

Tapered valve guides / 3 angle valves seats / etc: are all well known as is removing any obvious interuptors, but to get a head that is the best possible from that casting, you need to airflow test it / full stop....
It is effectively a cylinder head / inlet tract / tb / air speed dyno...

Ive seen over 100kws at the wheels gain from stuff that has never even been near a flowbench...and Ive seen losses form failed experimentations.

Doc, when you can get almost 900 hp from a pretty much standard head, I wouldnt be too worried about anything untill you want more power than that from the factory casting.
The standard head just needs a little massaging.


PS the original question was what is the cfm of a standard head , wasnt it ...


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## bigmikespec (Sep 5, 2008)

That being said Glenn we all know big boost can mask poor head flow characteristics! 

I am still hanging to see some of Andy's work on RB26 heads. Show it off Andy... or one of his customers. 

Better yet; what head work do you offer your customers? Do you do it in "stages" which seems a popular way to do it


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## R.I.P.S NZ (May 7, 2004)

GT-R Glenn said:


> After several years of experimenting, you can make the airflow characteristics change.


Agreed, top end head porting is not something one can expect from mucking around at home with a die grinder or in the early stages of development. 




GT-R Glenn said:


> You can without a doubt, get an increase in a standard head without flow testing it....


Agreed.



GT-R Glenn said:


> Ive seen over 100kws at the wheels gain from stuff that has never even been near a flowbench...and Ive seen losses form failed experimentations.


Agreed.



GT-R Glenn said:


> Doc, when you can get almost 900 hp from a pretty much standard head, I wouldnt be too worried about anything untill you want more power than that from the factory casting.
> The standard head just needs a little massaging.


Agreed, 10s in a full weight GTR with a totally stock head (even cams and springs) is no problem.




bigmikespec said:


> That being said Glenn we all know big boost can mask poor head flow characteristics!


Spot on :thumbsup:, how many guys on here have even "boasted" about running 2.5bar or even 3bar boost (thinking it was cool) and yet never seemed to deliver results at the track anywhere near in keeping with that much boost?


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## GT-R Glenn (Nov 9, 2002)

Ah yes definatly, sorry my bad.
Theres actually a few differences between pressure on the stem side of the valve vs the head (cylinder side) in vacuum /
Agreed.


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## Corsa1 (Sep 8, 2003)

I thought it wouldn't belong before it got into a slating match this is one of the reasons I didn't answer the original question, this is why I never post pics up of my work I.e. exhaust manifolds heads or any other stuff we may do because it will only get slaged off by all the other arm chair technicians you build your engines I will build my.[toys out of pram]


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## wax (Nov 21, 2010)

[email protected] said:


> They are a development tool as you can test different valve seat angles air speed cam lift, the only people who slag them off are the ones who don't own one who wants to build an engine to keep taking the head off to try different things on the ports but ever one to there own


Of course it was nothing to do with your well crafted response that turned it into a slagging match was it.


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## rb30r34 (Jun 30, 2008)

[email protected] said:


> I thought it wouldn't belong before it got into a slating match this is one of the reasons I didn't answer the original question, this is why I never post pics up of my work I.e. exhaust manifolds heads or any other stuff we may do because it will only get slaged off by all the other arm chair technicians you build your engines I will build my.[toys out of pram]


You cant make big claims about awesome heads without something to back it up man. The guys just want to see your work and results. 

BTW it should read:

I thought it wouldn't be long before it got into a slating match, this is one of the reasons I didn't answer the original question. This is why I never post up pics of my work. I.e, Exhaust manifolds, heads or any other stuff we may do because it will only get slagged off by all the other arm chair technicians. You build your engines, I will build mine.

30 seconds of proof reading makes all the difference mate.


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## Corsa1 (Sep 8, 2003)

Whose made big clams, show me?


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## rb30r34 (Jun 30, 2008)

The big oversize valve thread for example. Some of us are genuinely interested in what your doing and would very much like to see your progress.


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## Corsa1 (Sep 8, 2003)

But I don't need to post pics up just to prove to you guys over there it can be done.


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## rb30r34 (Jun 30, 2008)

I know it can be done. 3mm oversize valves in an rb head was done a long time ago in nz.


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## Corsa1 (Sep 8, 2003)

Good I hoped it worked.


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## bigmikespec (Sep 5, 2008)

Rb30r34 do you have any other info on this RB head done in NZ?

You can't be that sensitive to criticism Andy, if our opinions don't matter to you it should be no big deal if you share some info on what you do. As I have said before I have a genuine interest as do others... If you don't want to share anything other than snide comments then don't bother being a member of the forum.


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## tarmac terror (Jul 16, 2003)

bigmikespec said:


> Rb30r34 do you have any other info on this RB head done in NZ?
> 
> You can't be that sensitive to criticism Andy, if our opinions don't matter to you it should be no big deal if you share some info on what you do. As I have said before I have a genuine interest as do others... If you don't want to share anything other than snide comments then don't bother being a member of the forum.


Harsh. 

I dont see why someone should be forced to provide pics etc of work done if they dont want to. There are certain aspects of engine development that are comercially sensitive and posting pics would just be plain daft. If someone wants a head done by Andy then they pay the money and get the work done. Posting pics has the potential to allow all and sundry to copy and negate any commercial benefit of spending huge amounts of development time.

There are others out there that have requested that pics are not distributed of certain elements of engine work etc so its nothing new.

I,too, would like a step-by-step guide to building the ultimate RB head (with pics)but not naive enough to think that any company is actually going to do that!!

TT


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## Corsa1 (Sep 8, 2003)

bigmikespec said:


> Rb30r34 do you have any other info on this RB head done in NZ?
> 
> You can't be that sensitive to criticism Andy, if our opinions don't matter to you it should be no big deal if you share some info on what you do. As I have said before I have a genuine interest as do others... If you don't want to share anything other than snide comments then don't bother being a member of the forum.


Ok I apologise for what I said.:nervous:


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## scoooby slayer (Jun 13, 2009)

when my new head is fitted i will put my new dyno run on this thread, it will be run with same boost,cams at same timing first anyways so i will have a comparable power plot from the same dyno.


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## DrGtr (Jul 18, 2009)

scoooby slayer said:


> when my new head is fitted i will put my new dyno run on this thread, it will be run with same boost,cams at same timing first anyways so i will have a comparable power plot from the same dyno.


now you are talking.


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## DrGtr (Jul 18, 2009)

DrGtr said:


> i have no idea what flowbench it is i will let you know in a week when i go back.


my bad english :chairshot , i was replying after andy and wanted to say that i have no idea what kind of flow bench the machine shop have, at the place they are going to measure my head , cause he mentioned that the values are related to the size of the flow bench.


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## bigmikespec (Sep 5, 2008)

No need to be sorry Andy just stop being so stand off-ish. There are people here enthusiastic and excited about what you are doing the least you an do is be a bit forthcoming about what you do and how you go about achieving. No one is silly enough to post all their secrets but you won't give anything away by talking about it.

Anyway, you mentioned making valve seats from Trojan, you using that for guides as well?


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## GT-R Glenn (Nov 9, 2002)

Andy , I cant see anywhere anyone has slagged off what you can or cannot do ?
Arm chair technician ?
You seem to have come in with a highly defensive comment rather randomly ?
Im confused, happy to discuss head mods though , if I can be ass'd typing what I can say in a 10th of the time ...


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## R.I.P.S NZ (May 7, 2004)

I can't see where the problem is either.

All anyone wants to see is some results, some cars out there doing well, some good power relative to boost on the dyno, some high mph for the turbo/boost used and dyno graphs showing a good solid, well balanced power curve that would do well on track.

I havn't seen anyone say Andy was full of shyte, in fact, quite the opersite and *I personally think the work I've seen looks good, just no need for all the drama as soon as we show a genuine interest.*

If cars with Andy's heads, manifolds etc were out there absolutly kicking a$$ and we were all scractching our heads as to why, then fair enough I suppose.

Keep up the good work Andy but try not to be so defensive and easily offended, if guys are going to spend the $$ they want to see the dyno graphs, real world results on track, the timeslips and the trophies/records.


