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  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

Stock cylinder compression???

  • Thread starter Thread starter youwin
  • Start date Start date Feb 12, 2007
Y

youwin

New Member
Feb 22, 2006
7
0
0
Feb 12, 2007
#1
  • Feb 12, 2007
  • #1
ive done all the sreaching i can its time to call out the big guns...you's guys.

i have a fully bolt-on 98 GT with about 115,000 on the clock, it put down 225RWHP about a year ago in the identicle trim it is in, the only thing im interested in next is a SCT tune and about a 50-60 shot for those few people i need it for ( i live in ricer central).

when i checked the compression about 6 months ago all the cylinders read 145 except for numbers 6 and 7 they read 135, and 138. i did a few oil changes with "engine restore" and the latest was 148 all around and both 6 and 7 were at 145. now before i go and tune her and even think about adding DRY nitrous of all things to a motor as old as mine and with the miles shes got, i need to know what they were supposed to be at stock???

If any of you can help i have failed completely in trying to retrieve the right numbers for what the compression should be. also im not interested in trying to tear into this motor at all i have 2 years left in college then its a complete rebuild of the entire car. so if thses numbers are way off then ill just 86 both the tune and the nitrous, but if there pretty close to where they should be, and WIFE permitting then i will go ahead further with my plans.
 

fast97gt

Active Member
Jan 2, 2007
1,082
2
49
north carolina
Feb 12, 2007
#2
  • Feb 12, 2007
  • #2
iight bear with me, some might not agree, but im taking this out of a repair manual. your lowest reading cylinder should be within than 15psi than your highest reading cylinder. but the min. cylinder press. cant be no less than 100psi.
so if your readings are above 140psi you should be fine.
 
Y

youwin

New Member
Feb 22, 2006
7
0
0
Feb 12, 2007
#3
  • Feb 12, 2007
  • #3
that'll work for me.
 
Y

youwin

New Member
Feb 22, 2006
7
0
0
Feb 12, 2007
#4
  • Feb 12, 2007
  • #4
so one guy has an ideah of were it "should" be for my compression
 

LaserRed01GT

Banned
Oct 3, 2006
739
3
0
Clearwater, FL
Feb 12, 2007
#5
  • Feb 12, 2007
  • #5
The cylinders should measure within 25% of each other.

Here is the compression chart:

View attachment 403871
 
Y

youwin

New Member
Feb 22, 2006
7
0
0
Feb 12, 2007
#6
  • Feb 12, 2007
  • #6
thanks for the chart, now off for a tune...
 

LaserRed01GT

Banned
Oct 3, 2006
739
3
0
Clearwater, FL
Feb 12, 2007
#7
  • Feb 12, 2007
  • #7
Anytime Brent. Hey do me favor and PM me the details of how it goes with Jeremy when and if you should choose to use him.
 
Y

youwin

New Member
Feb 22, 2006
7
0
0
Feb 12, 2007
#8
  • Feb 12, 2007
  • #8
will do, gunna call him up tomarrow on my day off
 
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