Compression Test 125-130 Across

[krummel21]

I would like to get everyone's opinion on my compression test results:

1: 130
2: 132
3: 130
4: 125

The modifications for this engine are:

Mild port and polish, 101300 Comp Cams (similiar to 280s), and stock 6-bolt bottom end.

I just changed the oil and there was no coolant in it and there is no oil in my coolant.


Thanks for your help ahead of time.

 

[jaredwhamilton]

How many Miles are on the motor?

 

[92AWDHX40]

Opinon on engine those numbers dont look bad on my 6 bolt.

 

[SPYDERGSTTUNER]

I have those exact same cams on my stroker, I had 155 all across the board which I thought was low but depending on the miles,wear and tear on your motor, and a few other factors as long as all numbers are -+15 of each other you should b OK.


Did you do a cold or hot compression test? Was the throttle plate open?

 

[krummel21]

Thanks for the fast responses. The engine has around 80,000 miles on it and the compression test was done warm and throttle plate was open.

Do you guys think it is getting to the end of it's life and I need to look getting a new engine before having it tuned or should I be OK. I have an engine lined up now, I just want to make sure I actually need it.

Thanks again

 

[Maikus08]

Do you feel any abnormal function or behavior on your car, on the city on the highway... going really fast...
I want to know with those number if the proper functionality of the car can be sensed...

 

[krummel21]

Since the car isn't tuned i don't rev past 3k and don't have a chance to really tell if i have lost a lot of power. But it does cruise just fine.

 

[donniekak]

Looks ok for 7.8:1 compression, and 280's. What's Important is that there are no huge differences.

 

[Maikus08]

Since the car isn't tuned i don't rev past 3k and don't have a chance to really tell if i have lost a lot of power. But it does cruise just fine.

shouldn't you had to make the test compression befote the tunning?

 

[Captn]

I think you're ok as long as the numbers are within 15% of each other. If it was me though I would rebuild.

 

[nickk90]

If you are really worried do a leakdown test. It will tell you more than a compression test.

 

[Maikus08]

If you are really worried do a leakdown test. It will tell you more than a compression test.

you mean a boost leak test?

 

[bryanwheat]

you mean a boost leak test?

No, a leakdown test is what he is talking about. You pressurize the cylinders to see if it is leaking from the valves or rings.

 

[Abe'sGST]

you mean a boost leak test?

no he means a leakdown test

 

[bryanwheat]

no he means a leakdown test...if his compression goes up significantly on any cylinder that tells him his rings are on their way out and time for a rebuild.

I think that you are confusing a leakdown test with a wet compression test.

 

[Abe'sGST]

By those numbers I would think the results look low compared to most vehicles, I'm not too sure how much compression these engines usually have. If you don't feel anything bad when driving and under WOT (you need to drive it under WOT to see how it runs) you should be ok since the numbers aren't too bad apart from each other.

 

[bcjjones]

Leakdown test wouldn't be a bad idea, and dont confuse that with a wet compression test.

 

[Abe'sGST]

I think that you are confusing a leakdown test with a wet compression test.

! I can't believe I just said that, sorry man getting sleepy.

EDIT: Just removed my post so I won't confuse someone.

 

[jed344]

Aren't those numbers kinda low for a 6bolt though even? My 7 bolt with 148k on it tested at 150-160 across the board.

 

[bryanwheat]

Aren't those numbers kinda low for a 6bolt though even? My 7 bolt with 148k on it tested at 150-160 across the board.

He does have bigger cams which could cause the compression to be a little lower. The compression tester could be reading low also.

 

[krummel21]

I ordered a leak down tester yesterday, my question about that though is with cams like these will the valves be closed at TDC or is one of them already starting to open?

 

[BogusSVO]

Set it at TDC, start the leakdown test, if it is abnormal, rock the crank with a ratchet and see if it falls into place.

 

[banshee04]

The compression results look good to me. As long as there pretty close to each other, its most likely fine.

Also, gauges read differently. Ive had a Snap-On, Harbor Freight, Craftsman and each one had a bit different results.

 

[krummel21]

Is a leak down test even necessary on this since all of the cylinders are showing close to the same numbers?

 

[DSMTyson]

A 6 bolt with that many miles would normally have 140-155psi across the board.

Thats low, but acceptable I guess...