Tested Compression....thoughts?

five_o_stang

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Nov 22, 2004

#1

• Nov 22, 2004

• #1

Thanks for the info on my remote starter...turns out I just misread the directions.

In any case, I got the compression tested. As some of you may no from another post of mine, I'm trying to decide between a build up from scratch..or go ahead an continue using my current shortblock (165K miles).

Here are the results:

Cyl #1 Compression rated at about 165psi (this was about 15psi lower than the others. First stroke read about 120psi then uniform increases up till peak compression on 5th stroke. 2nd try yielded same results.

Cyl #2 First stroke read about 120psi then steady increases to 180psi

Cyl #3, 4, 5, 6, 7 were same as Cyl #2.

Cyl #8 First stroke about 120psi...then on the third and fourth stroke it kinda stayed around 150psi..then on 5th stroke on it read 180psi. I repeated the test on this cylinder twice with same results.

Gimme some opinions on these numbers....I gotta decide quick cuz i need to tell my mom to either A) get me a shortblock...or B) new mods ..for Christmas.


Thanks in advance...I'll be back in an hr or so to check posts.

 

HISSIN50

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#2

• Nov 22, 2004

• #2

i would be quite happy with those numbers myself.

 

90mustangGT

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#3

• Nov 22, 2004

• #3

Sounds pretty good. When I did a compression test on mine, it read all within 10lbs of each other. The first stroke it only read aroun 40-50psi, and built up steadily to a best of 165, and a worse of 155. Good compression, but a little slow to build. I did a leakdown test and found I had between 26-50% leakdown. That chimed the death bell for my shortblock. It is currently being torn down.

 

HISSIN50

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#4

• Nov 22, 2004

• #4

Jason, is the Silverado a new ride for ya (while the stang is down and for future towing, etc)?

 

five_o_stang

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Nov 22, 2004

#5

• Nov 22, 2004

• #5

How would those numbers fair in terms of strappin on a blower (over the next couple of years...probably at 180K miles on the shortblock)....the build up i'm planning would net about 450hp (flywheel) or atleast that's where I'm gonna try to cap my limit w/ a stock block for safe reliability.

Any other thoughts on that?..

 

HISSIN50

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#6

• Nov 22, 2004

• #6

five_o_stang said:

How would those numbers fair in terms of strappin on a blower (over the next couple of years...probably at 180K miles on the shortblock)....the build up i'm planning would net about 450hp (flywheel) or atleast that's where I'm gonna try to cap my limit w/ a stock block for safe reliability.

Any other thoughts on that?..

Click to expand...

depending upon how you set it up, i dont see a problem with it personally (im not as blower savvy as some folks in here). who knows, by then you might have a fresh mill in there anyhow. when it gets to be time, i might check compression (and i would do a leakdown test too) and go from there.

my two cents.
good luck.

 

90mustangGT

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Nov 23, 2004

#7

• Nov 23, 2004

• #7

HISSIN50 said:

Jason, is the Silverado a new ride for ya (while the stang is down and for future towing, etc)?

Click to expand...

Yup, my new ride. I got it earlier this month. I love it. I had a Grand Am for a daily driver, not only was it a girl's car but it was just a POS. I really wanted to save money to invest in the 5.0, like a 347 and such but I wanted something nice that I could just drive. The truck is real quiet, rides real nice, total oppisite of the mustang. Plus I will have something as you said, to tow the mustang when I need it. Gas milege is pretty good on it for a full size truck, and it will scoot when I get on it, has alot of top end pull. Buddy of mine who's a Silverado enthusiast says the motor puts down about what it is rated to the wheels, and only weight 4000lbs, if not under.

 

HISSIN50

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#8

• Nov 23, 2004

• #8

Jason glad to hear you finally got yourself a truck (knew you had wanted one). less work than the Ranger-5.0 tranplant too.

a quiet DD can be nice, so i know what you mean (i find that when cars get too modded, i have to be a the 'mood' to drive them; a clean DD is great). enjoy!

 

8

87'GTstang

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#9

• Nov 23, 2004

• #9

If you clock higher than 90 psi on the first stroke, and each cylinder is +/- 10% of each other, then you should be fine. A leak down test will tell you the real tale of the engine, but with the way the rest of it looks, you should be good for a blower. Just keep in mind though, whatever deficiencies you have in your engine, the blower will only accelerate it.

 

Michael Yount

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Nov 23, 2004

#10

• Nov 23, 2004

• #10

While the numbers are respectable, if you're planning on boost on a 165K short block, I'd rebuild. If you're just gonna add H/C/I - I'd probably feel comfortable with the shortblock the way it is. But with that many miles on it, and the added stresses that boost brings - I'd want to be certain that everything is in good shape. Seems easier to invest a bit more while you've got it out for a clean up bore, new rings and bearings. Just me though - kinda conservative.

 

five_o_stang

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Nov 23, 2004

#11

• Nov 23, 2004

• #11

yeah..i'm still really debating this. I was thinkin' about getting a used shortblock...tearing it down..have everything machined..put it back together and then start a slow engine build up until i have everything I want then stick it in the car...but at the same time I wanna throw everything I can at my current motor for the "fast now" greed that lives within me. Ugh...this is frustrating. Of course...if I strap the blower on there....a new bottom end isn't really THAT expensive..hehe.. oh well...i'm gonna keep mulling this over. Thanks for the tips guys.

 

Michael Yount

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Nov 24, 2004

#12

• Nov 24, 2004

• #12

Slow and steady wins the engine building race. Take your time - you'll be glad that you did.