1 3/4 headers vs 1 7/8 headers my experience
#21
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I have had LG 1 3/4 long tubes on my car (bought the car with them) and it ran well (471whp 439 wtq). I bought another set of 1 3/4th from another vendor and installed. Very noticable power loss thru out. The only visual difference was the primary length runners. Lg's were much longer.
I since sold the 2nd set of headers and bought a set of Stainless Works 1 7/8th long tubes. I havent had another dyno run on this setup yet, but I can safely say that I have picked up all the lost power and then some. Down low it isnt noticable, but when the RPM's get up there is when it is felt. The car pulls much better compaired to the LG 1 3/4 vs the SW 1 7/8. I suspect that the engine is making near as much power on the SW's down low as the LG's were and then picks up more up top. Which is to be expected.
I hope to have the car dyno'ed again, but I want to wait until about the same time as the last dyno so I can compair similar conditions. (it was mid June in the south west 100degree weather when the 471/439 was put down)
I wanted larger primaries and I paid to get them. I also have learned the hard way to research and buy performace parts with a end goal in mind. The 1 7/8ths are there for my end goal, not my current goal. I am happy with them.
I since sold the 2nd set of headers and bought a set of Stainless Works 1 7/8th long tubes. I havent had another dyno run on this setup yet, but I can safely say that I have picked up all the lost power and then some. Down low it isnt noticable, but when the RPM's get up there is when it is felt. The car pulls much better compaired to the LG 1 3/4 vs the SW 1 7/8. I suspect that the engine is making near as much power on the SW's down low as the LG's were and then picks up more up top. Which is to be expected.
I hope to have the car dyno'ed again, but I want to wait until about the same time as the last dyno so I can compair similar conditions. (it was mid June in the south west 100degree weather when the 471/439 was put down)
I wanted larger primaries and I paid to get them. I also have learned the hard way to research and buy performace parts with a end goal in mind. The 1 7/8ths are there for my end goal, not my current goal. I am happy with them.
#23
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If so, it needs to be expanded/ported to 1 7/8 inches to avoid losing velocity. After that, it could even use a different cam. Then it needs to be tuned. The "combo" has to get modified.
Remember, 1 3/4inches = 1 6/8inches.
#26
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What port is 1 5/8 inches? The oem cylinder head exhaust port?
If so, it needs to be expanded/ported to 1 7/8 inches to avoid losing velocity. After that, it could even use a different cam. Then it needs to be tuned. The "combo" has to get modified.
Remember, 1 3/4inches = 1 6/8inches.
If so, it needs to be expanded/ported to 1 7/8 inches to avoid losing velocity. After that, it could even use a different cam. Then it needs to be tuned. The "combo" has to get modified.
Remember, 1 3/4inches = 1 6/8inches.
Your privilege to type in any tech forums should be revoked.
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#29
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because not everyone with a 2010+ camaro is still at 376ci theres alot of big cube guys out there and there is a need for the aftermarket parts to support it. its not hard to get a lsx engine over 440 cubes with iron blocks these days
Ls1s never came in alot of cars but they make swap headers for them its because theres people out there that do it and there is a market
Ls1s never came in alot of cars but they make swap headers for them its because theres people out there that do it and there is a market
#30
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According to Louis, not Lou, they make them because their customers demanded it. I'm certain if you ask them their opinion on which header to get, they will say 1 3/4.
#31
because not everyone with a 2010+ camaro is still at 376ci theres alot of big cube guys out there and there is a need for the aftermarket parts to support it. its not hard to get a lsx engine over 440 cubes with iron blocks these days
Ls1s never came in alot of cars but they make swap headers for them its because theres people out there that do it and there is a market
Ls1s never came in alot of cars but they make swap headers for them its because theres people out there that do it and there is a market
#32
What port is 1 5/8 inches? The oem cylinder head exhaust port?
If so, it needs to be expanded/ported to 1 7/8 inches to avoid losing velocity. After that, it could even use a different cam. Then it needs to be tuned. The "combo" has to get modified.
Remember, 1 3/4inches = 1 6/8inches.
