1 3/4 vs. 1 7/8 Headers
Instructor
Joined: Nov 2006
Posts: 210
Likes: 0
From: Columbus IN
Velocity is the issue here. The smaller tubes have a higher velocity which equates to torque at a lower RPM. Around here everyone goes with the big sizes and if your really going to modify this makes sense. The C6 is a 360+ inch engine, not a 426, 427, or a 440. Keep everything in proportion and you'll have a more "streetable" car is that's what you're after.
Instructor
Joined: Nov 2006
Posts: 210
Likes: 0
From: Columbus IN
Most people it seems start differently than you. They do the bolt ons first and then go into the engine. When you put the cam in, the CAI, headers and the Bullets you'll end up not utilizing the potential of the fore mentioned mods without doing something to the intake side. You will. Go with the 1 7/8 headers, you will utilize the increased flow at a future date, even it you don't realize it now.
Drifting
Joined: Nov 2002
Posts: 1,651
Likes: 125
From: laguna niguel ca
I went with 1 3/4 kooks even when I moved from an LS2 modded to 461rwhp/435rwtq to a stroked L92 with CNC'ed L92 heads,4.1 crank 427ci. I asked Andy Green @ A&A who did my motor,and he said the difference would be about 10rwhp at the top end. Currently the motor makes 525rwhp/500rwtq. i didn't think 10 hp over what I already have
would even make a difference in the performance that i could feel. So I stayed with the 1 3/4 size. Now if the gains were 20plus hp, and simular in torque, then yea the upgrade would be worth it. My opinion anyway. Don't get me wrong, there nothing wrong with 1 7/8 primaries, if I'ed had those at the start I'm sure I would have keep them. One should also remember that motors with shorter strokes and large primary tubes like the 1 7/8 size tend to go soft on the low end unless you have a BIG cam with a long duration.
andreas g.
would even make a difference in the performance that i could feel. So I stayed with the 1 3/4 size. Now if the gains were 20plus hp, and simular in torque, then yea the upgrade would be worth it. My opinion anyway. Don't get me wrong, there nothing wrong with 1 7/8 primaries, if I'ed had those at the start I'm sure I would have keep them. One should also remember that motors with shorter strokes and large primary tubes like the 1 7/8 size tend to go soft on the low end unless you have a BIG cam with a long duration.
andreas g.
Former Vendor
Joined: Sep 2007
Posts: 5,511
Likes: 22
From: Southern MD
We have found on the LS2/LS3, there is no noticable difference between 1 3/4" and 1 7/8". So basically, if you never plan on more than say 475 rwhp, than buy 1 3/4" Kooks. If there is even the slightest chance you may go higher than that, get 1 7/8"
Thanks!
Thanks!
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Instructor
Joined: Nov 2006
Posts: 210
Likes: 0
From: Columbus IN
Which ever size you decide on contact Branden @ Maryland Speed prior to buying. He killed everyone else on Kooks and the customer service is AMAZING!
Race Director
Joined: Oct 2004
Posts: 10,516
Likes: 2
From: Virginia Bch VA
Cruise-In VI Veteran
Cruise-In VII Veteran
St. Jude Donor '06
My understanding is that unless you stroke or go Forced Induction, You are better off with the 1 & 3/4 - more low end TQ. That's what I did.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
LG did the testing on a 427 for the LG 1 7/8 primaries and scrapped the design when the final product yeilded no gain anywhere in the power band but lost TQ in the low end. As far as Lou is concerned the 1 3/4 is the best on a 427 so the smaller displacement sizes will fare better with the 1 3/4. Also a max effort 6 liter can move more air than a mild 403 so the word stroker shouldnt automatically be making a case for bigger primaries. This applies to head runner size too. So many people jump to 225 runners just because its a stroker.
Cartek also stated that the 1 3/4 bested the bigger primaries over the years in actual track results. They recommend the smaller size.
Since peak numbers tend to impress most people, bigger will continue to be pushed since dyno, and not track numbers, will be the bottom line.
Cartek also stated that the 1 3/4 bested the bigger primaries over the years in actual track results. They recommend the smaller size.
Since peak numbers tend to impress most people, bigger will continue to be pushed since dyno, and not track numbers, will be the bottom line.
Pro
Joined: Apr 2007
Posts: 663
Likes: 0
From: Arvada CO
Based on this thread I did call Branden. You were correct, he spent a lot of time on the phone going over every aspect with me. And the best part was the price which included Cherry red high temp coating and free shipping. Can't wait to install them. Thanks for the info.
Instructor
Joined: Nov 2006
Posts: 210
Likes: 0
From: Columbus IN
Based on this thread I did call Branden. You were correct, he spent a lot of time on the phone going over every aspect with me. And the best part was the price which included Cherry red high temp coating and free shipping. Can't wait to install them. Thanks for the info.
Race Director
Joined: Oct 2004
Posts: 10,516
Likes: 2
From: Virginia Bch VA
Cruise-In VI Veteran
Cruise-In VII Veteran
St. Jude Donor '06
LG did the testing on a 427 for the LG 1 7/8 primaries and scrapped the design when the final product yeilded no gain anywhere in the power band but lost TQ in the low end. As far as Lou is concerned the 1 3/4 is the best on a 427 so the smaller displacement sizes will fare better with the 1 3/4. Also a max effort 6 liter can move more air than a mild 403 so the word stroker shouldnt automatically be making a case for bigger primaries. This applies to head runner size too. So many people jump to 225 runners just because its a stroker.
Cartek also stated that the 1 3/4 bested the bigger primaries over the years in actual track results. They recommend the smaller size.
Since peak numbers tend to impress most people, bigger will continue to be pushed since dyno, and not track numbers, will be the bottom line.
Cartek also stated that the 1 3/4 bested the bigger primaries over the years in actual track results. They recommend the smaller size.
Since peak numbers tend to impress most people, bigger will continue to be pushed since dyno, and not track numbers, will be the bottom line.
Racer
Joined: Jul 2007
Posts: 276
Likes: 0
From: Lynchburg VA
St. Jude Donor '11
Check out this thread:
http://forums.corvetteforum.com/show....php?t=1811524
It appears from Lou's graph at LG that the 1 7/8" headers are no where close to comparing to the 1 3/4" headers. There's a 25 RWHP gain in the 3.5 - 5.0 K RPM band! So if I had it to do over again, I would go with the 1 3/4" Headers.
http://forums.corvetteforum.com/show....php?t=1811524
It appears from Lou's graph at LG that the 1 7/8" headers are no where close to comparing to the 1 3/4" headers. There's a 25 RWHP gain in the 3.5 - 5.0 K RPM band! So if I had it to do over again, I would go with the 1 3/4" Headers.
