With all this talk about compression,I have a question: if a motor has 11:1
compession with a 54cc chamber and all variables stay the same, how much
compression does the engine have with a 64cc chamber?
----- Original Message -----
From: Ronak, TP (Timothy) <Timothy.P.Ronak@akzo-nobel.com>
To: 'Bob Palmer' <rpalmer@ames.ucsd.edu>
Cc: 'Tiger News Group List' <tigers@autox.team.net>
Sent: Friday, January 21, 2000 10:14 AM
Subject: RE: Performance Tuning the Tiger
> 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
>
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