Originally Posted by cossie400
a mate of mine had his cossie on the rollers today at engine advantages and made 550bhp@ 28 psi of boost
trouble is he was aiming a bit higher but when the boost was uped all you'd get is alot of compresor stall. what would cause this? his spec is gt35, rs500 inlet, 8 greens, 7:2.1 comp, grp a ported head, bd16 inlet and bd14 exhaust cam. the only thing we can think of is the exhaust cam is to small because the air is getting in but can't consume it into the exhaust quick enough causing the turbo to stall? any input would be apprieciated thanks.
well .. i think i can explain the reason .. and also the reason I dont use rollerbearing turbo's above 400 bhp!
the problem is in the design if you ask me, we have tried 5 engines with rollerbearing turbo's for rally purposes (2 cosworth and 3 evo 7 engines)
they all went bang because of the rollerbearings being eaten by the engine, after some research it showed that the axle was giving way when you go off throttle (up and above 2 bar or 28 psi or more)
this seems to wreck the rollerbearing and since going off throttle happens a lot on a rally car
the engines never made it to the finish line..
and we quit using them in the rally because we like to make it to the finish line
garett only gives support up to 2.6 bar (1.6 bar absolute)..
which is to low for the rally..
nowadays it seems you can get hybrid ones which should do better but i am not trying anymore