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## Infomotive (Oct 22, 2009)

bigmikespec said:


> Rb30r34 do you have any other info on this RB head done in NZ?
> 
> Head in question is my creation, and yes i use it.
> Jason


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## bigmikespec (Sep 5, 2008)

That is excellent mate!

What is the rest of your configuration? So both intake and exhaust valves are +3.0mm? Or just inlet?


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## GT-R Glenn (Nov 9, 2002)

I would like to see any kind of back to back comparison with a standard head vs a 3mm oversize valve head.
Any dyno curve or any flowbench data would be good to see.

I dont understand the logic behind going so big, not saying it doesnt work, just saying I would love to see how the flow and engine response would alter and it would be very obvious as a graph etc:


It is my understanding the exhaust side on a force fed engine you are usually best to go to better than 85% valve size to port Ø infact 100% is ideal.
Is that the result with 3mm o/s ?
What about the inlet ....


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## bigmikespec (Sep 5, 2008)

I would have thought going that much larger you would have issues about flowing around the valve being so close to the cylinder bore. There are some general rules regarding valve cross sectional area vs bore. I thought it was around 50% (ish)... will have to go back and have a look.


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## R.I.P.S NZ (May 7, 2004)

All this talk is really going to go no-where, there's WAY to many variables even after this theoretical majic head is bolted on.

Back to back engine dyno testing would be good for comparisons of a specific modification but for me, low 7s with less than 2 bar boost on petrol = something is working OK and I don't really care what. :thumbsup:


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## bigmikespec (Sep 5, 2008)

I agree Rob but the discussions are interesting; it is not what is flows (in volume) but how it flows it!


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## R.I.P.S NZ (May 7, 2004)

bigmikespec said:


> it is not what is flows (in volume) but how it flows it!


I agree, thats why worrying about peek cfm is not important, just like guys who have a million hp eventually, in most cases they are slower than the guys with a nice broad 500,000 .


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## Infomotive (Oct 22, 2009)

bigmikespec said:


> That is excellent mate!
> 
> What is the rest of your configuration? So both intake and exhaust valves are +3.0mm? Or just inlet?


1mm over (bore) RB30Det. VCT 25 head. Std ex valves(was blowing out the budget)
Over 550kww pump 98
138 mph in circuit spec on quater(no traction at only 500kww)
Will give more details when have time.


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## Infomotive (Oct 22, 2009)

GT-R Glenn said:


> I would like to see any kind of back to back comparison with a standard head vs a 3mm oversize valve head.
> Any dyno curve or any flowbench data would be good to see.
> 
> I dont understand the logic behind going so big, not saying it doesnt work, just saying I would love to see how the flow and engine response would alter and it would be very obvious as a graph etc:


Will try and russel up some dyno data for you Glen.
Jason


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## GT-R Glenn (Nov 9, 2002)

That would be awesome cheers Jas.

Rob, it is all mumbo jumbo, however,theres an interesting crossover between atmo engines and blown engines when you take into consideration that a blown engine with 3 atmospheres of boost being forced into it now also needs to get 3 times as much exhaust gas out of the cylinder / and what happens to petrol and air which is combined and then sheared off the air molecules when it is shoved into a small hole, which as far as I know should alter atomisation etc:


The reality of how it works under boost is actually quite interesting.


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## bigmikespec (Sep 5, 2008)

Infomotive said:


> 1mm over (bore) RB30Det. VCT 25 head. Std ex valves(was blowing out the budget)
> Over 550kww pump 98
> 138 mph in circuit spec on quater(no traction at only 500kww)
> Will give more details when have time.


Yes more details please! Turbo, etc...

Are the RB25 valves smaller anyway? So +3.0mm on the intake and standard exhaust.


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## Infomotive (Oct 22, 2009)

Yeah from memory they are about .3xmm smaller than 26 std. only notes i can find for std 25 valve is 34.12mm. Running 37mm valve on inlet with std ex untill stage three of head(ex valves) so 2.88 mm bigger than original in my application.
Turbo is 1AR TO4Z. Going to 1.15 AR shortly and bigger comp wheel.
More when i have time.
Jason


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## DrGtr (Jul 18, 2009)

It would be interesting to see some pictures if you have Jason and you dont mind.


