compression ratio '85
Thread Starter
Race Director
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compression ratio '85
My brother needs a motor for his truck, I have the original motor out of my '85 and an old set of 64cc heads. does anyone know what the compression ratio would end up at if you put 64cc heads on a stock '85.
thanks Greg
:cheers:
thanks Greg
:cheers:
Le Mans Master
Joined: Apr 2000
Posts: 6,341
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From: Shelton CT
Re: compression ratio '85 (atotalnincompoop)
IF the '85 engine is in good condition and compression is still good on it, I'd guess 9.8 or around there.
Stock is 9.5 with 74cc or is it 76cc iron smog heads..
Stock is 9.5 with 74cc or is it 76cc iron smog heads..
Drifting
Joined: Nov 2001
Posts: 1,783
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From: Latham NY
Re: compression ratio '85 (atotalnincompoop)
Try this compression ratio calculator:
http://www.rbracing-rsr.com/compstaticcalc.html
http://www.rbracing-rsr.com/compstaticcalc.html
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From: The Top of Utah
Re: compression ratio '85 (MrNuke)
IF the '85 engine is in good condition and compression is still good on it, I'd guess 9.8 or around there.
ok, but what if i changed the heads from 76cc to 64cc?
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[Modified by CFI-EFI, 8:10 PM 6/19/2003]
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Re: compression ratio '85 (CFI-EFI)
IF the compression ratio is in fact 9.0:1 with 76 CCs, You're looking at an increase to 10.2:1 :yesnod:
You don't need those equations if you know the original ratio and the changes in chamber volume.
R1,R2 = comp ratio, before and after
D = displacement per cylinder (350/8 cid = 716.6 cc)
C1,C2 = cyl head vol, before and after
CC= combustion chamber volume
R2 = 1+ D / [D / ( R1 - 1 ) + C2 - C1]
:cheers:
[Modified by CentralCoaster, 3:13 AM 6/20/2003]
You don't need those equations if you know the original ratio and the changes in chamber volume.
R1,R2 = comp ratio, before and after
D = displacement per cylinder (350/8 cid = 716.6 cc)
C1,C2 = cyl head vol, before and after
CC= combustion chamber volume
R2 = 1+ D / [D / ( R1 - 1 ) + C2 - C1]
:cheers:
[Modified by CentralCoaster, 3:13 AM 6/20/2003]
Thread Starter
Race Director
Joined: Mar 2002
Posts: 12,968
Likes: 0
Re: compression ratio '85 (CentralCoaster)
IF the compression ratio is in fact 9.0:1 with 76 CCs, You're looking at an increase to 10.2:1 :yesnod:
You don't need those equations if you know the original ratio and the changes in chamber volume.
R1,R2 = comp ratio, before and after
D = displacement per cylinder (350/8 cid = 716.6 cc)
C1,C2 = cyl head vol, before and after
CC= combustion chamber volume
R2 = 1+ D / [D / ( R1 - 1 ) + C2 - C1]
:cheers:
[Modified by CentralCoaster, 3:13 AM 6/20/2003]
You don't need those equations if you know the original ratio and the changes in chamber volume.
R1,R2 = comp ratio, before and after
D = displacement per cylinder (350/8 cid = 716.6 cc)
C1,C2 = cyl head vol, before and after
CC= combustion chamber volume
R2 = 1+ D / [D / ( R1 - 1 ) + C2 - C1]
:cheers:
[Modified by CentralCoaster, 3:13 AM 6/20/2003]