Bob,
195 ....so I was told ... is about the optimal pressure to avoid excessive
heat generation on the compression stroke and not use too much power to
compress the next charge when running pump gas. If you were to optimally
tune your engine you could probably retard the cam 1 degree close the
intakes a little later drop the cylinder pressure for an average of 195
(190-200 range between cylinders) and get a little more power out and it
might even run slightly cooler. IMHO This explains why you do not have
detonation. But didn't you run the car at 60 degrees advance. I hope now you
are around 36-38 Total at 5000+ RPM. I hope someday I can go for a ride.
Regards,
Tim Ronak
-----Original Message-----
From: Bob Palmer [mailto:rpalmer@ames.ucsd.edu]
Sent: Friday, January 21, 2000 8:57 AM
To: Ronak, TP (Timothy); MWood24020@aol.com;
TSMIT@isotel.com; rdmallory@earthling.net; Ronak, Timothy P;
tigers@autox.team.net
Subject: RE: Performance Tuning the Tiger
Tim,
After you guys taught me the proper way to do a compression
test (plugs
pulled, WOT) I get 195-205 psig depending on which cylinder
and which day.
I'm at sea level here, but of course that doesn't affect
psig, just psia.
Bob
At 07:57 AM 1/21/00 -0600, Ronak, TP (Timothy) wrote:
>Bob,
>I have to agree with you about the effect removing and
sharp spots from the
>combustion area will have on detonation. The key to
avoiding the excessive
>pressures is by changing where the Intake valve closes in
relation to the
>piston traveling up on the compression stroke. What is your
cylinder
>pressure warm with all of the plugs out ... or have you
tested it? The
>method I will use on y 302 will be to chose the desired cam
profile and then
>increase compression (or advance the cam) until I obtain
about 195 lbs
>cylinder pressure cranking. My experience is similar to
yours in that
>compression is fine provided that the combination once
assembled gives you a
>usable cylinder pressure. It may be that the guy who has to
run race gas
>needs to install a cam with a little more overlap or one
that closes the
>intake valve a little later reducing the amount of cylinder
pressure the
>piston can build. I do know that back in the race car days
we had an engine
>that was 14:1 (remember that car Theo .. it was blue and
yellow) it made
>over 220 cranking cylinder pressure and we had to run C-14
and methanol in a
>15% and 85% ratio respectively or it detonated like crazy.
>My 2 cents too,
>Tim Ronak
>B382000680
>PS: It is amazing how a well placed email gets us back on
the performance
>topic....YEEHaaaww!
Robert L. Palmer
UCSD, Dept. of AMES
619-822-1037 (o)
760-599-9927 (h)
rpalmer@ucsd.edu
rpalmer@cts.com
|