head work hp guess

[hypedz34]

just wondering after port and polish job on intake and exhaust about how much hp would i gain from this?engine is a z 3.4 dohc.any help is appreciated.also where could i get headers for this engine?or will headers from another car fit and flow better?any help is greatly appreciated

[robertisaar]

depends on how much you port out, what kind of radiuses you make and how much the engine actually needs it.

[hypedz34]

what do you mean by how much the engine needs it?also i plan to port match to the gasket.

[robertisaar]

if the heads aren't the biggest restriction, not only will you not gain a lot of power, you'll likely hurt power in lower-RPMs as well due to lost flow velocity.

[Superdave]

I don't think port flow is an issue with that engine.. you need bigger cams to make use of what you have.

[pocket-rocket]

if the heads aren't the biggest restriction, not only will you not gain a lot of power, you'll likely hurt power in lower-RPMs as well due to lost flow velocity.

The 91 gained a good amount down low with P&P heads and the 13* cam timing (well before the 6&6 was around). Anything over 3k rpm's launching was as Ben called it "Instant tire death." Michael from FFP even commented "Woah, you have low end nut!" when I gave him a ride in it before the Canada 60v6 meet many many moons ago. That set of heads I helped port, and it was one of Ben's earlier sets of heads before the flow bench got set up. I use the term P&P loosely because it was more of a clean up and smoothing process more than an actual port job. So yeah, I agree with porting them. Don't hog them out any, just clean up flaws, smooth stuff out and don't polish the intake side or fuel will fall out of suspension in the air, hurting performance.

[HayesPerformance]

Same, I port matched, NOT extruded (increasing the intake runner width)

On the 91-95 intakes I have seen a couple where the guides for matching the upper and lower intake wouldn't match them so one or two of the end ports had the lower causing a slight "shelf" or "ridge" hindering flow, even thought the ports on the upper intake were faintly smaller, so that supposedly that doesn't happen.