1 7/8 AR Headers on a lightly modded ls1
How much is a "bunch"? Any actual back to back tests to show this on paper? I personally cannot imagine the difference being much or worthy of enough to convince me to buy $1k headers more then once for the same car...however I would gladly admit i'm wrong if thats the case!
I ran 1 3/4-1 7/8" with 3 1/2 HVMC on my bolt on car, and now currently cam only and I can't say there is any adverse side effects, not to mention my bolt on only car(NO fast 90/or E water pump) through 9" rear still made 353rwhp/357rwtq. IMO much of the advice given in this thread is worth exactly what you paid for it, and thats nothing.
I love how people are making a big deal about 1 7/8" primaries being too large like its really gonna have a huge effect on performance and torque output. Even if there is a minor loss compared to a 1 3/4-3" collector header it will be insignificant on a bolt on car, its not like it will negate the whole gain of the header swap anyways. Planning ahead to meet current and future goals is smart. When your shelling out that much money for headers, why would u want to do it more then once.
I love how people are making a big deal about 1 7/8" primaries being too large like its really gonna have a huge effect on performance and torque output. Even if there is a minor loss compared to a 1 3/4-3" collector header it will be insignificant on a bolt on car, its not like it will negate the whole gain of the header swap anyways. Planning ahead to meet current and future goals is smart. When your shelling out that much money for headers, why would u want to do it more then once.
then what would be the point of selling 1 3/4's if everyone should just go with 1 7/8? thats a stupid statment IMO. i honestly dont think you will lose much but optimal? i think not.
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
1 7/8 headers are going to do nothing but hurt you in almost all cases on a NA 346ci LS1. People actually think more flow = more power. That is the problem, and it's horrible misinformation. You only need exactly as much flow as you need to not be a restriction. More flow will just hurt exhaust velocity and kill low end power.
Ive done similar testing on engine dyno's....350 CID engines producing around 500 HP.....1 .75 will make 10-15 more ft/lbs on the bottom and middle of the curve. It will be very high in the RPM band before a 1.875 pimary tube header will even get close (on that type of displacement and power level).
What most of you guys miss the boat on is part throttle "feel" and tip in power (just squeezing the throttle a little to lightly accelerate).....the smaller header would be night and day better in both scenarios.
That kind if stuff cant be measured on a dyno....WOT numbers dont tell the whole story.
Drive the same ride the OP desribed in this thread with both header choices and the decision of which ones to purchase would be much clearer.
Hell....even the 402 would benefit from the 1.75 tubes if your primary concern was enhancing usable torque in everyday driving while still retaining the ability to make respectable peak power (if you wanted to build a stroker that enhanced the "street" side of the street/strip equation).
While some of you would scoff at that idea, others would be more open to it. It all depends on your goals and the type of driver you are.
And for some of you guys jumping up and down about buying the two sets of headers, you are not factoring in the fact that if it truly isnt a long time before the larger motor goes in he would easily be able to recover .65-.75 cents on the dollar selling a low mileage set of quality name brand headers to someone else looking to save a few bucks. So in the end it costs you a few hundred to enjoy and optimize your current situation (for what will likely be longer than you think). In the big picture when it comes to all the mod money your going to spend (especially when your talking about stroker engines and such), thats a drop in the bucket....
Tony
What most of you guys miss the boat on is part throttle "feel" and tip in power (just squeezing the throttle a little to lightly accelerate).....the smaller header would be night and day better in both scenarios.
That kind if stuff cant be measured on a dyno....WOT numbers dont tell the whole story.
Drive the same ride the OP desribed in this thread with both header choices and the decision of which ones to purchase would be much clearer.
Hell....even the 402 would benefit from the 1.75 tubes if your primary concern was enhancing usable torque in everyday driving while still retaining the ability to make respectable peak power (if you wanted to build a stroker that enhanced the "street" side of the street/strip equation).
While some of you would scoff at that idea, others would be more open to it. It all depends on your goals and the type of driver you are.
And for some of you guys jumping up and down about buying the two sets of headers, you are not factoring in the fact that if it truly isnt a long time before the larger motor goes in he would easily be able to recover .65-.75 cents on the dollar selling a low mileage set of quality name brand headers to someone else looking to save a few bucks. So in the end it costs you a few hundred to enjoy and optimize your current situation (for what will likely be longer than you think). In the big picture when it comes to all the mod money your going to spend (especially when your talking about stroker engines and such), thats a drop in the bucket....
Tony
i say buy the 1 7/8" primary tube headers so you don't have to deal with selling the "right" header later. in the grand scheme of things, if the car makes say - 10 hp LESS with the big headers, so what? you saved yourself the hassle of selling the others online later, shipping them, etc etc. if and when you build your other motor you already have headers, if not...so what?
do what is convenient and makes the most sense to you - it is your car, your time, and your money. i'm in the same boat now, i have a fairly radical 370 build on a stand right next to a near stock 99 ws6. i'm buying 1 7/8" headers and not looking back. buy headers once and don't worry about it.
do what is convenient and makes the most sense to you - it is your car, your time, and your money. i'm in the same boat now, i have a fairly radical 370 build on a stand right next to a near stock 99 ws6. i'm buying 1 7/8" headers and not looking back. buy headers once and don't worry about it.
Ive done similar testing on engine dyno's....350 CID engines producing around 500 HP.....1 .75 will make 10-15 more ft/lbs on the bottom and middle of the curve. It will be very high in the RPM band before a 1.875 pimary tube header will even get close (on that type of displacement and power level).
What most of you guys miss the boat on is part throttle "feel" and tip in power (just squeezing the throttle a little to lightly accelerate).....the smaller header would be night and day better in both scenarios.
That kind if stuff cant be measured on a dyno....WOT numbers dont tell the whole story.
Drive the same ride the OP desribed in this thread with both header choices and the decision of which ones to purchase would be much clearer.
Hell....even the 402 would benefit from the 1.75 tubes if your primary concern was enhancing usable torque in everyday driving while still retaining the ability to make respectable peak power (if you wanted to build a stroker that enhanced the "street" side of the street/strip equation).
While some of you would scoff at that idea, others would be more open to it. It all depends on your goals and the type of driver you are.
And for some of you guys jumping up and down about buying the two sets of headers, you are not factoring in the fact that if it truly isnt a long time before the larger motor goes in he would easily be able to recover .65-.75 cents on the dollar selling a low mileage set of quality name brand headers to someone else looking to save a few bucks. So in the end it costs you a few hundred to enjoy and optimize your current situation (for what will likely be longer than you think). In the big picture when it comes to all the mod money your going to spend (especially when your talking about stroker engines and such), thats a drop in the bucket....
Tony
What most of you guys miss the boat on is part throttle "feel" and tip in power (just squeezing the throttle a little to lightly accelerate).....the smaller header would be night and day better in both scenarios.
That kind if stuff cant be measured on a dyno....WOT numbers dont tell the whole story.
Drive the same ride the OP desribed in this thread with both header choices and the decision of which ones to purchase would be much clearer.
Hell....even the 402 would benefit from the 1.75 tubes if your primary concern was enhancing usable torque in everyday driving while still retaining the ability to make respectable peak power (if you wanted to build a stroker that enhanced the "street" side of the street/strip equation).
While some of you would scoff at that idea, others would be more open to it. It all depends on your goals and the type of driver you are.
And for some of you guys jumping up and down about buying the two sets of headers, you are not factoring in the fact that if it truly isnt a long time before the larger motor goes in he would easily be able to recover .65-.75 cents on the dollar selling a low mileage set of quality name brand headers to someone else looking to save a few bucks. So in the end it costs you a few hundred to enjoy and optimize your current situation (for what will likely be longer than you think). In the big picture when it comes to all the mod money your going to spend (especially when your talking about stroker engines and such), thats a drop in the bucket....
Tony
If I had plans to build bigger in the future I wouldn't buy $1K+ headers more then once. Omec and ChocoCoco, 1 3/4" headers have their place....never did I say they didn't. Some people never have plans of upgrading to the same extent as others, and why don't u go find a calculator and figure out the primary length needed as well as the optimal primary size....u might just find that 1 3/4 isn't the optimal size for the stock engine either.
