1 3/4 vs 1 7/8 header comparison

[speedracer1000]

so im lookin into buying longtubes and i would like to see a side by side dyno comparison of a bolt on car with 1 3/4 and 1 7/8 headers and then a comparison on a boosted setup. im thinking on a bolt on car the 1 3/4 may be the way to go i realize that if ur looking for a bigger peak number u may get more with the 1 7/8 but thats not where we really need it with our cars, my opinion of course but if i could gain more power down low and only sacrifice a few hp up top thats what i would be after. i plan to supercharge the car tho over the winter so im curious as to how much the 1 3/4 may choke it at the 6-700 hp level. i realize this would be alot of work to find out on a dyno jus wondering if anyone has some insight.

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[MyLilPony]

If you plan to boost why even consider 1 3/4... Lots of other conversations on this topic but if you want an accurate comparison your best bet is to do it yourself with your car on your dyno in similar conditions. The difference at NA levels is nominal but you won't lose anything by going bigger.

As for boosted you pick up more HP with lower boost levels with 7/8 and headers make a huge difference in boosted applications so bigger is always better. So again, if you plan to go boosted why consider 3/4?

 

[Weather Man]

1 3/4 for n/a

 

[speedracer1000]

i realize that 1 7/8 might be better for a high rpm peak number with boost. no doubt that it would be better on a boosted app. but what about midrange where u spend most of the time in a street car. and i disagree about bigger is better. thats not true. theres alot more to it than jus a pipe size. u dont jus go putting the biggest intake, heads, and exhaust on any old engine and expect it to run better. everything has to be sized accordingly. i would like o jus see the differences between the 2 on paper to see what does what yanno.

 

[Weather Man]

i realize that 1 7/8 might be better for a high rpm peak number with boost. no doubt that it would be better on a boosted app. but what about midrange where u spend most of the time in a street car. and i disagree about bigger is better. thats not true. theres alot more to it than jus a pipe size. u dont jus go putting the biggest intake, heads, and exhaust on any old engine and expect it to run better. everything has to be sized accordingly. i would like o jus see the differences between the 2 on paper to see what does what yanno.

On supercharged modular cars over 800 HP space limitations make it very difficult to go to big. Working with 2 inch or bigger primaries gets very hard (and expensive). From what I have seen over the years, they do not give away much, if any, down low. If you could shoe horn in a 2 1/4, maybe the low end would suffer.

My 3V is getting a 3.4 whipple and will be using 1 7/8 with 3.5 collector ARH setup. I would have loved to step it to 2 inch, but costs get crazy for any expected HP increase.

 

[Higgs Boson]

My 1050 hp C7 I have 1 7/8 headers.

unless you are going to have over 750 or 800 then you really don't need more than 3/4....

 

[speedracer1000]

yea space is another reason im leaning towards 1 3/4. im jus curious how much it would choke it in the higher rpms with boost. doubt low to mid would suffer much but 600rwhp is right about the borderline power level where 1 7/8 should be had.

 

[Mike Jesse]

My concern is not the primary size, but rather the choke point at the end of collector.

Look at a full 3 in. exhaust from the end of the collector back.

I have not seen a test on this subject, be can only speculate that the neck down
to 2 1/4 in. dia. cannot be good.

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