Can we put the header question to rest
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Pro
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From: Lake Lure NC
Can we put the header question to rest
Here is my issue. I am debating Stainless Steel header (1 5/8) over the EM mild steel headers (1 3/4). I have and will be using the Corsa cat back system. Currently, my engine build is fairly stock, however in the future (not near) I would like to go to a stroker motor. I am running a 6 speed, so the Stainless Works headers will fit my car.
Pro's for Stainless:
Never rust
Function well on a stock to mildly mod vette
Cons for Stainless:
If I ever upgrade to a stroker engine I will need to repurchase headers.
Pro's EM Mild Steel:
Coated
Function well on a stock and Mod vette
Cons EM Mild Steel:
Some say you lose torque on a stock engine
Will evidentially need to recoat. (What is the average life of the coating?)
So with all this said, on my current configuration would you get the Stainless headers or the EM? I like the idea of no rust and longevity with the stainless; however I may need to get over it for performance. Forum thoughts please.
Pro's for Stainless:
Never rust
Function well on a stock to mildly mod vette
Cons for Stainless:
If I ever upgrade to a stroker engine I will need to repurchase headers.
Pro's EM Mild Steel:
Coated
Function well on a stock and Mod vette
Cons EM Mild Steel:
Some say you lose torque on a stock engine
Will evidentially need to recoat. (What is the average life of the coating?)
So with all this said, on my current configuration would you get the Stainless headers or the EM? I like the idea of no rust and longevity with the stainless; however I may need to get over it for performance. Forum thoughts please.
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From: St. Peters MO Sometimes you have to prove yourself by doing alot of killing or alot of dying...
Originally Posted by mothersworry
Cons for Stainless:
If I ever upgrade to a stroker engine I will need to repurchase headers.
Pro's EM Mild Steel:
Coated
Function well on a stock and Mod vette
Cons EM Mild Steel:
Some say you lose torque on a stock engine
Will evidentially need to recoat. (What is the average life of the coating?)
If I ever upgrade to a stroker engine I will need to repurchase headers.
Pro's EM Mild Steel:
Coated
Function well on a stock and Mod vette
Cons EM Mild Steel:
Some say you lose torque on a stock engine
Will evidentially need to recoat. (What is the average life of the coating?)
Team Owner
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From: I'm the walkin dude I can see all of the world...
St. Jude Donor '03
1 5/8th headers are also large enough for 383 stroker engines too. Ski and Corky didn't need them until way up there in cubic inches. You can also get a 1 5/8 from EM if you want them.
Also I am happy with my 1 3/4 Hookers on my basiclly stock motor. There is no big torque loss but from what CFI-EFI says there is some torque to be gained by sticking with the 1 5/8ths. My wallet just didn't allow for a quality set of 1 5/8th so I went with the Hookers.
Also I am happy with my 1 3/4 Hookers on my basiclly stock motor. There is no big torque loss but from what CFI-EFI says there is some torque to be gained by sticking with the 1 5/8ths. My wallet just didn't allow for a quality set of 1 5/8th so I went with the Hookers.
Last edited by Mr Mojo; Jan 6, 2005 at 07:24 PM. Reason: sig pic too large
Race Director
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Originally Posted by VictorRussell'92
Ski and Corky didn't need them until way up there in cubic inches.
Nobody has ever done back to back dyno / track testing with 1 5/8 vs 1 3/4 headers on these cars so it's really impossible to tell anything with any certainty.
These numbers are just rough estimates because they assume 100% volumetric efficiency of the motor, but take a look just the same.
A 434 turning 5000 RPM's would flow 627 CFM
A 350 turning 6500 RPM's would flow 657 CFM
A 383 turning 7000 RPM's would flow 775 CFM
So you can see it's more complicated than just a simple displacement question. A large displacement low RPM motor may well require a smaller header size than a smaller displacement high RPM motor. Intake / heads / cams all play a role.
Last edited by Nathan Plemons; Jan 6, 2005 at 11:01 AM.
Le Mans Master
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From: Jenison MI
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St. Jude Donor '06
EM makes a nice system that hooks right up to the Corsa cat back. I have this setup and I must say, this was the easiest set of headers I have ever installed. Beautiful.
Race Director
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From: The Top of Utah
Originally Posted by mothersworry
Here is my issue. I am debating Stainless Steel header (1 5/8) over the EM mild steel headers (1 3/4). I have and will be using the Corsa cat back system. Currently, my engine build is fairly stock, however in the future (not near) I would like to go to a stroker motor. I am running a 6 speed, so the Stainless Works headers will fit my car.
RACE ON!!!
Team Owner
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From: I'm the walkin dude I can see all of the world...
St. Jude Donor '03
Originally Posted by Nathan Plemons
But they also don't turn extremely high RPM's either. Essentially there is no blanket answer. Personally I belive that 1 3/4 is the way to go from the results that I have seen first hand, others will argue.
Nobody has ever done back to back dyno / track testing with 1 5/8 vs 1 3/4 headers on these cars so it's really impossible to tell anything with any certainty.
These numbers are just rough estimates because they assume 100% volumetric efficiency of the motor, but take a look just the same.
A 434 turning 5000 RPM's would flow 627 CFM
A 350 turning 6500 RPM's would flow 657 CFM
A 383 turning 7000 RPM's would flow 775 CFM
So you can see it's more complicated than just a simple displacement question. A large displacement low RPM motor may well require a smaller header size than a smaller displacement high RPM motor. Intake / heads / cams all play a role.
Nobody has ever done back to back dyno / track testing with 1 5/8 vs 1 3/4 headers on these cars so it's really impossible to tell anything with any certainty.
