# Varsity's Matte Daytona Blue 2011 on Dyno



## [email protected] (May 16, 2003)

Varsity's Matte Daytona Blue 2011 on Cartec Dyno running Cobb Tuning AccessPORT with gtc remap & Y-pipe.











Stock run- 537ps / 702nm torque

GTC custom tune top map 17psi/custom cam, fuel & ign timing- 609ps / 807nm


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## Adamantium (Jun 24, 2002)

Is this the first Cobb'd 2011 in this country?

Very nice numbers - well done.

Can you put the torque into lbft for us. I think it's /1.3 or something.


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## ROG350Z (Jun 15, 2008)

Nice one Ben - similar numbers to MY10 tuned then - full Titan and Custom tune 99 stage two is about 595 BHP and 600 lb ft is it not?

Must get mine redone after Cobb tune just to check....

PS it is really noticeable running 95-97 map in Scotland as 97 RON super only thing available that engine feels flat and stinks of fuel when you start it up. Can't wait t get V Power back in her and turn her back up.


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## [email protected] (May 16, 2003)

Adamantium said:


> Is this the first Cobb'd 2011 in this country?
> 
> Very nice numbers - well done.
> 
> Can you put the torque into lbft for us. I think it's /1.3 or something.


Thanks Adam.

it's the first one with a nice video  have done a few in UK, Germany, France, Sweden and UAE.


807nm in lb/ft 595.24


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## [email protected] (May 16, 2003)

ROG350Z said:


> Nice one Ben - similar numbers to MY10 tuned then - full Titan and Custom tune 99 stage two is about 595 BHP and 600 lb ft is it not?
> 
> Must get mine redone after Cobb tune just to check....
> 
> PS it is really noticeable running 95-97 map in Scotland as 97 RON super only thing available that engine feels flat and stinks of fuel when you start it up. Can't wait t get V Power back in her and turn her back up.


another GTR dyno day would be nice


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## alloy (Apr 29, 2005)

ROG350Z said:


> Nice one Ben - similar numbers to MY10 tuned then - full Titan and Custom tune 99 stage two is about 595 BHP and 600 lb ft is it not?
> 
> Must get mine redone after Cobb tune just to check....
> 
> PS it is really noticeable running 95-97 map in Scotland as 97 RON super only thing available that engine feels flat and stinks of fuel when you start it up. Can't wait t get V Power back in her and turn her back up.


Yup, my MY09 went from a base figure of 504bhp 494ftlbs to 591bhp 627ftlbs with intakes and remap (already had the y-pipe on for the base run)


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## w8pmc (Sep 16, 2010)

Niiiice. Car looks fantastic:clap:

So the headline figures (of course taking into account different dyno's on different days etc.) are about 10bhp higher & similar torque to a similar tuned MY10?

Does this then confirm (or go some way) that the MY11 power increases over earlier models are purely an ECU tweak to get that extra stock 45bhp?

Ben, how similar are the logs between the 2 cars stock & mapped?

My feet are itching as i feel drawn to an MY12 next year:runaway:


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## [email protected] (May 16, 2003)

Hi Paul,

don't sell your current car just yet 


MY2011 power gains over MY09/10 down to:


increased boost
slightly larger turbo suction pipes
very minor ign timing increase
cam timing

A comparison of the intake cam timing of the CBA(2009) Nissan GT-R to a DBA(2011). If you look at the pictures below you will see a lot more cam advance in the mid range, and even a little less advance near the top of the range. Dyno tested a 2009 vs a 2011 and the chart shows a bit more midrange power at the same amount of boost.

oem 2009 cam










oem 2011 cam











Yes logs between two remapped models can be very similar can only take it so far with oem rods, oem 570cc injectors, oem intake, oem turbo, suitable Airfuel etc.. in mind.


could easily have achieved higher dyno figures by running more timing, leaner and ramping up the mid range wastegate duty cycle to 95-100% like some U.S tuners have been doing to achieve 23psi but we keep stock engines at 17psi.


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## Adamantium (Jun 24, 2002)

Ben,

Is it safe to run the same timing in the 2010 as the 2011? Do we know for certain that the base valve timing and cam profiles are the same?