I want to thank everyone for their input, especially you, Tony. Thanks for taking the time.
Practically and financially, I am very happy with my choice. Buy once, buy right.
Performance wise, I have put forth a theory I am willing to put my money on and possibly be wrong. That is, that the big tube headers will show gains all over. The good part is being wrong has no penalty, only a smaller benefit. The numbers will tell a lot once I see the graph.
However, I think Tony hit it on the head when he said WOT numbers don't tell the whole story. Having worked at a Chevy dealership for 3 years, I understand every day driveability concerns fairly well. Not as well as some, but well enough to make decisions that are easy to live with. All things being equal, the 1.75s might make more torque at part throttle. My ***-dyno says that, untuned, there is no difference. It feels like a total wash idling along, 1/4 gas, half gas, 3/4, and WOT. I did add cats, keep that in mind too. I have been paying attention to the way it drives at all times, and there is no discernible difference either way. I can't wait to see how the tune affects it.
Usually, maximizing torque under the curve equates to good VE and good MPG. I can tell you that my MPG over the last 120 miles (1/4 tank) driven since the swap is unchanged, maybe even picked up one...and I have been all OVER the gas. Between my butt dyno and the fuel gauge, it looks promising that I didn't lose much/any "down low"/at part throttle. The dyno will tell the WOT story. Long term mileage will tell even more. I don't know if LMR does any street/part throttle tuning, since it takes half a day to a day, I assume yes but that is an assumption.
Sorry, this car has never seen the track so I can't give any good data there. It felt like a very high 12 car before, it still does.
I am comfortable predicting that if I am wrong, I won't lose much. I am very interested to see how it dynos and drives after the tune by LMR, who also did work and the last tune.
The differences that are obvious are:
1. Sound - deeper, quieter (cats), no rasp (cats), more refined
2. Some backfiring on decel - tells me I may pick up a few ponies and foot pounds with the tuning
3. Fitment - these damn big primaries are banging the crossmember. I am hoping poly motor mounts fix it without trading one annoying noise for another. I know the poly trans mount + rubber motor mounts made for an obnoxiously horribly loud setup. I am hoping the opposite setup works quietly.
4. The quality of ARH's setup is phenomenal. Clearly, these are as good as any out there, and 1.875 headers should not have gone in as "easily" as they did.
5. LMR does great work and I like dealing with them
Thanks again,
More to come tonight...Jason
Practically and financially, I am very happy with my choice. Buy once, buy right.
Performance wise, I have put forth a theory I am willing to put my money on and possibly be wrong. That is, that the big tube headers will show gains all over. The good part is being wrong has no penalty, only a smaller benefit. The numbers will tell a lot once I see the graph.
However, I think Tony hit it on the head when he said WOT numbers don't tell the whole story. Having worked at a Chevy dealership for 3 years, I understand every day driveability concerns fairly well. Not as well as some, but well enough to make decisions that are easy to live with. All things being equal, the 1.75s might make more torque at part throttle. My ***-dyno says that, untuned, there is no difference. It feels like a total wash idling along, 1/4 gas, half gas, 3/4, and WOT. I did add cats, keep that in mind too. I have been paying attention to the way it drives at all times, and there is no discernible difference either way. I can't wait to see how the tune affects it.
Usually, maximizing torque under the curve equates to good VE and good MPG. I can tell you that my MPG over the last 120 miles (1/4 tank) driven since the swap is unchanged, maybe even picked up one...and I have been all OVER the gas. Between my butt dyno and the fuel gauge, it looks promising that I didn't lose much/any "down low"/at part throttle. The dyno will tell the WOT story. Long term mileage will tell even more. I don't know if LMR does any street/part throttle tuning, since it takes half a day to a day, I assume yes but that is an assumption.
Sorry, this car has never seen the track so I can't give any good data there. It felt like a very high 12 car before, it still does.
I am comfortable predicting that if I am wrong, I won't lose much. I am very interested to see how it dynos and drives after the tune by LMR, who also did work and the last tune.
