What should compression numbers be??

[Jeremy Hohn]

SDPATT and I are going to check compression on my car to see if that is causing loss of torque. What numbers should we be seeing? Thanks.

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Jeremy

1993 atx 126k miles
ENGINE:
-SHOSHOP underdrive pulleys
-SHOSHOP cold air induction
-SHOSHOP 80mm MAF
-Ted Breaux LPM
-Performance Plus y-pipe
-SHOSHOP catback exhaust with Magnaflow chrome tips
-Redline Water Wetter
-fresh 60k (SDPATT)
TRANNY:
-Rebuilt 94/95 axod tranny with trans-go kit and Redline Type 3 ATX fluid
BRAKES:
KVR cadmium plated and cross drilled rotors with performance friction pads
APPEARANCE:
-Colgan hood cover with SHO lettering
-Lund blackouts front and back
-Cincysho white face gauges
-black body filled s-h-o lettering
-Blazer fog lights
-PIAA high output headlamp bulbs (fratperformance.com)
-fish-tank bulbs installed
-wclewis "powered by yamaha" black badges

 

[drivinhard]

Most healthy SHO's tend to be 200+. Be sure to do it with the car warmed up.

The 3.2L in the 89 went 213, and 210 on the other 5. Suz's 91 was 218, and 220 on the other 5.

The first 89 I had was all over the board, from 175 to 210. Burned oil like crazy. And still ran 14.30's @ 98+ mph. So don't put all your stock in good compression numbers.

Just another curious question, do you have your tranny overfilled by a bit?

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White 92
SR71SHO - racer '89

 

[olympic]

I agree with drivenhard, have the engine warmed up. Also, do the test with all 6 plugs out and hold the throttle body open so the engine can get air. Specific numbers arn't as important as having all 6 within a small range of PSI.

 

[Fmaitland]

According to the Ford Manual I have, 1995 SHO, you warm the engine with correct oil level and viscosity,
remove all plugs,
set throttle to wide open,
start with cylinder #1,
do 5 compression strokes and record the highest value, making note of the required # of strokes to record the highest,
do the others with the same number of strokes recording the value,
On SHO 3.0L & 3.2L the reading of the lowest cylinder should be within 85-100 percent of the highest reading,
the table they give for the SHO starts with if the max is 134 then the lowest has to be a min of 114,
the top of the table is Max 250 min of 213
Hope this helps as I tried to condense the manual into this reply.
Good Luck,
Fred

 

[luigisho]

Hey, nice job Fred. Are you the one whose daughter's SHO is acting up? Just wondering how that was going.
Jeremy good luck. I'm sure you and Scott will be able to pinpoint the problem.