Acceptable compression numbers???
#1
Drifting
Thread Starter
Acceptable compression numbers???
What is the acceptable range for compression on my 1986 951. I used to know, but I get mixed-up between numbers for a 928, 911, 944 and a 951. I just slipped a couple of teeth on mine and I'm hoping and praying that it's ok! Where should it be?
#6
Instructor
Join Date: Dec 2004
Location: mississippi
Posts: 117
Likes: 0
Received 0 Likes
on
0 Posts
it's ok. if the compression of each cylinder is within 15% of each other i consider this normal wear.
if it's not burning oil or other low compression side effects, i'd drive it like i stole it.
if it's not burning oil or other low compression side effects, i'd drive it like i stole it.
#7
Wax On, Wax Off
Rennlist Member
Rennlist Member
Join Date: May 2003
Location: 5280 ft above the sea
Posts: 17,727
Likes: 0
Received 4 Likes
on
4 Posts
Oilslick, if it's a 951, you still have hope maybe. 951's have lower compression pistons, and therefore these may still be good... there may still be life in that engine...the fact that they are uniform is a good thing, but do they hold the pressure? what's the leakdown?
Trending Topics
#8
Drifting
Thread Starter
I didn't have them do a leakdown. They just called back and said they think it is ok. There is no valve noise and it seems to run great. WHEW! I think I may have dodged a major bullet, here. They said when the last person did the timing belt, they did not tighten the nut that holds the tensioner in place and when it got loose enough, the belt just slipped 2 teeth, maybe 3. He said there is no evidence that the valves are damaged and the 135 across, is pretty common for a 951 that is 20 yrs old and has 100k miles. YeeHaw! My day just got a lot better!
#10
Drifting
Thread Starter
Oh yeah, today...I feel...like the luckiest man...on the face of the earth....
Hey Mike- I've always liked those Conquests. I remember, back in '87 I had an MR2 that I thought was the shiznit and I could never keep up with the Conquests. What kind of real performance does your car have? Looks like you have some mods. What were the stock HP/Tourqe #'s on those and what do you have now? What about reliability?
Hey Mike- I've always liked those Conquests. I remember, back in '87 I had an MR2 that I thought was the shiznit and I could never keep up with the Conquests. What kind of real performance does your car have? Looks like you have some mods. What were the stock HP/Tourqe #'s on those and what do you have now? What about reliability?
#11
Rennlist Member
I checked my 951 about a month ago and got mid to low 140s across the board (I do not remember all of the numbers, but the lowest was 142 and the highest was 145). My mechanic said that was what I wanted to see ...
On a side note, I checked my daily driver this past weekend (prompted by engine light showing a misfire on number 3 cylinder) and got 215, 220, 160, 220 ... after getting myself worked up about it, I decided to check / adjust the valve clearances ... 240 across the board after that.
On a side note, I checked my daily driver this past weekend (prompted by engine light showing a misfire on number 3 cylinder) and got 215, 220, 160, 220 ... after getting myself worked up about it, I decided to check / adjust the valve clearances ... 240 across the board after that.
#12
Race Director
I ran a check on my 944 NA motor. It came to 138 to 140 for all 4 cylinders. I did not worry. Not really sure if that is high or low, but they are quite uniform. The motor made power however and I am not sure if I trusted the absolute value on the gauge. I did like the uniformity however.
#15
Race Car
On a side note, I checked my daily driver this past weekend (prompted by engine light showing a misfire on number 3 cylinder) and got 215, 220, 160, 220 ... after getting myself worked up about it, I decided to check / adjust the valve clearances ... 240 across the board after that.
Then again, our engine lights don't show a misfire on the #3 cylinder either.
Here's a general rule of thumb for 944 motors.
180+ Great
150+ Good
130+ Getting pretty worn.
-130 time to rebuild
That's the guide I follow
For a 951, I think it's more like
150+ Great
140+ Good
125+ Getting worn
-125 time to rebuild
However, a lot of that is strictly personal opinion.
For a comparison, The results from my previous compression test are as follows:
1: 96
2: 91
3: 105
4: 90
And, my car still runs, drives and spanks a few civics here and there.