compression readings for a new 1987 xr2 150

[EBENZER]

Guys whats the compression readings on a stock new 1987 xr2. I have read everything from 120 to 140?

 

[Bob_VT]

Re: compression readings for a new 1987 xr2 150

The key is balanced compression ....all cylinder's being within 10% of each other.

It could be 90 lbs and run great all the way up to 160 lbs

10% is the key

 

[JB]

Re: compression readings for a new 1987 xr2 150

We get this question (What should compression be?) five or six times a day, 365 days a year. That means I have seen it over 18,000 times.

The answer is always the same: There is no psi specification. There are too many variables.

The specification is for comparison among the cylinders. When measured in identical manner at the same time all cylinders should fall within a 10-15% range. That will be a healthy engine whether it is measuring 80psi or 165psi.

 

[EBENZER]

Re: compression readings for a new 1987 xr2 150

thanks bob..i know 10% between cylinders. so what your saying is compression varies even between same new engine. so is there a low point.. i mean is 80 to low..

 

[Dukedog]

Re: compression readings for a new 1987 xr2 150

If tha guage is accurate thats LOW! Time ta take a look............

 

[sschefer]

Re: compression readings for a new 1987 xr2 150

Guys whats the compression readings on a stock new 1987 xr2. I have read everything from 120 to 140?

A freshly built 2.0l motor with exhaust reliefs in the cylinders and stock uncut heads will produce 115-120lbs of compression.

Contrary to popular belief a V-6 Merc with 100lbs of compression will be harder to start, prone to flooding and not reach recommended WOT RPM's unless under propped.

You can take that to the bank...

 

[Faztbullet]

Re: compression readings for a new 1987 xr2 150

If tha guage is accurate thats LOW! Time ta take a look............

100% agree Ddog!!!! The 1987/88 block was the BEST 2.0 block and has no idle reliefs, has the "hemi" heads and compression is around 120-130psi and 110psi would be low. From the factory it was about 160 hp.This block with a little port massaging and some bolt on mod's can make a easy 185hp @ 6500 rpm where the idle relief cut blocks hit a wall at 5800 rpm.

 

[sschefer]

Re: compression readings for a new 1987 xr2 150

100% agree Ddog!!!! The 1987/88 block was the BEST 2.0 block and has no idle reliefs, has the "hemi" heads and compression is around 120-130psi and 110psi would be low. From the factory it was about 160 hp.This block with a little port massaging and some bolt on mod's can make a easy 185hp @ 6500 rpm where the idle relief cut blocks hit a wall at 5800 rpm.

Ebenzer, FB's given you the numbers you were asking for.

You say its a new 87. Does that mean that it's the original powerhead recently rebuilt or is it a replacement powerhead? If you could look on the block above and just to the left of #5 there will be a number cast into the block. It should start with 884-xxxx or something similar. If you post that, we can tell you exactly what your compression should be.