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How short can a downpipe be?

1K views 11 replies 3 participants last post by  gustavm 
#1 · (Edited)
Im getting a 3 inch dp done tommorow and Im wondering what the minimum length can be and still be effective . I was thinking only to the junction just behind the of the engine then back to standard exhaust which in my case is a resinator and 2 1/4 inch pipe through to a glasspack standard rear muffler with twin megaphone type tail pipes. Obviously later with funds availiable more 3 inch pipe could be added .BTW Battery is under the air intake pipe so a nice initial curve is not a problem
 
#3 ·
To safely support about 12-14 lbs boost and increase spool up time . No big turbo or high horse power stuff . Id like to leave the rest fairly standard to keep that old fishing boat sound ! The guys are working on it at the moment and have decided to only go to the end of the engine block just after the hanger in 3 inch .Will give you all a report once Ive driven it.
 
#8 · (Edited)
Maybe to prevent corrosion ? Paul did the same thing on my 9000 3 inch DP I must check if its still black after a couple of years .Im sure its just ordinary steel . The engine revs more freely and the car seems lighter ! that has to be a good sign. I may continue the 3 inch pipe one day . Bilstein rear shocks next.
 
#9 ·
Looks good. Much improved over the stock, but Saab had other requirements and constraints. If you have not done already, put the turbine heat shield back in place. I ran with mine off, but with a turbine fiberglass cozy and would have hot soak start issues. Seems like the hall sensor failed to give signal when it got too hot.

When you say pulls at 1500 in fifth, what boost are you getting if any or is it boosting quicker?
 
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