1 3/4 Header vs 1 7/8 Header
Team Owner
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From: salem OR
Really? You stuck on dyno numbers? Spinmonster and every expert hasn't said enough? All the technical posts by the experts not gone thru to you? Seriously, I have been viewing this thread and you keep fighting an uphill battle, almost like watching the battle at " HAMBURGER HILL
"
When an LS3 with heads and cam package and 1 7/8 headers does 10.66@132 ( N/A) then you can claim it beats the 1 3/4 performance.. Please show me one example of the track performance of your claims with the 1 7/8's!!
"When an LS3 with heads and cam package and 1 7/8 headers does 10.66@132 ( N/A) then you can claim it beats the 1 3/4 performance.. Please show me one example of the track performance of your claims with the 1 7/8's!!
you didn't read my posts either! Go bother the other forum!
Tech Contributor
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
What a way to start out the week.
I guess everyone had their cup of coffee.
I think I'll head off to bed for a while and get up later for a nice wood shop project while the snow blows around.
I guess everyone had their cup of coffee.
I think I'll head off to bed for a while and get up later for a nice wood shop project while the snow blows around.
Race Director
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From: Southampton NJ
Hang on to those Kook's 1 3/4 because I'll be wanting to switch back
to 1 3/4 if It doesn't do better with 1 7/8's. I wish I would have tried the 3 x-pipe first but I should get the numbers finally this week. I want to add I was in the 1 3/4 camp but a few 1 7/8 dyno's with ls-3's
are showing really well. My test is with the blower to see the difference.
Ls-2's I would stay 1 3/4 for sure those results are old and do show the 1 3/4's working better. But the ls-3's the best dyno numbers are 1 7/8's
to 1 3/4 if It doesn't do better with 1 7/8's. I wish I would have tried the 3 x-pipe first but I should get the numbers finally this week. I want to add I was in the 1 3/4 camp but a few 1 7/8 dyno's with ls-3's
are showing really well. My test is with the blower to see the difference.
Ls-2's I would stay 1 3/4 for sure those results are old and do show the 1 3/4's working better. But the ls-3's the best dyno numbers are 1 7/8's
i have seen the exhaust wars go on for 40 years all the way to 5" pipes.
nothing wrong with testing , its somthing to do
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From: Southampton NJ
Tech Contributor
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I posted the sheets in 3 places. All motors to 427 LS7's show no gains with the bigger primary. Thats why LG didnt make a 1 7/8. The prototypes didnt gain anywhere and lost down low.
Its been my finding that RPM plays the biggest role. Solid roller to 8k+ is where it makes huge differences going to 1 7/8 or 2" like my dart was with a 426 that wound out to 10k. Looking over my collection of non LS engine data it seems around 5800 and up is where it makes a serious difference. At 9k its 100hp for the 2" on my hemi over 1 3/4 stepped to 1 7/8.
Last edited by SpinMonster; Dec 1, 2008 at 08:30 AM.
Tech Contributor
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St. Jude Donor '08-'09-'10-'11
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From: Southampton NJ
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St. Jude Donor '08
. Here is my contribution, it's called common sense. Here is what you quoted Spin on post # 13
I was in the 1 3/4 camp till I see that the highest hp 08 stock cars use 1 7/8.
As always since you own the part it makes it the most efficient part, just like your 3.73 debates versus 4.10's. I am done with this thread.
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Race Director
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From: Southampton NJ
Tech Contributor
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Race Director
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From: Southampton NJ
Tech Contributor
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
When you say Colorado, everyone pictures Aspen the land of skiing with big snow.
I'm in Colorado Springs....its a desert with desert level precipitation. We get little snows often but it doesnt amount to much. I bought a Hummer anyway. It has an 8cyl LS engine!!!!!
Race Director
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From: Southampton NJ
When you say you're from NY everyone pictures Manhattan, not the farmland upstate or eastern Long Island where I grew up; also on a farm.
When you say Colorado, everyone pictures Aspen the land of skiing with big snow.
I'm in Colorado Springs....its a desert with desert level precipitation. We get little snows often but it doesnt amount to much. I bought a Hummer anyway. It has an 8cyl LS engine!!!!!
