# supercharging a GT-R.



## kismetcapitan (Nov 25, 2005)

we all do a lot of talk about turbos, and the RB26 is really a turbo-lover's engine. But there is the existence of Claire's supercharged Skyline, and I was thinking - what would an RB26 with a huge supercharger be like? Any supercharger experts here? I wonder if a, say 500bhp supercharged GT-R would be more tractable and handle better than a 500bhp turbocharged counterpart?

Or would twincharging be the only real way to add a supercharger to an RB26 - a small supercharger to prime the low-end and help to quickly spool up some massive single turbo?

It's Sunday morning, I'm tired, at work, Hiddink put the Russians through to the semifinals, and I'm generally in a daze


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

Personally I can't think of any advantage worthy enough to justify a supercharger over a turbo even at 500hp.

Blowers take alot of power to drive them, they are heavy, quite often noisey (although they can sound nice) inefficient compared to a modern turbo and I've never seen a small supercharged engine out perform a similar engine properly set up with a turbo.

Depending on the application, there may be 'some' situations where a supercharger could be an advantage, but not in most car situations IMO

Rob


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## MostH8D (May 22, 2008)

i've read a couple of threads about guys trying to twincharge their evos and it was generally disappointing. after tons of work they never could get performance where it should be. i have read about successful twincharging in an STi but to me it sounds hit or miss. it would be great to be on boost from idle to redline but i think the complexity of the set up wouldn't justify the cost and performance increase. just my .02

id love to see it work though.


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## SkylineUSA (Jun 29, 2001)

Superchargers are roughly 75% efficient, while turbos are 90%

The only adv you will ever have using a positive displacement charger is under 3500RPMs, after that turbos win hands down.

Straight turbos will beat twin charging as well because of the efficiency issue again.


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## beaumackenzie (Jan 21, 2008)

yep and that is why a turbo AE111 will always beat its supercharged brother. (toyota trueno/levin)


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## SkylineUSA (Jun 29, 2001)

beaumackenzie said:


> yep and that is why a turbo AE111 will always beat its supercharged brother. (toyota trueno/levin)


One exception, under 3500rpms:thumbsup:


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## R32 Combat (Jan 29, 2004)

The worlds fastest cars are supercharged. So if you want a very very fast car, then surely supercharging is the way to go.


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## MostH8D (May 22, 2008)

which cars are you talking about i particular?

when you say fastest in the world i think bugatti veryon with 4 turbos in it.


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## paul cawson (Jul 3, 2003)

Hemi V8 Power


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## SkylineUSA (Jun 29, 2001)

R32 Combat said:


> The worlds fastest cars are supercharged. So if you want a very very fast car, then surely supercharging is the way to go.



Class limitations


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## SkylineUSA (Jun 29, 2001)

MostH8D said:


> which cars are you talking about i particular?
> 
> when you say fastest in the world i think bugatti veryon with 4 turbos in it.


The cars that do a 1/4 in almost 4sec


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## R32 Combat (Jan 29, 2004)

The Veyron is crap. I'm talking 6000hp engines.

How many of those have turbos??

That will be non then.

A big fat ZERO


MMmmm, turbo v's supercharger.

That argument goes on...


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## paul cawson (Jul 3, 2003)

SkylineUSA said:


> The cars that do a 1/4 in almost 4sec


0 to 100 in under a second = Blown Hemi


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## SkylineUSA (Jun 29, 2001)

All hail :bowdown1: Blown Hemi :bowdown1: 

Where it all really started:thumbsup: killin the competition.

Turbos are still better:wavey:


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## gtrlux (Mar 8, 2006)

The problem I see with s/c is the base N/A engine!! The RB26DE would have how much power?? 200+?? . . . to supercharge that to 600HP will cost the death and I doupt any s/c contructor would have ever tried to invest in that field.

The VQ35DE has got plenty in that domain. 420P s/C is common in the US, but you start with a 3.5 liter displacement, lots of torque at low rev, and 280HP minimum!


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## MostH8D (May 22, 2008)

jet cars dont have a s/c

of course you can talk about cars with million dollar engines that dont burn 98 RON. 

are we talking about street cars?


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## gtr R33 lee (Nov 11, 2004)

Having had a fair few merc V8 Kompressors inc the E55, CL55 SL55 allthough there approx 500 bhp and the torque is available at such low revs i belive theres nothing like a turbo'd vehicle allthough the mercs can move with there near 2 ton wieght !


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## R32 Combat (Jan 29, 2004)

A jet engine IS a supercharger...


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## Muffleman (Apr 1, 2008)

The thing about superchargers is the torque curve, I mapped a supercharged Marcos Mantis GT a few weeks ago and it made 517bhp BUT it made 300lbft at 2300rpms !!! Big broad torque curve.....nice. 

Oh, and I'm a turbo fan by the way


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## SkylineUSA (Jun 29, 2001)

FL.OV CV V VCNJB ,, GZX


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## Cris (Sep 17, 2007)

This really depends on what type of supercharger you are talking about. A traditional roots type blower is indeed less efficient that a turbo. A centrifugal blower is very similar to a turbo but not quite as efficient. Now the intersting thing is a whipple type supercharger. These are the units you will see on the High end Mercs, Keonigseggyweggybeddyleggyteddy, Ford GT et al. Apparently these are more efficient than turbos. When I had a look at them they were £6k so a little more expensive than a turbo...


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## SkylineUSA (Jun 29, 2001)

Cris said:


> Apparently these are more efficient than turbos.


Not sure where you got that info from, but is not the case.


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## Miguel - Newera (Sep 18, 2003)

Last time I visitted Bee-R was with Tweenierob, Gez & Lamb. We each went out in their twin charged R32 GT-R (Std turbos) with Imai San at the wheel. Plenty of torque from about 1,500 rpm. Charger was used to help the turbos to spool from low revs and would switch off at higher revs, once the turbo's were blowing strongly.


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## kismetcapitan (Nov 25, 2005)

I'd love to see how Bee*R plumbed the twincharging system. Nitrous is one way to prime and get a turbo system going at low rpm, but isn't practical by any means. But a supercharger would be, if it could be plumbed in correctly.

I think I'll talk with my builder - he does Rotrex chargers, maybe they have one that can lower my boost threshold on my 2860-5s a couple thousand rpm 

And yes, Mercedes sure has the supercharging thing down - the CLK-DTM is utter madness from idle. Yes, the fun is over by 6000rpm but it pulls like a monster from the get go. Big supercharged V8 vs the low displacement/high boost that's our game.


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## SkylineUSA (Jun 29, 2001)

Unless you dis-engage the superchager drive completely at 4000rpms, you will lose up to 200hp on top, maybe more. Plumbing really is not the total issue.


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

The only 'positives' anyone has said so far is torque below 3500rpm, in all honesty, as performance people, who is ever really going to be operating in anger in that rpm area?

As for the blown Hemi's, I love em, king of top fuel no issue there but imagine if it was open season and the japs came out with a 500 inch turbo'd engine, there is no question the turbo engine would make more power within the same basic rules.

The power is not the issue in top fuel anymore anyway, its all the rules imposed by iunsurance companies to try and slow them down so we'll never see 'open season, do whatever you like, 500 inch engines in top fuel'

Rob


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## G40tee (Feb 25, 2008)

Video of E40 - Photobucket - Video and Image Hosting


i dont care that superchargers are less efficient but man they sound good!

Thats a vid when we were testing belt set ups with my polo.
4.5k rev limit, race engine with no full throttle available, had to have progessive throttle to get full power couldnt just mash it due to safety map on rebuilt engine. (engine was run in but didnt have time or money to get mapped)


I did love the instant power that the supercharger gave out but i dread to think the amount of power it sapped doing it! Run down on the engine was huge due to the blower running from the belts. You lift off and you notice you slow down alot quicker than a turbo'd or N/A motor.


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## Lith (Oct 5, 2006)

SkylineUSA said:


> One exception, under 3500rpms:thumbsup:


Depends on the turbo size - a GTZ with a turbo which well matched to max out at the same point as the SC12 will make more power everywhere.... modern turbos trump them all around. 

Where class restrictions allow, previously supercharger dominated classes in V8 drag racing are now dominated by turbocharged setups and ET and trap speed records are being set left right and centre. 

Here is an example - I believe this holds the 10.5" drag radial record, at about 6.3 seconds. This run is a 1/8th mile run, but gives an idea:

Video - Tim Lynch another sick pass from the twin 88mm 449ci ford


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

I like the way the front wheels almost never touch the track, awesome :clap: 

Another car doing well with turbo's is that torrana from Aussie.

Rob


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## G40tee (Feb 25, 2008)

amen to above! no front wheels on floor is awesome!
the true power of a blown v8!


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

G40tee said:


> amen to above! no front wheels on floor is awesome!
> the true power of a blown v8!


Just so we are clear for everyone and there's no confusion, how about Blown is Super charged, turbo is turbo'd. 

The car in the above vid is just sick, crooked, buckled and stink and its turbo'd :clap: 

Rob


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## Lith (Oct 5, 2006)

G40tee said:


> amen to above! no front wheels on floor is awesome!
> the true power of a blown v8!


Just to clarify (as some people only call supercharged cars blown) that the car in that video runs a pair of Garrett GT4788Rs as far as I understand.


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## paul cawson (Jul 3, 2003)

Not to be confused with Blown cars above


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

> The worlds fastest cars are supercharged. So if you want a very very fast car, then surely supercharging is the way to go.





> The Veyron is crap. I'm talking 6000hp engines.
> 
> How many of those have turbos??
> 
> ...


Some provocative comments there,
How many turbochargers have you seen that spool up instantly and make 6000 hp ?
In fact how many manufacturers of turbo's make one that will suit those needs ?
The ONLY reason ,I will assume you are refering to top fuel type cars, they run them is because they need instantanious response , they are generally massive capacity engines based on 1960's designs running nitro which Im sure you know is a slow burning fuel very well suited to a slow reving high capacity engine.
As for being the fastest, I think you might find they are the fastest in 400 metres ,but thats all they can do.
Im sure theres been a thread here before on this subject......
No reason why you cant have a small supercharger come in instantly and then have some turbo's take over at a given boost or engine speed , like the lancias grpb cars


Actually its a similar agrument to the one from the v8 dragmasters series, where they match up jap imports against v8 cars.
All the v8 cars run auto trans or trick auto trans and run consistant times , due to stall converters and I guess lots of practice.
The vast majority of import cars (at the time) were running manual's (lets face it auto's are for girls and people who cant drive anyway)but the bottom line is they work better in a drag car.giving my better consistancy.
So they match up some v8 that runs CONSISTANT xxx time against a jap import that's best ever time is xxx and then when the v8 wins , go "there ya go v8s are much better than jap/rice imports"

Shrug ....


Dear Bugatti,
Apparently you Veyron is shit, please install a 8000cc supercharged engine that uses 80 litres per kilometre driven makes 6000hp and needs a rebuild after every 10 or so seconds of running.
Apparently theres a market for one in the UK somewhere.


