Headers tube diameter.

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Jax

Jax

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Guys,

I am kind of debating what should be the size of my headers, either 1 5/8" or 1 7/8"

My engine should be making around 500 to 600 HP.
Is a small block 410.

What should be the size of the headers???? I need to huse hugged headers in my car do to clearences issues, but all hugged headers I have found are 1 5/8"....
 
At 410 inches they need to be 1.875 at 500 hp. As it gets closer to 600 you need 2 inch and a 4 inch collector.

BTW the 1.875 headers should have a 3.5 collector. And both will probably need 18-20 inch long collectors.

I should add that at 340 inches and 7000 RPM I am using 1.875 headers with a 3.5 inch collector.
 
well...... It looks like I will need to custom fab my headers...

Any input on good DIY 1 7/8" kits ?
 
I dont think bigger is always the best choice for headers.
Dyi headers can leave you frustrated and cussing the attempt quickl
y. Be warned.
buy a bunch of j bends, collectors, and flanges,from anyone or go to columbia river bends, I think thats the name? Also dont get hung up on dropping alot of coin on merge collectors.
 
Friend of mine is running a 416ci small block with indy 360-2 heads, solid roller etc. Has 500hp at the wheels through a high stall auto (other cars ran on the same dyno at the same show and the dyno is very close to his tuners dyno, other cars were also consistent). He is running 1 3/4" primary tri y headers, not 4 into 1s. People told him he would need bigger primary pipes.
 
MidTexCuda said:
I dont think bigger is always the best choice for headers.
Dyi headers can leave you frustrated and cussing the attempt quickl
y. Be warned.
buy a bunch of j bends, collectors, and flanges,from anyone or go to columbia river bends, I think thats the name? Also dont get hung up on dropping alot of coin on merge collectors.
Click to expand...

If the slate is clean, meaning you are building a custom set with the goal to max power in a certain rpm range for a given engine and there are no restrictions because of chassis or usage - I'd agree 100%.
But, once you look at packaging restrictions (suspension, access, etc), limited collector length and size, on an engine that has to make power over a loarge rpm range and various throttle openings, a camshaft that is designed for wide rpm ranges, and feeding into a set of pipes and mufflers downstream... In that circumstance primary and collector size can be boiled down to bigger is better. This is with N/A stuff - not turbocharged.
 
Bigger isn't always better. Depending on whether it's 500 or 600, you could go either way. I was going to go with 1 7/8 TTi on my 408 stroker which is 500hp. I spoke to the TTi people and they told me that 1 5/8 was just fine for my horsepower and the 1 7/8 would be more than I need and would rob me of torque. He said if I was in the 600hp range I would be better served by 1 7/8. Just thought I would pass along what the header gods told me.
 
I ran 1-7/8" on a small block Ford years back. I had studied up on all the sizing formulas and reasons why to use certain sizes and decided on this larger size to avoid restricting the other good breathing parts in the engine: heads and intake. Welding on a set of long collectors, about 21" total, did make a noticeable improvement on the low end torque. Engine was only 325-350 HP tops, with higher torque numbers, and was used over a wide RPM range. So I can't imagine not using 1-7/8' for 500 OR 600 HP. And Yaller Rose's point on size when getting towards 600 HP seems just common sense.

BTW, size fitment was not any problem in that particular Ford chassis, but there were no torsion bar to deal with.
 
My 416 made 565hp / 522tq with crappy 1-5/8 tri y's.
Now has 1-3/4 stepped 1-7/8 4into1
Didn't get a chance to re-dyno after the pipe change so don't know how much the small pipes held it back
 
Moper I was trying to make the point that Jax did not need to make a custom set of headers but if he wanted my thoughts on what to buy and where to shop. Imo
I think some off shelf headers would be fine.
If I read the second part of you post correctly you are saying on average street/strip engine build bigger is better and I dont agree unless it is on a supercharged engine. On a average engine with a broad power band going to big header can have a negative effect. he needs to pick a set of off the shelf headers that fit his cam and heads.
 
MidTexCuda said:
Moper I was trying to make the point that Jax did not need to make a custom set of headers but if he wanted my thoughts on what to buy and where to shop. Imo
I think some off shelf headers would be fine.
If I read the second part of you post correctly you are saying on average street/strip engine build bigger is better and I dont agree unless it is on a supercharged engine. On a average engine with a broad power band going to big header can have a negative effect. he needs to pick a set of off the shelf headers that fit his cam and heads.
Click to expand...



I am going to use 1.875 headers on my 340 on the street. Should fire it off next week and dyno later in the month.

I actually have a set of 1.75 headers if I really felt like spending money at the dyno. I already know the result but the interwebs guys always want numbers for free.
 
I have 1.75 going on my 340 here shortly (may or june?) when I get the motor back from the machine shop. I've always had good luck with them.
 
I have noticed a lot of big block headers are 1 7/8"... Is there any big block engine that has the same flange dimensions that the small block? Then I may be able to buy the headers under a big block engine, but still fit them on my small block
 
Jax said:
I have noticed a lot of big block headers are 1 7/8"... Is there any big block engine that has the same flange dimensions that the small block? Then I may be able to buy the headers under a big block engine, but still fit them on my small block
Click to expand...
aaaaa - NO !
 