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## Corsa1 (Sep 8, 2003)

I will wait till mine is on the engine then see what it does, I no it works on the bench but only on a set size of bore Iam a big fan of big bore short stroke. the main thing I was looking at is the ex side hence why we did the exhaust manifold and some new cams.Its good to see some one else has done some development work on a RB head and not just me.


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## rb30r34 (Jun 30, 2008)

[email protected] said:


> Its good to see some one else has done some development work on a RB head and not just me.


Jase built his one years ago mate.


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## Corsa1 (Sep 8, 2003)

Good it just shows it can be done


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## MMT (Nov 10, 2010)

tarmac terror said:


> Harsh.
> 
> I dont see why someone should be forced to provide pics etc of work done if they dont want to. There are certain aspects of engine development that are comercially sensitive and posting pics would just be plain daft. If someone wants a head done by Andy then they pay the money and get the work done. Posting pics has the potential to allow all and sundry to copy and negate any commercial benefit of spending huge amounts of development time.
> 
> ...


I agree with TT.

I've seen this head and some of the development work that Andy has put into achieving it. Its not my place or any of his other customers to divulge his development work or break confidentiality. 
Thing is with Andy and this BB, he rarely comes on and never really spouts his own work, its generally others that know him and the quality of work he produces that want to refer him to other people so they can benefit from his craftsmanship. 

Just remember, Andy gives good head.  :chairshot


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## tarmac terror (Jul 16, 2003)

MMT said:


> Just remember, Andy gives good head.  :chairshot


LOL...an oldie, but a goodie.

:chuckle:

TT


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## rb30r34 (Jun 30, 2008)

MMT said:


> I agree with TT.
> 
> I've seen this head and some of the development work that Andy has put into achieving it. Its not my place or any of his other customers to divulge his development work or break confidentiality.
> Thing is with Andy and this BB, he rarely comes on and never really spouts his own work, its generally others that know him and the quality of work he produces that want to refer him to other people so they can benefit from his craftsmanship.
> ...


We just want to see some engines that hes built running and performing. Have you got one?


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## WHITER33 (Feb 4, 2009)

My 26 head had a little tickle. Nothing major.









Teal> std exhaust
Red> modified exhaust
Green> std intake
Grey> modified intake

CFM runs up the left y-axis

Red line across the top is test pressure on the right y-axis

x-axis is valve lift. Tested at .050" (approx 1.25mm) increments. Std ports are tested up to .400" (10mm), modified ones to .450" (11.25mm) lift.


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## DrGtr (Jul 18, 2009)

nice comparison it seems you have a prove of cfm increase there. Not bad 180 for the exhaust without major changes. what did you modify on the head? porting ? cams ? valves? polish?


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## tarmac terror (Jul 16, 2003)

rb30r34 said:


> We just want to see some engines that hes built running and performing. Have you got one?


No, I haven't.

TT


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## WHITER33 (Feb 4, 2009)

DrGtr said:


> nice comparison it seems you have a prove of cfm increase there. Not bad 180 for the exhaust without major changes. what did you modify on the head? porting ? cams ? valves? polish?


Its had a little port work (About 14hrs from memory)and the bump taken out of the exhaust. .5mm oversize valves and running 280 degree cams

The work probably didnt need doing for my power level but the head needed to be cleaned up anyway so I thought why not. lol


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## WHITER33 (Feb 4, 2009)

I do have some before and after pics I will put up once I can find them


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## DrGtr (Jul 18, 2009)

hmm interesting! lets have a look.


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## bigmikespec (Sep 5, 2008)

What turbochargers are you using Whiter33?


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## Infomotive (Oct 22, 2009)

Here is before and after first untuned partial run both on wg pressure.
JasonURL=http://imageshack.us/photo/my-images/33/jasonsstdvalvevbigvalve.jpg/]







[/URL]


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## Neesan (Jun 26, 2011)

bigmikespec said:


> Rb30r34 do you have any other info on this RB head done in NZ?
> 
> You can't be that sensitive to criticism Andy, if our opinions don't matter to you it should be no big deal if you share some info on what you do. As I have said before I have a genuine interest as do others... If you don't want to share anything other than snide comments then don't bother being a member of the forum.


