Have a standard bore 4.32 2295 TRW/Speed Pro pistons. Lets assume stock deck height, 6.76 stock rod, stock 3.75 stroke, and corrected 88cc heads using a 4.49 diameter gasket at .038-.040 thick compressed.
My swag is saying 9.6:1-9.8:1 or so.
I cant find much info on these pistons, as far as dome volume. Summit list them at -12 cc or so.. The negative (-) part is throwing me off.

Its been more than a few years since ive heard mention of those. I put together a motor back in the 80s with them, if i remember trw used to list them as a "12.5-1" piston but i think they come out somewhere around 11.4-1. Hope that helps

Thanks
Yea I recall the adv compression was way up there.
No way they are that high. With a uncut deck they are .060 in the hole, or there bouts. Combined with a 88cc head they cant be much more than 10:1 if that.
I mean a near zero deck -4cc valve relief stroker engine 493-499 cid is real close to 11:1 with eddy heads 84cc

The " - " is a dome. When you figure compression ratios, a negative is actualy the amount of cc it is displacing in the bore so to speak. Negative is a dome, positive is a flat top with reliefs. The relief would be a valve pocket/s.

Theoretical C/R because the 2295 is a 2.029 C/H piston:

# of Cyl. 8
Bore 4.3200
Stroke 3.7500
Rod Len. 6.760
Gskt Bore 4.490
Comp. Gskt .0400
Block Deck Ht. 10.7200
Top ring down 0.280
Chamb. Vol. 88.0
Dome (-) Dish -12.00
Piston / deck 0.000

Total volume 988.49
Cylinder volume 900.72
Clearance volume 87.77
Gasket volume 10.38
Top ring volume 1.39
Deck volume 0.00
Piston top land 4.275
1/2 Stroke 1.875
Comp. Ht. 2.085
Cubic Inches 439.72
Compression ratio 11.26

Now lets do it at the 2.029 ( .051 in the hole):

# of Cyl. 8
Bore 4.3200
Stroke 3.7500
Rod Len. 6.768
Gskt Bore 4.490
Comp. Gskt .0400
Block Deck Ht. 10.7200
Top ring down 0.280
Chamb. Vol. 88.0
Dome (-) Dish (+) -12.00
Piston / deck 0.051

Total volume 1000.74
Cylinder volume 900.72
Clearance volume100.02
Gasket volume 10.38
Top ring volume 1.39
Deck volume 12.25
Piston top land 4.275
1/2 Stroke 1.875
Comp. Ht. 2.026
Cubic Inches 439.72
Compression ratio 10.01

Todd Rules
Thanks Buddy

speed pro trw shows comp height 2.029 with 11.34 to 1 with 88cc and 10.34 with 78.5cc but it doesn't give no info on what head gasket or how far down in the hole they are getting those #'s from. http://www.campbellenterprises.com/mopar_speed_pro_trw_forged_pistons.htm

I got 9.9:1 with 0.060" in the hole.

I have a 1976 TRW performance parts catalog, it show that the L2295F stock bore has a 13.10 effective dome volume, with a .022 thick head gasket and a deck clearance of .020 with a 85.40 CC combustion chamber you should have 11.90 to 1 comp. ratio. you can use the dome volume to plug into one of the on line calculator with different deck hieghts and combustion chamber volumes to get the calculated compression ratio of what you have listed. I have used the exact same numbers on Wallaces and KB sites and ended up with different compression ratio

Thats a 35 year old spec! The " newer" Speed Pro catalogs have it listed as -12 and 2.029.

I have 2 sets in front of me, one which is like the old S/P 7025P and the other is actually marked as a L2295F....both are 2.029 ( within a few thousandths.I personally modified the one set over 15 years ago, and its the same C/H.

My math is correct. 1.875 + 2.029 + 6.768 + 10.672 + (.051 in hole) =10.723...close enough to call 10.725