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## [email protected] (May 16, 2003)

The stock 2011 cam timing map looks quite good and ourselves, cobb and others have been running custom since 09. Gains from intake cam advance during spool helps turbo response and midrange torque, taking some cam timing out helps the top a little bit

we understand stock cams same


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## *MAGIC* (Oct 21, 2009)

Awesome job and fantastic colour GTR :smokin: :chuckle:

Robbie


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## Anders_R35 (Jul 20, 2011)

What a result and that's with only a y-pipe and no rear exhaust section?

Anders


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## w8pmc (Sep 16, 2010)

Anders_R35 said:


> What a result and that's with only a y-pipe and no rear exhaust section?
> 
> Anders


& a GTC Custom Tune:thumbsup:

The "Y" pipe will be adding about 15-20 & the tune provides the balance.

My MY10 with the above but a full Titan system, not just the "Y" pipe produced 595bhp. The cat-back element alone is unlikely to produce more than about 10bhp.


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## Anders_R35 (Jul 20, 2011)

w8pmc said:


> & a GTC Custom Tune:thumbsup:
> 
> The "Y" pipe will be adding about 15-20 & the tune provides the balance.
> 
> My MY10 with the above but a full Titan system, not just the "Y" pipe produced 595bhp. The cat-back element alone is unlikely to produce more than about 10bhp.


Ah right, I thought full exhaust was required for circa 600bhp as Litchfield include it as part of their 580bhp kit.

Anders


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## David.Yu (Jun 28, 2001)

Actually, when we tested my car with just a Milltek Y-pipe vs Rich-GT's totally standard car back in 2009, we registered 512hp vs 506hp, so not even 10hp in a Y-pipe. 

However a really good cat-back can add more, my Akrapovic replacing the Milltek Y-pipe added another 24hp at max power, and 30hp lower down the rev range, with no additional tweaks to the tuning.


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## w8pmc (Sep 16, 2010)

David.Yu said:


> Actually, when we tested my car with just a Milltek Y-pipe vs Rich-GT's totally standard car back in 2009, we registered 512hp vs 506hp, so not even 10hp in a Y-pipe.
> 
> However a really good cat-back can add more, my Akrapovic replacing the Milltek Y-pipe added another 24hp at max power, and 30hp lower down the rev range, with no additional tweaks to the tuning.


David, were all those runs done on the same day etc.? I'd expect the cat-back to offer further increases but no more than a "Y" pipe would, so roughly 10 for the "Y" & a further 10 for the cat-back. I never ran my car on a RR stock or with just the "Y" & i've got the GTC Titan so perhaps the Akropovic (lucky ****er) does open up better gains.

Just re-read your post, you replaced the Milly "Y" pipe for Akro as well as fitting the Akro cat-back?


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## David.Yu (Jun 28, 2001)

w8pmc said:


> David, were all those runs done on the same day etc.? I'd expect the cat-back to offer further increases but no more than a "Y" pipe would, so roughly 10 for the "Y" & a further 10 for the cat-back. I never ran my car on a RR stock or with just the "Y" & i've got the GTC Titan so perhaps the Akropovic (lucky ****er) does open up better gains.
> 
> Just re-read your post, you replaced the Milly "Y" pipe for Akro as well as fitting the Akro cat-back?


Yup, same day, same dyno, same operator. My car had 2k miles on it, Rich's only 1k, so the Y-pipe could arguably have made less than the 6hp difference we measured.

And yes, the Akro cat-back (with a resonated Y-pipe, unlike the non-resonated Milltek Y-pipe) was measured back to back against the Milltek y-pipe set up, so it's possible the increase over completely stock could have been greater still.


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## Rich-GT (Apr 2, 2008)

Worth adding that on the same day we then tested both cars with what was then the Off the shelf Cobb Stage 1 map.

My car, otherwise standard, then produced 542HP & David's again another 6HP or so. Thing that suprised me the most was how similar the graphs were for our two cars throughout the rev range. Biggest difference was below 4000RPM.

Have not had mine on the rollers since the custom Stage 2 99Ron Tune, everything else still standard. However seat of the pants & Drag strip show considerable gains. Leaves me uncertain as to how much gain is got from Y Pipe & Zorst, as I feel most of the gain comes from the tune.