Mike,

There was a guy in the motherland who recently posted a thread about his GT-R

making 400+++ KW using some pretty big valves, Ryan.. something was his forum name, maybe talk to him.


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## bigmikespec (Sep 5, 2008)

Thanks I know Ryan.


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## Neesan (Jun 26, 2011)

bigmikespec said:


> Thanks I know Ryan.


Hey man,

Sorry, didn't know !

slightly OT, what are you building wanting to know about valves that big ?

Cheers,

Mitch.


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## WHITER33 (Feb 4, 2009)

bigmikespec said:


> What turbochargers are you using Whiter33?


Garrett T51


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## bigmikespec (Sep 5, 2008)

Ryan is using Ferrea +1.0mm valves same as what I have (but my head is not built yet). He has had very good results but he has got to a point where his engine flows more than his turbochargers (or the turbine housings).

Heads are interesting stuff... I am just excited with new things people are trying and it is good discussion. I am interested as to how the flow of mixture is around the valve as with being so big it would be closer to the bore than usual.


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## Corsa1 (Sep 8, 2003)

I no the 37mm one only works on a 87mm plus bore, But do you get the same effect when its blown in rather than drawn in you can't simulate that, that's when the dyno comes in mike


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## NISFAN (Oct 11, 2003)

[email protected] said:


> ....... But do you get the same effect when its blown in rather than drawn in you can't simulate that, that's when the dyno comes in mike


Odd statement from a head porting expert, air always flows from a high pressure to a low pressure, forced induction doesn't change that principal, just means the outside pressure is higher than it would be in a naturally aspirated engine.


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## Corsa1 (Sep 8, 2003)

But Iam on about air speed around the valve head, but it all so effects how it flows into the chamber. the size of the valve also effects the pressure recovery in the combustion chamber, which can only be checked by sitting the port on the bench and putting it on the exhaust flow.


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## Red R Racing (Aug 22, 2009)

bigmikespec said:


> I would have thought going that much larger you would have issues about flowing around the valve being so close to the cylinder bore. There are some general rules regarding valve cross sectional area vs bore. I thought it was around 50% (ish)... will have to go back and have a look.


a valve that big in the nominated bore size may look great on a flow bench but thats the only place it will be impressive. The pressure recovery would be poor as the air speed on the wall side would slow significantly faster than the open. Remember that the trick is to keep the air speed around the valve head even and ensure any slowing of the airspeed as it is entering the cylinder is drawn out over the longest possible period. This is what keeps vortex issues at bay and what makes good horsepower, not a rediculous sized valve and a number off the superflow that in the real world means very little. 

In reality whats makes engines perform best will never be seen at 28" on a flow bench as well as what makes them a dud will not be either. 

This is why we never quote flow bench numbers for any of our heads and generally people who ask for them clearly dont understand how insignificant they are.

EDIT: Andy didn't see your post above, how were the numbers? any wet flow data?


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## Neesan (Jun 26, 2011)

bigmikespec said:


> Ryan is using Ferrea +1.0mm valves same as what I have (but my head is not built yet). He has had very good results but he has got to a point where his engine flows more than his turbochargers (or the turbine housings).
> 
> Heads are interesting stuff... I am just excited with new things people are trying and it is good discussion. I am interested as to how the flow of mixture is around the valve as with being so big it would be closer to the bore than usual.


I agree,

Something I have been thinking about is the actual percentage ratio of valve area inlet to exhaust.

Generally people only go oversize in increments such as +1mm , +2mm etc etc.

But as the inlet and exhaust valves are not of matched proportion, would this not effect the area ratio's of the valve areas, and what effect would this have on the performance of the cylinder head ?

Surely this would effect the pressure differential you guys are talking about ?


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## DrGtr (Jul 18, 2009)

Neesan said:


> I agree,
> 
> Something I have been thinking about is the actual percentage ratio of valve area inlet to exhaust.
> 
> ...


Interesting though i would like to know too!!