When you say Colorado, everyone pictures Aspen the land of skiing with big snow.
I'm in Colorado Springs....its a desert with desert level precipitation. We get little snows often but it doesnt amount to much. I bought a Hummer anyway. It has an 8cyl LS engine!!!!!
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Le Mans Master
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From: Austin TX
So you're saying the typical 224 or 228 cam on an LS2 would have no difference in power with different primary sizes. Without exception I have never seen a 1 7/8 make as much power under the curve as a smaller header. Lower powered stock displacement engines make more power, especially down low, with smaller primaries.
I have seen stock engines do better with the smaller primary and thats as little overlap as it gets.
Unless you have a dyno sheet to support the theory, I would say there must be a variable missing in the scavenging theory with less overlap.
As for displacement this is a 1 3/4 vs 1 7/8 on stock displacement and with a smaller cam than GTOdoug's example, the trend doesnt support less of an effect with less overlap. This link below is to a 234 cam on a 114 which is much smaller and has less overlap than Doug's car but the same headers. Peak power has no difference but as high as 5800rpm there is a more pronounced difference even greater than Doug found with a 40rwtq increase at some points. Even a stock cammed car will benefit from the smaller header.
http://www.lgmotorsports.com/gallery...707&fullsize=1
I have so many dyno swap sheets but dont want to make this an LG header war so I have a new/unused set of Kooks 1 3/4 to swap out for anyone wanting to test the theory on their 1 7/8 car with any level of mods. I am interested in gaining data points and learning more myself so the person participating will not have to keep my headers. I will put their headers back on their car again after the dyno test regardless of outcome. This way a Kooks vs Kooks or a AR vs Kooks data point can be had so people dont acuse me of falsifying data or other agenda for LG's gain.
On the flip side, I dont see anyone posting up findings supporting their 'bigger is better' posts. Lets also keep in mind that a cat can go bad or other single mechanical error that will make some data points erroneous so the trend is what we should look at, not a single contrarian data point. I see a clear trend.
I have seen stock engines do better with the smaller primary and thats as little overlap as it gets.
Unless you have a dyno sheet to support the theory, I would say there must be a variable missing in the scavenging theory with less overlap.
As for displacement this is a 1 3/4 vs 1 7/8 on stock displacement and with a smaller cam than GTOdoug's example, the trend doesnt support less of an effect with less overlap. This link below is to a 234 cam on a 114 which is much smaller and has less overlap than Doug's car but the same headers. Peak power has no difference but as high as 5800rpm there is a more pronounced difference even greater than Doug found with a 40rwtq increase at some points. Even a stock cammed car will benefit from the smaller header.
http://www.lgmotorsports.com/gallery...707&fullsize=1
I have so many dyno swap sheets but dont want to make this an LG header war so I have a new/unused set of Kooks 1 3/4 to swap out for anyone wanting to test the theory on their 1 7/8 car with any level of mods. I am interested in gaining data points and learning more myself so the person participating will not have to keep my headers. I will put their headers back on their car again after the dyno test regardless of outcome. This way a Kooks vs Kooks or a AR vs Kooks data point can be had so people dont acuse me of falsifying data or other agenda for LG's gain.
On the flip side, I dont see anyone posting up findings supporting their 'bigger is better' posts. Lets also keep in mind that a cat can go bad or other single mechanical error that will make some data points erroneous so the trend is what we should look at, not a single contrarian data point. I see a clear trend.
Last edited by AirBusPilot; Dec 1, 2008 at 01:54 PM.
Le Mans Master
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From: Austin TX
Very good explanation airbuspilot, but I need to correct you on two things if you don't mind:
Forced Induction cars are no different from their N/A counterparts when it comes to exhaust requirements; they need and benefit from headers just like any other car; the supercharger increases the amount of exhaust gas volume the engine moves, that's all; you will still see gains from scavenging that gas. Turbo cars are more complex because you can incurr a lag penalty from the added exhaust gas pipe volume and increased heat losses, but even there the right headers can gain power and torque.
