Turbo size for a 632 cubes
10-20-2005, 10:00 AM
#1
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Turbo size for a 632 cubes I know this is not a LSX motor, but a buddy of mine is building a 632 and is looking into going turbo instead of nitrous. The question is what size turbo will be efinciant at 25 to 30 lbs of boost. He is wanting to go single and we have been talking about a 88 or 101mm. I don't really know how to read compressor maps so I figured I would ask since there are a few good turbo guroos on here.
10-20-2005, 10:06 AM
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I don't have a good answer because I haven't looked at maps or anything, but I will tell you they are easy to figure out and read. www.forcedinductions.com has many maps and some explination on how to read and use them. Same with www.turbomustangs.com. I don't know where you'd get the air consumption numbers, though.
I'd guess and say twin T70-74's, or at least a 94mm single.
EDIT: looking around at a chart for a 496 you'd need twin 76's for that and 30psi (at only 6500rpm)...so what smokin says right below here is right...twin 88's or like a 106+
I'd guess and say twin T70-74's, or at least a 94mm single.
EDIT: looking around at a chart for a 496 you'd need twin 76's for that and 30psi (at only 6500rpm)...so what smokin says right below here is right...twin 88's or like a 106+
Last edited by RyanJ; 10-20-2005 at 10:16 AM.
10-20-2005, 10:26 AM
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Air consumption is pretty easy to figure:
CI/2 x rpm/1728 x VE x.069 = pounds per minutes (ppm) of air N/A
Divide CI by two to account for a power stroke every 2 revs. 1728 is how many CI in a CFM. .069 is how many pounds of air in a cubic foot. Volumetric efficiency is about .85 for a stock motor, .90 for a mildly built and .95 for a big cam, etc. Those are ballpark VE's.
Now for boost:
The pressure ratio = (14.7+ boost psi)/14.7
The 14.7 psi is normal atmospheric pressure.
Now that you have the 2 figures, just multiply the ppm N/A by the pressure ratio for the air demand at that rpm.
Ex:
632/2 x 6000/1728 x .95 x .069 = 71.9 ppm N/A
(14.7+30)/14.7 = 3.04 pressure ratio
71.9 x 3.04 = 218.6 ppm of air @ 6000 rpm and 30 psi boost
10.86 hp per pound of air makes it 218.6 x 10.86 = 2375 crank hp. BTW that's about 3200 CFM.
That's some purty big numbers. HTH
CI/2 x rpm/1728 x VE x.069 = pounds per minutes (ppm) of air N/A
Divide CI by two to account for a power stroke every 2 revs. 1728 is how many CI in a CFM. .069 is how many pounds of air in a cubic foot. Volumetric efficiency is about .85 for a stock motor, .90 for a mildly built and .95 for a big cam, etc. Those are ballpark VE's.
Now for boost:
The pressure ratio = (14.7+ boost psi)/14.7
The 14.7 psi is normal atmospheric pressure.
Now that you have the 2 figures, just multiply the ppm N/A by the pressure ratio for the air demand at that rpm.
Ex:
632/2 x 6000/1728 x .95 x .069 = 71.9 ppm N/A
(14.7+30)/14.7 = 3.04 pressure ratio
71.9 x 3.04 = 218.6 ppm of air @ 6000 rpm and 30 psi boost
10.86 hp per pound of air makes it 218.6 x 10.86 = 2375 crank hp. BTW that's about 3200 CFM.
That's some purty big numbers. HTH
10-20-2005, 10:31 AM
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He is wanting to make 2500 to 3000 hp. So it seems that twins is the way to go. Also the car is set up to run in the 1/8 not the 1/4. I assume this will play a factor in what AR housing will be used to spool say two 88's quickly?
10-20-2005, 10:34 AM
#7
1/8th mile, you don't have the luxury of back dooring like alot of the large single turbo cars do. You would need a 101 minimum for that power level.
What tire does he have to run? Getting a pair of 80's or 88's lit with 600+ cube won't be a problem. But putting it to the track will
What tire does he have to run? Getting a pair of 80's or 88's lit with 600+ cube won't be a problem. But putting it to the track will
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10-20-2005, 11:51 AM
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Originally Posted by y2khawk
1/8th mile, you don't have the luxury of back dooring like alot of the large single turbo cars do. You would need a 101 minimum for that power level.
What tire does he have to run? Getting a pair of 80's or 88's lit with 600+ cube won't be a problem. But putting it to the track will
What tire does he have to run? Getting a pair of 80's or 88's lit with 600+ cube won't be a problem. But putting it to the track will
The car will run 10.5 W' or will be able to run 33x15's. i talked to him at lunch I guess it's twin 88's! This is going in a 68 camaro by the way.
10-20-2005, 12:08 PM
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106 if single, Twin 88's or 91 for the dual configuration. With 632CI's lag is not an issue. Let us know if you need any help. We work with alot of 10.5 guys.
10-20-2005, 01:45 PM
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Originally Posted by JZ 97 SS 1500
Not enough tire for twin 106's. Brand tried it and stepped down and he is running a 700+ ci engine.
If you are going with the 88s I would go with the Big 88 not the GT-47 Units that the smaller motor guys are running. What about twin GT55 91s which are smaller on the exhaust side than a standard 91 thumper.
10-20-2005, 02:04 PM
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John, your right, people still think its as easy as slapping turbos on and cranking up the boost..hehe. As John mentioned, if your going 88, then go TV chassis 88 with full TV wheels. GT47 88 wheels are small. Lots of backpressure will come even with a small cube motor 350-400ci running a single GT47 if your trying to make stupid amounts of power.
JZ
JZ
10-20-2005, 02:13 PM
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Originally Posted by JZ 97 SS 1500
106 if single, Twin 88's or 91 for the dual configuration. With 632CI's lag is not an issue. Let us know if you need any help. We work with alot of 10.5 guys.
Also the motor he said is being built @ 7.1 compression. So I'm assuming it's going to have to have the boost dumped to it to make some power.
10-20-2005, 02:28 PM
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Originally Posted by JZ 97 SS 1500
Who built the motor?? Is it a Fulton engine??
No, I forgot the guys name that he told me, but I know it's a local guy here in NC. will find out tomorrow.
10-20-2005, 02:32 PM
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got a friend of a friend that's building a 565 chev BB and has EFI, FAST engine management and a single turbo... est. around 2,500 h.p. he's using a prototype turbonetics 110mm turbo. 
i think he's the only one who has it - hence prototype. his name is MARK and he's a badass ****.
i think he's the only one who has it - hence prototype. his name is MARK and he's a badass ****.
10-20-2005, 07:55 PM
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Originally Posted by JZ 97 SS 1500
John, your right, people still think its as easy as slapping turbos on and cranking up the boost..hehe. As John mentioned, if your going 88, then go TV chassis 88 with full TV wheels. GT47 88 wheels are small. Lots of backpressure will come even with a small cube motor 350-400ci running a single GT47 if your trying to make stupid amounts of power.
JZ
JZ