Jax said:
I have noticed a lot of big block headers are 1 7/8"... Is there any big block engine that has the same flange dimensions that the small block? Then I may be able to buy the headers under a big block engine, but still fit them on my small block
Click to expand...

A small block Chevy is close dimensionally but how would you get Chevy headers to fir your chassis?

You are either stuck with CI manifolds or PAY someone to build you headers.

I have built about a half dozen headers and I won't do it again. Way too much work.
 
My car is a dodge conquest.... so actually body is not an issue...
 
yellow rose said:
A small block Chevy is close dimensionally but how would you get Chevy headers to fir your chassis?

You are either stuck with CI manifolds or PAY someone to build you headers.

I have built about a half dozen headers and I won't do it again. Way too much work.
Click to expand...

CI Manifolds?? what does CI stand for?
 
Mopar to ya said:
Bigger isn't always better. Depending on whether it's 500 or 600, you could go either way. I was going to go with 1 7/8 TTi on my 408 stroker which is 500hp. I spoke to the TTi people and they told me that 1 5/8 was just fine for my horsepower and the 1 7/8 would be more than I need and would rob me of torque. He said if I was in the 600hp range I would be better served by 1 7/8. Just thought I would pass along what the header gods told me.
Click to expand...

Just wanted to elaborate on what was said here. The TTI's are actually stepped, from 1 5/8" to 1 3/4". They "act" like the bigger size without the disadvantage of restriction downstream like a straight 1 5/8" would have, especially as you go up in HP. At least up to the point where you do need bigger tubes.

My philosophy has always been that it's normally better to lean on the conservative side for best results anyway.

CI = cast iron
 
Locomotion said:
Just wanted to elaborate on what was said here. The TTI's are actually stepped, from 1 5/8" to 1 3/4". They "act" like the bigger size without the disadvantage of restriction downstream like a straight 1 5/8" would have, especially as you go up in HP. At least up to the point where you do need bigger tubes.

My philosophy has always been that it's normally better to lean on the conservative side for best results anyway.

CI = cast iron
Click to expand...


What class are you running Myron? Have you tested stepped headers back to back verses a large (what I consider large, or larger) tube header? I used 1.75 headers back when everyone was saying they were too big. Then I changed combos, and bought the 5303 Hookers. I knew I had gone the right was just pulling it out of the shop to put it on the trailer.

I ask, because I know a guy who is running G stock IIRC and he tested stepped headers and merge collectors and all that. His results mirrored mine. When the lengths were correct, the diameter was less important, especially in the collector.

That is not to say if you were just working to reduce exhaust lobe centerline, or to reduce exhaust timing, say, to gain intake effectiveness you won't find merge collectors and smaller primary tube diameter more effective, specifically when considering 4-2-1 headers.

In my experience, the testing required exceeds most budgets. That is why I was wondering how extensively you followed the step header testing. I know Joe Sherman has found nothing as of yet, but I have not talked to him in a year or so. It could be the way I port, or what I expect to see when spec'ing a cam that makes those things ineffective. What are your thoughts?
 
I run IHRA J/CM (crate motor) @ 3,540+ lbs, in which the 360 has better specs than "regular" Stockers. But I've "only" run a best of 11.14 @ 117 on a 12.25 index. (There are some "regular" Stock 340's and 360's as fast as mid-10's.) I also have an NHRA 3,800 lb J/SA 360 Aspen wagon which I'm still sorting out and eventually expecting around 12.00 on a 12.45 index. All VERY rules-restricted.

I somewhat recall an article about Joe Sherman and what was a pretty fast, but possibly somewhat unconventional Nova. But no rules.

Yes, time and budget limit my testing. Custom headers are definitely out of my budget, so off-the-shelf will have to do. It was over 10 years ago that I switched from the 1 7/8 headers that came with my Dart to the TTI 1 5/8"-1 3/4" stepped. All I can say is that if I didn't see a positive difference in my particular application, then i would have switched to 1 7/8" TTIs since then. Although worth considering, to compare them now isn't feasible at this time either . But as mentioned in another thread, adding an X-pipe and UltraFlo mufflers helped what I have. I have heard of a few other fast small block Stockers, that have more time & resources, use TTI stepped, and in some cases cut the original collectors off and installed the merged versions.

I hate to fall back on that old saying that "each combo is different", "your results may vary", but it still does apply, whether it be steps, diameter, collector style, etc. Too many variable for a clear answer for everyone. Racing, like life, if full of compromises and you do the best you can within your limitations. I won't be among the fastest, but I'll get as close as I can.

I've also spoken with some fast Stock racers who have used even smaller primary exit pipes, sometimes actually port matched, but then stepped up 1 or 2 steps, with claimed good results. But even "good" has it's variables. Some Stock racers will be ecstatic with a .05 gain, which can often be within a margin of error to most people. Depends how many variables were taken out of the testing.

As for cam lobes and their relationship with the rest of the combo....I have to rely on the cam companies for specs based on what I have and then adjust the rest around that afterwards looking for gains.

Bottom line is that I barely have enough time to establish baselines and test with what I have, much less to be swapping parts, changing cam specs, etc. But when I do have an opportunity, I do the best I can. I just wouldn't say something helped me if I wasn't sure it did, even with a margin of error.
 
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