Rich


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## David.Yu (Jun 28, 2001)

Rich-GT said:


> Worth adding that on the same day we then tested both cars with what was then the Off the shelf Cobb Stage 1 map.
> 
> My car, otherwise standard, then produced 542HP & David's again another 6HP or so. Thing that suprised me the most was how similar the graphs were for our two cars were throughout the rev range. Biggest difference was below 4000RPM.
> 
> ...


As I've said, good exhaust can add up to 30hp, (and loses over 17kg in the Akro's case), but at the risk of being too noisy for some drive-by noise limits.

Intake added a fair bit too, about 20hp in the case of my Cobb ones.

Definitely on the law of diminishing returns after that.
Downpipes would yield maybe another 15hp or so, but relatively massive labour cost, ditto the larger 2011 turbo intake pipes that have been proven to add another 10hp.


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## w8pmc (Sep 16, 2010)

David.Yu said:


> As I've said, good exhaust can add up to 30hp, (and loses over 17kg in the Akro's case), but at the risk of being too noisy for some drive-by noise limits.
> 
> Intake added a fair bit too, about 20hp in the case of my Cobb ones.
> 
> ...


Only ever RR'd my car with full zorst & custom tune (intakes & injectors have gone on since then), so no idea what gains each component provided & although i did a run with the stock map, it's not an exact science given the Titan was on & therefore the stock map wasn't really suitable.

Still 30bhp is a big gain for a cat-back zorst & i'll never know if the Titan offers similar gains standalone. Likewise to the Akro though, it does shed a load of weight over the OEM system (can't recall the exact numbers).

Based on the SVM 650R package, i'm only minus the downpipes & am avoiding these due to concerns about noise limits on track. Didn't realise the turbo intake pipes could give increases so may investigate those (depending on costs etc.).

Wish the modding bug could stay away but the force is strong in the GT-R:squintdan


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## Ventsi (Jul 25, 2009)

I think you can't compare cars like that. The proper way to compare power gains after upgrades is to dyno the car while it's still stock, apply the upgrades and dyno it again. Same day, same fuel, same ENGINE. You don't think all engines are exactly the same, do you?

Anyway, as far as I understand, equally tuned 2011 and 2009 have very little difference in the output, correct?


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## Litchfield (Feb 26, 2008)

we have found the 2011 to make slightly more, 5-10bhp. This is probably down to the larger turbo intake pipes.


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## Ventsi (Jul 25, 2009)

Cool, so I shouldn't feel scre*ed that a new model comes out only two years after I bought mine brand new


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## Anders_R35 (Jul 20, 2011)

Litchfield said:


> we have found the 2011 to make slightly more, 5-10bhp. This is probably down to the larger turbo intake pipes.


On your website a stage 1 upgrade with Y-pipe and ECUTEK is listed @ 550bhp (assuming these Stages are for 2010 and older models).

The OP has achieved circa 600bhp with Y-pipe, remap and COBB custom tune. That's a 50bhp difference? I'm not familair with the Cartec dyno and how accurate that one is (I don't want to start a debate on this), but the base run @ 537ps doesn't seem far off the money.

So is the OP's figure an exception to the norm, or is the 2011 acheiving much better figures for just a Y-pipe and tune?

Anders


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## Litchfield (Feb 26, 2008)

We tend to run a stage 1 tune quite gently and typically we see 560-570bhp as experience says it is always better to under quote and over perform  Either way it is a nice result Ben


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## Anders_R35 (Jul 20, 2011)

Litchfield said:


> We tend to run a stage 1 tune quite gently and typically we see 560-570bhp as experience says it is always better to under quote and over perform  Either way it is a nice result Ben


That's fair enough 

I'll be down for some 400mm Alcons and Y-pipe sometime in Sept.

Anders


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## Adamantium (Jun 24, 2002)

Ben,

Quick question,

What is the puff of smoke at 43 seconds caused by?

I would expect it when changing gears due to the slight overfuel on lift off (assuming there is an infinitely short lift off period on this gearbox), but midway through an in gear run it seems a little odd.


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## [email protected] (May 16, 2003)

don't know what particular map that was i didn't cut vid, but possibly one of the richer & lower timing maps, but we do also slightly richen the spool area to help with torque, cooling etc.. downside bit of smoke lesser of two evils.


