What compression are these pistons (pic)

My Black Beast

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Jul 18, 2002

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Lakeland, FL

Jan 17, 2006

#1

• Jan 17, 2006

• #1

Hey, I just took the heads off the car and I know the engine has been rebuilt before I got the car. I was just wondering if anyone knows around what compression ratio those pistons are giving me. I have stock heads on it also. Thanks, Mike

 

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Rick 91GT

Mustang Master

Nov 29, 1999

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PA

Jan 17, 2006

#2

• Jan 17, 2006

• #2

I would say with a stock head you would be in the 8.XX range. CC the reliefs, once you know how much volume they take up I could give you an accurate number. Do they have a PT# scribed in the tops under all the build up?

 

My Black Beast

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Jul 18, 2002

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Lakeland, FL

Jan 18, 2006

#3

• Jan 18, 2006

• #3

Since they are domed pistons, wouldn't that raise the compression? Isn't the stock compression like 9:1. Mike

 

poneypower89

Now everyone in the world will know I wanna bang t

Dec 6, 2004

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Indianapolis, Indiana

Jan 18, 2006

#4

• Jan 18, 2006

• #4

Yes, if they are doomed pistons the compression should raise. We (some buddies) built a 302 last year with some doomed pistions and stock heads.. compression was right around 11:1... but its hard to tell by just looking at ur pistons what compression you may be running.

 

1

1SLO306

My 97 GTP owns you ALL!

Mar 31, 2005

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17

Muhlenberg, ky

Jan 18, 2006

#5

• Jan 18, 2006

• #5

poneypower89 said:

but its hard to tell by just looking at ur pistons what compression you may be running.

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I was thinking the same

 

MadDAWG_zr2

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Jan 6, 2004

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Jan 18, 2006

#6

• Jan 18, 2006

• #6

those look like the Keith Black pop up pistion. when I ran them with a 58cc head they were just short of 11:1 on a 0.040 over bore.

 

retro50

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Jul 15, 2003

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Plymouth,MA

Jan 18, 2006

#7

• Jan 18, 2006

• #7

They look like the old TRW's to me! If they have a .440 dome there probably TRW Forged. If they have a .200 dome then there probably Keith Black Hyperutectic. If they are the K.B. pistons then You'll have high 9's-low 10's on the compression ratio with a 60c.c. head, uncut block and around a .042 gasket. I don't have a Federal Mogul Book in front of me to give you a round about figure on the TRW's.

 

My Black Beast

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Jul 18, 2002

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Lakeland, FL

Jan 18, 2006

#8

• Jan 18, 2006

• #8

retro50 said:

They look like the old TRW's to me! If they have a .440 dome there probably TRW Forged. If they have a .200 dome then there probably Keith Black Hyperutectic. If they are the K.B. pistons then You'll have high 9's-low 10's on the compression ratio with a 60c.c. head, uncut block and around a .042 gasket. I don't have a Federal Mogul Book in front of me to give you a round about figure on the TRW's.

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Dude, right on the money!! TRW sounded a little familiar so I checked the pistons and one of them said TRW and they all said L2249N 030. Can anyone tell me anything about these pistons?

Somebody sure knows their pistons...

Thanks, Mike

 

bill302

Active Member

Nov 2, 2005

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alabama,gadsden

Jan 18, 2006

#9

• Jan 18, 2006

• #9

.440 dome, Part #'s starting with "L" = Forged,bored .30 over

 

bill302

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Nov 2, 2005

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alabama,gadsden

Jan 18, 2006

#10

• Jan 18, 2006

• #10

with a 60 cc head you have 10.3:1

 

My Black Beast

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Lakeland, FL

Jan 18, 2006

#11

• Jan 18, 2006

• #11

The previous owner said that the engine is a 306. Would that still be true if I have .030 pistons? I thought 306's would have .040, or am I completely off base here? Thanks, Mike

 

M

mikemustang289

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Jan 12, 2006

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mesa, az

Jan 18, 2006

#12

• Jan 18, 2006

• #12

.040 over is a 308

 

bill302

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Nov 2, 2005

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alabama,gadsden

Jan 18, 2006

#13

• Jan 18, 2006

• #13

a 306 is a 302 bored over .030. without stroker kit you have a 306.

 

retro50

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Jul 15, 2003

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Plymouth,MA

Jan 18, 2006

#14

• Jan 18, 2006

• #14

Pistons are L2249NF They made these in std.+.030. Bore sizes only. They have a 1.600 Compression Height and a .440 dome. The listed compression Ratio is anywhere from 9.91- 12.85 depending on the cylinder head c.c. (chamber size). With a stock 60 c.c. Head (69-70 351-w) the compression ratio is listed as 11.17:1 with a .036 gasket and the quench pad on the piston down in the cylinder .010. I'd say your compression is in the high 10's with a E-7 Head without knowing any specifics. I got these #'s out of an old 1989 TRW catalog I had Laying around. The ring grooves are listed as 1/16"x1/16"x3/16". Put on a good set of heads and match a cam and int/ex systems and the car will fly. The stock heads are not a good match for those pistons unless they are worked pretty good.

 

My Black Beast

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Lakeland, FL

Jan 19, 2006

#15

• Jan 19, 2006

• #15

bill302 said:

a 306 is a 302 bored over .030. without stroker kit you have a 306.

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Thanks a lot guys. I guess I got a little confused with the numbers. I am going to be putting the car up for sale since I just bought a house and I am going to focus on the 2.3T for now. This info will help in selling the car. Thanks again, Mike