Compression questions? (Page 2/2)
cvxjet APR 02, 09:54 PM
Rats! I believe you are right....I did all my engine stuff back 13 years ago.....(That is a bad excuse...)

As far as 4 Valve vs 2 valve, most four valve engines cannot have much quench- no room in the combustion chamber because of the FOUR valves- They can have swirl but it is not as effective as the 2 valve TDC Quench.

Bottom line; Latest Camaro SS vs Latest Mustang GT- they are within 50 lbs of each other, and both had manual tranys. The Camaro has both quicker acceleration and better MPG. Ford had to bring out a turbo 6 in their F150 to compete with the GM LT V8s- The Coyote sucks gas compared to the LTs....

I run into this all the time..."2 valves are better unless you are artificially limited in displacement"......"No way! Four valves are the FUTURE!!! They are better in every way....Why, they are high tech- the Formula one cars all use them so they MUST be the best!!!!"

Ford can't GIVE their Coyote engine away to boat manufacturers- without multiple gears, the four valve deficiency shows up even worse....
pmbrunelle APR 03, 01:21 AM

quote
Originally posted by fieroguru:
E85 is nearly 1.00 per gallon cheaper than 91-93 anymore



You should be comparing price per Btu, rather than price per gallon.
hercimer01 APR 03, 02:17 AM
Thanks everyone so far for the input.
Man my head is just swimming in all these numbers.
The image poster is down for now but I'll try to run the numbers. They came from this.
https://butlerperformance.c...sion-calculator.html

4.030 bore
3.75 stroke
64cc heads
7cc piston vol
.015 deck clearance
.045 gasket
------------------
10.37:1 CR

If I go to 19cc pistons with .025 head gasket, that's
9.57:1

The 260,260/.440,.440 cam 110 LSA (CL12-206-16)
is meant for towing. That's where I am with the 10.37:1 CR for now. Also I plan to go with 1.6 rockers.

If I do the 19cc pistons to get to 9.57:1 could I run 87 octane or mid grade?

[This message has been edited by hercimer01 (edited 04-03-2020).]

Blacktree APR 03, 12:57 PM

quote
Originally posted by hercimer01: If I do the 19cc pistons to get to 9.57:1 could I run 87 octane or mid grade?


I think mid-grade would be OK; 87 octane... maybe? You could play it safe with the spark timing. Or if the engine has a knock sensor, you should be OK.