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## [email protected] (May 16, 2003)

Anders_R35 said:


> On your website a stage 1 upgrade with Y-pipe and ECUTEK is listed @ 550bhp (assuming these Stages are for 2010 and older models).
> 
> The OP has achieved circa 600bhp with Y-pipe, remap and COBB custom tune. That's a 50bhp difference? I'm not familair with the Cartec dyno and how accurate that one is (I don't want to start a debate on this), but the base run @ 537ps doesn't seem far off the money.
> 
> ...



honestly not worth trying to compare two different GT-R's, dyno's, spec etc...


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## Varsity (Oct 24, 2009)

The car runs excellent, with standard and high tune maps.

As the car lives most of its life here in Germany, you know where, then I would like to work with Ben to get a moderate 570-580 and increased torque. 

I am not a numbers person and really could care what it does on paper, the dyno was for others to see and as a favour to Ben. (PAUL, no comments please!)

The car impresses anyone who drives it, std or otherwise and there are not so many people who can catch it or pass pass it on the track. To tune it to within a gnats whisker of its life isn't worth it for me, I like it a little quicker but wholly reliable.

As for a dyno day, Doug at MRCTuning.com would be very much interested in doing this, even if it were to be hosted by someone here. Many of you already know him so maybe a quick email or call may get the ball rolling.

My old car is also on MRC's youtube video list, this is also with 3 different maps from Ben.

I love my car, I also love driving it! May the affair continue.

Cheers


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## Eric Laybourne (Apr 27, 2009)

David.Yu said:


> Actually, when we tested my car with just a Milltek Y-pipe vs Rich-GT's totally standard car back in 2009, we registered 512hp vs 506hp, so not even 10hp in a Y-pipe.
> 
> However a really good cat-back can add more, my Akrapovic replacing the Milltek Y-pipe added another 24hp at max power, and 30hp lower down the rev range, with no additional tweaks to the tuning.


David - I'm thinking of having an akro fitted and as you know the quoted hp increase is 17hp and 41ftlbs . What did you actually get on the rolling road ( my car is std 2009 ) and how did you find exhaust note and in car noise at speed ?
Driving impressions and any improvement in mpg ? Thanks


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## David.Yu (Jun 28, 2001)

My car was already custom tuned when I replaced the Milltek Y-pipe with the Akrapovic Evolution cat-back. Added 24hp max power, 30hp peak difference and 37lb.ft.

No louder than Milltek Y-pipe, less drone, no change in mpg that I noticed.

There's a detailed write up with photos on Auto-Journals.com. Search for Nissan GT-R and you should be able to find it.


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## Varsity (Oct 24, 2009)

David.Yu said:


> My car was already custom tuned when I replaced the Milltek Y-pipe with the Akrapovic Evolution cat-back. Added 24hp max power, 30hp peak difference and 37lb.ft.
> 
> No louder than Milltek Y-pipe, less drone, no change in mpg that I noticed.
> 
> There's a detailed write up with photos on Auto-Journals.com. Search for Nissan GT-R and you should be able to find it.


In real on the road terms, what does this do to the drive of the car, in your opinion?

Do you drive it on the track or is it just a road car and do you think the massive cost represents a worthwhile modification?

What difference is the Ak over a Miltek cat back?

Cheers


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## w8pmc (Sep 16, 2010)

Varsity said:


> The car runs excellent, with standard and high tune maps.
> 
> As the car lives most of its life here in Germany, you know where, then I would like to work with Ben to get a moderate 570-580 and increased torque.
> 
> ...


Learnt my dyno lesson a couple of years bac Figures to be viewed a little like Sunday Sport articles, some of the content will ring true but the headlines are to be taken with a pinch of salt.

Totally agree, it's possible to go mad with these cars but at what cost? I too wanted performance improvements but not at the cost of reliability or day to day drivability.

Looking almost defo that I'll be over the 1st weekend of Sept? You about? Would love to get a pax lap in a tuned MY11:clap:


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## w8pmc (Sep 16, 2010)

Although a stunning exhaust, they're just too rich for my blood as the gains over say a Titan or Milly appear to be purely cosmetic & at double the price it's a big price to pay.


