At what point is a 4" Downpipe a noticable restriction
11-10-2008, 11:32 AM
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At what point is a 4" Downpipe a noticable restriction I have recently noticed that the car doesn't seem to respond to boost increases much past 21 psi or so (no increase in IATs so it appears I'm not out of compressor). Car has been 171 mph @ 3450 lbs and has put up 1213RWHP on a dynojet at this boost level...
I'm guessing the downpipe is starting to choke due to the 4" diameter. At this level...how much would I expect to gain by going to a true 5" ID pipe?
I'm guessing the downpipe is starting to choke due to the 4" diameter. At this level...how much would I expect to gain by going to a true 5" ID pipe?
11-10-2008, 12:47 PM
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I agree with Hellbent. Spetter helped my buddy tune his twin exile 47-88 434 sbc and they installed a fitting right into the exhaust housing to monitor turbine back pressure on the DFI. It helped them realize where they were at and how much turbo they had left in it.
Glenn
Glenn
11-10-2008, 01:11 PM
#4
Is it a 4in exhaust housing or a 5in.exhaust housing. If it is a 5in. ex. housing, it was manufactered that way for a reason? Not being a smart azz, just stating the obvious? You might have found the exhaust limit with that turbo necking it down to a 4in.