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## R.I.P.S NZ (May 7, 2004)

Its common for top end blown, NOS or turbo'd engines to have the exhaust flow ratio very high when compared to stock or a mild street type head.

Getting it in is not so hard, getting it out is where its at.


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## scoooby slayer (Jun 13, 2009)

R.I.P.S NZ said:


> Its common for top end blown, NOS or turbo'd engines to have the exhaust flow ratio very high when compared to stock or a mild street type head.
> 
> Getting it in is not so hard, getting it out is where its at.


this is exactly what andy said to me when i picked my head up that the exhaust side took the most time.


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## GT-R Glenn (Nov 9, 2002)

Yeah...



> it is all mumbo jumbo, however,theres an interesting crossover between atmo engines and blown engines when you take into consideration that a blown engine with 3 atmospheres of boost being forced into it now also needs to get 3 times as much exhaust gas out of the cylinder /


F1 's blown next year ./..
Awesome


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## Neesan (Jun 26, 2011)

R.I.P.S NZ said:


> Its common for top end blown, NOS or turbo'd engines to have the exhaust flow ratio very high when compared to stock or a mild street type head.
> 
> Getting it in is not so hard, getting it out is where its at.


Where does using staggared camshaft specs come into this, IE duration and lift in relations to:

One another, the valve sizes and finally engine speed.

I ask because I have been criticized in the past for running a larger duration and lift in my exhaust cam 264 IN 10mm and 272 EX 10.2mm But I saw this as a better option given the size of the standard RB26 exhaust valve.

Cheers,

Mitch.


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## bigmikespec (Sep 5, 2008)

[email protected] said:


> I no the 37mm one only works on a 87mm plus bore, But do you get the same effect when its blown in rather than drawn in you can't simulate that, that's when the dyno comes in mike


If you had the plumbs going a 88mm bore would be the way to go, sleeve the block for added strength. 

Andy, are you hoping to achieve equal flow (or as close as possible) between intake and exhaust? 

Neesan if you have low mounts on OEM manifolds dont even worry about larger duration cams; you dont want a lot over overlap.


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## Neesan (Jun 26, 2011)

bigmikespec said:


> If you had the plumbs going a 88mm bore would be the way to go, sleeve the block for added strength.
> 
> Andy, are you hoping to achieve equal flow (or as close as possible) between intake and exhaust?
> 
> Neesan if you have low mounts on OEM manifolds dont even worry about larger duration cams; you dont want a lot over overlap.


-5's with ported OEM manifolds (HPC coated) is the plan.

for 400AWKW.

Why no cams I would have thought mild cams and porting would help at this sort of setup.


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## rb30r34 (Jun 30, 2008)

I have low mounts and would be wasting my time on standard cams. Gtrs's wouldnt reach their potential on stock cams.


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## Sub Boy (Jan 28, 2008)

^^^^ what he said

Even with -5's a set on 260deg 9.15 lift cams made a huge difference to waking them up, I would think with -10's you would need 270's with 10ish lift to make the most from them


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## bigmikespec (Sep 5, 2008)

Low mount turbos are compromised on a RB26 because of limitations with the exhaust side. Small internally wastegated turbine housings create a restriction (back pressure. With large duration cams (forget lift for now) the overlap will cause reversion of exhaust. 

Large tubular manifold, big single turbo with large turbine housing is a different story. With the ratio of manifold pressure and exhaust manifold back pressure closer to 1:1 then overlap is desirable.


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## Corsa1 (Sep 8, 2003)

If you look at the manifold we have build with the large turbo it is designed to work with the cams we have done 310 degrees 13mm lift but what we have done is open the exhaust valve very early. Mike I would love to 89mm with liners, I will go 88mm to try it.


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## bigmikespec (Sep 5, 2008)

[email protected] said:


> If you look at the manifold we have build with the large turbo it is designed to work with the cams we have done 310 degrees 13mm lift but what we have done is open the exhaust valve very early. Mike I would love to 89mm with liners, I will go 88mm to try it.


Andy have you done anything to measure the velocity around the valves to see if the flow is consistent around the seat? 