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## David.Yu (Jun 28, 2001)

w8pmc said:


> Although a stunning exhaust, they're just too rich for my blood as the gains over say a Titan or Milly appear to be purely cosmetic & at double the price it's a big price to pay.


Where did you get the "purely cosmetic" bit from? I published my dyno results 20 months ago, and not one Titan or Milltek customer has produced their bolt on difference figures since then. Read into that what you will...

Not knocking other brands, but to say that the Akrapovic's advantage is "purely cosmetic" is incorrect IMO.
BTW, compare the prices of the premium Japanese Ti exhausts and the Akro does not seem that unreasonable, especially as I've not seen dyno proven increases from any of those either.

There is a reason Akrapovic have won 50+ bike championships and Porsche/BMW chose them to supply the OEM systems for their flagship models...


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## mickv (May 27, 2009)

Undoubtedly the Akro is a superbly made exhaust system, but it's an expensive route to and extra 30bhp or ft/lbs, whichever way you look at it.


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## Adamantium (Jun 24, 2002)

for me it's more about the sound than the performance, but for that money I could buy one heck of a great hifi.


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## alloy (Apr 29, 2005)

David.Yu said:


> Where did you get the "purely cosmetic" bit from? I published my dyno results 20 months ago, and not one Titan or Milltek customer has produced their bolt on difference figures since then. Read into that what you will...
> 
> Not knocking other brands, but to say that the Akrapovic's advantage is "purely cosmetic" is incorrect IMO.
> BTW, compare the prices of the premium Japanese Ti exhausts and the Akro does not seem that unreasonable, especially as I've not seen dyno proven increases from any of those either.
> ...


I wonder who is on the payroll over at Akrapovic :runaway:

Whilst no data for other brands has been published, there is no difference i have seen in real world performance between cars with the same mods bar one with Akrapovic and the other with a different brand exhaust....

surely a catback is all pretty generic anyway, yes i appreciate bends and welds etc....but the designs all look the same to me, so if there is any performance over another brand im guessing in the real world it is almost less than negligible


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## w8pmc (Sep 16, 2010)

David.Yu said:


> Where did you get the "purely cosmetic" bit from? I published my dyno results 20 months ago, and not one Titan or Milltek customer has produced their bolt on difference figures since then. Read into that what you will...
> 
> Not knocking other brands, but to say that the Akrapovic's advantage is "purely cosmetic" is incorrect IMO.
> BTW, compare the prices of the premium Japanese Ti exhausts and the Akro does not seem that unreasonable, especially as I've not seen dyno proven increases from any of those either.
> ...


David, I've no hard facts as my car only hit the dyne with a Titan cat-back & GTC tune, but that was 595bhp so I'm sure the zorst had some part to play.

I'm no expert on mechanics but I doubt the gains between aftermarket zorsts differ by much & although the Akro is stunning I wouldn't expect it's gains to be any greater than it's competitors although that's only my opinion.


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## Varsity (Oct 24, 2009)

David.Yu said:


> Where did you get the "purely cosmetic" bit from? I published my dyno results 20 months ago, and not one Titan or Milltek customer has produced their bolt on difference figures since then. Read into that what you will...
> 
> Not knocking other brands, but to say that the Akrapovic's advantage is "purely cosmetic" is incorrect IMO.
> BTW, compare the prices of the premium Japanese Ti exhausts and the Akro does not seem that unreasonable, especially as I've not seen dyno proven increases from any of those either.
> ...


I think you will find the exhaust manufacturers did not win the championships/races on their own merrit, it will have been the teams, with drivers, engines, chassis set up etc etc. So many variables.

Maybe Chubby or Ian can chime in here, Miltek promotion or not, and have his say about whether AP is better and for what reasons.

I was also talking about MY11 cars, not pre MY11 cars.

If someone offered me a free AP exhaust, would I say no, probably not and who knows if it was good I would promote it too.

Cheers


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## David.Yu (Jun 28, 2001)

Varsity said:


> I think you will find the exhaust manufacturers did not win the championships/races on their own merrit, it will have been the teams, with drivers, engines, chassis set up etc etc. So many variables.
> 
> Maybe Chubby or Ian can chime in here, Miltek promotion or not, and have his say about whether AP is better and for what reasons.
> 
> ...


