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Old 7th May 2017, 04:28
ozi jim ozi jim is offline
Join Date: Apr 2015
Location: Sydney Aust
Posts: 72
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Standard engines often require back pressure in the exhaust to help with the scavenge effect in the cylinder combustion cycle,
putting a larger pipe or removing the muffler may not always give you the results if you go to large or no restriction.
On my GT40 I removed the triple pass mufflers for a s/steel hotdog muffler to get a better note.
It shortened the system by 2 muffler lengths and it lost 15rwhp.
I made reducer cones to go on the outlet that clamped on at the dyno.
When I found the one that got the 15hp back I then welded a copy of that on the tail pipe.
It is a 2 1/4 system necked down to 2'' at the end ( a cone then 2" pipe).
You need to start with a figure.
You can do a standing or rolling start timed over distance if you dont want to pay for a dyno.
I have no doubt their is an app to do the same measure, my driftbox has a HP mode and it calculates HP.
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