Big, bigger, biggest......turbo!

[Jeffer]

Hi guys,

I've noticed the goal posts are moved concerning big power. There are now a couple of 500+ hp cars driving about, but 600+ even beyond 700 HP is within reach for some people.

Therefore I'd like to source as much info on IL5 turbo/engine setups with big power (600+ hp). Especially Turbo's. So we have a nice overview of what sort of power is gained with what type of turbo.

Thanks!

Jeffry....with 700 hp on his mind for the near future

[Doug_RS2]

I know of a GT42R running 700bhp in Germany - but it doesn't boost until late 5s and he is using a custom crank.

[4WheelDrifter]

Damn Jeffry. Now you're going to have to go for 800bhp!

[HPmuirt]

I know of a GT42R running 700bhp in Germany - but it doesn't boost until late 5s and he is using a custom crank.

Well Audi managed 750BHP in their IMSA race cars and had a claimed 1000BHP in the mid-engined IL5 rally car that they were building when group B was banned.

However, for a road car, if you are going to end up using a huge laggy turbo, which boosts as late as Doug says, then why not look at doing what Audi never did and use 2 turbos.... a small one to boost the revs up until the BIG one kicks in

Can you tell that I am an ideas man - I get others to actually make it work

Cheers n

Si

[jogi730]

Designing an EM for that would be fun!
Cheers
Chris

[BRY]

Use a supercharger instead, proven by Lancia and the guy that works at Power Engineering on his Fiesta.

[S2 Ant]

Nitrous?

[whakiewes]

Building a twin turbo setup wouldn't be hard. We've done it on BMW's for years. The exhaust manifold is no different than any other. I would run two pipes, and then three pipes. Your problem though is building the sequential turbo setup. Its always been a problem in RX7. So now you are stuck running two equally sized turbo's, but ease at a much more efficient boost, say 14psi to achieve your combined boost of 28psi. But you same problem exists that now you two or three cylinders trying to pump up a turbo to achieve 14psi, which isn't very easy. So there is going to be a boost threshold per power that you can't overcome. Using the Garrett turbo's is one way, as the GT's ball bearing setups provide a much lower boost threshold than say using a KKK K31 or K29. One turbo that a lot of big power guys use are the Holset and Schwitzer. The Holset HX35 and HX40 are easily capable of sustaining 40psi, but using the same technology as the GT series, it spools rather quickly. This would probably be the equivalent to the GT40R/42R.

The bottom line is regarless of how your build your setup, your going to be stuck with some boost threshold. There are ways to help this though. Porting and upgraded camshafts will help, as will your tuning. Anything to help the engine breath better. An anti-lag setup would be useful as well for drag racers and stop light racers. If your redline is 8000rpms, when you shift in almost every gear, your going to be well above 5000rpms, so your lag might be 1-1.5 seconds at MOST. Your largest threshold will be in the first gear off the line start, because even going from a redline slip, your still going to bog down, or emit a large amount of smoke depending on where your power is, and in either form your not very fast. An anti-lag setup would help this, as well as your gear shifts, keeping the turbo moderatly spooled at all times. Just expect rebuilds quite often.

Also, one more thing to note. A lot of times I see a large misuse of turbo terms. Turbo lag is the time it takes for your engine to develop enough energy to spool the turbo into boost, not full boost, just out of vaccum. Boost threshold is the RPM in which the engine can develop enough energy to spool the turbo. So saying the turbo doesn't boost until 5000rpms isn't because the turbo is laggy, its because 2.3L isn't big enough to spin a 71mm compressor fast enough to produce postive boost. Ways to over come this...anti-lag, head work, cams shafts, non-restrictive intercooling, larger exhaust piping, smaller wastegate, improved exhaust manifold design, raised compression (all you 8.3-8.5:1).

Bottom line, if you want 28, 30, 40 or whatever psi, your going to have to wait for it. I'm up for getting a longer stroke crank if I get enough orders...2.6L?

Wes

[Audi Parts Guru]

Hi guys,

I've noticed the goal posts are moved concerning big power. There are now a couple of 500+ hp cars driving about, but 600+ even beyond 700 HP is within reach for some people.

Therefore I'd like to source as much info on IL5 turbo/engine setups with big power (600+ hp). Especially Turbo's. So we have a nice overview of what sort of power is gained with what type of turbo.

Thanks!

Jeffry....with 700 hp on his mind for the near future

Go for it Jeffry

[palles2]

Hi

I am getting a garret gt35bb with 1.06 hot side on, hoping for 650 hk...

[Henka]

At least in Sweden/Norway/Finland/Denmark, Audi engines with roughly 800hp has been used for at least a couple of years. 1000hp, now that's a real challange.

[dan_b]

1000hp -hey, VAG have done it with the Bugatti Veryon - 16 cylinders and 4 turbos, 1 turbo for each bank of 4 cylinders. Easy!

Wonder what Mihnea could do with that engine?!

[corrado]

Like mentioned by whakiewes the bigger the turbo the more energy will be needed to move the turbine wheel.

The key to using a big turbo is good flow and cc. If you are limited in the cc area than look in other places.
Big power on low cc cars running turbos will be in the very high rpm. Build the engine to rev to 10k why not 12. Match the cams for the rpm, extensive headwork, larger valves, solid lifters, 4" downpipe and exhaust system,tubular equal length manifods. Have a good rod/stroke ratio, lighten and balance all rotational wheels/pulleys.


Honda guys are using GT42r turbos and producing around 750whp from a 1.8, power comes in around 6.5k.

The old days F1 cars are known for their crazy volumetric flow characteristics, they all spun big turbos on small 1.5 V6 engines and the only way they did it is rpm and flow. Its an extreme example I know, they iddle at 5-6k

[Rusty]

Use a supercharger instead, proven by Lancia and the guy that works at Power Engineering on his Fiesta.

A supercharger/turbocharger hybrid is an awesome idea. Are you referring to the mk.1 fiest running about 300bhp? It's a great example of engineering your way around a problem. The only serious issue would be space in the S2 engine bay. I'm sure some serious relocation of cooling parts may help but it's going to be tight with a large turbo. Mind you, could just do what Hacke has and relocate the turbo too!

[audiman]

Im gonna be aiming for about 600bhp, thats gonna make the car fast enough IMO. Plus thats gonna be into the annual rebuild area!! I guess if it doesnt feel fast enough, then i can introduce some nitrous for good fun! LOL.