These numbers are just rough estimates because they assume 100% volumetric efficiency of the motor, but take a look just the same.
A 434 turning 5000 RPM's would flow 627 CFM
A 350 turning 6500 RPM's would flow 657 CFM
A 383 turning 7000 RPM's would flow 775 CFM
So you can see it's more complicated than just a simple displacement question. A large displacement low RPM motor may well require a smaller header size than a smaller displacement high RPM motor. Intake / heads / cams all play a role.
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Burning Brakes
Joined: Nov 2003
Posts: 914
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From: Redding Ca
WE all hate to buy the same item twice because we got the wrong thing the first time. However, you said the bigger engine is not in the near future. So that is one count in favor of the smaller mild steel. Many of our current expectations change over time, so you may not even get to the larger engine. For example, you might sell the car for something else instead.
Secondly, the smaller headers will work well with a larger anyway. I sometimes think we all can get caught up searching for the last HP or ft/lb of torque. You can always change them in the future if it becomes a big deal.
I'd go with the best header for your current expectations rather than a "maybe". (Spoken by a guy who has bought the same item twice several times)
It turns out to be an annoyance more than anything else. It also gives one "character"
Secondly, the smaller headers will work well with a larger anyway. I sometimes think we all can get caught up searching for the last HP or ft/lb of torque. You can always change them in the future if it becomes a big deal.
I'd go with the best header for your current expectations rather than a "maybe". (Spoken by a guy who has bought the same item twice several times)
It turns out to be an annoyance more than anything else. It also gives one "character"
Race Director
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Originally Posted by VictorRussell'92
Yeah, don't get me wrong I really think 1 3/4 is fine. Heck thats what I got. I just was pointing out that I don't think it is a big deal whichever way he goes. I think alot of this Header stuff is much ado about nada.
The numbers come from the following calculations:
For one revolution only 4 cylinders would be on the intake stroke, thus the effective displacement is only half of the total displacement, or displacement per revolution. Multiply the displacement per revolution by RPM to get CFM.
Again these numbers assume 100% airflow into and out of othe engine, actual numbers will be significantly smaller. Interesting about those 1000 CFM throttle bodies on 350 motors huh?
Safety Car
Joined: Sep 2000
Posts: 3,524
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From: Hinckley Ohio
Originally Posted by Nathan Plemons
Interesting about those 1000 CFM throttle bodies on 350 motors huh?
Just what do CFM ratings of various devices really mean.....so if we put a 1000cfm throttle body into an intake manifold that flows ???? into heads that flow????, all these thru a MAF that flows ????,
what do we really end up with???
My point is that flow ratings come about with a pressure drop of some sort, so if we do "oversize" each component, don't we end with a system that flows better???? thus more power potential......
I am still pretty convinced that an "oversized" throttle body won't hurt anything and will result in some kind of gain....plus cost of 58mm=costof 52mm so why not??? Same with oversized MAF or air cleaner system if they are available...
Back to the original post, I seriously question that 1-5/8 vs 1-3/4 is really a BIG deal........I'll get my new EM's on soon and see what I gain....but I'll never know what the 1-5/8 would have done...but I don't plan on loosing any sleep over it...
Melting Slicks
Joined: May 2001
Posts: 3,270
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From: Winchester VA
Cruise-In V Veteran
Originally Posted by LT4BUD
Some day I will dig into this topic so I can make an intelligent observation........but for now I will post a question out of a lot of ignorance...
Just what do CFM ratings of various devices really mean.....so if we put a 1000cfm throttle body into an intake manifold that flows ???? into heads that flow????, all these thru a MAF that flows ????,
what do we really end up with???
My point is that flow ratings come about with a pressure drop of some sort, so if we do "oversize" each component, don't we end with a system that flows better???? thus more power potential......
Just what do CFM ratings of various devices really mean.....so if we put a 1000cfm throttle body into an intake manifold that flows ???? into heads that flow????, all these thru a MAF that flows ????,
what do we really end up with???
My point is that flow ratings come about with a pressure drop of some sort, so if we do "oversize" each component, don't we end with a system that flows better???? thus more power potential......
On thread topic, I think CFI makes a good point about not losing vs gaining and, given a streetable combo, could anyone tell the difference? I would think certainly not. The ultimate decision may be better made based on quality, fitment and price.
Burning Brakes
Joined: Nov 2003
Posts: 914
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From: Redding Ca
What do you guys think, worthy of another thread?? I think so, started off with the #'s provided by Nathan as a reference. I have a few observations and would like to know if they are misguided
........................................ ............
I'd like a lot of dicussion on this topic. My interest is at what levels Cylinder head intake flow become too small for the size of the engine. Specifically, would a ported AFR 195 (flows about like an unported AFR 210) be able to produce good "streetable power" on a 415-427 cu inch motor? By streetable power, I mean around 500 hp at 5,500 to 6,000 rpm, assuming LPE 219 cam and SR induction. I am pretty sure the induction and cam are adequate for that power level, but do not know about the heads . I want to keep EO compliant heads and the AFR 195 do that.
........................................ ............
I'd like a lot of dicussion on this topic. My interest is at what levels Cylinder head intake flow become too small for the size of the engine. Specifically, would a ported AFR 195 (flows about like an unported AFR 210) be able to produce good "streetable power" on a 415-427 cu inch motor? By streetable power, I mean around 500 hp at 5,500 to 6,000 rpm, assuming LPE 219 cam and SR induction. I am pretty sure the induction and cam are adequate for that power level, but do not know about the heads . I want to keep EO compliant heads and the AFR 195 do that.