Re: Head Work

[Glen Powell <gpowell@acacianet.com>]

At 12:33 PM 3/22/96, Martin Slotterback wrote:
>Hey,
>     What about extude hone for the intake, head, and exhust.? I 
>would not go big valves unless you want to lose low end power for 
>high end speed. Somthing about cyclinder head velocities or 
>whatever... I think extrude hone will be the best thing to do to 
>the head and manifolds for a few reasons. One being that the 
>prosess removes material from the entire runner not just the ends 
>where you can get a grinder. It smooths the material in a flow 
>pattern much like water erodes a river bank in a natural efecient 
>manner. So more POWER and more MPG all at the same time. But leave 
>the turbo alone. Again the high end thing.
>

Sure sounds good in theory!

What we found was that the head (TQC) was the overall limiting factor to
flow. When the head work was complete, big valves installed and flow was
satisfactory for the intended power output the 2-piece exh and the stock
intake were then flowed to determine if they would be limiters to the flow
of the head. With simple port-matching and minor clean-up both the 2-piece
and the intake both readily outflowed the head and the time and expense of
extrude-hone on these piece would have been a waste -- invested those $$$
elsewhere (more headwork, big-bore and custom pistons). Moral: spend your
$$$ on headwork and if you want to extrude-hone something do the head, or,
as an alternative, you could always work on the head.

On the big valves -- I don't think big valves really hurt low end power with
forced induction -- it's very different from atmo here.



-glen