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C4 or C6

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Old 02-05-2008, 07:42 AM
  #1  
majpain78
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Default C4 or C6

I have a 71 mustang with a 9 inch rear and i just put in a 351cj I had alot of work done too. I am making around 500 horse power to the rear wheels. I have my old C4 i had in this car with a 302 and I have the C6 that came with the engine, which would be better to build up and use?
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Old 02-05-2008, 08:30 AM
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dodgestang
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Default RE: C4 or C6

Sorry...I have to ask this question. What have you done to the motor to think you are making 500 to the rear wheels (especially since you haven't even picked out a trans a c6 will have a higher parasidec loss than a c4......so depending on the trans you will have higher or lower RWHP numbers).

To answer directly a 'well built' c4 can work in HP applications in a street car at higher HP levels. A c6 was 'designed' for more power but isn't 'required', however if you are making an honest 580-600+ FWHP I would prefer the beefier c6 just because I hate breaking things
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Old 02-05-2008, 10:03 AM
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majpain78
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Default RE: C4 or C6

Ihave had it bored 30 over and i have now stroked it to a 408,I took the stock heads (4v) and did a 3 angle valve job to them as well as ported and polished it, match ported the heads and intake to all my gaskets for improved air flow. I installed a blue printed oil pump and a holley high volume fuel pump. a edlebrock performer intake. A high volume water pump. I replaced the cam with a 280/280 duration i got custom ground for me from comp cams. and of course i balanced and blue printed the hole thing. Oh and i put a 750 thunder on it as well, and for at the moment i have been using the C4 cause i had it rebuilt and put a tran pack on it from B&M and its been holding well but was curious if i should just redo the C6 instead of pulling the C4 and redoing it.
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Old 02-05-2008, 10:07 AM
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rmodel65
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Default RE: C4 or C6

nice looking car
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Old 02-05-2008, 10:19 AM
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dodgestang
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Default RE: C4 or C6

ORIGINAL: majpain78

Ihave had it bored 30 over and i have now stroked it to a 408,I took the stock heads (4v) and did a 3 angle valve job to them as well as ported and polished it, match ported the heads and intake to all my gaskets for improved air flow. I installed a blue printed oil pump and a holley high volume fuel pump. a edlebrock performer intake. A high volume water pump. I replaced the cam with a 280/280 duration i got custom ground for me from comp cams. and of course i balanced and blue printed the hole thing. Oh and i put a 750 thunder on it as well, and for at the moment i have been using the C4 cause i had it rebuilt and put a tran pack on it from B&M and its been holding well but was curious if i should just redo the C6 instead of pulling the C4 and redoing it.
That sounds like 350-400 at the back tires if the cam has .060 lift or less based on my limited understanding

I would use the c4 at that power level.

and just to be clear I didn't/don't want to turn your question into a power level debate...I just wanted to make sure I understood where you were at in order to answer your question about which trans
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Old 02-05-2008, 10:55 AM
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fastbackford351
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Default RE: C4 or C6

I'm kinda partial to my C6 but that is more heart than head. A well-built C4 would handle the power you are laying down.

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Old 02-06-2008, 06:53 AM
  #7  
majpain78
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Default RE: C4 or C6

so let me get this right the C4 will work if i rebuild it with better parts but if i want something bullet proof build the C6?
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Old 02-06-2008, 07:09 AM
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dodgestang
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Default RE: C4 or C6

ORIGINAL: majpain78

so let me get this right the C4 will work if i rebuild it with better parts but if i want something bullet proof build the C6?
If you are making 600 FWHP which would be approx 500 RWHP I would use a c6
If you are making 500 FWHP or less which would be 350-425 ish RWHP I would use a built up c4
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Old 02-06-2008, 10:33 AM
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Default RE: C4 or C6

A reputable build on a small block C6 would probably be cheaper, but as others have said, a good C4 build, while probably more expensive, will handle the power and put a little more to the ground.
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