LS1 Exhaust header design question to the pros! (Lou, I'm looking at you!)
03-11-2007, 05:28 AM
#1
On The Tree
Thread Starter
iTrader: (1)
Join Date: Jun 2004
Location: SF Bay Area
Posts: 122
Likes: 0
Received 0 Likes
on
0 Posts
LS1 Exhaust header design question to the pros! (Lou, I'm looking at you!) I'm in the market for a new set of headers for my LS1-powered car, and I'm trying to decide between 1 3/4" vs. 1 7/8". Yeah, I know, the age-old debate.
I've read a lot of posts and done quite a bit of searching. The fact that the 1 3/4" LG headers are among the best out there in terms of performance is compelling. The fact that LG is even using the 1 3/4" on 7 liter motors is even more interesting. Common wisdom suggests that a larger header would be better, but the numbers speak for themselves.
Anyway, my question is a bit more specific. I really wish I could purchase a set of LG headers for my car, but being that it's a 1994 Mazda RX7, I'm out of luck. (Unless Lou wants to get into the massive Mazda/GM hybrid market--all 100 of us!)
I've got a 5.7L motor but will be upgrading to a 7.0L motor soon. There are only two companies that offer headers for my car presently. I'm trying to decide if I should go with the 1 3/4" or 1 7/8". (Custom headers are also an option.)
You should assume that the design and packaging does not allow for things like equal-length or optimal-length runners. You should assume that the design process overall has significant compromises and was not at the same level as a high-end set of headers for a Vette or F-Body. You should also assume that I'm not going to run dual exhausts; the system will go 4-2-1 into a 3.5" system after the Y.
Basically I'm worried that smaller headers (1 3/4") might only work when they are designed properly, and when this isn't the case they become a restriction. Or, to put it another way: for a large displacement motor, which would be better--a poorly designed smaller header or poorly designed big one?
Thanks in advance for the feedback.
-ch
I've read a lot of posts and done quite a bit of searching. The fact that the 1 3/4" LG headers are among the best out there in terms of performance is compelling. The fact that LG is even using the 1 3/4" on 7 liter motors is even more interesting. Common wisdom suggests that a larger header would be better, but the numbers speak for themselves.
Anyway, my question is a bit more specific. I really wish I could purchase a set of LG headers for my car, but being that it's a 1994 Mazda RX7, I'm out of luck. (Unless Lou wants to get into the massive Mazda/GM hybrid market--all 100 of us!)
I've got a 5.7L motor but will be upgrading to a 7.0L motor soon. There are only two companies that offer headers for my car presently. I'm trying to decide if I should go with the 1 3/4" or 1 7/8". (Custom headers are also an option.)
You should assume that the design and packaging does not allow for things like equal-length or optimal-length runners. You should assume that the design process overall has significant compromises and was not at the same level as a high-end set of headers for a Vette or F-Body. You should also assume that I'm not going to run dual exhausts; the system will go 4-2-1 into a 3.5" system after the Y.
Basically I'm worried that smaller headers (1 3/4") might only work when they are designed properly, and when this isn't the case they become a restriction. Or, to put it another way: for a large displacement motor, which would be better--a poorly designed smaller header or poorly designed big one?
Thanks in advance for the feedback.
-ch
03-11-2007, 02:20 PM
#3
On The Tree
Thread Starter
iTrader: (1)
Join Date: Jun 2004
Location: SF Bay Area
Posts: 122
Likes: 0
Received 0 Likes
on
0 Posts
Okay, so explain this:
http://www.lgmotorsports.com/catalog...oducts_id=1515
# All Stainless Steel mandrel bent construction using 304 stainless alloy
# These headers are true long tubes at 32 inches long
# 1.75 inch primary tubes, perfect for mild to wild LS7 engines
-ch
http://www.lgmotorsports.com/catalog...oducts_id=1515
# All Stainless Steel mandrel bent construction using 304 stainless alloy
# These headers are true long tubes at 32 inches long
# 1.75 inch primary tubes, perfect for mild to wild LS7 engines
-ch
03-11-2007, 03:59 PM
#4
12 Second Club
iTrader: (15)
Join Date: Sep 2004
Location: Kingwood, TX
Posts: 576
Likes: 0
Received 0 Likes
on
0 Posts
I'm just going from what I have seen. Obviously, the LG headers are going to make more power then most 1.875" headers becase of the nice merge collector and the amount of R&D that went into thier developement. The experience I have used is from my friend's 408ci T/A, he went from 1.75" pacesetters to 1.875" stepped to 2" Kooks with a 3.5" merge collector, and picked up quite a bit of power everywhere. In all honesty it's up to you, and in some applications (like on a C5 / C6) 1.875" headers may not be necessary because of truely well designed 1.75" headers, but I am just giving what information I have learned. 
Good luck with the buildup!
Good luck with the buildup! 