FORCED INDUCTION Turbos | Superchargers | Intercoolers | H2O/Meth Injection

what size downpipe?

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Old 02-19-2010, 02:21 AM
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Default what size downpipe?

Im swapping to front mount and I need to know what downpipe to use. is bigger always better? The truck will stay with the current setup until I run a boost motor and Id like to get something for the long run.
Old 02-19-2010, 07:51 AM
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Originally Posted by sowaidi
Is bigger always better?
Yes. 3"-5" has been used.
Old 02-19-2010, 08:30 AM
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I'm running a 3.5 on mine and love it!
Old 02-19-2010, 09:53 AM
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Rule of thumb is 1.25 x the exduser of the turbine. So a MP T70 has a 64.5mm exhaust wheel, so 64.5 x 1.25 = 80.62mm/25.4 =3.17"
Old 02-19-2010, 10:38 AM
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ok newton with all your physics and ****! haha! listen to this guy cause he def knows what he is doing.......
Old 02-19-2010, 10:57 AM
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3.5 would prolly suit ur needs well
Old 02-19-2010, 01:28 PM
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the largest turbo im planning to run would be a T70 or a T76. so going with a 4 downpipe wouldnt hurt but a 3 would seem a little small.
Old 02-19-2010, 02:03 PM
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Two words..........



Pressure Differential
Old 02-19-2010, 09:02 PM
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Originally Posted by Wilde Racing
Two words..........



Pressure Differential
cliff notes
Old 02-19-2010, 09:24 PM
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Aren't 4" diesel kits easier to find than 3.5"? Not that it matters, but finding a nice mandrel bent peice than clears your rear axle is not always easy - I know that there are a lot of 4" kits out there. I used a 4" kit for a 99-02 Dodge Cummins, every thing up to the downpipe fit great, I only had to add a 45 at the turbo. thats my 2 cents.....


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