Rally Car Technicals

[Tomerville]

I was always led to believe that turbocharged rally cars did not use blow off valves in order to release pressure because the drivers tend to be on the throttle so much, there was no need, and spilling the pressure so quickly would not benefit in the car's performance.

I was wondering:
1.) Is this true?
2.) If not, how do they release the pressure?
3.) Are there any magazines with specifications?

-Any help and or insight would be much appreciated.

[mindgam3]

http://www.google.co.uk/search?hl=en&q=wrc+wastegate&spell=1

quick search on google should give u some answers ;)

Its mentioned enough so i guess so

[Wutputt]

A wastegate isn't a blow off valve ;)

A wastegate is used to cut boost so the turbo won't create too much boost and destroy the engine or turbo itself. When the boost becomes to high the wastegate opens a bypass channel over the turbine so the boost won't rise anyfurther.
A blow off valve or dumb valve, is used to keep to turbo spinning when the driver releases the throttle. So the boost won't drop to far and enough boost is available when reaccelerating. A VTA (Vent to Air) BOV (Blow Off Valve) vents the air on the compression side of the turbocompressor when releasing the throttle. That way the turbo isn't decelerated to hard by the pressured air.

Rally drivers certainly release throttle quite a lot, otherwise they would end up in the scenery. I think WRC rallycars don't use BOV's though (I'm not sure), cause they have a special anti lag system (ALS) that keeps injecting fuel into the cylinders for a while after the driver releases the throttle. Since their will be no ignition, the fuel/air mixture will start burning in the exhaust manifold and keep the turbo spinning. Actually ALS isn’t really good for the exhaust manifold and the turbo, but a WRC rallycar doesn’t have to last for more than 200.000 miles like a normal car ;)

[Wutputt]

A wastegate isn't a blow off valve ;)


no shit.... :shock: :wink:
:D

Well, since you guys were all talking about wastegates and the topic opener about blow off valves, it could have been a useful hint ;)

[23790554]

you can order a new EVO 8 MR FQ-400 with anti-lag

[Tomerville]

wow, I knew about ALS, but didn't know WRC cars used them...thanks for all the helps guys

[homemade wrx]

I imagine they tune the cars to run without BOV's...I know with my Link 44s I would tune everything. Even anti-lag :twisted:
with the turboed formula SAE cars, a similar set up is run, with the pre -turbo restrictor and so on. The cars don't have BOV's.
besides the rally engines are designed to only last 500 miles!! :shock: