Headers for V8 cars, Please read
12-03-03, 04:18 PM
#46
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First of all, I never said that I was very knowledgeable about designing headers. I ride and race 2-stroke motorcycles and understand that velocity, scavenging and resonance plays an important role in the powerband structure. Also I have built (from premade pieces) and seen some headers for NA application on higher powered rotary engine. Rotaries have high pressure pulses due to the abrubt exhuast port opening.
But I never said I was an expert. I guess you are an all knowing expert? Care to clarify your expertise?
And I never said that I wanted equal length headers. I was just asking. You can reread my previous messages.
-Jeff
P.S. I did not receive a PM from you.
But I never said I was an expert. I guess you are an all knowing expert? Care to clarify your expertise?
And I never said that I wanted equal length headers. I was just asking. You can reread my previous messages.
-Jeff
P.S. I did not receive a PM from you.
Originally posted by jbrady
Jeff, of course you have already received my direct email reply to your request but I would like to address your above statement "more top-end power without sacraficing any low-end ". Of course this is not meant to retort you as you are very knowledgable on this subject. Rather to help the majority of readers that are not exhaust experts and must rely on what others tell them.
While I agree it is of course theoretically possible to produce a higher power exhaust header/manifold by optimizing the length to the RPM window targeted... the real world situation shows that the added expense, increased installation difficulty and deviation from factory emissions configuration make long tubes a poor choice for 99% of road cars. Also, the KEY to making power is optimizing flow. This a accomplished by creating the lowest possible pressure at the exhaust port during the last half of the exhaust event when in cylinder pressures are dropping rapidly and the pressure differential becomes most important. Long tube headers isolate the individual ports and create a resonance tune effect dictated by tube length and diameter. This tune only happens in a small RPM window. Above and below that RPM the main effect is due to velocity scavenging. Velocity scavenging is the key to the HFVS header and is designed to enhance the effect from low to high rpm. The performance difference between the HFVS and a very well designed ELLT (equal length long tube) design is unlikely to be noticeable from the drivers seat. A poorly designed ELLT will actually hurt performance in various RPM ranges compared to even the FACTORY manifold
I for one would be very unhappy to spend big bucks and make all the sacrifices needed for ELLT only to have a car that is LESS responsive in most driving conditions.
So, for an expert like yourself the ELLT is maybe a reasonable choice but I wanted everyone to understand they are not sacrificing by using the HFVS design with a good cat back secondary system (key to the overall performance of ANY wide RPM operating system).
Jeff, of course you have already received my direct email reply to your request but I would like to address your above statement "more top-end power without sacraficing any low-end ". Of course this is not meant to retort you as you are very knowledgable on this subject. Rather to help the majority of readers that are not exhaust experts and must rely on what others tell them.
While I agree it is of course theoretically possible to produce a higher power exhaust header/manifold by optimizing the length to the RPM window targeted... the real world situation shows that the added expense, increased installation difficulty and deviation from factory emissions configuration make long tubes a poor choice for 99% of road cars. Also, the KEY to making power is optimizing flow. This a accomplished by creating the lowest possible pressure at the exhaust port during the last half of the exhaust event when in cylinder pressures are dropping rapidly and the pressure differential becomes most important. Long tube headers isolate the individual ports and create a resonance tune effect dictated by tube length and diameter. This tune only happens in a small RPM window. Above and below that RPM the main effect is due to velocity scavenging. Velocity scavenging is the key to the HFVS header and is designed to enhance the effect from low to high rpm. The performance difference between the HFVS and a very well designed ELLT (equal length long tube) design is unlikely to be noticeable from the drivers seat. A poorly designed ELLT will actually hurt performance in various RPM ranges compared to even the FACTORY manifold
I for one would be very unhappy to spend big bucks and make all the sacrifices needed for ELLT only to have a car that is LESS responsive in most driving conditions.
So, for an expert like yourself the ELLT is maybe a reasonable choice but I wanted everyone to understand they are not sacrificing by using the HFVS design with a good cat back secondary system (key to the overall performance of ANY wide RPM operating system).