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

Hey Rob, when I was at college (last century) I was reading about Pete Lodges Baloo doing (cant remember the exact time) but the caption was something like 
"Lodge runs 8.4 with blown hemi" and remember thinking I wonder how well it would go with a good engine (thinking it was blown up) .....
Anyway, we've all learnt a bit since then lol


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## Lith (Oct 5, 2006)

GT-R Glenn said:


> Dear Bugatti,
> Apparently you Veyron is shit, please install a 8000cc supercharged engine that uses 80 litres per kilometre driven makes 6000hp and needs a rebuild after every 10 or so seconds of running.
> Apparently theres a market for one in the UK somewhere.


:clap: There is no real debate, turbocharging can do everything supercharging can - but not the other way around. Turbocharging is the better technology. Superchargers hang around still because classes require it. Just like turbos got kicked out of F1, not because NA is better - but because with turbos they were just too fast


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## playasyougo (Nov 29, 2003)

I found this:

http://img.photobucket.com/albums/v153/lpb86/rb-26dettsupercharged.jpg


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

Unless you could disengage the drive to the blower at a certain rpm you'd be going backwards in the long run I'd say.

Top fuel blowers take over 1000hp just to drive them, some passenger cars blowers use 150-200hp, still can't beat a well setup turbo IMO.


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## Lith (Oct 5, 2006)

Yep, I still reckon that if you want more low down torque - get a bigger motor 

Garrett do kits for some OEM supercharged setups to improve down low torque and power overall... gotta be saying something!


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

Either this site or the au one has done this discussion in depth already.


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## MostH8D (May 22, 2008)

GT-R Glenn said:


> Some provocative comments there,
> How many turbochargers have you seen that spool up instantly and make 6000 hp ?
> In fact how many manufacturers of turbo's make one that will suit those needs ?
> The ONLY reason ,I will assume you are refering to top fuel type cars, they run them is because they need instantanious response , they are generally massive capacity engines based on 1960's designs running nitro which Im sure you know is a slow burning fuel very well suited to a slow reving high capacity engine.
> ...


Glen, 

the same guy thinks a jet engine is the same thing as a supercharger. go figure.


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## paul cawson (Jul 3, 2003)

Its easy to make a turbo into a jet engine, you just need to add a spark plug and fuel to the turbine side and off you go.
Something to keep the kids amused with


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## SkylineUSA (Jun 29, 2001)

R.I.P.S NZ said:


> Unless you could disengage the drive to the blower at a certain rpm you'd be going backwards in the long run I'd say.
> 
> still can't beat a well setup turbo IMO.



Great minds think a like:thumbsup:


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## R32 Combat (Jan 29, 2004)

MostHated

You've obviously never made a jet engine from a supercharger turbocharger. You should, they are immense fun, but be careful, it just might blow your head out your arse.


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## MostH8D (May 22, 2008)

R32 Combat said:


> A jet engine IS a supercharger...


what are you crying about?:bawling: 

what you said there has nothing to do with your original post on the comment.

cry on. dont get mad over the internet. there is always someone better than you. im just glad you now realise this.:clap:


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## Rick C (May 24, 2005)

R32 Combat said:


> A jet engine IS a supercharger...


A jet engine is closer to a turbo in terms of how it works. In fact, you can make a turbo into a home made-jet.

YouTube - homemade jet engine


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## Domo-kun (Mar 2, 2007)

*Bee*R S15 Twin Charged* (Tsuchiya Keiichi at the wheel).






Ogura TX12 Supercharger & TD06 25 G Turbo, rated @ 350 bhp. (With uprated internals max output 500 bhp).


*Finnish Diesel Power!!!* 
Valtonen Motorsport (here in Finland) has built Mercedes Benz W123 wagon, with 2 turbos & 1 supercharger. 1700 Nw!!! :smokin: 

















This engine sits in this car :chuckle: 
















The first twin charged version looked like this...









The sleeper

Valtonen builts engines for the TeamFalken.fi (Nordic Drifting Series).


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## Howsie (Feb 25, 2002)

This has been done to death.

http://www.gtr.co.uk/forum/upload/6700-supercharger-well.html?highlight=super+charger


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## MostH8D (May 22, 2008)

Forced Air Technologies

this had twin 35r turbos at one time.


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## paul cawson (Jul 3, 2003)

For drag racing only, could we use a diving cylinder to spool the turbos for instant super charger like power. 300 Bar aimed at the Turbine impeller through a nozzle should do the trick


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## Wanabee Kiwi (Mar 31, 2007)

This is the only twincharge RB26DETT(S) i've seen. Personally i like superchargers but turbo's are by far more practical and the better technology


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## MostH8D (May 22, 2008)

wonder if there are any stats on that...looks nice.

not so much like a jet engine though as i've been told it would.


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## Cris (Sep 17, 2007)

SkylineUSA said:


> Not sure where you got that info from, but is not the case.


Quick google finds this:

Whipple Industries

Obviously pinch of salt needed but I've heard similar things from elsewhere


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## Cris (Sep 17, 2007)

Lith said:


> :clap: There is no real debate, turbocharging can do everything supercharging can - but not the other way around. Turbocharging is the better technology. Superchargers hang around still because classes require it. Just like turbos got kicked out of F1, not because NA is better - but because with turbos they were just too fast


With respect it depends on what better is doesn't it?

Speak to someone like Gordon Murray and he'll tell you that turbos are pointless and N/A is the way to go. Ferrari, Lambo and Pagani would agree too.

All three options have benefits in certain circumstances.

There is a reason that a Veyron with 1000bhp uses turbos but the Koenig..... with 1000bhp uses a supercharger. Neither of these car races anywhere so they are hardy bound by any rules.

Also have a look at the Caparo T1 (unless the name has changed again). Some fairly clever chaps decided to supercharge it.

