Question about Cut-outs
Thread Starter
Advanced
Joined: Feb 2002
Posts: 75
Likes: 0
From: Santa Clarita CA
Question about Cut-outs
I have welded a pair of cut-outs directly behind a pair of Doug Thorley headers. It's amazing how LOUD (and sometimes fun) open headers can be. I'll have people lookin for me (they can hear me) before I'm even near them. Anyway, how "safe" is it to run uncorked. I've heard that the cold air can run back up open headers and crack a head (which is a big concern since I have aluminum heads). I've always heard that open headers reduces torque, but increases high RPM HP due to loss of back pressure. Any help would be great!!
Melting Slicks
Joined: Aug 2000
Posts: 2,310
Likes: 1
Re: Question about Cut-outs (Prufrock17)
"I've heard that the cold air can run back up open headers and crack a head "
I was told this about running open manifolds. Not sure about headers though. I know my brother ran open headers in his '55 Chevy SBC quite a bit with no problems. Are they long tube headers?
"I've always heard that open headers reduces torque, but increases high RPM HP due to loss of back pressure"
Heard the same, and will say that my car couldn't get out of its own way from a stop when I had open manifolds. Again, I'm not sure that'd be a big problem with long tube headers.
Anyway, you're back TTT, so those with header experience may have something to add.
[Modified by jerryp58, 11:39 AM 2/26/2002]
I was told this about running open manifolds. Not sure about headers though. I know my brother ran open headers in his '55 Chevy SBC quite a bit with no problems. Are they long tube headers?
"I've always heard that open headers reduces torque, but increases high RPM HP due to loss of back pressure"
Heard the same, and will say that my car couldn't get out of its own way from a stop when I had open manifolds. Again, I'm not sure that'd be a big problem with long tube headers.
Anyway, you're back TTT, so those with header experience may have something to add.
[Modified by jerryp58, 11:39 AM 2/26/2002]
Drifting
Joined: Mar 2001
Posts: 1,411
Likes: 2
From: St. Louis, Missouri
Re: Question about Cut-outs (Prufrock17)
Anyway, how "safe" is it to run uncorked. I've heard that the cold air can run back up open headers and crack a head (which is a big concern since I have aluminum heads). I've always heard that open headers reduces torque, but increases high RPM HP due to loss of back pressure. Any help would be great!!
Santa Clarita is a great town. I travel there on business about 4 times a year and I stay at the Hyatt. I enjoy Santa Clarita and Valencia. :cheers:
Team Owner
Joined: Feb 1999
Posts: 29,077
Likes: 0
From: Deep East Texas
Re: Question about Cut-outs (Prufrock17)
We used to weld a pipe nipple on to the exhaust pipes, under the car on each side where you would have normally connected lakes pipes. A pipe cap was used to close the cut out and you could take it off with your hand (and a rag to keep from getting burned). We ran them opened for days at a time and didn't have a bit of problems.... Except tickets for excessive noise. :yesnod:
Safety Car
Joined: Apr 2001
Posts: 4,795
Likes: 1
From: Regina Saskatchewan, Canada.
Re: Question about Cut-outs (Neo Fender)
I mocked up an engine real quick in Desktop Dyno 2000. The only changes I made between the two tests were open small tube headers vs. small tube headers with mufflers. The results are surprising.
