rml:
I would add that the compression on the later head is lower, so
you will want to mill the later head to regain compression. And as long
as you are doing that, you might as well mill it enough to bring it up
to about 9.5:1 (or even higher if you are willing to run premium gas). I
*think* the earlier heads were 8.5:1 stock.
According to my Desktop dyno software, raising the compression
on a later head from 7.75:1 to 9.5:1 adds 12HP. What that ignores is
that the power is added throughout the entire rev range not just top
end, *AND* fuel economy goes up as well.
So between the improved breathing of the late head and manifold,
and increasing the compression via milling the engine really comes
alive. You can keep up with Miatas pretty easily.
Vance
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On
Behalf Of Robert Lang
Sent: November 14, 2007 9:10 AM
To: Robert Breazeale
Cc: 6 Pack
Subject: RE: [6pack] Early vs Late Head
On Wed, 14 Nov 2007, Robert Breazeale wrote:
> I don't mean to hijack this topic, but I've been following it with
interest.
> I was wondering, is there any advantage in putting the later head onto
an
> early block? Or is it even possible?
The late head will bolt right up to the block. No probs there.
You WILL have to change the intake manifold to the later style. I'm not
sure if the carb air cleaner will clear the TR250 inner fender, but it
should. AS you may know, the late-style cars have a different inner
fender
(probably the same as the PI cars.
regards,
rml
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