hello everyone..

I got intercooled magnacharger on my gmc 05 4.8L 5speed manual with 3.70 stock pulley, i'm thinking to increase the psi by changing the pulley useing 3.40 pulley size. My question is do i need a major engine work? or its safe with stock engine ?

 

I've been running a 3.25" pulley on my '03 4.8 and haven't broken anything yet (in fact I just tore down the engine to verify) but then I'm not very lead-footed either. I guesstimate you'll make around 9 psi boost, so if you are careful to stay away from 87 octane gas (i.e. don't let the mother-in-law fill the tank ) you should be OK. Two things you might want to consider. 1) stay away from really high (5000+) rpm's. The '05's fueling system isn't as adaptable to boost and tends to go lean at high rpm's. 2) You might want to have someone with tuning software tweak your PE onset vs. %TPS. A smaller pulley means boost comes on earlier, so the PE mode, which ensures enough fuel, should come on earlier as well. And of course what's life without a few legalisms? 1) you'll void your warranty and 2) if you live in a state with emissions testing, they will have a cow if they find out you changed the pulley. Well this is probably more than you wanted to know so I'll shut up.

BTW: You'll love the extra power .

 

Stop!

Without a proper tune for the smaller pulley (more boost) you risk engine destruction!
Find a local dyno tuner.

 

Thank you guys i appreciate your support,,

i'll change the pulley today and i'm going with HpTuner