Jekyl

For years I have heard how the wrc cars run 300bhp which is simple enough from a 2ltr block but how on Earth do they achieve 479lb-ft of torque on the same engine? On reading the engine specs I understand that this consists of a H-4. Flat four-cylinder, 16valve engine with Bore 92.0mm & stroke: 75.0mm. Standard subaru programmable management with power: 300bhp @ 5500rpm & torque:650Nm @ 3000rpm. I am very much fascinated by this & would appreciate any explanations. Thanks alot.

Butty

iTrader: (2)

The 300 hp limit is due to a 34mm turbo inlet.
The high torque is from high boost (3.5 bar), fine timing management and a very strong engine!

GazTheHat

3.5 bar

Terminator X

iTrader: (7)

Rebuilt each day @ 3.5 bar?!

TX.

Shaun

Boost, High Compression and Higher Octane fuel.

Easy!

KAS35RSTI

iTrader: (73)

I would imagine the WRC cars also go through some serious headwork?

Jekyl

3.5 bar surely though to acheive an engine as ferocious as this is from a combination of things otherwise people would simply ask for this on there road cars? interesting though as google search had not shown anything.

Splitpin

More than that, although most of it is delivered at relatively low engine speeds. The restrictor prevents high boost levels being maintained as the revs climb - which is why the headline power figure remains relatively low.

Some do. However, not that many people driving road cars are prepared for, or able to afford either the up-front costs of building an engine to that sort of spec, or engine/turbo rebuilds every 500-1000km - or the cost of race fuel.

The specs you're reading are more than a bit misleading btw. WRC cars do not run "Standard Subaru programmable managment"! The bore and stroke numbers are accurate but they're about the only things that are.

Google doesn't know everything - especially when some of the things you're asking about are effectively trade secrets.

Butty

iTrader: (2)

The 3.5 bar stuck in my mind from an article on the Prodrive website back a few years, but it was an upper limit of a boost range.

stevie1982

iTrader: (16)

Always wondered this myself although my sti has 440lb @1.9 bar on a 2.0ltr by the way

mik

What Splitpin said.

Engines are just air pumps. Restrictor plate is intended to keep max power levels down.

At lower engine speeds the restrictor is less of an issue, so you can achieve an advantage by pumping the boost up - hence serious torque in the mid range. Gives them a power band which is very Turbodiesel-like.

KAS35RSTI

iTrader: (73)

Totally agree with that statement. Sometimes you have to take in what you read & see with a pinch of salt.

Jekyl

Very useful info & a big thanks as this really has helped to understand how these figs were achieved. Splitpin, the programmable subaru ecu part was the info that was from the Autofiend website after they tested the v10 wrc car . Nice one for answering my many questions. Cheers

Godspeed Brakes

iTrader: (259)

They are running very high compressions as well , around 12 to 1 , I think thats why they are getting more horsepower now than at first , they are around 330-340hp now , a friend of mine has an S12 , and he says his torque is about 700nm , its certainly sharp out of junctions and hairpins.
Its amazing off the line , it will change from 1st 2nd and 3rd automatically then you use the paddle change from there, mind you , it cost him £280k so I would expect some toys

Jekyl

Definately Lol