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

There is an on-going thread in the Videos section that is getting ran over my misinformation and bashing. I posted this link above in there somewhere but it definately didn't get looked at too much. So I just wanted to post it up so everyone could get some facts about. It's a good read and get's down to the purpose of the system.

It helped me to understand it more.

thanks to another IC member for the link!

 

Thanks for posting that linked article. I've read a similar explanation in the past as it relates to the WRC but it was an older article that didn't mention the mandatory restrictor that they've used for many years.

There is one misnomer that is commonly used, though. 'Turbo lag' is sort of a misleading term. A better term might be 'boost lag' because the turbo's rotating parts are always spinning while the engine is running. The problem is that depending on the many variables mentioned in the article, the turbo may not be within its operating range to provide positive manifold pressure (boost) at a useable lower engine rpm range, hence boost lag.

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0==WW==0
"…axles of evil…" - george w. bush

 

That is an interesting site, but the author is quite opinionated (it is a personal site, not any official capacity for WRC or FIA) and is not an objective source. Read his article on "turbo restrictors" (which are known as intake restrictors) for an example.

One thing readers should take away from that article is how this type of anti-lag is extremely destructive, and no streetable vehicle would possibly survive even 50 miles using such a system. Even with the strict WRC rules about repairs and rebuilds, I'm willing to bet that competition vehicles replace the turbo and exhaust (and all supporting parts) every 100 miles of track time or less, and those parts in the first place are built to extreme tolerances well above what is available (to the street/tuner market). Any car that you hear on the street backfiring like a rally car isn't long for this world. Also, it is quite possible to shoot flame out of your exhaust and even have extended tailpipe fires without having an anti-lag system involved; you just use a full atmospheric blow-off valve and tune the car excessively rich.

There are also many other anti-lag techniques, such as external wastegates (boost is dumped right out of the turbo, giving it an extra "spin" to keep the velocity high) and sequential twin-turbo systems that use a small turbo to keep the manifold pressure high while the big turbo builds positive boost. I've also heard of systems (catching on in Europe) which use a small supercharger to maintain boost pressure off throttle, and EGR systems which shunt wastegated boost back into the exhaust system to prevent vacuum. All of these have the added advantage of not making your engine explode.

 

Or how about variable turbine geometry turbos, such as they are starting to use in Porsches and have been using in diesels for years now.

 

Can you find more information about these? What makes them different from twin-scroll setups?

 

Twin scroll setups are completely different. This will give you an idea of what's behind the VTG (or VGT, if you prefer) in diesels.

http://www.findarticles.com/p/articl...4/ai_n13780293

And here's a quick little write up on the Porsches...

http://www.autoblog.com/2005/11/27/n...bine-geometry/

Pretty cool idea in my opinion. We'll see how long it takes them to make direct replacement turbos for other cars.