Last edited by aristo400; 12-03-03 at 04:20 PM.
12-03-03, 04:51 PM
#47
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Originally posted by aristo400
But I never said I was an expert. I guess you are an all knowing expert? Care to clarify your expertise?
P.S. I did not receive a PM from you.
But I never said I was an expert. I guess you are an all knowing expert? Care to clarify your expertise?
P.S. I did not receive a PM from you.
I also think he said he sent you an email, not a PM.
12-04-03, 08:11 AM
#49
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so how many ppl are in? is the project started? i think you guys might want to put a link from the main forum to here, since i just found it today. maybe there is others that have no idea about this idea...
12-04-03, 09:26 AM
#50
Lexus Champion
Originally posted by aristo400
First of all, I never said that I was very knowledgeable about designing headers. I ride and race 2-stroke motorcycles and understand that velocity, scavenging and resonance plays an important role in the powerband structure. Also I have built (from premade pieces) and seen some headers for NA application on higher powered rotary engine. Rotaries have high pressure pulses due to the abrubt exhuast port opening.
But I never said I was an expert. I guess you are an all knowing expert? Care to clarify your expertise?
And I never said that I wanted equal length headers. I was just asking. You can reread my previous messages.
-Jeff
P.S. I did not receive a PM from you.
First of all, I never said that I was very knowledgeable about designing headers. I ride and race 2-stroke motorcycles and understand that velocity, scavenging and resonance plays an important role in the powerband structure. Also I have built (from premade pieces) and seen some headers for NA application on higher powered rotary engine. Rotaries have high pressure pulses due to the abrubt exhuast port opening.
But I never said I was an expert. I guess you are an all knowing expert? Care to clarify your expertise?
And I never said that I wanted equal length headers. I was just asking. You can reread my previous messages.
-Jeff
P.S. I did not receive a PM from you.
I did not mean to insult you in any way. And I do apologize for I was actually confusing you with someone else that I had just emailed. Also, while you may not consider yourself an expert on header design your experience with 2 strokes and rotaries places you way above the general automotive population regarding exhaust dynamic knowledge.
Am I and expert? That is relative but my exhaust header experience dates to 1978 and I have direct hands on experience in many automotive high performance applications including turbocharging the 12a and 13b rotaries, I4, I5, I6, V6, V8 and V12 engines including 1500hp 510cid twin turbo offshore power boat engines. No one can or ever will know everything about anything so I would never make that claim. I do have some unusual insights and have discussed various designs with many experts including Corky Bell (whom I worked for in 1989-1990), Smokey Yunick (RIP)(30 minute phone conversation regarding his heat expansion cycle engines and the potential of applying it to rotary engines of which he worked with GM on their rotary program that never made production) and Jim Fueling (RIP) back in 1990 who informed me of actually building an engine with a roots supercharger in the exhaust to aid scavenging), and Jack Burns of Burns Stainless who expanded on the functionality of the merge collector, Tom Cloutier who worked with me on computer modeling exhaust flow in multiple configurations for the cat back system I am designing for my LS400, and of course the craftsman who is to build our HFSV headers under whom Jack Burns originally worked prior to founding Burns Stainless. Many, many more but hopefully this will give you an idea. Am I an expert? You can make up your own mind. Truthfully, I am not concerned with that title.
So, my response to your post was sincere and that is why I worded it as such. Did I answer your question on the reason for the shorty design vs a long tube design? If not or if you have any more specific questions I have not addressed feel free to post here or send me a PM or email.
12-04-03, 09:30 AM
#51
Lexus Champion
Originally posted by koreanpers
so how many ppl are in? is the project started? i think you guys might want to put a link from the main forum to here, since i just found it today. maybe there is others that have no idea about this idea...
so how many ppl are in? is the project started? i think you guys might want to put a link from the main forum to here, since i just found it today. maybe there is others that have no idea about this idea...
