Anybody know what the compression is supposed to be on one of these stock? I just did a compression check and have nothing to compare the numbers to. The high/low spread was only 5.5% with 69,500 miles on the clock, so I'm happy about that. I'm just wondering what "the" number is supposed to be. Thanks!
I am sure one of our resident experts will chime in soon(I think the compression is 10.5:1?), but in case they take a while, shoot Cam or Hemi31 a PM. Sometimes they are too busy to look for new threads, so PM's are sometimes faster.
OK, as a frame of reference, here were my readings by cylinder in psi: 1 - 200 2 - 190 3 - 195 4 - 195 5 - 191 6 - 194 7 - 200 8 - 189
I know the range is good between the cylinders, but I can't help but wondering what the number is supposed to be. I mean if my numbers ranged from 140 - 147, that's an acceptable spread between cylinders, but sucks overall. Know what I mean?
1 atmosphere at sea level = 14.7 psi compress that by a factor of 10.3 (10.3:1) and you get 151.4 psi right? and you're getting closer to 200 psi? 200 / 14.7 = 13.6:1 compression. You might want to keep a close eye on your head bolts.
I've seen that formula on another SRT forum, but then I tried using it on past vehicles I've owned and it hasn't been close to correct on any of them. Because of that, I dismissed it as being wrong. All of my past vehicles have been turbocharged, but I don't know why that would make a difference as they aren't building boost when cranking over the engine.
The only reason I can think of is that the air temperature goes up significantly as you compress it that much?
