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  #1  
Old 07-26-2007, 08:35 PM
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subzali subzali is offline
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Default He he...engine compression numbers

This is pretty awesome. I don't think these are exact, but they're within 5 psi (I left the paper in the truck. This is after warming it up for a few minutes, and cranking it over for about 4 seconds which I'm pretty sure is more than three compression cycles.

(DRY)
#1 - 110
#2 - 110
#3 - 105
#4 - 100
#5 - 105
#6 - 110

(WITH A COUPLE SQUIRTS OF OIL)
#1 - 115
#2 - 115
#3 - 110
#4 - 102
#5 - 110
#6 - 112

I think it's supposed to be around 140-150 right? Well I don't know what to say the stupid thing runs great! Maybe I'll try cranking it for a little longer in the morning to see if that makes a difference.
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  #2  
Old 07-27-2007, 03:21 PM
SteveH SteveH is offline
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The best 2F I ever measured in Denver was 119 at 5000' of elevation. At my 7000', I see 112 as a good number. So, your numbers are pretty even and good enough. Adjust the valves and drive it and don't worry about it.

Realize that compression testers can be off quite a bit, as they age and get knocked around.

Steve
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Old 07-27-2007, 07:06 PM
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That's funny, I guess spec is 113-137 or something like that. I just bought this brand new gauge and this was the first time it's ever been used. But if that's typical for this altitude, then I won't worry about it. The thing pulls hard all the way through the speed range, pulls many hills at 50-60 and can go upwards of 70-75 when it's a little flatter.
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1977 FJ40 2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering, soon to lose the Sanden OBA to go back to factory emissions
1996 FZJ80 1FZ-FE factory lockers + Safari Turbo , CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
2000 Tundra Limited TRD 2UZ-FE SOLD
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Old 07-28-2007, 08:20 PM
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Low compression isn't too bad if the numbers are still in the same range as one another. It is more a concern when you have 5 cylinders at 145, and one at 90psi.

I think your numbers aren't awesome, but they are consistant!

FWIW, mine came in at 120ish before I redid the head, then they jumped up a bit.

Drew
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Old 07-29-2007, 06:53 AM
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Yeah what I meant by awesome was that they were surprisingly low for how good the truck runs! I was actually kinda disappointed that they were so low, but now I know I can look forward to more performance if/when I play around to get those back up!
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Old 07-29-2007, 09:50 AM
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...If it ain't broke!!....
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Rezarf <><
My rig... "Maude"
1976 FJ40 with some stuff and some leaks.

1999 UZJ 100 Series bone stock ready to rock AKA:The backup minivan

2012 Toyota Sienna Minivan, fastest Toyota in the stable.

My camping trailer build up thread.

"You 80 guys are just a Sawzall away from nirvana." -Red Chili
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Old 07-29-2007, 03:14 PM
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fix it till it is!
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Old 07-29-2007, 08:39 PM
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Don't worry I have enough junk that's broke to keep me busy for a while...and like I said the truck runs great!
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TLCA# 13684
Rising Sun Bio
1977 FJ40 2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering, soon to lose the Sanden OBA to go back to factory emissions
1996 FZJ80 1FZ-FE factory lockers + Safari Turbo , CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
2000 Tundra Limited TRD 2UZ-FE SOLD
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Old 07-29-2007, 09:17 PM
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Quote:
Originally Posted by Red_Chili View Post
fix it till it is!
LOL!
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My rig... "Maude"
1976 FJ40 with some stuff and some leaks.

1999 UZJ 100 Series bone stock ready to rock AKA:The backup minivan

2012 Toyota Sienna Minivan, fastest Toyota in the stable.

My camping trailer build up thread.

"You 80 guys are just a Sawzall away from nirvana." -Red Chili
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Old 12-17-2010, 08:09 AM
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I wanted to resurrect this thread because we never talked about adjusting the compression readings for altitude. Can someone verify with me how this is done? Do you just take the ratio of atmospheric pressure at sea level to the atmospheric pressure where you're taking the reading, and multiply that by the reading the gauge gives you?

So,

Psea/Palt*Calt=Csea --> 14.7/10.6*Calt=Csea --> 1.39*Calt=Csea

Psea=atmospheric pressure at sea level (14.7 psi)
Palt=atmospheric pressure at altitude where reading is taken (10.6 psi)
Calt=compression reading at altitude where reading is taken
Csea=what compression reading would be at sea level

The reason I'm not sure about this is that if I take the numbers from above I get:
#1 - 166
#2 - 166
#3 - 159
#4 - 147
#5 - 159
#6 - 161

which seems to high for me, especially after seeing the condition of my cylinders a couple years ago.

I'm feeling stupid.
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TLCA# 13684
Rising Sun Bio
1977 FJ40 2F "Brahma" + Lockright, tach, Warn 8274, FJ60 Power Steering, soon to lose the Sanden OBA to go back to factory emissions
1996 FZJ80 1FZ-FE factory lockers + Safari Turbo , CDL switch, cup holder, AATLAS1X leather, heated seats and JDM switches
2000 Tundra Limited TRD 2UZ-FE SOLD
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