bumpin_records

iTrader: (19)

I was wandering is a 4 inch downpipe big enough for a PT 91.5? I dont think i can get a 5 in downpipe between the engine and k member. I have a spohn k member and tube solid motor mounts.

Josh@KY-Turbo

iTrader: (120)

I think the 4" would be fine. You dont plan on it running out the back of the car do you? I would just run the shortest legnth I could get away with, and let it rock and roll.

bumpin_records

iTrader: (19)

well i was thing once though the k member i go oval all the way out. what you think and thanks

Josh@KY-Turbo

iTrader: (120)

Dont really know about the oval pipe. Round 4" and Oval 4" should have the same surface are. The last time I ran a 91.5mm on anything was back in my Ford days. We rab a 4" DP for about 4 feet and put a 5" case Burns muffler on the end of it simply because we had to have a muffler. It was loud. Its was fast. It made us happy .

bumpin_records

iTrader: (19)

well thanks for the answers

Josh@KY-Turbo

iTrader: (120)

No problem.

pozesd99'

iTrader: (3)

i have a question, if someone runs a 4" squash tube,isn't that more restrictive than the 4" cirlce lol.
the circumferance is different, but will it make a difference

52172

iTrader: (2)

not a physicist, but yes the squash tube does not flow as well thats why everyone if they have the room runs circular tubing. I believe the main reason is you can unrestrict the flow with circular tubing while making bends more easily. When you start bending oval tubing the higher the restriction.

Fireball

iTrader: (21)

I'm running a 4" on my FI98x turbo...I think you should be fine up to ~1500 hp