New/Modified Header Design?

[twistin]

I can tig weld so if you req help and its not to late...
Also were are you taking the header for coating? hope its not koolcoat.

[Daryl Smith]

At this point I'm good on the welding, but it's always good to know someone who can.
Do you weld aluminum? Stainless? Is it a hobby, or are you a certified welder?

Haven't had time to drop the header off yet. Who do you recommend for ceramic coating?

The 'Dyno Day' sounds like a great idea, not sure how much interest there would be.....Now would be the time to start setting it up, maybe for May or June? Got a bit more info? Dyno type? Business? Pictures......? (Dyno Day in BC thread?) We could always invite the Z or 510 crowd if interest is low........

[twistin]

Go with Rocket cermacoat 604 855 6632 they also have a web site with prices and all.

Hobby and my job (not cert.) can do aluminum.
Dyno is DynoJet.

[Daryl Smith]

Another Header related thread:
http://speedtalk.com/forum/viewtopic.php?f=1&t=41105" onclick="window.open(this.href);return false;

Seems just adding a merge collector on your existing header may not give you the increase you expect....

[Solex68]

Hindsight is 20/20. Should the header be a close re-design of the racing headers. Not the one in the Nissan Comp catalog (if there was one there) but the ones they actually raced with. I think a lot of saw the one in the Roadster Mag #103, Aug 2014 Pg 6. Of course this was "News" to me as I thought the off-the-shelf was sufficient. Daryl Smith you are ahead of our time.


I have an old rusty U20 header I think I need to cut where the four tubes come down and join them in a 4-2-1 fashion rather than the 4-1 they are currently in. It would not be as good as Bre but the scavenging would be improved.

[Daryl Smith]

Actually, I think I'm about 20 yrs late! But, I guess they didn't quite have the knowledge then that they have now......

Two quotes from Calvin Elston of Elston Exhaust Inc. from the previous quoted thread:

"It is highly unlikely you will ever see a gain in top end power with just a collector change on a given header.
It is a lot more probable that you will see an increase in bottom end power but not at a rpm that you wanted to see gains."

There is lots in this thread about optimizing tubing size and length (possibly shortening), as well as cam changes, to get the most out of a header. It's sometimes hard to distinguish 'street' from 'race' in the conversation.
My first thought when I read the above was "What about 3 collectors?" Since I changed from a 4-1 standard collector to 4-2-1 with 3 merge collectors, while keeping the same primary size (1 1/2") but shorter, to change to 1 5/8" for the secondary......Since all I've read the last few years points to a smaller primary for these engines at 4-1, and the PipeMax program I have points to this sizing for a 4-2-1, I have to think I'm heading in the right direction. At least, if not optimized, an improvement.
The other things I take away from that quote is "not likely" or... there is a small possibility, you'll have to try it......and "probable to see an increase in bottom end power". For a street engine I'll take any power increase at whatever rpm, as long as it's not hurting top end power, which it doesn't sound like it would!

"The exhaust system is just as intrigal a part of any given engine as valve timing, intake size, valve size you name it. It is not the cheapest part nor the most expensive but it is the most un-respected and misunderstood. "


You have to remember when reading this thread that most of the guys commenting are hardcore, longterm, performance engine guys. So...if they are not understanding it all..........I'm just doin' the best I can without a big budget!

Good thread, highly recommend reading the whole thing if you have time.

[Daryl Smith]

The other thing to consider is they are also mostly discussing/comparing newer, better designed headers, for the V8 crowd (mostly with good heads/ports), NOT a 4 cyl header, such as we have available, that has not changed in 30+ years, on a head with poor exhaust ports........

Hard to believe I started this thread 9 years ago.......... and I'm STILL finding new information!

Greg,
I would be REALLY interested to see the results of the U20 header being changed to a 4-2-1 as I did earlier in this thread for my 1800. It SEEMS to work, but no dyno #'s to actually compare.

[SLOroadster]

I'd really like a good set of headers for my car. A set like the BRE ones would be fantastic, but finding a set to duplicate might be tricky. I'm making good power with the normal 4-1 headers, I'd also be really interested in what I'd find with a set of good ones.

Will

[Daryl Smith]

Here's a picture of my engine the week before Shedd:


http://www.311s.org/phpBB3/gallery/view ... ic_id=1788" onclick="window.open(this.href);return false;

Picture won't come up direct so link included.......

[Solex68]

That header looks great. You have a magnificent design. The only improvement I could think of is to bend 45 near the starter and another 45 at the end to smooth it out a bit but that is a lot of fabrication since all 4 pipes would need to be bent for the first 45. With that said, I don't remember what is happening with the frame in that area but from the photo, the 90 looks tighter than it needs to be. Well done.

