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A few questions about turbo exhaust..

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Old 10-23-03, 08:42 AM
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A few questions about turbo exhaust..

Im going and picking up an 88 Turbo2 this weekend. The car has a full 2.5" RB turbo-back exhaust. I'm planning on a lot of upgrades, including hybrid turbo, FMIC, looking for close to 300RWHP. Will the 2.5" exhaust be a big restriction, as opposed to 3"? If so, I might just get a 3" DP, and have a midpipe going from 3" to 2.5", to bolt up to the cat-back (might sound kinda dumb..but I have a nice cat-back that is 2.5 and I really dont want to sell it) What do you think?
Old 10-23-03, 11:05 AM
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Do a barrel roll!

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^- Amd yes I did search, but no one seemed to answer the question of whether or not a 2.5" DP and MP will be much worse than a 3"

https://www.rx7club.com/showthread.p...t&pagenumber=1
Old 10-23-03, 12:11 PM
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From what I've read, turbo's are not as sensitive to exhaust tune - as long as they breathe freely.
Your setup may not be perfect, but it should work well.
It's the NA's that are more fussy about smooth increasing pipe size.
Old 10-23-03, 01:59 PM
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The cross sectional area of a 2.5 inch pipe is 4.9 square inches, the cross sectional area of a 3 inch pipe is 7.06 inches thats roughy 31% more air volume that can travel through the 3inch pipe, therefore, the 3inch pipe is going to be MUCH less restrictive.. HOWEVER.. 300RWHP is totally opbtainable with a 2.5 inch system., you should have no problems from restriction with that goal. 350 HP + definately go with a 3" system.

HOWEVER.... I hope by hybrid turbo you are also planing on either having the wastegate ported or going with a new manifold and an external wastegate AND a Standa Alone ECU like a microtek or a Haltec... If you use the stock manifold.... you are going to have nasty problems with the wastegate and boost creep.
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