Are 1 3/4 headers too big? Are 1 5/8 better? Any suggestions or ideas? Thanks Jamie
Longtube questions...
- Thread starter 03DarkShadow
- Start date
Why dont you use the search function you F***ing newbie.
Just kidding. Holla
Just kidding. Holla
A**HOLE!!!! j/k holla
Jimmy V's Cobra is in MM&FF I just got today getting 1 5/8 JDM (Kooks) put on. Only gained 7 peak rwhp (467 rwhp total - he has exhaust and other mods) but gained 27 rwhp at 5100 rpm. So big gains in mid range. He picked up lots of mid range torque - 15 rwtq average gain between 3k and 6k with peak of 27 lb-ft at 4600 rpm and average gain of 21 lb-ft from 3-5K.
Depends on your HP level. I forget the exact numbers but once you hit around 500+ RWHP, 1 3/4 would be a good choice. Anything under that and 1 5/8 is fine. Check with a performance and/or muffler shop. My LTs are from www.ls1motorsports.comClick on "cobra parts" then exhaust,.
Last edited:
I would and did go with the 1 5/8 headers.I took Jim D'Amore's recommendation and i am pleased with the results..A car making more boost would prolly show more peak gains even with the 1 5/8's.
Where 1 3/4 would be needed is really yet to be determined.
Where 1 3/4 would be needed is really yet to be determined.
Last edited:
long tubes
It all depends on what you want to do with the car and how much power you want to make. Some people have said that long tubes are not worth anything and others have said that anything over 1 5/8" is too big; it all depends on how much hp you want to make and how much money you are willing to spend. The two things you need to look at when deciding which header tube size to use is the expected hp level and the rpm you want/expect the motor to make power. With each step up in tube size you make, you shift the power band upwards trading lower rpm torque for higher rpm hp. My headers are 1 ¾” to 1 7/8” and were made that size in anticipation of the Kenne Bell I plan on installing in a year or so. In the one dyno run I've had so far the car made 405 hp @ 6200, where it was shut off, and 374 lb. ft. @ 4200. The hp graph looked like a straight line, it was still climbing when it was shut down, and my a/f was off the chart rich. Did my car make as much hp as some? No. The headers also softened up the low-end torque as well. Some may say this is a perfect example of why long tubes aren't worth anything on these cars, but keep in mind my headers were designed to support around 650 hp not 400. July 2 my 2.75 R.R. upper goes on and the car goes back on the dyno to have a chip burned for it so we’ll see how it compares then. I.M.H.O. a 1 5/8 to 1 3/4 step would probably be the right size the way the car is now.
It all depends on what you want to do with the car and how much power you want to make. Some people have said that long tubes are not worth anything and others have said that anything over 1 5/8" is too big; it all depends on how much hp you want to make and how much money you are willing to spend. The two things you need to look at when deciding which header tube size to use is the expected hp level and the rpm you want/expect the motor to make power. With each step up in tube size you make, you shift the power band upwards trading lower rpm torque for higher rpm hp. My headers are 1 ¾” to 1 7/8” and were made that size in anticipation of the Kenne Bell I plan on installing in a year or so. In the one dyno run I've had so far the car made 405 hp @ 6200, where it was shut off, and 374 lb. ft. @ 4200. The hp graph looked like a straight line, it was still climbing when it was shut down, and my a/f was off the chart rich. Did my car make as much hp as some? No. The headers also softened up the low-end torque as well. Some may say this is a perfect example of why long tubes aren't worth anything on these cars, but keep in mind my headers were designed to support around 650 hp not 400. July 2 my 2.75 R.R. upper goes on and the car goes back on the dyno to have a chip burned for it so we’ll see how it compares then. I.M.H.O. a 1 5/8 to 1 3/4 step would probably be the right size the way the car is now.
Im waiting for you to post that new dyno run w/ the 2.75. 
Users who are viewing this thread
