Datsun Roadster Forum-311s.org

Linda,
The two headers I posted pictures of work, but are not quite where I would like. Next time I'm feeling rich and find someone skilled and reliable who can build me a header, I have one more design I'd like to try using input from PipeMax and Speedtalk threads and posts from Calvin Elston.

Mike,
From what I have read, the size of the pipe is almost totally related to the horsepower output, although the 'tightness' of the bends can effect the flow, tight bends may require an increase in diameter.

Greg,
Have yet to build my 3rd and FINAL header. May not happen. So far, just the two posted in this thread.

Alvin,
I agree with JT on that one, 1 5/8" and larger primaries just too big for 99% of the cars here, racing or 2.3L stroker maybe...
As always, I'd like to know the actual pipe OD's and the outlet diameter??

The whole point of this thread was to get 4-2-1 headers built to suit the engines we use, not mammoth sized racing headers. Smaller primaries are needed for any gains with the 1600 engine.
EDIT: Keep posting those anyway Alvin, it's always good to see what is being done with headers for these engines, even if it doesn't 'appear' to be progressive.....

JT,
I agree with most of your assessment. I thnk the Sharp manual has a picture of a 4-2-1 header that stated it was good for 9 hp, I believe on a U20?
Fact is, almost all of the 4-2-1 header comparisons I've seen show larger gains in the mid rpm range in both power and torque. I believe this was Lou's assessment also? So, even tho single digit total gains, there should be gains almost throughout the rpm range, and better throttle response.
Would mean a re-tune on the on the carburator also....

Cheers,

Not technically header related (but could be on custom header), 'anti-reversion chambers' look to be an interesting developement for the exhaust system. Little known, but, apparently have been around for many years....

Google Search:
https://www.google.com/search?client=fi ... n+chambers

More info from SpeedTalk:
https://www.speed-talk.com/forum/viewto ... =1&t=57507

Food for thought.....

Very interesting. Smallest in/out diameter tube is 3", my exhaust is 2.25. Looks like the inside of the muffler has a step to stop the wave... could something be made to reproduce that effect and then welded into the exhaust, or is it patented etc?

Hytech seems to have removed their website

Daryl,
Where would you put this in the exhaust system?

Could this be made as the collector also?

Ron,
I am going to put it in just after the exhaust passes thru the first section of the frame.
I did wonder about putting it close to the last 2-1 collector on my header....honestly...I just don't know.... I will ask John tomorrow when I call.

Daryl Smith wrote: Thu Feb 25, 2021 10:48 pm Ron,
I am going to put it in just after the exhaust passes thru the first section of the frame.
I did wonder about putting it close to the last 2-1 collector on my header....honestly...I just don't know.... I will ask John tomorrow when I call.

This is what I was thinking too. That price is very reasonable. I had originally thought you were getting something (2 of them, not 2") that would fit into your primaries, thus my previous question. I'm pretty sure the first pipe in mine is 2.25" but it's been a while... that may be after the muffler. This certainly sounds interesting and so far I have not seen anyone claiming it's bunk (and it's patented). More torque is always Welcome! Thanks as always for presenting this idea to the forum, let's see what's what!

A 2015 article on headers and anti-reversion....
Header near the end of the article on that 4 cyl looks really long.
https://nasaspeed.news/tech/engine/the- ... an-engine/

Interesting read, thanks.
I’m predicting Frankie will be getting anti-reversion chambers.

You have a Vacuum in the exhaust esp in header pipes , ever hear a old 60s or 70s pu with only glass packs rev then let off you can see it such the steamed gas back into the pipe but vacuum ,it helps pull the exhaust out of the head
Have you been to the drag strip , and some guy decided to run open headers ( disconnected the exhaust back) down it ,and it's the biggest dog barely makes power ,he gets booed out of the place ...at least thats the way I remember it in my rearview mirror ,I was 16

Geoff,
I would already have them except they never arrived after I talked to a header builder in the states and ordered several.........Don't know what happened, but, unable to contact the fellow since....??
I have a couple ideas to combat reversion....will update when I begin testing.....
I see a few problems with the R16.
Both intake and exhaust ports are much bigger than they need to be for the engine output and they can both contribute to reversion.
The available headers are also excessively large (for stock and mildly modified engines) and do work to direct exhaust to the back of the car but do not provide a performance boost, or combat reversion in any way. Even a 4-2-1 header in the sizes available would not help a stock/mild engine.
On the positive side, both stock intake and exhaust valves are large enough to be able to make 130 - 140 hp with the right supporting parts (cam, header, intake, ignition) and prep (3 or more angle valve grind, mild porting).

Re: exhaust port - the straight, rectangular portion is too big, which is the latter 2/3s.

Many motorcycles on the bends in the header pipes ...at the beginning of the bend have a slim plate that separates the flow into inside and out side of the bend to improve flow at that point
It could be done on the initial bend out of the port have to be 4140 to last though

I think dealing with reversion is the next step in improving things. After watching the David Vizard YouTube video I'm wondering if my engine experiences a fair amount of it (more than typical with the mods done?) and it may contribute to some of the issues I find when trying to tune the EFI on this engine. I hope to return to exploring options on how to address this soon. Building a new header with reversion chambers in it would be expensive, while the plate idea discussed by David V. I mentioned elsewhere may be an answer.

Curiosity can be a terrible thing....
Decided I have to try a header designed from all I've read, and the PipeMax program....
Played with a mockup to get the simplest/easiest design possible, and am quite surprised at how close it will be to an equal length header...
Had some parts kicking around the shop and it would be a shame to not try....so off to the fabricator by the end of the week.

What if here Daryl....do you think if starter motor wasn't on this side and Nissan designed it on the other side, would this give more space and possibly give a "better" exhaust header system....?