I paid a very large sum (more than the cost of a new Milltek or GTC if it's any of your business) for my Akrapovic exhaust after the agreed six month review period. Watch what accusations you fling around matey...
(I was also replying to w8pmc, who does not own a 2011 car.)


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## Varsity (Oct 24, 2009)

David.Yu said:


> I paid a very large sum (more than the cost of a new Milltek or GTC if it's any of your business) for my Akrapovic exhaust after the agreed six month review period. Watch what accusations you fling around matey...
> (I was also replying to w8pmc, who does not own a 2011 car.)


Touch a nerve?

I said I would have one if it was for free, meaning that I wouldn't pay that much for one.

For some of us the cars are fast enough and our driving skills shine through.

Matey!


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## Varsity (Oct 24, 2009)

alloy said:


> I wonder who is on the payroll over at Akrapovic :runaway:


:chairshot


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## Litchfield (Feb 26, 2008)

I would agree with David about the Akrapovic system as I think they are the benchmark in terms of quality, Milltek have said the same. I guess it depends what you want / value in a exhaust system. I don't think there will much of a difference in any performance in exhausts of this size. We choose to fit Milltek as they tick all the boxes for our needs and they are a excellent British company to deal with.

Regards

Iain


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## Adamantium (Jun 24, 2002)

I'm sorry to say this but I don't believe all exhausts are the same.

This is not a dig at the titan in case anyone thinks it is but I have serious concerns about any non-mandrel bent exhaust. It's not the pie cut bends that worry so much as the quality of the internal welding at the joins. 

A pie cut bend will have an effect on flow alone yes, but anything other than a perfect join will introduce serious turbulence which are effectively diameter restrictions, being on the bends makes them much worse.

For this reason, on a Titanium exhaust I would only ever go with mandrel bendign, and that's what you pay for.

I would love someone to do a back to back test of a pie-cut bend Ti exhaust against an identical design and diameter Ti exhaust which is mandrel bent, but then I guess since the two don't exist from the same company it will never happen.

Regardless I am umming and ahhing constantly about the Akrapovic, but again it's for reasons of sound.


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## TAZZMAXX (Mar 9, 2010)

Adamantium said:


> I'm sorry to say this but I don't believe all exhausts are the same.
> 
> This is not a dig at the titan in case anyone thinks it is but I have serious concerns about any non-mandrel bent exhaust. It's not the pie cut bends that worry so much as the quality of the internal welding at the joins.
> 
> ...


I won't disagree with you but by the very nature of the route the R35 silencers take, I would think there's more disruption to flow by the sequence of bends than the actual construction of them. Those pie cut segments will no doubt have been tube lasered (gap free joints) and then argon purge welded. With the correct gas backing pressure the internal bead will give a near enough flat profile having minimum penetration thus causing minimum flow restriction or turbulence. Internally it will also be as oxide free, if not more so, than the external weld.

Yes, a mandrel bent tube will be better than a segmental one, but ultimately, the path they take decides how the flow is restricted. It's all about degrees of difference and how much of them are real world or perceived.


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## DRAGON (Nov 12, 2003)

Adamantium said:


> I'm sorry to say this but I don't believe all exhausts are the same.
> 
> This is not a dig at the titan in case anyone thinks it is but I have serious concerns about any non-mandrel bent exhaust. It's not the pie cut bends that worry so much as the quality of the internal welding at the joins.
> 
> ...


Titanium welds are generally very flat, turbulance isnt an issue.
Turbo car exhausts are VERY simple from a performance point of view, the bigger the better. I wouldnt get caught up in the details of it. Basically pick an exhaust size that will support your chosen power level.
I have the 90mm Titan, because it is suitable for the current power level of the car, and the Titanium is lighter and looks cool


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## Adamantium (Jun 24, 2002)

Thanks for the simplistic explanation, but regardless of how flat the welds are (if done right) they generate more turbulence than a smooth or better polished constant radius bend. Turbulence produces eddie localised currents through which the central column of gas cannot flow. This creates in use a strangulation of the gas stream.

While you can choose a 90mm pipe, your effective diameter might be nothing like as much as that.

Compared with a 70mm it will flow more gas, but compared with a better welded or mandrel bent pipe it won't flow as much.

I don't think you should be content with just picking an exhaust size as there are other factors such as design and quality that will have a fundamental effect on the performance.