The differences that are obvious are:
1. Sound - deeper, quieter (cats), no rasp (cats), more refined
2. Some backfiring on decel - tells me I may pick up a few ponies and foot pounds with the tuning
3. Fitment - these damn big primaries are banging the crossmember. I am hoping poly motor mounts fix it without trading one annoying noise for another. I know the poly trans mount + rubber motor mounts made for an obnoxiously horribly loud setup. I am hoping the opposite setup works quietly.
4. The quality of ARH's setup is phenomenal. Clearly, these are as good as any out there, and 1.875 headers should not have gone in as "easily" as they did.
5. LMR does great work and I like dealing with them
Thanks again,
More to come tonight...Jason
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
Theres a pretty generic answer! You claim 10-15tq in the bottom and midrange and yet it wouldn't show on a dyno? I have driven witn 1 3/4" headers vs my headers and you can't feel the difference. The difference is far from this "night and day" you describe. Most would say the FAST 90 he has would not be optimal for his setup(including multiple sponsers) as well, but he has that as well.
If I had plans to build bigger in the future I wouldn't buy $1K+ headers more then once. Omec and ChocoCoco, 1 3/4" headers have their place....never did I say they didn't. Some people never have plans of upgrading to the same extent as others, and why don't u go find a calculator and figure out the primary length needed as well as the optimal primary size....u might just find that 1 3/4 isn't the optimal size for the stock engine either.
If I had plans to build bigger in the future I wouldn't buy $1K+ headers more then once. Omec and ChocoCoco, 1 3/4" headers have their place....never did I say they didn't. Some people never have plans of upgrading to the same extent as others, and why don't u go find a calculator and figure out the primary length needed as well as the optimal primary size....u might just find that 1 3/4 isn't the optimal size for the stock engine either.
Explain to me how you're going to track part throttle rwhp/rwtq on the dyno? Believe it or not, but the vast majority of us on this site will not be going WOT 98% of the time. Most of the time, we're just cruising or accelerating with traffic, and a 1 3/4" header will be superior in nearly all occurrences. Why pay more for larger primaries, have more fitment/install issues, then have less overall power? Like Tony so wisely said, even if you buy the 1 3/4" headers now, you'll be able to recover 2/3 of the money by selling them used a few years down the road. Some of you guys will spend thousands upon thousands of dollars on powertrain and drivetrain components, then bitch about $200 extra spent on headers. It boggles the mind.
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Verdad Gallardo Hmm...Tony Mamo from Airflow Research, one of the most respected names in racing, or some randomass guy on LS1tech I've never heard of...who should I listen to....
Explain to me how you're going to track part throttle rwhp/rwtq on the dyno? Believe it or not, but the vast majority of us on this site will not be going WOT 98% of the time. Most of the time, we're just cruising or accelerating with traffic, and a 1 3/4" header will be superior in nearly all occurrences. Why pay more for larger primaries, have more fitment/install issues, then have less overall power? Like Tony so wisely said, even if you buy the 1 3/4" headers now, you'll be able to recover 2/3 of the money by selling them used a few years down the road. Some of you guys will spend thousands upon thousands of dollars on powertrain and drivetrain components, then bitch about $200 extra spent on headers. It boggles the mind.
Explain to me how you're going to track part throttle rwhp/rwtq on the dyno? Believe it or not, but the vast majority of us on this site will not be going WOT 98% of the time. Most of the time, we're just cruising or accelerating with traffic, and a 1 3/4" header will be superior in nearly all occurrences. Why pay more for larger primaries, have more fitment/install issues, then have less overall power? Like Tony so wisely said, even if you buy the 1 3/4" headers now, you'll be able to recover 2/3 of the money by selling them used a few years down the road. Some of you guys will spend thousands upon thousands of dollars on powertrain and drivetrain components, then bitch about $200 extra spent on headers. It boggles the mind.
BigKap...
The 1.875 is the wrong choice for the OP's described combination and IMO most stock displacement N/A builds unless its very aggressive with a solid roller and a 7500 RPM usable power curve. Is it better than a stock exhaust manifold....of course and I stated that in my original post.
You want to argue differently be my guest....
