M20 Header Options in 2019

[digger]

Quality looks good construction wise and they don't have shitty bends right at the flange like some.

I dont get why make bold claims quoting exact numbers and not back them up with proper evidence about exactly what was compared (exhaust setup and engine specs) and the outcome in terms of dyno sheet overlays ? It would be much more credible. It always pays to remember the exhaust is a system and what happens after the primary is probably as important as the primary itself which comes back to what the comparison was and why any changes occurred.

Some casual observations are the pipe sizes are way larger than what is recommended by some of the best professional exhaust guys out there have found works best. Those sizes are capable of probably 500bhp atleast so how effective can they really be on a 250hp engine where the port is lucky to be 1-1/4"?

There are people that push 6-3, 6-2 or 6-1 but the differences are going to better in some areas and worse in others. There is no magic solution that bests all that's just how wave tuning works you get positive and negative waves.

6-2 is usually chosen because of easier packaiging plus with 240* separation of pulses there isn't much need for 360* separation that the 6-3 produces. 6-1 might be able to make more peak within a narrow rpm band as the strength of scavenging should be a bit higher but you lose out elsewhere.

I haven't tested all the different configurations but 1D simulations predict it's not worth deviating from a tried and true 6-2 when I do my custom set soon.

[vehicular]

Who is AAF ?

This:

https://advancedautofab.com/p/aaf-m20-race-header/

[vehicular]

Whats your HP goal?

Bout tree fiddy.

I had about a novel typed up to explain that I'm not really the scrub that this thread probably makes me sounds like, but... I guess I just want whatever I can get out of a reasonable street motor? I'm not trying to do an F1 engine dev program, just build a warmed up street car with good manners, AC, low enough compression that I can run 89 without pinging it to death, etc.

I'd be happy with 200-225whp, it sounding cool, and the motor looking like it belongs in the engine bay.

[e30austin]

Advanced Auto Fabrication, out of Spokane, Washington, USA. Popular amongst the PRO-3 crowd.

[digger]

Who is AAF ?

[moatilliatta]

Whats your HP goal?

[vehicular]

I've never seen AAF headers before now. Are there any tests out there other than their own claims? I'm willing to buy that their 6-3-1 configuration might make more power than traditional 6-2 BMW headers, but I don't about 1 3/4" primaries, and I especially don't know about their dramatically unequal primary lengths.

[moatilliatta]

AAF headers?

[digger]

Yes there is certainly a lack of quality available which is odd given the popularity of modified m20 is as still very high.

[vehicular]

If I'm going to weld anything to the collectors, it will be vbands. My issue was not wanting to clamp slips over the collectors if I could buy the headers already coated. Since you can't get them from IE at all right now, I'm kind of in a bind.

[digger]

Weld stainless extension for the slip on part so you can keep it bare and then get it coated inside and out for the mild steel part

[vehicular]

Given you are running a stroker engine, the old BavAuto header primaries are going to be severely undersized (@ 1 3/8"). Not to mention, they were also made from mild steel.

With all due respect, the IE's fit your bill better than any other option currently available. You just seem slightly abject to that reality. Lastly, have you checked to see if IE will weld on an 02 bung (or anything else for that matter)?

You guys are probably right. I had a mild steel Boig header on a Miata for years, and it made power, fit fine, etc, but it still corroded over time in the slip joints, even with nice Nitroplate coating on it. I'm just leary of dealing with it on a daily again.

If there was somebody local who could do the coating I would be less whiny about it, but I don't think there's anybody around here since Nitroplate in Nashville stopped doing direct customer work.

I was really hoping that somebody had tried the Becker headers. I don't even really mind that they're Chinesium if they fit.

[E30-TourZing]

Given you are running a stroker engine, the old BavAuto header primaries are going to be severely undersized (@ 1 3/8"). Not to mention, they were also made from mild steel.

With all due respect, the IE's fit your bill better than any other option currently available. You just seem slightly abject to that reality. Lastly, have you checked to see if IE will weld on an 02 bung (or anything else for that matter)?

I appreciate your testimony on the Bav auto headers. I am aware these have a smaller diameter then other options, but I didn't think the performance difference would be massively different.

I have super appreciated all the write-ups you have done about M20 strokers, and its very apparent your knowledge is vast. Have you personally seen results from a dyno/butt-dyno with 1 3/8 vs 1.5" on a 2.9-3.1 M20?

The reason I ask is due to the fact a close friend of mine is a master welder, and I feel we may custom make some stainless headers if the difference is significant enough. Parts coming to Canada are soooo expensive, so it's almost better to employ a metal artist then buy something ready made.

[kronus]

^^ IE has been out of long tubes for a while now. I had to find mine second hand.

[SkiFree]

Given you are running a stroker engine, the old BavAuto header primaries are going to be severely undersized (@ 1 3/8"). Not to mention, they were also made from mild steel.

With all due respect, the IE's fit your bill better than any other option currently available. You just seem slightly abject to that reality. Lastly, have you checked to see if IE will weld on an 02 bung (or anything else for that matter)?