[the_husk]

Originally Posted by 2500ak

Well, other than the turbo itself, the cam is the most pivotal component in the setup assuming that the supporting components are strong enough to withstand the increased strain.


With the stock cam 500rwhp isn't going to work well, if at all. The stock GenIII cams were designed with one thing in mind, emissions. 190/191 on a 114 LSA.

The low durations will make it incapable of flowing anywhere near the engines potential.

But you don't want a hotcam either. Excessive overlap will bleed off boost compression and waste precious boost, not to mention the gas that'll get scavenged out with it.

Keep the overlap in check with wide LSA. A wide lobe sep will lower mid range compression on a N/A engine but in a boosted setup there's no reason not to keep it nice and wide. S/C cams tend to go from 114 and max out at about 118.5 LSA, but with a turbo 121 - 131 LSA is sometimes preferable.

You'll need more intake duration to let the higher volume air and fuel fill the chambers, but much more importantly you need a good exhaust bias to get the burnt stuff out of there. At the very least keep it around 8 degrees, which is a good number but you can go higher within reason.

Probably a good idea to keep the the intake duration within the 22x range and the exhaust duration below the low 23x.


Really high lift won't do a lot, but it'll add stress. The lm7 heads reach peak flow at .550/.550 not much reason to go higher than that.

The CheaTR cam from tr is a good example
214/230 with a 117 LSA


Lingelfelter really leads the pack when it comes to turbocharged GenIII's


For S/C the GT2-3 is a classic
207 / 220 with a 118.5 LSA

But with a turbo, I'd be more inclined to think a grind like the GT7 would work better
208 / 230 on a 121 LSA


Make sure you remove weak spots in the engine. Upgrade the timing chain to the heavy duty one, get springs that can handle the lift and then some. All the usual weak links.

Very goo info, but don't forget hardened pushrods.