If so, it needs to be expanded/ported to 1 7/8 inches to avoid losing velocity. After that, it could even use a different cam. Then it needs to be tuned. The "combo" has to get modified.
Remember, 1 3/4inches = 1 6/8inches.
Louis is a smart guy, but besides market demand there's another reason as well: people are building larger HP motors. The formula as I was told (I'm not an engineer) is round tube moves 115 CFM/square inch (1 7/8" = 215.6 CFM) and 2.2 CFM is required per HP. This means 1 7/8 tubes support up to 781 HP (215.6/2.2x8), but 3" collectors only support 739 HP. This does not tell the lower HP limit of 1 7/8 but gives you the upper limit.
#33
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I'm not sure this is exactly correct. Certainly port matching is always of value, but if you are expading the exhaust port you are reducing velocity. I'd bet Diet Coke would agree with me on this.
Louis is a smart guy, but besides market demand there's another reason as well: people are building larger HP motors. The formula as I was told (I'm not an engineer) is round tube moves 115 CFM/square inch (1 7/8" = 215.6 CFM) and 2.2 CFM is required per HP. This means 1 7/8 tubes support up to 781 HP (215.6/2.2x8), but 3" collectors only support 739 HP. This does not tell the lower HP limit of 1 7/8 but gives you the upper limit.
Louis is a smart guy, but besides market demand there's another reason as well: people are building larger HP motors. The formula as I was told (I'm not an engineer) is round tube moves 115 CFM/square inch (1 7/8" = 215.6 CFM) and 2.2 CFM is required per HP. This means 1 7/8 tubes support up to 781 HP (215.6/2.2x8), but 3" collectors only support 739 HP. This does not tell the lower HP limit of 1 7/8 but gives you the upper limit.
A stepped header will always make more power then a straight header, because it keeps velocity high, while also increasing peak flow. F1 headers can have as many steps as you have fingers, as they are obviously meticulously hand-made to accomodate this principle. I have 1 7/8 straight headers on my 429, but am considering switching to a 1 3/4 ---> 1 7/8 ---> 2" custom header in the future. I have no doubt it would be worth a free 10rwhp and 10tq. In the OP's case, the 1 3/4 is obviously a far superior design to the 1 7/8 which has much shorter primaries with many more bends. It isnt fair to compare the two headers, even if they are from the same MFR.
#34
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You guys remember this test...
http://www.carcraft.com/techarticles...o_numbers.html
Seems like pretty straight forward results from back to back testing on a very mild setup.
http://www.carcraft.com/techarticles...o_numbers.html
Seems like pretty straight forward results from back to back testing on a very mild setup.
#37
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#40
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1 7/8 tube is not 1.875 square inches of area, it is 2.761 square inches (and thus 317.515 cfm according to your formula, wherever it came from).
A stepped header will always make more power then a straight header, because it keeps velocity high, while also increasing peak flow. F1 headers can have as many steps as you have fingers, as they are obviously meticulously hand-made to accomodate this principle. I have 1 7/8 straight headers on my 429, but am considering switching to a 1 3/4 ---> 1 7/8 ---> 2" custom header in the future. I have no doubt it would be worth a free 10rwhp and 10tq. In the OP's case, the 1 3/4 is obviously a far superior design to the 1 7/8 which has much shorter primaries with many more bends. It isnt fair to compare the two headers, even if they are from the same MFR.
A stepped header will always make more power then a straight header, because it keeps velocity high, while also increasing peak flow. F1 headers can have as many steps as you have fingers, as they are obviously meticulously hand-made to accomodate this principle. I have 1 7/8 straight headers on my 429, but am considering switching to a 1 3/4 ---> 1 7/8 ---> 2" custom header in the future. I have no doubt it would be worth a free 10rwhp and 10tq. In the OP's case, the 1 3/4 is obviously a far superior design to the 1 7/8 which has much shorter primaries with many more bends. It isnt fair to compare the two headers, even if they are from the same MFR.
Something you should consider is tubing is sold by the OD. 1 3/4" headers have a 1.680 ID depending on the gauge of the tubing.