Estimated gain from 1 3/4 to 1 5/8 - 1 7/8 Stepped?
03-10-2009, 08:16 PM
#1
Estimated gain from 1 3/4 to 1 5/8 - 1 7/8 Stepped? Looking at swapping back from my Hedman 5/8-7/8's to a 1 3/4 header. Reasons being I like change and having a true catback.
Anyway, lets look at this as a gain and go from a 3/4 TO a 5/8-7/8 rather then going back.
We'll say the car makes 800fwhp. So, the gains might be?
Anyway, lets look at this as a gain and go from a 3/4 TO a 5/8-7/8 rather then going back.
We'll say the car makes 800fwhp. So, the gains might be?
03-10-2009, 08:49 PM
#4
Attempting to calculate the gain would be fruitless, because there are tons of variables that come into play. You COULD, on the other hand, calculate what diameter pipe (and length) you would need for optimal torque output.
I've had this article bookmarked for awhile - definitely good reading. Check it out.
http://www.carcraft.com/techarticles...ics/index.html
I've had this article bookmarked for awhile - definitely good reading. Check it out.
http://www.carcraft.com/techarticles...ics/index.html
03-10-2009, 09:10 PM
#5
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Alright, I'm bored and I'm a post *****, but since we're going with theoretical gains here it only makes sense for me to toss in Desktop Dyno numbers 
LT1 is the first 2, and then since you wanted 800 hp, that'll be the next 2. As for 800, how about 600? 598hp @ 6500 and 529tq @ 5500 baseline which will be through manifolds and mufflers, and what is made through open headers is the gain over the 'stock exhaust'. A better comparison than the LT1.
And thats what the math says, be it close to real life or not I'm not sure since I can't specify the header dimensions :\ I only get to choose if it's Stepped or not.
EDIT: Hmm, just noticed that it's not "Long" tubes but "LARGE" tubes... Oh well.
LT1 is the first 2, and then since you wanted 800 hp, that'll be the next 2. As for 800, how about 600? 598hp @ 6500 and 529tq @ 5500 baseline which will be through manifolds and mufflers, and what is made through open headers is the gain over the 'stock exhaust'. A better comparison than the LT1.
And thats what the math says, be it close to real life or not I'm not sure since I can't specify the header dimensions :\ I only get to choose if it's Stepped or not.
EDIT: Hmm, just noticed that it's not "Long" tubes but "LARGE" tubes... Oh well.
03-11-2009, 08:06 AM
#6
I ran the stepped Hedmans and switch to 1 3/4" Hookers and actually picked up a little! This is in my LT1 Stocker. I currently run the 1 3/4" - 1 7/8" Kooks, but haven't run a back to back test. I can tell you that the performance changes that I have seen betwean different headers have been minor once the A/F ratio was right.
03-11-2009, 01:54 PM
#7
For that engine you need Hedman 1 7/8 with the 3.5 inch collector. Thats what I have. Seems you need them more than I with that big shot of spray.
I read a header test in a mag on a big block, the bigger the header the more power it made.
DOnt you have a wheelstand problem? Bigger header will kill some of the low end tq.
I read a header test in a mag on a big block, the bigger the header the more power it made.
DOnt you have a wheelstand problem? Bigger header will kill some of the low end tq.