Personally I like turbo charging but if someone offered me a supercharged v12 two-stroke engine I'd hardly turn them down!


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## SkylineUSA (Jun 29, 2001)

Cris said:


> Quick google finds this:
> 
> Whipple Industries
> 
> Obviously pinch of salt needed but I've heard similar things from elsewhere


That information is miss-leading, turbos a lot more efficient than 60-75%:thumbsup: 

Everything you read, specially coming from a biased source, is not the best to back a debate


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## R32 Combat (Jan 29, 2004)

How efficient are turbos? The best I've seen on a compressor map is 75%, and arn't bigger turbos more efficient than smaller ones?


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## SkylineUSA (Jun 29, 2001)

I pulled this quote from a pro-supercharger site, SuperchargersOnline.com :: Turbo vs. Supercharger



"Efficiency: This is the turbo's biggest advantage. The turbocharger is generally more economical to operate as it as it is driven primarily by potential energy in the exhaust gasses that would otherwise be lost out the exhaust, whereas a supercharger draws power from the crank, which can be used to turn the wheels. The turbocharger's impeller is also powered only under boost conditions, so there is less parasitic drag while the impeller is not spinning. The turbocharger, however, is not free of inefficiency as it does create additional exhaust backpressure and exhaust flow interruption." 

I do like salt opcorn: though.


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## SkylineUSA (Jun 29, 2001)

R32 Combat said:


> How efficient are turbos? The best I've seen on a compressor map is 75%, and arn't bigger turbos more efficient than smaller ones?


I'll check my Corky Bell manual, but they were in the 90% range when compared to supercharges. There might be an issue with what we are talking about as far as what aspect of efficiency we are comparing?


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## Cris (Sep 17, 2007)

SkylineUSA said:


> That information is miss-leading, turbos a lot more efficient than 60-75%:thumbsup:
> 
> Everything you read, specially coming from a biased source, is not the best to back a debate


Oh I agree but I have heard this from a number of sources. Now if the detail is even vaguely correct then they are approaching turbo levels. Had it just been advertising blurb I'd just put it down to sales bollox but when the like of Mercedes, Lotus Engineering et al are saying it I take a bit more notice.


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## R32 Combat (Jan 29, 2004)

I was looking here

TurboByGarrett.com - Catalog

They seen to range from 62-78%. Bigger being better.

I'm not sure how they come to the figs though.


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## SkylineUSA (Jun 29, 2001)

So, I am reading my bible (Corky Bell's Maximum Boost), and I come across what he has as mid 70s for turbo efficiency. Now, with that being said, if you go to Vortech Engineering: Centrifugal Supercharger Manufacturer, Superchargers, Supercharging Systems and look at their supercharger efficiencies, they are in the 70s as well, but we all know turbos are more efficient, but they say they are roughly the same????? 

I do not like to give bad info, so I am researching for my own peice of mind.


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## paul cawson (Jul 3, 2003)

A centrifugal Super charger has the same compressor side as a turbo so will be as efficient. There is just the power loss from it being engine driven to factor in


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## Cris (Sep 17, 2007)

SkylineUSA said:


> So, I am reading my bible (Corky Bell's Maximum Boost), and I come across what he has as mid 70s for turbo efficiency. Now, with that being said, if you go to Vortech Engineering: Centrifugal Supercharger Manufacturer, Superchargers, Supercharging Systems and look at their supercharger efficiencies, they are in the 70s as well, but we all know turbos are more efficient, but they say they are roughly the same?????
> 
> I do not like to give bad info, so I am researching for my own peice of mind.


Bear in mind that the known - turbos are much more efficient may well come from the comparison with Roots type superchargers.

If you're talking about centrifugal blowers then the 'charger' bit is/can be identical between turbo and super. So the differential is that the turbo will create more exhaust back-pressure (and perhaps harm your ability to pulse tune the exhaust) and will heat the charge more; the super will leach power from the engine.

The energy costs for the super will be lower (lower inlet temp) but it's power must come directly from the engine.

I would imagine that things would still fall in the turbo's favour but I can believe that a centrifugal charger is much more efficient than Roots. If the Lyscholm is as good as the centrifugal then perhaps they are narrowing the gap further.

Pointless (as the source is undefined) but from wiki:

"Roots blowers tend to be 40–50% efficient at high boost levels. Centrifugal Superchargers are 70–85% efficient. Lysholm-style blowers can be nearly as efficient as their centrifugal counterparts over a narrow range of load/speed/boost, for which the system must be specifically designed."


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## SkylineUSA (Jun 29, 2001)

paul cawson said:


> A centrifugal Super charger has the same compressor side as a turbo so will be as efficient. There is just the power loss from it being engine driven to factor in


Agreed:thumbsup:


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## SkylineUSA (Jun 29, 2001)

Cris said:


> The energy costs for the super will be lower (lower inlet temp) but it's power must come directly from the engine.


This is were I had my 90% for turbos, but I cannot find my source. 

The whipple site only states Adiabatic efficiency, not what is lost in total for the process, so like I was saying it is kind of misleading.


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## R32 Combat (Jan 29, 2004)

Let us not forget that a turbo isn't driven for free. It causes exhaust back pressure, which costs hp.

So a belt driven centrifugal supercharger is almost certainly more efficient than a turbo.


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## SkylineUSA (Jun 29, 2001)

R32 Combat said:


> So a belt driven centrifugal supercharger is almost certainly more efficient than a turbo.


Being a bit cynical are we Andy


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## Cris (Sep 17, 2007)

R32 Combat said:


> Let us not forget that a turbo isn't driven for free. It causes exhaust back pressure, which costs hp.
> 
> So a belt driven centrifugal supercharger is almost certainly more efficient than a turbo.


