Help me figure out my compression ratio
#1
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Car: 1992 Firebird
Engine: 350TBI
Transmission: 700r4
Axle/Gears: Ford 9in 4.10
Help me figure out my compression ratio
113 Vette heads
Stock internal 305TBI
0.038 gasket thickness
4.130 gasket bore [no idea if I bought the right head gasket]
3.48 stroke
3.736 cyl bore
Thanks guys!
Stock internal 305TBI
0.038 gasket thickness
4.130 gasket bore [no idea if I bought the right head gasket]
3.48 stroke
3.736 cyl bore
Thanks guys!
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Car: 87 trans am
Engine: 5.7
Transmission: t-5
Axle/Gears: 9 bolt posi 3:27
Re: Help me figure out my compression ratio
with the info given if you go to this site you can calculate it http://www.torinocobra.com/Randys_tools.htm as with what you provided i calculated your compression to be about 10.4 to 1. if you know your deck height and piston dish or dome then you can get a more accurate calculation.
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Car: 1992 Firebird
Engine: 350TBI
Transmission: 700r4
Axle/Gears: Ford 9in 4.10
Re: Help me figure out my compression ratio
Hmmm, thanks. But that seems a little high for what I need.
Im going with a supercharger, and I heard id need to be in the 9:1 area so I dont get detonation.
What size gasket do the 305s use? Maybe ill just buy a thicker gasket, see if I can lower compression a little.
Im going with a supercharger, and I heard id need to be in the 9:1 area so I dont get detonation.
What size gasket do the 305s use? Maybe ill just buy a thicker gasket, see if I can lower compression a little.
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Car: 1992 Firebird
Engine: 350TBI
Transmission: 700r4
Axle/Gears: Ford 9in 4.10
Re: Help me figure out my compression ratio
I used this boost compression ratio calculator
http://www.rbracing-rsr.com/compression.htm
and with 6psi I got a CR of 14.67:1, which seems way high for street gas.
I thought the stock 305TBI heads had the same head size as the 113 heads at 58cc, the supercharger I got is made for the 305/350TBI engines, so I think something has to be off here.
http://www.rbracing-rsr.com/compression.htm
and with 6psi I got a CR of 14.67:1, which seems way high for street gas.
I thought the stock 305TBI heads had the same head size as the 113 heads at 58cc, the supercharger I got is made for the 305/350TBI engines, so I think something has to be off here.
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Car: 87 trans am
Engine: 5.7
Transmission: t-5
Axle/Gears: 9 bolt posi 3:27
Re: Help me figure out my compression ratio
whats your piston dish/dome volume and your deck height that will help in the calculations
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Car: 89 Camaro RS
Engine: LO3 TBI
Transmission: 700R4 => WC T-5
Axle/Gears: 3.42 Open Diff
Re: Help me figure out my compression ratio
Well if you haven't decked the block then you have a .025 deck height.
What did your pistons look like? Dish or flat top? Basically it's going to be 5cc or 8cc piston volume.
8cc pistons = 8.93:1
5cc pistons = 9.24:1
What sort of cam are you running?
EDIT
going to run the XFI268 I see in your sig?
What did your pistons look like? Dish or flat top? Basically it's going to be 5cc or 8cc piston volume.
8cc pistons = 8.93:1
5cc pistons = 9.24:1
What sort of cam are you running?
EDIT
going to run the XFI268 I see in your sig?
Last edited by Saabster; 08-17-2008 at 07:41 AM.
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#8
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Car: 1992 Firebird
Engine: 350TBI
Transmission: 700r4
Axle/Gears: Ford 9in 4.10
Re: Help me figure out my compression ratio
Thanks!
And yes, I am going to run the XFI268, its sitting right in my garage.
Not sure about the pistons, engine is still sitting in the car, ive been working on the rear end/brakes getting all that set before I moved on to the engine.
But it would be whatever stock was.
And yes, I am going to run the XFI268, its sitting right in my garage.
Not sure about the pistons, engine is still sitting in the car, ive been working on the rear end/brakes getting all that set before I moved on to the engine.
But it would be whatever stock was.
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