[CarbonJoe]

According to the Subaru World Rally Team site, the FIA limits BHP on WRC engines to 300 BHP. It then goes on to say that the WRC engine (2.0L boxer) produces 2.5 times the torque as the roadgoing STI. Since the USDM STI is rated at 290 lb ft., that means that the WRC engine is producing 725 lb ft of torque. They indicate the turbo they use can handle 60psi boost , and that the turbo operates at up to 1000 deg C.

Subaru World Rally Team

Any ideas as to how they produce so much torque without violating the 300 BHP limit?

[The Black Beauty]

woa I have no idea but thats crazy

[Spaceman]

Wow!!

[STUKA]

Did you ever see how much it cost to make a WRC car? Everything on the car is different except for the body shape. The power train is so much different than a stock STI.

[Spaceman]

^^^

"It helps to bear in mind that the engine alone is worth around three times the cost of a new Subaru Impreza WRX STI, and the cost of the turbo itself is more than enough to buy yourself a Subaru Justy!

But don’t go raiding your bank just yet; even if you are willing to spend the cost of a small hatchback on a single turbo, they are supplied specially to the Subaru World Rally team by Japanese manufacturer IHI."

[kts262]

I do know that a lot of rally series have restrictors on the turbo inlet to limit the amount of air going in, usually 32mm or 34mm. I know they have those on Group-N, the WRC probably has something similar, which would limit horsepower.

The rest I guess would be other restrictor plates or tuning.

[caveguru]

I was not prepared to accept the statement about 2.5x torque until I read this statement:

the latest rally Impreza is still able to accelerate to 60mph from standstill in under three seconds even on gravel

dang!

The other teams used to use a Garrett turbo called a TR30R. These are being made available to the general public this year for ~$6k and have stuff like CNC'd titanium compressor wheels and such. I haven't seen as detailed a write-up on what goes into the IHI turbo, but I'm sure it's on par.

I do wonder about the turbo diagram in that article. The turbine housing looks like a traditional single-inlet, but what is that second housing towards the bottom of that diagram?

Frank

[Spaceman]

SWRT - An Icon Evolves

[paikman]

There used to be a pair of full rally EVOs that got tuned at the dyno at the shop i used to work at, since we had a load-bearing type (DynaPack) and the cars are really crazy. They did have the restrictor plates and power delivery is probably similar to wrc cars. It's very, very strong torque, it would be like 550w torque and power dies off at like 4500 rpm
, would be like 260whp, 550wtorque lol

[RoninHatch]

So it would be more than capable of making 500hp but its just choked up via the restrictor plate?

[Digitalfiend]

Originally Posted by RoninHatch

So it would be more than capable of making 500hp but its just choked up via the restrictor plate?

Exactly.

[USNSTI]

HP = Torque X RPM Divided by 5252

I am not sure how they do it?

[USNSTI]

I guess they must shift at less than 2000 RPM? Or else that whole article is bogus?

[Digitalfiend]

Originally Posted by USNSTI

HP = Torque X RPM Divided by 5252

I am not sure how they do it?

With the restrictor plate, the torque curve must look like a cliff face, so it's probably a very narrow torque band. There is just so much torque and the car is so light that it still gets moving.

[paikman]

Yep. The plate effectively kills that equation since you never get to the "cross-over" section of the map on torque vs hp haha. no air, no power at upper rpm, no hp!