I'd say that there's too many variables to make that statement.

I wonder if the additional heat from a turbo plays a significant role.

For example supercharged diesels are not common (I can't name one current car with this set-up). I wonder if the lower combustion temps in diesels make the heat transfer to the turbo smaller thus offset the issue so relatively improve turbo efficiency????


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## paul cawson (Jul 3, 2003)

Cris said:


> I wonder if the additional heat from a turbo plays a significant role.
> 
> For example supercharged diesels are not common (I can't name one current car with this set-up). I wonder if the lower combustion temps in diesels make the heat transfer to the turbo smaller thus offset the issue so relatively improve turbo efficiency????


Yes thats why VNT turbos can be used on diesels to further improve efficiency


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## Lith (Oct 5, 2006)

R32 Combat said:


> Let us not forget that a turbo isn't driven for free. It causes exhaust back pressure, which costs hp.
> 
> So a belt driven centrifugal supercharger is almost certainly more efficient than a turbo.


A turbo causes back pressure, its true the turbo does create some back pressure which costs horsepower - thats the sum total of its loss. The statement you made is under the assumption that the centrifugal loses less, which is very very unlikely to be true.

The fact that a supercharger has a physical drain on the engine itself and it pulls enough to make sure that it makes boost pretty much from the get go, and carries on through the whole rev range kind of indicates to me the losses from it are going to be quite substantial all the way. 

I have seen the odd drag teams try superchargers on imports to be different and under the idea that they have no lag and give nothing away to turbos and the cases I have seen its usually a maximum of two seasons of mediocre results before they give up and go turbo. And the cases I have seen have ran centrifugal superchargers.... there is a team running in NZ with a supercharger in a full tube frame R34 "GTR", I'd wager they end up binning it.


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

> This has been done to death.


Cheers Howsie...

Wheres Mycroft ? I miss his posts and using dictionary.com after reading them ....


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

> Trust me, this will end up in a disaster. Turbos are only design to operate at speeds between 10,000 and 15,000 rpm - NOT 80,000 to 85,000 which is what your is probably doing.


WTF ?????

Actually its a gas turbine ....


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## Cris (Sep 17, 2007)

Lith said:


> A turbo causes back pressure, its true the turbo does create some back pressure which costs horsepower - thats the sum total of its loss. The statement you made is under the assumption that the centrifugal loses less, which is very very unlikely to be true.


It's not just loss though it's how much energy you have to put in to get something out (efficiency). A turbo will have a high charge temp than an SC so you either live with that or intercool it (the charge). If you intercool it then you get pressure loss. To overcome the pressure loss etc etc etc

The thing to note is that the top end cars who use SCs use Whipple/Lysholm system. These are supposed to combine the benefits of the Roots blower with that of the centrifugal blower. I wonder if their cost is stopping greater acceptance...


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## kismetcapitan (Nov 25, 2005)

I just read up on the Whipple blowers and they can move a LOT of air at 2 bars pressure. That sounds like enough boost for me - BUT....just how many hp does it cost to drive that Whipple when it's flowing max cfm at 2 bars boost pressure????

The system is expensive, but not any more so than, say, the cost of converting to topmount turbos.


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## Lith (Oct 5, 2006)

Cris said:


> A turbo will have a high charge temp than an SC so you either live with that or intercool it (the charge). If you intercool it then you get pressure loss. To overcome the pressure loss etc etc etc


Why do you think turbo would have a higher charge temp than a supercharger? Given the more efficient centrifugal use the same type of compressor configuration as a turbocharger I find it a little hard to swallow.


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## MostH8D (May 22, 2008)

i would assume it has something to do the heat engine or rankine cycle, loosely.

work in = work out in the thermal balance equation.

the temperature of the fluid goes up due to the work the turbine does on the system. at 150k rpm that's alot of work. add to that the temperature increase due to compressing the fluid and i would imagine the heat soak from the exhaust side all play factors into this.

its been a while since i've had to think about that thermal stuff.


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## mandhdrijfhout (Mar 13, 2006)

*Race FX RWD GTR*

This a Pro Import RWD R34 GTR Skykine in N.Z and has a Pro Charger and runs from what I have read 900hp on methanol. Is RB30 bottom with a RB25 head.
Has run a best of 9.26 @ 245kph (152mph)




























































More Pics here
Photos


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## Lith (Oct 5, 2006)

Yep thats one of the ones I referred to earlier - reached 9.2s so far, when you consider RIPS's street 240Z at this stage shits on it with a heavier street legal chassis on DOT tires without using Methanol/NOS it kinda says something?

I'm sure the R34 will go quicker, but at this stage I am dubious about if its going to go fast enough to justify the fact its a 3litre methanol snorting tube frame drag car.


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## Cris (Sep 17, 2007)

Lith said:


> Why do you think turbo would have a higher charge temp than a supercharger? Given the more efficient centrifugal use the same type of compressor configuration as a turbocharger I find it a little hard to swallow.


Turbo's produce high charge temps because the turbo gets hot! Anything which sits right next to your exhaust is going to get hot, especially if the other half of it is part of the exhaust.

You must have seen plenty of pictures of turbos glowing red hot. You don't see SCs glowing.


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## Cris (Sep 17, 2007)

MostH8D said:


> i would assume it has something to do the heat engine or rankine cycle, loosely.
> 
> work in = work out in the thermal balance equation.
> 
> ...


As per previous post the exhaust side transferring heat to the intake is the difference.

My understanding is that the compression side of things is where the lysholm/whipple units get their benefit from.


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## Lith (Oct 5, 2006)

I really don't think that makes THAT much of a difference. If it is the case, its surprising there aren't supercharged setups performing as well as the turbocharged equivalents!


