Broken -in Stroker Compression Numbers

[woodjeep]

Posted this on another site...might be of interest to someone here

My 96 stroker motor now has about 26000 on it...286K for the rest of the jeep, and I just replaced the plugs for the first time..Extremely clean and textbook color..The gaps started out at around .040 because I am running a higher voltage coil. My gauge only goes to .045 and that slides thru easily but it still ran smooth. I did a compression test and was pretty surprised . I ran the whole row between 180 and 188 psi...two and four were 185/188..five was 182 and the rest were a hair above 180..I gave the engine about a 3 or 4 second crank for each one.

I did a compression test on the old stock motor many years ago with about 220K on it and got these results...


Hi, I finally got around to doing a compression check since I was replacing the plugs anyway. Cyls 1-5 were between 135-150 give or take a psi or 2. It seemed that 3 and 4 were closest to 150. I could not get the tool into plug 6 without moving harnesses around so I didn't check it. I had all the plugs out, on a warm engine and I removed the fuel pump relay so not to spray fuel all over the place. I had the throttle jammed wide open and gave about 10 seconds cranking on each measurement. This is the original motor with 217K on it. Orig headgasket. All in all, I was suprised they were so even. Hope this helps


I run regular 87 gas in this motor and run 31 inch Revo;s with the stock 3.55 rear so the engine turns pretty slow at Highway speeds...2000rpm at 70mph...It rarely pings, and just a little if I really load it up below 1500 in OD and my vacuum drops close to 0...If I get the rpm's back above 1500 my vacuum gets closer to 10 or more and any minor pinging stops. Pretty happy with the way the plugs looked and was very surprised with the compression numbers

[SilverXJ]

Comparing stock engine numbers to a stroker is pretty meaning less.. as it is comparing your stroker to a different one with different displacement, cam, etc. What you look for is a change across cylinders, yours looks good.

Why let the engine ping at all? Just try midgrade gas. Any pinging is not good for the engine.

[Cheromaniac]

I did a compression test and was pretty surprised . I ran the whole row between 180 and 188 psi...two and four were 185/188..five was 182 and the rest were a hair above 180..

I run regular 87 gas in this motor and run 31 inch Revo;s with the stock 3.55 rear so the engine turns pretty slow at Highway speeds...2000rpm at 70mph...It rarely pings, and just a little if I really load it up below 1500 in OD and my vacuum drops close to 0...If I get the rpm's back above 1500 my vacuum gets closer to 10 or more and any minor pinging stops. Pretty happy with the way the plugs looked and was very surprised with the compression numbers

Compression numbers are excellent and indicate that the DCR is fairly high. You might wanna run 89 octane gas though.

[6TIME]

I'm curious what your static compression was and what cam you used? If I had to guess with those comp #'s, I'd say your in the 9.5:1 range and 8.0 Dynamic. Should make a really snappy motor off the line