12-04-03, 09:47 AM
#52
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Originally posted by jbrady
Dave, he may have a point.
Dave, he may have a point.
12-04-03, 06:53 PM
#53
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Guys I think we want to move forward on this as soon as possible. I'll tack up a link this weekend with an annoucement after the meets are over to see if any guys missed it.
Anyone in the Phoenix area for R&D with a GS!?!?!?!
Anyone in the Phoenix area for R&D with a GS!?!?!?!
Last edited by DaveGS4; 12-04-03 at 07:08 PM.
12-04-03, 07:57 PM
#54
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Well, I missed this post before but I'm in now for sure. Thanks to Dave for making this a sticky.
Anyone have an idea how long it would take to get these installed if the engine did have to be lifted? I'm pretty sure I could bolt this on, but pulling the engine without a lift (not to mention experience doing so) would be out of the question for me. Basically I'm looking to get an idea what a dealer would charge to do the install if the engine did need to be pulled.
Also, I definitely think a deposit should be required so this guy doesn't get screwed around. Wouldn't somthing like $50 be reasonable?
Anyone have an idea how long it would take to get these installed if the engine did have to be lifted? I'm pretty sure I could bolt this on, but pulling the engine without a lift (not to mention experience doing so) would be out of the question for me. Basically I'm looking to get an idea what a dealer would charge to do the install if the engine did need to be pulled.
Also, I definitely think a deposit should be required so this guy doesn't get screwed around. Wouldn't somthing like $50 be reasonable?
12-05-03, 03:09 PM
#55
Too bad I don't have a GS4 
'cause I would do this in second...but for all those CA people worried about CARB certification, I would not worry too much since this would not impact the emissions requirement...and let's face it, this is probably the first time Joe Blow down at the local smog testing facility has probably tested a GS in the first place and has no clue as to what the STOCK parts vs. MODIFIED parts look like...and if your really worried, buy a heatshield to cover it up 
'cause I would do this in second...but for all those CA people worried about CARB certification, I would not worry too much since this would not impact the emissions requirement...and let's face it, this is probably the first time Joe Blow down at the local smog testing facility has probably tested a GS in the first place and has no clue as to what the STOCK parts vs. MODIFIED parts look like...and if your really worried, buy a heatshield to cover it up
12-05-03, 03:20 PM
#56
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Originally posted by aoverify
Well, I missed this post before but I'm in now for sure. Thanks to Dave for making this a sticky.
Anyone have an idea how long it would take to get these installed if the engine did have to be lifted? I'm pretty sure I could bolt this on, but pulling the engine without a lift (not to mention experience doing so) would be out of the question for me. Basically I'm looking to get an idea what a dealer would charge to do the install if the engine did need to be pulled.
Also, I definitely think a deposit should be required so this guy doesn't get screwed around. Wouldn't somthing like $50 be reasonable?
Well, I missed this post before but I'm in now for sure. Thanks to Dave for making this a sticky.
Anyone have an idea how long it would take to get these installed if the engine did have to be lifted? I'm pretty sure I could bolt this on, but pulling the engine without a lift (not to mention experience doing so) would be out of the question for me. Basically I'm looking to get an idea what a dealer would charge to do the install if the engine did need to be pulled.
Also, I definitely think a deposit should be required so this guy doesn't get screwed around. Wouldn't somthing like $50 be reasonable?
This will be awesome if it works
12-07-03, 10:02 PM
#57
Lexus Champion
Here are a couple pics of the PROBLEM... the stock manifolds...
The Passenger side: note the VERY short runners on the back 2 ports and the 90 degree angles
The Driver side is only slightly better with the back 2 ports being the worst.
For more info go here:
https://www.clublexus.com/forums/sho...hlight=air+box
The Passenger side: note the VERY short runners on the back 2 ports and the 90 degree angles
The Driver side is only slightly better with the back 2 ports being the worst.
For more info go here:
https://www.clublexus.com/forums/sho...hlight=air+box
Last edited by JBrady; 12-07-03 at 10:04 PM.
how bad is that?