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## MostH8D (May 22, 2008)

Cris said:


> As per previous post the exhaust side transferring heat to the intake is the difference.
> 
> My understanding is that the compression side of things is where the lysholm/whipple units get their benefit from.


++1


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## Andy Hornsby (Mar 22, 2003)

This has been tried, do a search on here, it will be there somewhere. I'm sure they had issues getting it mapped correctly for some reason.

http://img.photobucket.com/albums/v153/lpb86/rb-26dettsupercharged.jpg


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## Howsie (Feb 25, 2002)

De ja vu.


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## Cris (Sep 17, 2007)

Lith said:


> I really don't think that makes THAT much of a difference. If it is the case, its surprising there aren't supercharged setups performing as well as the turbocharged equivalents!


The question you got to ask is. If the whipple/lysholm units are so much less efficient than a turbo and cost more than a turbo why would they ever be used by high tech, high performance companies.

If there was a simple answer to the question we'd all have the same set-ups.


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## R32 Combat (Jan 29, 2004)

De ja vu all over again....:thumbsup:


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## kismetcapitan (Nov 25, 2005)

Cris said:


> The question you got to ask is. If the whipple/lysholm units are so much less efficient than a turbo and cost more than a turbo why would they ever be used by high tech, high performance companies.
> 
> If there was a simple answer to the question we'd all have the same set-ups.


I do wonder, if there's truly a better supercharger system out there now (the whipple twin-screw thing), it could simply be convention and going with the tried-and-true that keeps people from using them. You should check out a guitar message board - there's always something new and better, but it's amazing how much people still obsessively stick to 1950's technology, valve amps, and so on.


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## kingsley (Aug 26, 2002)

kismetcapitan said:


> I think I'll talk with my builder - he does Rotrex chargers, maybe they have one that can lower my boost threshold on my 2860-5s a couple thousand rpm


I wouldn't bother - if I remember correctly, Rotrex blowers are centrifugal.

In my opinion the main reason there's a market for centrifugal superchargers is aftermarket upgrades to n/a cars. They're easier to install than twin screw or roots blowers because you don't have to do so many changes to the intake plumbing and they're easier to install than turbos because you don't have to fiddle with the exhaust. However, the advantages pretty much end there.

They make very little boost at low rpm which is the main problem you're trying to solve by fitting a supercharger in the first place.

Admittedly they don't actually suffer from lag per se (unlike turbos) but don't mix lag with high boost threshold - centrifugal blowers might not suffer from lag but they do usually have a very high boost threshold (in that the boost usually rises with revs so you're not making full boost until top revs).



kismetcapitan said:


> And yes, Mercedes sure has the supercharging thing down - the CLK-DTM is utter madness from idle. Yes, the fun is over by 6000rpm but it pulls like a monster from the get go. Big supercharged V8 vs the low displacement/high boost that's our game.


It's madness from idle because it
a. has a large capacity, and
b. uses a positive displacement blower (so that it gets boost at pretty much all rpm, which you won't get with a centrifugal blower).


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## kingsley (Aug 26, 2002)

SkylineUSA said:


> Unless you dis-engage the superchager drive completely at 4000rpms, you will lose up to 200hp on top, maybe more. Plumbing really is not the total issue.


Where did you get that 200bhp drag figure from? Sounds an awful lot for a typical street setup to me.

Evidence suggests that on top fuel dragsters, the supercharger drag is about 10 - 12% of the resultant engine power, eg:

Top Fuel by the Numbers - Motor Trend

Bear in mind that this is also at very high boost, far higher than you'd use for a street application. At higher boost levels, the supercharger is working even harder per hp than it would at lower boost levels so I would have thought that the drivetrain drag imposed by a top fueler's supercharger would be a worst case scenario, even in just percentage terms rather than absolute terms?

That being the case, I'd hope a 500bhp supercharged RB (for example) might be looking at losses of about 50bhp to the supercharger. Admittedly that's still quite a lot but it's nothing like the 200bhp you're suggesting.

Please correct me if I'm wrong.


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## kingsley (Aug 26, 2002)

Lith said:


> And the cases I have seen have ran centrifugal superchargers.... there is a team running in NZ with a supercharger in a full tube frame R34 "GTR", I'd wager they end up binning it.


So would I - I don't see the point of replacing a turbo setup with a centrifugal supercharger for reasons I've already mentioned - seems madness to me!


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## kingsley (Aug 26, 2002)

R.I.P.S NZ said:


> The only 'positives' anyone has said so far is torque below 3500rpm, in all honesty, as performance people, who is ever really going to be operating in anger in that rpm area?


It depends on the application, really. Nobody seems to have mentioned throttle response yet, or (in a twin charge application) the ability to lower the boost threshold of a big turbo.

Once you're north of 4000rpm or whatever and on full turbo boost then yes, who cares about what it does low down. I personally like to be able to be cruising along and then if I decide to accelerate be able to do it effortlessly in the gear I'm in rather than having to find another gear. That doesn't work too well if you've got big turbos with a high boost threshold.

When I drove a supercharged Civic I just loved the instant throttle response. The car was only about half of the power of my GTR and nothing like as quick on the open road but on twisty roads the instant response of the supercharged engine was wicked fun.

If you're going to twin charge[1] then I agree that it'd be worth opening a bypass valve to minimise blower drive drag once revs are high enough for the turbo to do the job on its own. You might have to open it gradually (over the course of a few seconds?) though else the turbo might not be able to respond quickly enough to the extra boost demands it now has to suddenly meet, resulting in a momentary flat spot.

