Doing compression check; what are the numbers I need?

LXSTASY

Founding Member

Apr 25, 2000

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Long Island, NY

Jul 21, 2005

#1

• Jul 21, 2005

• #1

This Saturday I plan on doing a compression check before I go gung-ho on my HCI install. What are the numbers and average numbers I should be praying Friday night to get?
I've read 125-130, but then another post was suggesting 200 (which I think is wayyy to much), but non the less I still am confused.
Any numbers or tips would be great
Dan

 

Ourobos

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Apr 12, 2004

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Jul 21, 2005

#2

• Jul 21, 2005

• #2

Depends on different things.. You really want to see all eight numbers withing 10% of each other to be good to go.

 

90mustangGT

I felt sorry for girls because

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Jan 15, 2002

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Dallas, GA

Jul 21, 2005

#3

• Jul 21, 2005

• #3

As long as they are above 70psi and within 25%, so your good. The compression test numbers have a lot to do with the cam and other factors.

edit- 10% is what you really want as mentioned before, but 25% is "acceptable" but not nessasarlly good.

 

D

double drop top

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Apr 25, 2005

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Chandler Arizona

Jul 21, 2005

#4

• Jul 21, 2005

• #4

A leak down test is more important then the compression test. But I always do both to get a complete picture of the condition of my engines.

 

HISSIN50

"How long does it take to get help in here?

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Nov 29, 1999

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Jul 21, 2005

#5

• Jul 21, 2005

• #5

And though testing means differ, I would really not want to do a HCI on a motor which did not have even compression and a mean number of ~125 PSI (if you get lower numbers, at least do a Leakdown test first!).

Good luck.

 

LXSTASY

Founding Member

Apr 25, 2000

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Long Island, NY

Jul 22, 2005

#6

• Jul 22, 2005

• #6

Yea thanks guys,
I will do it and see what I come up with