There is a fella local to me that has an RB30 with liners and a 89mm bore. Not sure how much "meat" would be in the liner though.


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## rb30r34 (Jun 30, 2008)

Sub Boy said:


> ^^^^ what he said
> 
> Even with -5's a set on 260deg 9.15 lift cams made a huge difference to waking them up, I would think with -10's you would need 270's with 10ish lift to make the most from them


Yep bang on. I have 272's with 10.25 lift.


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## fun123 (Apr 16, 2010)

*valve sizes*

A bit off the RB topicbut interesting for those into engine development.

Here is a cross sectional pic of a Toyota F1 engine.

Obviously it has had a huge mount of R&D money spent on it, the inlet valves are very close together and they are also close to the cylinder wall. They must have decided that valve size was more importnat than the valve shrouding aspect.
Even though this is not a forced induction engine similar principles would surely apply.










Other things of interest are the shape of the top of the exhaust valve compared to the inlet, also the very low inclined angle of the inlet valve (Almost vertical)


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## bigmikespec (Sep 5, 2008)

The valve being close to the wall does diminish air flow around the valve, there are several examples that I have read where people have tested with their engines that have proved this. Can't post the link as you need to register.


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## fun123 (Apr 16, 2010)

bigmikespec said:


> The valve being close to the wall does diminish air flow around the valve, there are several examples that I have read where people have tested with their engines that have proved this. Can't post the link as you need to register.


Yes it makes sense what you say. I think with the F1 engine above it is probably less of an issue due to the valve opening away from the main flow (Due to the design of the almost straight intake tract)


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## bigmikespec (Sep 5, 2008)

Yes I did notice how straight the ports were. On the RB26 they need to make a sharper turn on the short side radius which does not help flow in that area. 

Bottom line is big valves need to be in a bigger bore! Some people have even taken a scallop on the top of the cylinder where the inlet valve is and believe it or not better results have been achieved by doing this.


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## fun123 (Apr 16, 2010)

bigmikespec said:


> Yes I did notice how straight the ports were. On the RB26 they need to make a sharper turn on the short side radius which does not help flow in that area.
> 
> Bottom line is big valves need to be in a bigger bore! Some people have even taken a scallop on the top of the cylinder where the inlet valve is and believe it or not better results have been achieved by doing this.


I think what you are saying sounds correct for a RB engine because of the valve angle to port shape relationship. 
In the F1 engine when the valve is fully open it is almost completely out of the way of the flow path so would probably have less flow around the sides compared to a conventional engine. Just my take on it?


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## bigmikespec (Sep 5, 2008)

fun123 said:


> I think what you are saying sounds correct for a RB engine because of the valve angle to port shape relationship.
> In the F1 engine when the valve is fully open it is almost completely out of the way of the flow path so would probably have less flow around the sides compared to a conventional engine. Just my take on it?


It is hard to say without knowing a lot more about the F1 engine. But that may be correct.

In regards to the RB if there was a reliable way of going out to an 88mm bore (or more) then I would do it but retain the OEM stroke of 73.7mm. Darton say you can go out to 87.5mm bore with their sleeve kit but pushing it out to 88mm and their exact words were that it did not leave much material and they did not recommend it.


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## black bnr32 (Jan 20, 2011)

Maybe a helpful data point:
BMW's M50-based motors had a bore spacing of 91mm vs the rb's 96.5mm. S54 motors have been proven above 900rwhp at 87mm bore (so 4mm wall thickness). more common, at least in the states, is an s50 with an 85mm bore and 91mm bore spacing making 600whp (550+ft-lbs torque). So, 6mm wall thickness.

O-rings in a figure 8 pattern are also common for high boost applications and small wall thickness.

Is there any reasons why RBs can't run similar wall thicknesses? Say, a 90mm bore with o-rings?


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## fun123 (Apr 16, 2010)

black bnr32 said:


> Maybe a helpful data point:
> BMW's M50-based motors had a bore spacing of 91mm vs the rb's 96.5mm. S54 motors have been proven above 900rwhp at 87mm bore (so 4mm wall thickness). more common, at least in the states, is an s50 with an 85mm bore and 91mm bore spacing making 600whp (550+ft-lbs torque). So, 6mm wall thickness.
> 
> O-rings in a figure 8 pattern are also common for high boost applications and small wall thickness.
> ...



A standard RB has a 86mm bore. Head sealing isn't the issue (O rings not needed) the problem is the cylinder wall thickness and its integrity


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## DrGtr (Jul 18, 2009)

fun123 said:


> A standard RB has a 86mm bore. Head sealing isn't the issue (O rings not needed) the problem is the cylinder wall thickness and its integrity


and here we come back to my dream block idea of someone making a cnc full aluminum block for all of us with much bigger bore size no? let say if it cost 3000usd it would sell like cakes.


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## black bnr32 (Jan 20, 2011)

fun123 said:


> A standard RB has a 86mm bore. Head sealing isn't the issue (O rings not needed) the problem is the cylinder wall thickness and its integrity


I see, thanks.


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## fun123 (Apr 16, 2010)

DrGtr said:


> and here we come back to my dream block idea of someone making a cnc full aluminum block for all of us with much bigger bore size no? let say if it cost 3000usd it would sell like cakes.


Would mean you would need a new head also to accomadate the larger bore spacing


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## Sub Boy (Jan 28, 2008)

DrGtr said:


> and here we come back to my dream block idea of someone making a cnc full aluminum block for all of us with much bigger bore size no? let say if it cost 3000usd it would sell like cakes.


Like this one? Welcome to Bullet Cylinder Heads - bullet products - bullet blocks

I'm sure if you requested a larger bore and longer stroke it wouldn't be an issue.


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## bigmikespec (Sep 5, 2008)

fun123 is right it would be too hard if you had to change bore spacing. Does that block have water jackets? You could machine a block with water jackets in better places, I have heard when guys have machined bores out over 90mm they have broken through water jackets.


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## DrGtr (Jul 18, 2009)

Sub Boy said:


> Like this one? Welcome to Bullet Cylinder Heads - bullet products - bullet blocks
> 
> I'm sure if you requested a larger bore and longer stroke it wouldn't be an issue.


After 2 years they are still doing the rb26 and the page didnt change, so it will never be done probably.


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## Jimefam (Apr 30, 2011)

I asked a company here in the US for a quote on an aluminum block and was told between $7500-8500 depending on the options I wanted. Was also told the price would go down dramatically if they could sell multiple units as the majority of that initial cost was doing that design for the CNC machine. Not sure if it would get down to the 3,000usd that you mentioned but I would think it would be close. Right now there are quite a few shops that could use the work here in the US and with the dollar being as weak as it is could be good value for other countries. I would jump on a 3k aluminum block made to my specs and believe your right that alot of others would too.


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## Sub Boy (Jan 28, 2008)

DrGtr said:


> After 2 years they are still doing the rb26 and the page didnt change, so it will never be done probably.


Have you asked them?

I emailed them ages ago, and they said they can make it as an RB30 with a 4x4 sump pattern....So I'm sure they can build what ever you want, it'll just cost the time for them to CAD it for you


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## DrGtr (Jul 18, 2009)

Jimefam said:


> I asked a company here in the US for a quote on an aluminum block and was told between $7500-8500 depending on the options I wanted. Was also told the price would go down dramatically if they could sell multiple units as the majority of that initial cost was doing that design for the CNC machine. Not sure if it would get down to the 3,000usd that you mentioned but I would think it would be close. Right now there are quite a few shops that could use the work here in the US and with the dollar being as weak as it is could be good value for other countries. I would jump on a 3k aluminum block made to my specs and believe your right that alot of others would too.


i am sure for 3000usd mark i am sure if we make a list who would buy one we will find a lot of people if i find one i will def extend my build and get one for 90+ bore but then i will have to change my plans cause i will go for the 1000hp mask but who cares if it is going to be low down from 3-4000rpm spooling


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## DrGtr (Jul 18, 2009)

Sub Boy said:


> Have you asked them?
> 
> I emailed them ages ago, and they said they can make it as an RB30 with a 4x4 sump pattern....So I'm sure they can build what ever you want, it'll just cost the time for them to CAD it for you


for how much?


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