The other thing about twin charging, as has been said on other threads before, is that you can afford to use a bigger turbo than you otherwise would, giving you the potential for higher top end power without having the driveability suffer.

I'm not claiming there aren't downsides because there are (especially the complexity of a twin charge setup and getting it to work well). It's just that many people on here don't seem to accept that there are upsides 


[1] or even if you're going the supercharger-only route and want decent cruise economy when you don't need the boost.


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## kingsley (Aug 26, 2002)

kismetcapitan said:


> I just read up on the Whipple blowers and they can move a LOT of air at 2 bars pressure. That sounds like enough boost for me - BUT....just how many hp does it cost to drive that Whipple when it's flowing max cfm at 2 bars boost pressure????
> 
> The system is expensive, but not any more so than, say, the cost of converting to topmount turbos.


I could be wrong but the efficiency figures that Whipple quote might only be applicable when running at the same pressure ratio that the blower naturally achieves through its own internal compression (which is about 1.6:1 ?). You might find that the efficiency drops off when you start running higher boost levels - worth checking.

Personally, I'd not be comfortable in a supercharger-only application running that much boost because of the mechanical drag that others have already mentioned. I'd prefer to get a turbo to run at, say, a 2.2:1 pressure ratio (ie what would normally produce about 1.2 bar) and then let the supercharger run at about 1.6:1, the combination should then result in about 2 bar of boost. If the supercharger is already doing some of the work, the turbo has less far to climb and so not only does it come in at lower rpm, I would be hopeful that the lag was reduced as well.

That said, I wouldn't fancy the engineering task of getting a twin charged system to work well unless I had a *lot* of time, a good workshop and data logging equipment!

As an aside, aren't Whipple blowers just rebadged Lysholm units? I don't mean "Lysholm" as in the generic type, I mean it as in the brand.


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

kingsley said:


> I personally like to be able to be cruising along and then if I decide to accelerate be able to do it effortlessly in the gear I'm in rather than having to find another gear. That doesn't work too well if you've got big turbos with a high boost threshold.


I agree to a point but that also depends on your engine/turbo combination.

3 examples we have done that spring to mind are:

1) R32 RB30dett (stock modified turbo's) full boost by 3500rpm, drive along in 5th gear at 3000rpm, plant your foot and have 1 bar of boost by 3200rpm, thats pretty good response in my book.

2) R34 RB30det (TO4z) pulls smoothly away from 2000rpm in 6th, not real strong till about 3500rpm but in 4th or 5th from 3000rpm its real nice and unless your after a real quick passing move no need to down shift.

3) R34 RB30det (GT42) very similar to the TO4z actually, did a pull from 3000rpm in 5th and it pulled just as quick as a mild GTR would be in a gear or 2 lower and then from 4500 to 8500 it was REAL strong.

Personally, I can't see us trying a supercharger of any type anytime soon.

Rob


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

Lith said:


> there is a team running in NZ with a supercharger in a full tube frame R34 "GTR", I'd wager they end up binning it.


If I was a betting man I'd also take that bet.
Its a beautiful car, extreemly well built, very light and with a suitable setup I'm sure it would be a 7 second car with ease.

Rob


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## Cris (Sep 17, 2007)

R.I.P.S NZ said:


> Personally, I can't see us trying a supercharger of any type anytime soon.
> 
> Rob


I think that is the key point. You'd need a pretty strong incentive and I just don't think it exists. If you had an N/A engine that you wanted to mod. When I was looking at MR2's I was quite keen on the v6 conversions. In that application an SC makes sense for packaging.

Why bother with a supercharger when you have an engine with a turbo on it already?


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

> No reason why you cant have a small supercharger come in instantly and then have some turbo's take over at a given boost or engine speed , like the lancias grpb cars





> No reason why you cant have a small supercharger come in instantly and then have some turbo's take over at a given boost or engine speed , like the lancias grpb cars





> No reason why you cant have a small supercharger come in instantly and then have some turbo's take over at a given boost or engine speed , like the lancias grpb cars


SIGH ....


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## Howsie (Feb 25, 2002)

Please go back and read the other thread!!! FFS.


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

> Please go back and read the other thread!!! FFS.


lol

Think of it as the "Search" button .....everyone knows its there , but seem to love to ignore it ....


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## Cris (Sep 17, 2007)

GT-R Glenn said:


> lol
> 
> Think of it as the "Search" button .....everyone knows its there , but seem to love to ignore it ....


Reading through the historic thread (mostly from 2002) I saw no mention of efficiency debate from this thread or replacing the turbos with a supercharger. It did have a lot of detail about twin charging which hasn't been the main discussion point here.

Perhaps your search button works differently to mine.


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## kismetcapitan (Nov 25, 2005)

that's really what I'm wondering as well - a twin screw supercharger can push the boost pressure (2 bars) and air volume as a pair of good-sized turbos, but I often see superchargers also measured by their "hp cost", as in, how many hp are lost in driving the supercharger at full power (for the supercharger).

If there's a supercharger that can move air as well as a pair of turbos that one would normally see on a GT-R, then it becomes a viable alternative. You lose top-end power, but that's also the downside to choosing N1 or GT-SS turbos. A supercharged GT-R making 450-500bhp could very well be an absolute street/circuit monster, and comfortably redline at an engine-prolonging 6500rpm. With 2530-turbos and up, 8000/8500rpm redlines aren't just what an RB26 **can** do, it's what it MUST do to have a wide enough power band.


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## Lith (Oct 5, 2006)

kismetcapitan said:


> You lose top-end power, but that's also the downside to choosing N1 or GT-SS turbos. A supercharged GT-R making 450-500bhp could very well be an absolute street/circuit monster, and comfortably redline at an engine-prolonging 6500rpm. With 2530-turbos and up, 8000/8500rpm redlines aren't just what an RB26 **can** do, it's what it MUST do to have a wide enough power band.