You want to discount the part throttle response and increase in low RPM and midrange torque from the proper sized primary tubes feel free once again.
Maybe we can get this guys opinion who just did exactly what we are discussing (on a 402 CID stroker engine no less) and is thrilled with the performance increase and response from the smaller tube....note that he saw double the gains in TQ I quoted above but some of that fact is due to the increase in primary length as well, not just from the smaller diameter. And the new exhaust has restrictive cats which his former exhaust did not. I bet the car feels like he put a larger engine in it at part throttle....
https://ls1tech.com/forums/dynamometer-results-comparisons/887349-403ci-motor-swapped-american-racing-lg-pro-longtubes.html
For you guys with an open mind looking to learn something check out the link above and read it twice if you have to.
Catch you guys later
Tony
The 1.875 is the wrong choice for the OP's described combination and IMO most stock displacement N/A builds unless its very aggressive with a solid roller and a 7500 RPM usable power curve. Is it better than a stock exhaust manifold....of course and I stated that in my original post.
You want to argue differently be my guest....
You want to discount the part throttle response and increase in low RPM and midrange torque from the proper sized primary tubes feel free once again.
Maybe we can get this guys opinion who just did exactly what we are discussing (on a 402 CID stroker engine no less) and is thrilled with the performance increase and response from the smaller tube....note that he saw double the gains in TQ I quoted above but some of that fact is due to the increase in primary length as well, not just from the smaller diameter. And the new exhaust has restrictive cats which his former exhaust did not. I bet the car feels like he put a larger engine in it at part throttle....
https://ls1tech.com/forums/dynamometer-results-comparisons/887349-403ci-motor-swapped-american-racing-lg-pro-longtubes.html
For you guys with an open mind looking to learn something check out the link above and read it twice if you have to.
Catch you guys later
Tony
BigKap...
The 1.875 is the wrong choice for the OP's described combination and IMO most stock displacement N/A builds unless its very aggressive with a solid roller and a 7500 RPM usable power curve. Is it better than a stock exhaust manifold....of course and I stated that in my original post.
You want to argue differently be my guest....
You want to discount the part throttle response and increase in low RPM and midrange torque from the proper sized primary tubes feel free once again.
Maybe we can get this guys opinion who just did exactly what we are discussing (on a 402 CID stroker engine no less) and is thrilled with the performance increase and response from the smaller tube....note that he saw double the gains in TQ I quoted above but some of that fact is due to the increase in primary length as well, not just from the smaller diameter. And the new exhaust has restrictive cats which his former exhaust did not. I bet the car feels like he put a larger engine in it at part throttle....
https://ls1tech.com/forums/showthread.php?t=887349
For you guys with an open mind looking to learn something check out the link above and read it twice if you have to.
Catch you guys later
Tony
The 1.875 is the wrong choice for the OP's described combination and IMO most stock displacement N/A builds unless its very aggressive with a solid roller and a 7500 RPM usable power curve. Is it better than a stock exhaust manifold....of course and I stated that in my original post.
You want to argue differently be my guest....
You want to discount the part throttle response and increase in low RPM and midrange torque from the proper sized primary tubes feel free once again.
Maybe we can get this guys opinion who just did exactly what we are discussing (on a 402 CID stroker engine no less) and is thrilled with the performance increase and response from the smaller tube....note that he saw double the gains in TQ I quoted above but some of that fact is due to the increase in primary length as well, not just from the smaller diameter. And the new exhaust has restrictive cats which his former exhaust did not. I bet the car feels like he put a larger engine in it at part throttle....
https://ls1tech.com/forums/showthread.php?t=887349
For you guys with an open mind looking to learn something check out the link above and read it twice if you have to.
