Ever notice how the rally cars backfire a lot? Unless anti-lag systems have changed, they used to work by retarding the ignition drastically so taht the fuel burns outside of the cylinders. Seeing as the manifolds are extremely hot the fuel would ignite there causing the backfire and spinning the turbo. There are also anti-lag valves for off throttle and braking which either redirect air to spin the turbo or actually let air through the throttle body plate even when closed.

[edit] I obviously don't have the 'guru' title under my name and, if you look at some of my posts, it's obvious why I don't have it . So, this is just my understanding of how it works and is how it has been explained to me in the past. I might be totally wrong.

 

This might help with an explanation...

http://www.rallycars.com/Cars/bangbang.html

 

I think he right....check ou tthis link...cool stuff

www.rallycars.com/Cars/bangbang.html

 

err...jinx

 

From what I hear, antilag systems put extreme wear on your motor and turbo. It's not recommended for street use.

 

You can tell they do run at lower rpm's. Listen to when they shift, it almost sounds like they're short shifting. But they definitely don't hang at high rpms for a long time.

 

I used to own a Celica GT-Four Carlos Santz (see here for further info http://www.alltrac.net/FAQ.html) I remember it being a big *** sized within the cars engine bay, I was told it didn't make huge hp but made some large serious torque, mine was road going version so it was de-tuned for economy but I could have had it tuned back up to race spec...it was sold for Supra TT after a number of memorable years...

It would be great if we could get a good combination of low-end and high-end power. Is this possible on single turbo? or would a twin turbo units of differing sizes be a better fit for the job? Is that even possible in small space of an EVO engine bay?

 

I am more interested in boost…

~50 psi - it is a pretty high number, isn't it? What do they do not to detonate? Are those cars running extremely high octane fuel? I have read somewhere that for WRC cars they do employ water injection systems but even then how do these cars can handle such a boost?

 

Maybe they have to rebuild the engine quite often maybe after every other race?!? (this is just pure speculation). If they do, we don't have that luxury...

 

High boost at low rpms and water injection keep detonation to a minimum.

Also, dont forget these cars aren't exactly Toyota Corolla's. The amount of research money poured into the car designs is more than you or your whole family will earn in 3 lifetimes.

 

Another way to do anti-lag is to simply not spark a particular cylinder periodically. The fuel/air mixture goes in, then is pushed out into the exhaust manifold unburned. The exhaust valve closes, the mixture, exposed to the high heat in the manifold, explodes. The only place for it to go is through the compressor wheel, so you've just sped up the turbo and produced boost.

There is that unfortunate side effect of exploding your exhaust system and/or turbo, though...

 

One of Tommie Makkinens old grp A/WRC EVO VI were sold to a Swedish rally driver and a friend of mine visited the shop that put together and tuned the engine. Engine is identical to the spec that they used in Makkinens car, it’s actually the same engine but now rebuilt as new. As you can see on the pics there are a lot of special things made to the engine but since it was also homologated for grp A it’s not as modified as the Lancer WRC 05 engine.

What I was told is that they run the engine optimized purely for torque. As mentioned above the 34mm restrictor makes the engine run out of puff at a fairly low rpm. In reality it’s not much use to go above 6000rpm and they shift gears early to stay below that point.

Apparently the turbo is not much bigger than the stock item, once again the restrictor makes it unnecessary to use a much bigger one. On this particular car the turbo even looked like a stock turbo but probably it has been modified as well but it used an internal WG. They run fairly high compression for a turbo engine, around 10:1, this together with a very high boost explains some of the torque. The cams looked like nothing my friend had ever seen, they seamed to be made from pipes rather than from cast metal. Then the cam lobes had been forced on to the pipe. Clutch was a triple carbon fibre AP. And the gearboxes were 6-speed sequential X-Track if I remember correctly.

I’ve had the privilege to watch the Swedish rally live a couple of times and seen and heard several of the WRC cars in the woods of northern Sweden. What is heard the most is the bangs from the ALS (anti lag system) the exhaust sound is very deep and throaty and not very loud. The loudest cars are the N/A fwd cars that rev a lot higher and have no turbo to reduce the sound either.

Sorry for the language here but at least you can look at the pictures

http://www.walfridsson.com/Bilder200...gge.htm#vecka2

http://www.walfridsson.com/Bilder200...er_wrctest.htm

 

nice pics man! I gotta get those guys to build me somethin crazY! I want a 6 speed sequential!

 

Yepp, me to, but they are VERY expensive and apparently they need to be rebuilt very often.