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## Adamantium (Jun 24, 2002)

TAZZMAXX said:


> I won't disagree with you but by the very nature of the route the R35 silencers take, I would think there's more disruption to flow by the sequence of bends than the actual construction of them. Those pie cut segments will no doubt have been tube lasered (gap free joints) and then argon purge welded. With the correct gas backing pressure the internal bead will give a near enough flat profile having minimum penetration thus causing minimum flow restriction or turbulence. Internally it will also be as oxide free, if not more so, than the external weld.
> 
> Yes, a mandrel bent tube will be better than a segmental one, but ultimately, the path they take decides how the flow is restricted. It's all about degrees of difference and how much of them are real world or perceived.


Sorry, didn't see this before. Very informative reply, thank you.


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## DRAGON (Nov 12, 2003)

Adamantium said:


> Thanks for the simplistic explanation, but regardless of how flat the welds are (if done right) they generate more turbulence than a smooth or better polished constant radius bend. Turbulence produces eddie localised currents through which the central column of gas cannot flow. This creates in use a strangulation of the gas stream.
> 
> While you can choose a 90mm pipe, your effective diameter might be nothing like as much as that.
> 
> ...


There honestly far more important things to worry about, other than Eddies Current!
Seriously, you could spend your time far more effectively researching other ways of making your car go fast.
Also if these localised currents are so bad, how come the Titan has run 9 seconds quarters and made over a 1000hp on the dyno.
Always trust results over theory.


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## David.Yu (Jun 28, 2001)

DRAGON said:


> Always trust results over theory.


I agree. Someone needs to do a simple before and after for the other brands of exhaust and report back. That's all I did and was astonished at the results, mainly because a) tuners had said that cat-backs wouldn't make any measurable gains and b) Akrapovic themselves only claimed 17hp, albeit on a stock car.

Never underestimate the power of understating. If I had been told to expect 30hp and got 24hp I would have been disappointed!


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## Adamantium (Jun 24, 2002)

DRAGON said:


> Always trust results over theory.


I prefer a mix of both but thanks for the advice.


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## [email protected] (May 16, 2003)

Dave sounds like you want to put yourself forward ?! pay for dyno, labour etc. etc. lol

tbh 30hp gain sounds bit ott, almost as silly as pipper's 80hp y-pipe claim (they didn't mention it also had an accessPORT). i'm sure i gave you a map tweek before that run. i'd rather have nice torque gain and good afr's.

very hard to accurately test, so many variables. running a bigger dia on a stock car will cause the oem air flow controlled boost control system to spike. we've seen it so did everyone at the dyno day


anyway still love Varsity's GT-R  glad you enjoyed trip to Germany, send me Germany datalogs please


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## sumo69 (Mar 31, 2008)

I understand that the Milltek rear section (when added to a Y pipe) will get another 15bhp due to the big reduction in back pressure.

Akrapovic is therefore about right??

D


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## David.Yu (Jun 28, 2001)

Benji Linney GTC said:


> Dave sounds like you want to put yourself forward ?! pay for dyno, labour etc. etc. lol
> 
> tbh 30hp gain sounds bit ott, almost as silly as pipper's 80hp y-pipe claim (they didn't mention it also had an accessPORT). i'm sure i gave you a map tweek before that run.


Why would I? I've already done my bit, spent my money and reported. Time for someone else to put their money where their mouth is and do a simple before and after. :thumbsup:

It was a 24hp max power gain, 30hp difference was further down the range. We've had this discussion before, but you definitely didn't tweak the tune between the before and after Akro dyno sessions. 

I measured 567hp with the Milltek Y pipe and your latest "WG3 99RON map" and emailed you about the result on 11/12/2009. Akro was then fitted and dynoed on 5/01/2010. Same RR, same operator, same (very cold!) conditions and recorded 591hp.

Definitely no map tweaking in between. I believe you were in S'pore at the time.

Anyway, I'm not knocking GTC or any other system. Just setting the record straight once and for all on my own personal experience.
For all I know, the GTC (which is 90mm after all) will record an even bigger difference; just waiting for someone to actually do it!


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## w8pmc (Sep 16, 2010)

Mine got 595 with a Titan & GTC Tune. Didn't have the benefit of a zorst only run though so I can't quote what the zorst alone provided.