Scavenging happens to some extent pretty much through the entire RPM range; the exhaust port opens and the exhaust gases leave with some velocity; the more velociy they have, the more vacuum they will create and the better scavenging is going to be; the velocity of a gas through a pipe is a function of pressure and pipe diameter; that is why you lose low end torque when you switch to larger primaries; the bigger pipe diameter causes a loss in exhaust gas velocity and thus you lose scavenging efficiency. The catch is that at the upper RPM range it is possible that the pipe diameter, if too small, begins to choke back the exhaust and produce excessive backpressure, causing top end loss...
Frankly, seeing as even a mild centrifugal setup is going to be able to spin tires well in excess of the speed limit, but make perhaps 30-50rwtq over a stock car at the RPMs most of us drive in (2000ish RPMs when you are in 6th gear doing 60-70MPH), I don't see the reasoning in trading low end for a little top end and going with the 1 7/8s; driving enjoyment is having power NOW, not 3 downshifts away
... But I am watching this thread carefully because Rock'n'blue 08's car runs a very similar setup to mine, so his results matter to me 
Forced Induction cars are no different from their N/A counterparts when it comes to exhaust requirements; they need and benefit from headers just like any other car; the supercharger increases the amount of exhaust gas volume the engine moves, that's all; you will still see gains from scavenging that gas. Turbo cars are more complex because you can incurr a lag penalty from the added exhaust gas pipe volume and increased heat losses, but even there the right headers can gain power and torque.
Scavenging happens to some extent pretty much through the entire RPM range; the exhaust port opens and the exhaust gases leave with some velocity; the more velociy they have, the more vacuum they will create and the better scavenging is going to be; the velocity of a gas through a pipe is a function of pressure and pipe diameter; that is why you lose low end torque when you switch to larger primaries; the bigger pipe diameter causes a loss in exhaust gas velocity and thus you lose scavenging efficiency. The catch is that at the upper RPM range it is possible that the pipe diameter, if too small, begins to choke back the exhaust and produce excessive backpressure, causing top end loss...
Frankly, seeing as even a mild centrifugal setup is going to be able to spin tires well in excess of the speed limit, but make perhaps 30-50rwtq over a stock car at the RPMs most of us drive in (2000ish RPMs when you are in 6th gear doing 60-70MPH), I don't see the reasoning in trading low end for a little top end and going with the 1 7/8s; driving enjoyment is having power NOW, not 3 downshifts away
... But I am watching this thread carefully because Rock'n'blue 08's car runs a very similar setup to mine, so his results matter to me As to your point that scavenging "happens to some extent pretty much through the entire RPM range" that might be true, but my point was that if you have the wrong size primary it might not happen at an rpm that is usable. Spin's comment concerning exhaust reversion comes to mind (when using too large of a pipe). As far as my comment on very low rpm's and scavenging, I'm still not sure if scavenging is really taking place, though you could be right.
Team Owner
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From: salem OR
I read every single post, you seem to always get into heated debates on parts that work. This goes back to the 4.10 debates with Spin, and now 1 7/8 headers. Why not just say yes 1 3/4 works, and until I have proven that 1 7/8 can do 10.66@132 on a LS3 N/A, I will further refrain from posting. . Here is my contribution, it's called common sense. Here is what you quoted Spin on post # 13I was in the 1 3/4 camp till I see that the highest hp 08 stock cars use 1 7/8.As always since you own the part it makes it the most efficient part, just like your 3.73 debates versus 4.10's. I am done with this thread.
. Here is my contribution, it's called common sense. Here is what you quoted Spin on post # 13I was in the 1 3/4 camp till I see that the highest hp 08 stock cars use 1 7/8.As always since you own the part it makes it the most efficient part, just like your 3.73 debates versus 4.10's. I am done with this thread. Get some proof instead of your hot air attacks. LIKe the 10.66 your crowing about was on 3.90's not your prized 4.10's. Check the geared cars on the fast list maybe one with 4.10's the rest 3.90's or 3.73's. Yep thats you Call names and argue with your hot air trying to get these threads closed. which you are good at ruining things, instead of raising real points and debating them.
Last edited by 3 Z06ZR1; Dec 1, 2008 at 06:21 PM.