DragSource

I have seen the topic of "which head is better" and so on a million times. It's pretty much common knowledge that the VTEC heads flow better than the LS heads, and that they have a better valvetrain to start with. . . but I have never seen a comparison of both heads fully ported and built. Also - this is speaking in terms of Forced Induction only. . . as this is the FI forum.

Of the heads, assuming they were both FULLY PORTED, and COMPLETELY rebuilt.

Would one head stand out remarkably above the other? Would there be a slight advantage to one over another. . . or none at all?

non-VTEC

the VTEC heads have largers intake valves and ports. you can only open up the non-VTEC intake ports so much without making it flow worse than stock.

the VTEC head will perform better even if they were both worked over pretty good..

i do belive some people have tried to get the non-VTEC head to flow as good or better than the VTEC head but its really hard and not many people can get it to flow.....maybe with new valve seats/larger valves???

DragSource

What about the LS head makes it so that if you open up the intake valve ports more than "so much" that it will flow worse?

tokesGTR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DragSource &raquo;</TD></TR><TR><TD CLASS="quote">What about the LS head makes it so that if you open up the intake valve ports more than "so much" that it will flow worse?

</TD></TR></TABLE>

You start to sacrifice velocity, swirl, and low lift flow to get another 1 or 2 CFM's on the top end. Remember on a cam with say .445 lift, the valve is only at .445" for a fraction of the entire time it's open, so if you throw away all your low lift potential for a bit more top end you can actually end up hurting power production. The VTEC head is cast differently, and allows more flow and power potential in a full on application.

DragSource

I see what you're saying.

So at any given PSI, on a full on race application - the vtec head will make more power.

How significant of a difference is it on 2 worked over heads. . . both ported?

I know it's hard to make comparisons b/c you can't really make a scenario with equal cams, etc to make it a legit comparison.

Lets just throw out a number. If I had a fully ported and built LS head w/ oversized valves, etc and I swapped it for a fully ported vtec head w/ all the goodies.. . . how much horsepower would I gain.

I know that's a rediculous question and impossible to answer - but I'd love to know!

thehatchninja

100 hp....trust me y0! one of mah homi3z did it.

DragSource

riiiiiggggggttttttt. . . .