Catch you guys later
Tony
Thread Starter
TECH Fanatic
iTrader: (70)
Joined: Oct 2005
Posts: 1,219
Likes: 0
From: Los Angeles, California (818)
ok guys calm down lol, i havent bought any headers yet, i want to, but i know there is more then just slapping things together thats why im asking for ur opinions, alot of people tell me already that my fast 90 with a nw 90 is overkill, well let me tell them this, i got the car tuned by 12secss and i feel a difference even with stock manifolds, all these parts that im putting on car are parts i can re use in my 408, so its not money i just through out the window, and if i do buy 1 3/4 i most likely wont sell them just to buy 1 7/8 later on when the power differnce is minimal, now if i get 1 7/8 i just dont see how i will lose that much power, and if i do it probably wont be felt, and the extra flow will benefit me above 3500 rpms, no matter what im getting the lts, just havent decided on the primary size, im looking at everyones case and opinion carefully just so i wont have to throw money out the window
The differences in those headers IS more then just the 1/8" primaries, so again your evidence u show is not proving your point. I didn't say specifically the 1 7/8" is better then 1 3/4", they certainly won't make or break the setup being the only difference. You'll have to excuse me for thinking differently, we don't all approach a problem the same pal, and unline a few others here I won't just take advice on a given subject. Not trying to argue nor am I trying to discredit your statement....but I feel the 10-15tq u stated is only in certain circumstances. I also don't think that currently or even with bolt ons/ or cam only he would need a Fast 90 either, but its not gonna hurt overall performance. As stated above I have driven 2 identical setups the only difference being the headers, and as far as feeling, there was nothing noticably different while driving....thats my experience, and it didn't come from reading it on a internet forum.
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
BigKap...
The 1.875 is the wrong choice for the OP's described combination and IMO most stock displacement N/A builds unless its very aggressive with a solid roller and a 7500 RPM usable power curve. Is it better than a stock exhaust manifold....of course and I stated that in my original post.
You want to argue differently be my guest....
You want to discount the part throttle response and increase in low RPM and midrange torque from the proper sized primary tubes feel free once again.
Maybe we can get this guys opinion who just did exactly what we are discussing (on a 402 CID stroker engine no less) and is thrilled with the performance increase and response from the smaller tube....note that he saw double the gains in TQ I quoted above but some of that fact is due to the increase in primary length as well, not just from the smaller diameter. And the new exhaust has restrictive cats which his former exhaust did not. I bet the car feels like he put a larger engine in it at part throttle....
https://ls1tech.com/forums/showthread.php?t=887349
For you guys with an open mind looking to learn something check out the link above and read it twice if you have to.
Catch you guys later
Tony
The 1.875 is the wrong choice for the OP's described combination and IMO most stock displacement N/A builds unless its very aggressive with a solid roller and a 7500 RPM usable power curve. Is it better than a stock exhaust manifold....of course and I stated that in my original post.
You want to argue differently be my guest....
You want to discount the part throttle response and increase in low RPM and midrange torque from the proper sized primary tubes feel free once again.
Maybe we can get this guys opinion who just did exactly what we are discussing (on a 402 CID stroker engine no less) and is thrilled with the performance increase and response from the smaller tube....note that he saw double the gains in TQ I quoted above but some of that fact is due to the increase in primary length as well, not just from the smaller diameter. And the new exhaust has restrictive cats which his former exhaust did not. I bet the car feels like he put a larger engine in it at part throttle....
https://ls1tech.com/forums/showthread.php?t=887349
For you guys with an open mind looking to learn something check out the link above and read it twice if you have to.
Catch you guys later
Tony
EDIT - Holy crap, Tony, I just read that thread you linked to. Those 1 3/4" LG's completely ANNIHILATED the 1 7/8" ARH headers. OMG. Going from ARH to LG was like going from stock manifolds and cats to longtubes and high flow fats. Holy ****. Amazing.
After reading that, my car's never getting more than 1 3/4" no matter what I do
And if I ever get a Corvette, LG Pro LT's or bust Things I have learned:
1. Poly motor mounts and stock tranny mount is the way to go
2. installing motor mounts with 1.875 headers is tougher
3. Due to #2, my dyno has to wait until tomorrow!! 
Thank you, Tony. The results from that thread do not surprise me at all. I've seen how important the following can be:
1. Header primary size
2. Stepped design
3. Overall design
4. Y pipe design
5. Catback
6. cats or no cats
7. which cats
8. the effect intake has on the exhaust
I've seen conventional wisdom both proved and fall on its face. I do know these LS motors like to breathe.
