1 3/4 headers vs 1 7/8 headers my experience
02-23-2012, 06:57 PM
#41
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Your cam and tune along with engine size will determine which header is best. Just because one person made more hp with 1 3/4 than 1 7/8ths doesn't mean anything in the big picture just that for that setup it was better. Headers are a SUPPORTING MOD which means they SUPPORT your other mods and engine.
02-23-2012, 10:14 PM
#42
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Remember, RPM is also a variable. Flow at 6,000 RPM is different from flow at 7,500 RPM.
There are a couple places you can go online to determine the proper header size and length.
There are a couple places you can go online to determine the proper header size and length.
02-23-2012, 10:44 PM
#43
Your cam and tune along with engine size will determine which header is best. Just because one person made more hp with 1 3/4 than 1 7/8ths doesn't mean anything in the big picture just that for that setup it was better. Headers are a SUPPORTING MOD which means they SUPPORT your other mods and engine.
Cam is a very important factor..if not the most important. I have 1 7/8 on my 408, Ported L92 Heads, Vic Jr Intake..it's all going together here ina few weeks with a Cam spec'd for that combo. That is what will get the power.
02-23-2012, 11:55 PM
#44
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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.
03-01-2012, 07:17 PM
#52
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If you were going to design a header for a 358 cubic inch naturally-aspirated engine, that runs from 5,600 to 9,300 rpms, and you want to make 830 crankshaft horsepower:
1) What size primary tube would you specify?
2) What size collector would you specify?
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1) What size primary tube would you specify?
2) What size collector would you specify?
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03-02-2012, 07:25 AM
#54
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Thanks for the reply.
The engine I described above is a NASCAR Sprint Cup engine. I visited two NASCAR engine shops the week of February 13th on my way to the Daytona 500.
What I found is they use for headers is 321L stainless steel. They do not find 304L stainless steel to have sufficient durability for a NASCAR race. They come out of the cylinder head with 1 7/8 inch primary 7 inches long. The next step is 2 1/8 inch tube 21 inches long. They use a 4 into 2 into 1 collector design for two reasons: 1) They get a slightly broader torque curve with the 4-2-1 design. 2) They do not have enough ground clearance to package a 4 into 1 header design.
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Last edited by Pumba; 06-01-2014 at 06:25 AM.
03-02-2012, 09:03 AM
#55
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Thanks for the reply.
The engine I described above is a NASCAR Sprint Cup engine. I visited two NASCAR engine shows the week of February 13th on my way to the Daytona 500.
What I found they use for headers is 321L stainless steel. They do not find 304L stainless steel to have sufficient durability for a NASCAR race. They come out of the cylinder head with 1 7/8 inch primary 7 inches long. The next step is 2 1/8 inch tube 21 inches long. They use a 4 into 2 into 1 collector design for two reasons: 1) They get a slightly broader torque curve with the 4-2-1 design. 2) They do not have enough ground clearance to package a 4 into 1 header design.
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The engine I described above is a NASCAR Sprint Cup engine. I visited two NASCAR engine shows the week of February 13th on my way to the Daytona 500.
What I found they use for headers is 321L stainless steel. They do not find 304L stainless steel to have sufficient durability for a NASCAR race. They come out of the cylinder head with 1 7/8 inch primary 7 inches long. The next step is 2 1/8 inch tube 21 inches long. They use a 4 into 2 into 1 collector design for two reasons: 1) They get a slightly broader torque curve with the 4-2-1 design. 2) They do not have enough ground clearance to package a 4 into 1 header design.
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I made a post on a Lame website trying to push ARH and Kook's into offering a 321L header but a ******* vendor who didn't like my post had it locked out after he made a number of stupid posts on it.
I started the thread with the fact that there was only one header company making 304 stainless headers, that was using the correct grade for stainless for a welded application. That grade is 304L not 304. After I made the post two of the companies posted that they did use 304L even though I had e-mails from them clearly stating they used 304 (I verified my facts 3x before posting)
304 or 304L would be my last choice for a stainless header. My first choice would be 321L. 321L costs more and is harder to bend than 304. Dynatech makes a header out of 203 stainless. 203 doesn't have the corrosion resistance that 304 has but it also doesn't have near as much problems with warping or cracking that 304 has when subjected to the heat of an exhaust port. Kook's will make a header out of 321L if you special order it.
At the time I had no intention of ever installing a supercharger so I bought the header made out of 304L. That was 9 months ago, now I'm going to be installing a Whipple in the next month or so.
Ain't life a bitch
If anyone has a set of stainless headers and is having problems with exhaust leaks, PM me and I will tell you an inexpensive way of fixing it.
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06-15-2012, 07:21 PM
#56
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Its amazing it took 33 posts for someone to point out these two headers are not even close to be the same. Same old crap comparing apples to oranges
06-20-2012, 06:28 PM
#57
I noticed those headers have an x-pipe that I haven't seen too much of. How does the power of that x-pipe stack up to a regular x-pipe like you get from summit racing? Any difference? Just curious
06-21-2012, 07:59 AM
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The theory behind the X-pipe that you see on the two different sets of L.G. Motorsports Super Pro Long Tube headers is that the exhaust gases flow down the 3-inch pipes from the collector toward the muffler they come to the siamese section of the X-pipe. At that point, if gases in the passenger side pipe feel a lower pressure in the driver side pipe they can cross over to that pipe. The same is true for the gases coming down the driver side pipe. Hence, the gases follow the past of least restistance, which results in more horsepower.
The standard X, or crossover pipe forces all the gases to cross to the other side of the system. This creates turbulence, reducing your horsepower.
07-14-2012, 09:10 AM
#59
Those two headers are not even close to the same design. I would like to see a least 2 examples of 1 7/8 with a lost in power on the same engine .Just not buying 1 3/4 will make more power. Check out this thread , same topic https://ls1tech.com/forums/generatio...d-1-3-4-a.html
