merge collectors
Thread Starter
Instructor
Joined: Mar 2010
Posts: 162
Likes: 8
merge collectors
I am about to start building a new set of headers for my 13.5:1 434 sbc.
Question, do merge collectors make more power. I ve searched everywhere and not found evidence to prove they do, with either dyno
comparisons or times. All the manufacturers say they do, dynotech,
edelbrock,stainless works,burns stainless etc, but none can show it.
Anyone in the real world know?
Question, do merge collectors make more power. I ve searched everywhere and not found evidence to prove they do, with either dyno
comparisons or times. All the manufacturers say they do, dynotech,
edelbrock,stainless works,burns stainless etc, but none can show it.
Anyone in the real world know?
Race Director
Joined: Jan 2000
Posts: 13,018
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Everytime I've seen them tested in real life they DO seem to pickup 5-10HP...but interestingly they have never shown a back to back improvement at the track on well sorted out cars that I've seen. One of those...*can't hurt* deals.
If you're doing new headers, I'd look into PipeMax from Larry Meaux. There is a lot to designing a great header system and his calculations seem to work out well.
Are you planning steps or not?
I know there is a trend towards smaller collectors with a venturi effect like merge collectors do. I understand there are some much smaller collectors/Venturi's INSIDE some of the huge ones you see on Pro Stock stuff.
If it's going to have exhaust on it...look into Vizards work on muffler and pipe sizing and how it relates to whatever you do with headers.
JIM
If you're doing new headers, I'd look into PipeMax from Larry Meaux. There is a lot to designing a great header system and his calculations seem to work out well.
Are you planning steps or not?
I know there is a trend towards smaller collectors with a venturi effect like merge collectors do. I understand there are some much smaller collectors/Venturi's INSIDE some of the huge ones you see on Pro Stock stuff.
If it's going to have exhaust on it...look into Vizards work on muffler and pipe sizing and how it relates to whatever you do with headers.
JIM
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Merge collectors have many design considerations to make them properly work. The smartest engine guy I know uses them but, said that a properly designed tri-y setup would probably be a better bet for me on my motor because of the RPM range I'm going to run it at 2600-8000RPM. We are going to try both set-ups at his shop, good thing because I could go broke trying to buy ther collectors that he alreay has laying around.
The motor in the photo below makes north of 2.75HP per cu/in @10,200RPM note the collectors, it had a set of merge collectors on it when it entered my friend's shop, it will NOT have them when it leaves to hopefully set some records.
The motor in the photo below makes north of 2.75HP per cu/in @10,200RPM note the collectors, it had a set of merge collectors on it when it entered my friend's shop, it will NOT have them when it leaves to hopefully set some records.
Thread Starter
Instructor
Joined: Mar 2010
Posts: 162
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Thanks Jim, i think i ll use the edelbrock stainless collectors which seem to be a real bargain price, have to wait and see what the quality is like. Stepped primaries, don t think
so, i m going to use a 2" pipe and reshape the end to fit the ports on the afr 227 heads.
Stainless throughout, hopefully last set of headers i ll need.
so, i m going to use a 2" pipe and reshape the end to fit the ports on the afr 227 heads.
Stainless throughout, hopefully last set of headers i ll need.
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Solid LT-1...interesting they had a 4/2/1 deal going on the collectors. Did they test 4/1 against them with a Merge?
You also get into issues with cam overlap as it's easy to overscavenge a cylinder with wrong cam.
I just did some dyno work a few weeks ago with a tight LSA single pattern on a nasty big block and it made about the same power or a little less than than the smaller/wide LSA/dual pattern it replaced but was a real fuel hog. Needed lots of fuel to make up for what was going out the exhaust.
2" is a pretty healthy header on a 427" motor....what kind of RPM are you expecting?
JIM
You also get into issues with cam overlap as it's easy to overscavenge a cylinder with wrong cam.
I just did some dyno work a few weeks ago with a tight LSA single pattern on a nasty big block and it made about the same power or a little less than than the smaller/wide LSA/dual pattern it replaced but was a real fuel hog. Needed lots of fuel to make up for what was going out the exhaust.
2" is a pretty healthy header on a 427" motor....what kind of RPM are you expecting?
JIM
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
That's going to be a LOT of fun. With all the juice...you might be right on headers!
JIM
JIM
Thread Starter
Instructor
Joined: Mar 2010
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Solid LT1 you say your rpm range is 2600 to 8000, but where in that range is your max power band. I ask this because tri y headers are usually more suitable for low rpm street engines, don t think 8000 rpm is a STREET engine.
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Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Solid LT-1...interesting they had a 4/2/1 deal going on the collectors. Did they test 4/1 against them with a Merge?
You also get into issues with cam overlap as it's easy to overscavenge a cylinder with wrong cam.
I just did some dyno work a few weeks ago with a tight LSA single pattern on a nasty big block and it made about the same power or a little less than than the smaller/wide LSA/dual pattern it replaced but was a real fuel hog. Needed lots of fuel to make up for what was going out the exhaust.
2" is a pretty healthy header on a 427" motor....what kind of RPM are you expecting?
JIM
You also get into issues with cam overlap as it's easy to overscavenge a cylinder with wrong cam.
I just did some dyno work a few weeks ago with a tight LSA single pattern on a nasty big block and it made about the same power or a little less than than the smaller/wide LSA/dual pattern it replaced but was a real fuel hog. Needed lots of fuel to make up for what was going out the exhaust.
2" is a pretty healthy header on a 427" motor....what kind of RPM are you expecting?
JIM
Motor was a project by another shop who couldn't complete the job so many parts are a compromise compared to what my friend Bob Wirth would have chosen. The 4into1 merge collectors on the headers (as delivered and used in baseline testing) were replaced by what you see here, power was improved. Motor makes better then 2.75HP per cu/in but, I am probably revealing more speed secrets here then my friend would want me to, so, I'll leave it at that.
Motor is showing some peak HP numbers at high 9000RPM area with 10,500 over rev. I'm amazed at the valvetrain stability (after some overpriced Jessel parts were replaced by some of Terry Mantons products, seems to be a familiar theme on the Speed Talk boards right now.)