I believe for the scavenging to work properly, all the pipes need to be the same length. Not sure if 1 & 4 are longer or not. Perhaps 1 & 4 need the 45/45 shortcut and 2&3 remain with their 90.

All my info is based on my memory and that has failed me many times so my 2 cents is pretty much worth 2 cents

[Down under 311]

Anyone looking at a tuned system... drove a car over hear with long tuned pipes 4 into 1 and gives great low down torque...

[Daryl Smith]

"Anyone looking at a tuned system... "

Just to be clear....A 'tuned' system would be custom built for your engine to match your cam, rpm range, displacement. An off the shelf unit will not be 'tuned' unless you build your engine to the spec that header was designed for. If not, you will likely still see gains, just not as good, it depends on how far off from the original engine build you are.

Will,
I wouldn't be so hot on a set of BRE headers if I were you. Lots has changed since then (40+ years?), and it's quite likely you could do a lot better.

Greg,
I had a couple of 4-2-1 headers made, pictured earlier in this thread, which were a better design. however the quality of the fabrication was unacceptable. The header on my engine now is a modified version of the header currently available from vendors.
Was a quick, cheap way to get a 4-2-1 header on my car with proper merge collectors. I would have liked the pipes a little farther forward, away from the starter, but I made it work with what I had available.

Equal length is more important on a 4 cylinder than a V8 for absolute best power, but not that critical. Just look at the factory exhaust or the aftermarket header, don't think they worried about it too much. As long as it's within a few inches of each other and a decent design, you'll see a good improvement.

Dave (dbrick),
You mentioned early in this thread that if it's only worth 9 hp it's not worth the trouble. That was from the Bob Sharp Competition Manual. If you look at the header they used for that on page 4-4, figure 4, I can sort of understand why.....the 2-3 tubes should be longer and the collectors could definitely be better.
The peak hp is not the whole story tho, as there should be a significant gain throughout the rpm band in both hp and torque.

hport wrote (in 2005):
"The 20U I would expect about a 10hp gain up to 5000 revs then not much to red line. The torque gain should be around 10-15ftlbs on a low end bias curve, peaking a mid range . The cost of a well made header is around $ 300- 400, i'm sure they can be gotten for less. "
Personally, I would be surprised if there weren't a higher hp gain above 5000 rpm.

If someone local wants to give it a try on their U20 or R16 (R20?) I can set you up with the fellow who built mine, and help with the setup of the welding rig I used.

I believe a 4-2-1 in the 1 1/2" - 1 5/8" - 2" or 2 1/4" would cover most of the 2 liter roadster engines (R20, U20) used on the street.

[SLOroadster]

"Anyone looking at a tuned system... "

Just to be clear....A 'tuned' system would be custom built for your engine to match your cam, rpm range, displacement. An off the shelf unit will not be 'tuned' unless you build your engine to the spec that header was designed for. If not, you will likely still see gains, just not as good, it depends on how far off from the original engine build you are.

Will,
I wouldn't be so hot on a set of BRE headers if I were you. Lots has changed since then (40+ years?), and it's quite likely you could do a lot better.

Yes I agree. A tuned system would be what I'm looking for. I said a BRE-like setup simply to refer to a set of good racing headers. A set of Lou's headers would be sweet but they are $2K plus $$$$ for shipping. I think I could find someone here in the US who could do a decent set that would work better than the standard 4-1 version that I have. I think this is about the last place I can find any gains in power without doing some crazy and expensive internal engine mods. Still, even with internal mods I'd still be missing hp based on the headers.

Will

[csp54]

Reading this with much interest, long running thread! Amazing that no one has really put a car on the rollers to see what you can gain. I like the 4-2-1 design. but I'm leaning toward the side dump design for lower weight(i know its maybe a couple pounds)

Where did you get your merge collectors?

Im Running the u20 with solexes, will be trying to get the primaries in the 1 5/8 with a 6 inch radii on the bends.

With the side dump i should be able to avoid the 90 at the bottom, any thoughts? I was planning on buying some flex and mocking up on the bare chassis. then building final product. what are your thoughts on primary length.

And 9 HP is a BIG DEAL on a car less than 2000Lbs

[Daryl Smith]

Merge collectors were from a company which is no longer in business, don't remember the name. There are still a few places to get them. Google search will find them.....

I have no excuse for the non-dyno except that I haven't left the car together in one configuration for long enough to get the tuning sorted....

I question why you think you need 1 5/8" primaries? Every calculation I've done to just over 200 hp shows 1 1/2" to be the best bet. Just vary the lengths and collector.

For your model, try some 1" grey PVC conduit and some plumbing 90* and 45* bends. Cuts easily, and use a heat gun to warm it up and bend for shallower angles. Screws work well to hold it together as well.