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74mm pulley

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2000 l67 commodore berlina
ive got a 74mm yella terra pulley ready 2 go on as soon as i get the a2a 1ntercooler. but on the zzp website they sat if u add a xpz cam(stg 3 l67 mace cam) & port the heads ect u can go a 74mm/2.9" pulley without a cooler. any thoughts!!! also does a 74mm need to b tunned to accept?
 

zeropalooba

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Hi Mic, I've got an L67 too but haven't gone down the route of a smaller pulley yet. I have done some reading though. The M90 really heats up the air charge as it pushes air into the lower intake manifold. The more air, the hotter it gets. As air gets hot, it pushes back against the m90 further limiting an already inefficient blower. Porting and camming it might help flow and that would indirectly help reduce the heating but I would imagine you'd still benefit from intercooling. And intercoolers look mad poking out from under the bumper.
In relation to the tune, the MAF sensor maxes out at a certain amount of air and if your blower is pushing more than this into the engine, you'll run lean and that could be bad. A tune would fix this. People talk about going to a MAFless tune to overcome the lack of resolution of the MAF sensor.
 
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immortality

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It's gonna need tuning with a smaller pulley and with a A2A plate especially. Ignore what they say on ZZP, the info is valid for their conditions and I suspect a lot of it has to do with how they do or rather don't tune the vehicles properly as I run smaller pulley and larger plug gaps then they say is possible with the only difference been I'm able to tune it myself. On my setup I basically max'd out the stock maf on 3.4" pulley (and all the other bolt on mods). I'm running 3.2" now but I only rev the engine to 5000rpm until I fit the L98 MAF and new valve springs.
 
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