Still stand by my original point in that it's advantages over other systems are more cosmetic. The Akro is a stunning system but I don't feel it represents an advantage over it's competitors given it's cost.


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## Varsity (Oct 24, 2009)

Benji Linney GTC said:


> Dave sounds like you want to put yourself forward ?! pay for dyno, labour etc. etc. lol
> 
> tbh 30hp gain sounds bit ott, almost as silly as pipper's 80hp y-pipe claim (they didn't mention it also had an accessPORT). i'm sure i gave you a map tweek before that run. i'd rather have nice torque gain and good afr's.
> 
> ...


Still here in Germany as we decided to stay for longer. Will do the logs when I get back.

Cheers


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## w8pmc (Sep 16, 2010)

Varsity said:


> Still here in Germany as we decided to stay for longer. Will do the logs when I get back.
> 
> Cheers


Plans have changed & i'm over on the 26th & 27th Sept. You about??


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## Varsity (Oct 24, 2009)

w8pmc said:


> Plans have changed & i'm over on the 26th & 27th Sept. You about??


Yes, we arrive on Thursday 22nd as we are sponsoring a car in the VLN series this year and the 4hour race is on Saturday 24th. I am also contemplating the trackday on the 27th, if work will allow.

Let me know where you are and I would be happy to buy you that beer, its been a while.

Cheers


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## w8pmc (Sep 16, 2010)

Varsity said:


> Yes, we arrive on Thursday 22nd as we are sponsoring a car in the VLN series this year and the 4hour race is on Saturday 24th. I am also contemplating the trackday on the 27th, if work will allow.
> 
> Let me know where you are and I would be happy to buy you that beer, its been a while.
> 
> Cheers


Nice one, i'm about to book onto the 27th Sept trackday

Booked into Tiergarten for the Monday & Tuesday evenings.


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## Varsity (Oct 24, 2009)

Had a text from Charlie at Miltek last week about a 90mm system for the MY11. If this is the case maybe one should go on the car and see what this does throughout the different stages.

I am now very interested in this subject and hope to be able to shed some light on it.


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## Ryan.g (Jul 27, 2007)

Adamantium said:


> Ben,
> 
> Quick question,
> 
> ...


Detonation will cause a puff of black smoke like that or a missfire will do it.

Either way there was an unstable combustion at that point.... Be worth double checking the logs on the car espically on the road as with the increased load it will more than likely be more obvious.

Ryan


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## Wheels (Aug 15, 2009)

Love this car.....have you done anything further to it lately...

Still running standard brakes for eg?????


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## Eric Laybourne (Apr 27, 2009)

Ben

What is the difference in boost from a 09 car to an 11 car ?

Many Thanks


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## Varsity (Oct 24, 2009)

Wheels said:


> Love this car.....have you done anything further to it lately...
> 
> Still running standard brakes for eg?????


All completely standard!

:thumbsup:


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## Wheels (Aug 15, 2009)

You have done well then to be taking it to the N ring with 609hp and not needed to update the brakes.....

Any signs of hairline cracks front or back yet then?

I had thought the brakes would be my first project but you've making me think they must be improved...


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## andrew186 (May 3, 2010)

love the colour of this car, saw it in the flesh at the ring as well and it looks sick as!


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## Varsity (Oct 24, 2009)

Wheels said:


> You have done well then to be taking it to the N ring with 609hp and not needed to update the brakes.....
> 
> Any signs of hairline cracks front or back yet then?
> 
> I had thought the brakes would be my first project but you've making me think they must be improved...


Change the pads for better ones from day one, take care of the discs and replace when required, allegedly.

I drive it a lot here and some track days in the UK, but I drive for fun and to the best of my abilities, which are far below that of what the car was build for or will do.

Whilst I would love to send £10-15k on tuning, I can't and would always have the back of mind worries about warranty, insurance and reliability.

I am happy with my STANDARD car!

:thumbsup:

Thats STANDARD, Mr HPC Nissan!


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## Varsity (Oct 24, 2009)

andrew186 said:


> love the colour of this car, saw it in the flesh at the ring as well and it looks sick as!


Thanks, appreciated.

Its a wonder and I love it very much.

Cheers


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