You will get about a 2% increase in HP. Increasing the compression ratio has
a greater effect if you have a longer duration cam. If you're having a run
on problem now, expect it to get worse. If you're using a DGV you can
purchase an electric idle circuit cutoff solenoid that you hook up to your
ignition. When you shut off the ignition it cuts off the fuel limiting
runon. Use high octane gas. The late model head is an open type combustion
chamber where the older head is a closed type. So even though the
compression ratio may be the same they will not behave the same. Valve size
was different too. I believe the higher compression pistons will only bring
you up to 8.8 : 1 you would have to cut the head a bit to achieve 9:1
Chris Reichle
creichle@nsc.msmail.miami.edu
----------
From: mgs-owner
To: mgs
Subject: Power Tuning
Date: Monday, October 27, 1997 9:39PM
Looking for some subjective opinions here. I am sure that all would agree
that an increase in compression ratio will yield an increase in H.P.
output. My question regards bang for the buck. Given an engine with an
8.0 to 1 compression ratio, vs. the same engine with a 9.0 to 1 ratio, what
% of increase would be expected. I am laying out my plans (and budget) for
my winter project, namely extracting more from a stock 77 B mill (sans
emissions, add Weber DGV). Trying to weigh the relative gain to be had by
swapping to higher comp. pistons vs. stock (without any other mods, for
comparison sake). I have confidence that many have opinions, and
potentially similar experience, so please pass along your ideas.
Regards,
Chris
|