Isn't this essentially what happens when you go for a smaller (basically undersized for the engine) turbo? For example, imagine a twin scroll GT3071R on an RB26DETT - in THAT instance it would be considered a mismatch but from all I am seeing here it would be effectively what people are saying is acceptable when picking a supercharger. Is that a fair comment?

A TS GT3071R on a proper manifold on an RB26 should be able to go over 450hp but would certainly be falling over below the revs an RB26 would normally want to run to, however would also have basically no lag and torque for Africa.


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## kingsley (Aug 26, 2002)

Lith said:


> Isn't this essentially what happens when you go for a smaller (basically undersized for the engine) turbo? For example, imagine a twin scroll GT3071R on an RB26DETT - in THAT instance it would be considered a mismatch but from all I am seeing here it would be effectively what people are saying is acceptable when picking a supercharger. Is that a fair comment?
> 
> A TS GT3071R on a proper manifold on an RB26 should be able to go over 450hp but would certainly be falling over below the revs an RB26 would normally want to run to, however would also have basically no lag and torque for Africa.


I see your point but don't agree that they're exactly the same.

I can't speak from direct experience but I would expect a well sorted 500bhp supercharged (not twin charged) GTR, when compared to a well sorted 500bhp turbocharged GTR, to (in no particular order)

a. have much better throttle response (ie no lag)
b. have strong torque much lower down
c. possibly have less mid range torque (partly depending on how the turbo car's boost was mapped)
d. use more fuel
e. be more effortless to drive
f. be slightly less adrenaline inducing
g. feel more refined
h. be easier to launch quickly, consistently
i. need a quieter exhaust system

This is, of course, assuming a decent positive displacement blower such as a Lysholm type unit, or perhaps an Eaton TVS. Emphatically NOT a centrifugal supercharger.

For me personally, the holy grail would be a twin charged setup but only if it was well set up, which we've agreed might not be that easy to do.


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## kismetcapitan (Nov 25, 2005)

I really gotta find out - how much hp does it cost to drive a Lysholm twin-screw when its making 2 bars boost pressure?


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## kingsley (Aug 26, 2002)

kismetcapitan said:


> I really gotta find out - how much hp does it cost to drive a Lysholm twin-screw when its making 2 bars boost pressure?


You might be able to get a rough idea by calculating the total amount of work it's doing and then dividing that by the product of all of the efficiencies (ie adiabatic, mechanical, drive belt efficiency etc).

How are you with physics?


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## kismetcapitan (Nov 25, 2005)

kingsley said:


> You might be able to get a rough idea by calculating the total amount of work it's doing and then dividing that by the product of all of the efficiencies (ie adiabatic, mechanical, drive belt efficiency etc).
> 
> How are you with physics?


not that good! I never got beyond basic calculus-based physics...


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## kingsley (Aug 26, 2002)

kismetcapitan said:


> not that good! I never got beyond basic calculus-based physics...


Hmm, we'll I'll have a go at some basic calculations. I suspect there will be some bits I miss out but it may be close enough to give you an idea.

The basic principle would be to calculate the amout of energy needed to compress a given amount of air to 2 bar and then work out how quickly your engine will use that amount of air, which then allows you to work out the power it needs to do it. Divide the result by the overall efficiency of the blower and the drive to get a more realistic crank power drain.

So, let's assume we're going to compress 3 cubic metres of air to 1 cubic metre. Imagine we're doing this with a piston having a 1 sq metre crown area and a 2m stroke. Pressure at BDC is atmospheric, or zero (relatively), and at TDC it's 2 bar. 2 bar of pressure is 200000 newtons per sq metre, so the force on the piston at TDC would be 200000N. Also, remembering that the force is zero at BDC, and that the pressure should (I think) rise linearly with piston travel, you can draw a graph of pressure vs piston travel which would be a straight line. The area under the line would be half of the graph (all of it at TDC, zero at BDC). So, I reckon the energy needed to compress that air, in joules, would be 0.5 x 200000 [newtons] x 2 [metres], = 200000 joules.

Now, how long will it take your engine to ingest 1 cubic metre of air at, say, 7000rpm?

Assume for the moment it's normally aspirated, perhaps 85% volumetric efficiency at 7000rpm. A 4 stroke 2568cc engine running 85% VE at 7000rpm would ingest 127.33 litres of air per second. So, a cubic metre (1000 litres) would last for 7.85 seconds.

So, the amount of energy you'd have to supply to compress a second's worth of air would be 200000 / 7.85, = 25466 joules. 25466 joules per second is 25466 watts, or 25.466kW.

As 1kW = 2.34 bhp, in horsepower that figure is about 34bhp.

Now remember that's at 100% efficiency.

I don't know whether the adiabatic efficiency needs to be factored in here because we're already working with outlet pressure (which would be affected by the temperature).

If we take a low figure to be pessimistic and say an overall efficiency of 60%, then the required power would be 34 / 0.6 = approx 57bhp.

Anyone - please correct me if I'm wrong here.


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## kingsley (Aug 26, 2002)

damn !


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## kingsley (Aug 26, 2002)

kingsley said:


> As 1kW = 2.34 bhp, in horsepower that figure is about 34bhp.


Oops, I meant 1kW = 1.34 bhp, not 2.34bhp. Typo ...


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## Lith (Oct 5, 2006)

Oh semi-relevant to this thread, I am loving this trend of the big V8 guys moving to turbos - looks like the 5s bracket could be pierced soon  

Andy Jensen's Page - Keystone Garage Club


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