Thread: L67 Engine Swap and Cam Decisions.

IS4 heads + XPZ = 380whp on 93 octane.

You need RPM and lift to make use of the heads, the extra duration of a xp/xpz makes more power on any head. The only cam that "throws away" power is the IS3/IS4/NIC cam due to its high cyl cleaning overlap... its a tradeoff for low octane fuel.

1.8 rockers may not lose horsepower, but they will not help over stock rockers. 1.7s will increase valve float, and reduce lift over stock, dyno proven loss of at least 5% horsepower.

Originally Posted by darkhorizon

IS4 heads + XPZ = 380whp on 93 octane.

You need RPM and lift to make use of the heads, the extra duration of a xp/xpz makes more power on any head. The only cam that "throws away" power is the IS3/IS4/NIC cam due to its high cyl cleaning overlap... its a tradeoff for low octane fuel.

1.8 rockers may not lose horsepower, but they will not help over stock rockers. 1.7s will increase valve float, and reduce lift over stock, dyno proven loss of at least 5% horsepower.

So VS cam and IS4 and 1.8 not a good idea? Will be using my xpz on my Gtx this is for my 40th vs cam build.