Most of all, I know the importance of how the combo works together as a unit. I have ridden in Tony's combo in an f-body: 224/228 afr spec cam, AFR205 heads, 1 3/4 kooks headers + ORY, LS6 mani (zain98 is a good friend) so I am well aware of how well Tony knows his stuff.
I'm not in a pissing match like some others in here. I have a theory and am willing to spend my money in my car to see if it holds in this particular application. I have seen many experts (which Tony certainly is) surprised in my time in many different fields. I just want to see how much sense it makes to buy for a 427 LS motor when you only have a 346 LS motor at the moment. I know how project timelines get delayed, believe me. My contention is: no loss at all anywhere. WORST case is a smaller than optimal gain. We'll see if I am right.
To be clear, the comparison will be the mods in sig with either:
MAC mids + ORY
ARH 1.875 + catted Y
both tuned for the mods on the same dyno by the same tuner.
Has to wait until tomorrow!
1. Poly motor mounts and stock tranny mount is the way to go
2. installing motor mounts with 1.875 headers is tougher
3. Due to #2, my dyno has to wait until tomorrow!!
Thank you, Tony. The results from that thread do not surprise me at all. I've seen how important the following can be:
1. Header primary size
2. Stepped design
3. Overall design
4. Y pipe design
5. Catback
6. cats or no cats
7. which cats
8. the effect intake has on the exhaust
I've seen conventional wisdom both proved and fall on its face. I do know these LS motors like to breathe.
Most of all, I know the importance of how the combo works together as a unit. I have ridden in Tony's combo in an f-body: 224/228 afr spec cam, AFR205 heads, 1 3/4 kooks headers + ORY, LS6 mani (zain98 is a good friend) so I am well aware of how well Tony knows his stuff.
I'm not in a pissing match like some others in here. I have a theory and am willing to spend my money in my car to see if it holds in this particular application. I have seen many experts (which Tony certainly is) surprised in my time in many different fields. I just want to see how much sense it makes to buy for a 427 LS motor when you only have a 346 LS motor at the moment. I know how project timelines get delayed, believe me.
My contention is: no loss at all anywhere. WORST case is a smaller than optimal gain. We'll see if I am right.To be clear, the comparison will be the mods in sig with either:
MAC mids + ORY
ARH 1.875 + catted Y
both tuned for the mods on the same dyno by the same tuner.
Has to wait until tomorrow!
I got an LS2 408 on big spray that I daily drive that has run a 9.52 @ 142 w/ 1 3/4 Jethot (brand) Long tube header thru 2 Borla 3" XR1's dumped right before the axle with a 3700 lb race weight. It should run a 9.0, 9.1 on my next trip out and carries the wheels thru the 60'. If the 1 3/4's can support that, I dont think that he will ever max them out unless he also goes big spray. I'm sure that these headers are costing me some power when I'm on the jug but NA I dont think that I am maxing them out.
I am not gonna argue anymore, its not worth it.
For the OP, I think 1 3/4 now is the better choice. Headers are very easy to sell and like Tony said those projects take longer than most think. In my situation, I have 1 7/8 that I bought intending for future use. To my surprise, when I swapped from 1 3/4 TTS I picked up 1.5 mph with stage 2 heads, ls6 cam, 4200 stall , 3.42 gears. The bad thing is no one will ever know whether this increase was from bigger primaries, better merge collector, or just an overall superior design of the QTP's compared to the TTS's. I would like to think that my 1 7/8's are helping me for my current situation. I'm fully intending on maxing out the stock short block NA, but the only way I would ever consider going back to a 1 3/4 primary is if LG decides they want to make some F body headers.
Check out this link. In this instance the 1 7/8 header showed superior to the 1 3/4 on a stock motor.
http://www.carcraft.com/techarticles...est/index.html
I am not saying this is always the case or that this test is right. But something to think about.
Btw those collectors just dont look right. IMO
http://www.carcraft.com/techarticles...est/index.html
I am not saying this is always the case or that this test is right. But something to think about.
Btw those collectors just dont look right. IMO
