Header size/sizing

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Texas Red

Texas Red

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Does header sizing make that much difference when one is comparing a header of 1-5/8" in comparision to a 1-7/8 " header on a combo street/race car?
When one thinks about the air pump theory yes CFM matters but to what degree? All out Racing? Yes! but for a combo street/ Race car.
Dyno testing on engine masters (whether you believe their testing or not is the question) has shown there was a difference but is it worth doing all the changes cost worthy to achieve that 5-8 extra HP?
No I am not chasing a record nor trying to set any here .... just asking for your opinions on perusing the change suggestion. Comments welcome. Thanks everyone.....Texas Red
 
Texas Red said:
Does header sizing make that much difference when one is comparing a header of 1-5/8" in comparision to a 1-7/8 " header on a combo street/race car?
When one thinks about the air pump theory yes CFM matters but to what degree? All out Racing? Yes! but for a combo street/ Race car.
Dyno testing on engine masters (whether you believe their testing or not is the question) has shown there was a difference but is it worth doing all the changes cost worthy to achieve that 5-8 extra HP?
No I am not chasing a record nor trying to set any here .... just asking for your opinions on perusing the change suggestion. Comments welcome. Thanks everyone.....Texas Red
Click to expand...
I recall one of those shows with Steve Dulcich and the other guy where they dynoed a motor with new headers and then proceeded , one tube at a time, to beat a huge dent in a tube blocking at least 50% of that tube, then dyno it again. After doing all 8 tubes the dyno showed hardly any difference in HP or torque.
 
I know this is gonna sound redundant,,,,,but it really matters on the engine.
For a car that is basically a street car with a once in a blue moon strip run,,,,,No,,,I don’t think you could see anything.
Now,,,when it’s truly a street/ strip car,,,,with maybe 65-70 % street time and a third of the time racing,,,,then Yes,,,,I believe you would see appreciable results.

And then,,,,the engine will come into play after that .
A very hot small block,,to a reasonably hot big block,,,,header size will make a noticeable improvement .
Remember,,,,the factory 340’s were pretty strong,,,,but honestly they were fairly tame .
Excellent engine,,,,good compression, ( should have been 11 to 1 ),,,good factory heads .
Should have had a cam with at least about .460-.470 lift,,,,,(solid ) .
They used factory Hi Perf exhaust manifolds,,,and really flowed very well for what they were .
I don’t think headers would have made a difference really.

Tommy
 
If you don't care about the max performance thing, tube size is a secondary consideration to fit and cost.

Fit is the #1 issue for me on SB A body cars. Give me a set of Dougs or tti over the old hooker copies.

Even on a mild engine, headers make a difference over the cast iron stuff on A body cars. Higher engine outputs, usually greater delta in raw numbers.
 
Texas Red said:
Does header sizing make that much difference when one is comparing a header of 1-5/8" in comparision to a 1-7/8 " header on a combo street/race car?
When one thinks about the air pump theory yes CFM matters but to what degree? All out Racing? Yes! but for a combo street/ Race car.
Dyno testing on engine masters (whether you believe their testing or not is the question) has shown there was a difference but is it worth doing all the changes cost worthy to achieve that 5-8 extra HP?
No I am not chasing a record nor trying to set any here .... just asking for your opinions on perusing the change suggestion. Comments welcome. Thanks everyone.....Texas Red
Click to expand...
no difference. Pick the size that fits your car the best. I’ve run well into the 9’s with 1-5/8” LA truck header with W2 heads.
 
Maybe it doesn't apply as much to an a body but I can tell you in a heavy car too large a tube will hurt performance everywhere less than full throttle.

My 73 Charger with a hot 465" RB liked 1 7/8 tubes better than 2" for normal driving and part throttle. Same with my 70 Polara with a 496 RB, it liked 1 3/4 better than 1 7/8.

Too big a header hurts more than too small of one in most cases. I will take a slight loss in top end HP over a loss of low end and mid range torque for a STREET car any day.

Race car may be a different scenario. With high stall converters and deep gears then you don't want any loss of top end HP at all.

Just my opinion.

Carry on

For the OP any reason you went straight from 1 5/8 to 1 7/8? No 1 3/4 for you car?
 
9secRR said:
no difference. Pick the size that fits your car the best. I’ve run well into the 9’s with 1-5/8” LA truck header with W2 heads.
Click to expand...

Was that in a truck? If so, I'd love to hear more about it!
 

The minimum I like is 1.750 for 340 inches.

I run 1.875 headers on my 340.

I have a 340 on the dyno. If I wanted to I'd test some TTI 1.625 headers verses my Hookers. I just don't feel like doing the test again.

The guys that say header sizing doesn't matter have engines that are numb to header sizing. Billy Godbold covered this in his book, as have many others.

When the LSA is too wide for the application, header size won't matter. An overlap triangle that is advanced from TDC will be numb to header sizing, among other things.
 
So many bad myths about headers out there.

after I watched Steve’s video when they bashed the headers, I realized all the myths are just that… a myth.
 
9secRR said:
So many bad myths about headers out there.

after I watched Steve’s video when they bashed the headers, I realized all the myths are just that… a myth.
Click to expand...


Yeah, Engine Masters never built an engine that was numb.
 
9secRR said:
it has nothing to do with engine masters or how they build an engine. all they did was prove the header myth.
Click to expand...


Did you see the specs on the whole build? Did you read Billy Godbold's book where he covers this very subject?

Cam timing will make an engine numb TO HEADERS. That's a fact. Their test was flawed. I can post a picture of the section in Godbold's book where he covers it, but it won't help. He's who the "engine masters" called when they ran into ****.

Header size matters if the engine is built for it.
 
At the very least I think people should base headers and carb size more on Hp level, eg. 500 hp is gonna be a similar amount of air be it a 318 or a 543.
 
I kinda want to say yes in my case, when I first put the 470 in my B-Body I used 1 3/4 headers, ran it for a season best was 10.98 in the 1/4, then put on a set of Hooker super comps, and new best of 10.65. I also moved the cam from 104.5 to 103.5, so maybe not entirely the headers
 
My 470 gained 26 hp , lost nothing.
Swap from 2 inch fenderwell hookers to tti 2.125 headers.
 
I always recommend the biggest tube you can afford.
 
MOPARMAGA said:
My 470 gained 26 hp , lost nothing.
Swap from 2 inch fenderwell hookers to tti 2.125 headers.
Click to expand...

Fenderwell hooker BB headers are horrendously long for anything making decent power.

OP wants something going on a street car and doesn't care about the max hp approach. Fit and cost are usually the biggest considerations in that arena.
I most cases, hooker 5204 1 3/4 headers work better than a TTi 1 7/8" header, they just don't fit as well. Pick what's important to you and pay your money! :)
 
crackedback said:
Fenderwell hooker BB headers are horrendously long for anything making decent power.

OP wants something going on a street car and doesn't care about the max hp approach. Fit and cost are usually the biggest considerations in that arena.
I most cases, hooker 5204 1 3/4 headers work better than a TTi 1 7/8" header, they just don't fit as well. Pick what's important to you and pay your money! :)
Click to expand...
Thanks, the OP directly asked if different sized headers make a difference, I gave a valid answer.
 
if you have a set of headers use them! You will NOT notice any difference on the street between 1 5/8 and 1 7/8.
 
I just made this swap on a healthy small block stroker.
Went from 1 5/8 Doug’s to a 1 3/4 to 1 7/8 step header.
Had/ have the same race muffs behind both.
Anyhow this is a car that is well sorted.
I picked up 40 horsepower on the ET slip with the change.
 
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