Header selection for 1.8l Miata

[ITABoy]

Andy,

Wondering if you would be willing to share some ideas on header selection for 1.8l Miata running in IT-A. Once had real good luck (dyno proven) with a tri-Y on a BMW 2002, but of course the Miata is an entirely different animal. The Mazda Speed 4 brancher is a good looking piece and claims to have lots of developement behind it, but it is very pricey. Thanks for any help you can provide.

Jim Epting

[ddewhurst]

How about looking at headers used on front running 1.8 Miata E production cars.

[Andy Bettencourt]

I use the MS header. It's the FP/EP header. Exhaust ports are small so don't go too big if you try and source an over the counter one. The stock unit is as close to a factory header as you may see so there are little gains to be had.

Info I have gathered on testing a bunch of systems hasn't showed more than a 1-2hp difference so some aftermarket guys focus more on the flexibility of the system. We found some power in the placement of the muffler and the sizing of the exhaust tubing.

[ITABoy]

I use the MS header. It's the FP/EP header. Exhaust ports are small so don't go too big if you try and source an over the counter one. The stock unit is as close to a factory header as you may see so there are little gains to be had.

Info I have gathered on testing a bunch of systems hasn't showed more than a 1-2hp difference so some aftermarket guys focus more on the flexibility of the system. We found some power in the placement of the muffler and the sizing of the exhaust tubing.

Good ideas all. Andy, are you saying that there is more than one MS header? Of course I could call them and ask, but it is Sunday

Also, you said, "The stock unit is as close to a factory header as you may see so there are little gains to be had." I'm confused by that sentence. Are you talking about the "stock" MS header?

[Andy Bettencourt]

Good ideas all. Andy, are you saying that there is more than one MS header? Of course I could call them and ask, but it is Sunday

Also, you said, "The stock unit is as close to a factory header as you may see so there are little gains to be had." I'm confused by that sentence. Are you talking about the "stock" MS header?

No, the stock exhaust manifold is a tubular header. Well sized and well designed.

I think there is only one MS header.

[ITABoy]

OK Andy, I got it. Thanks very much for the assistance

[IPRESS]

I had a Boig header and aslo a ricer Ebay special header. The Boig fit a little better. HP TQ was about the same. The ISC boys have a good deal on a whole exhaust for ITA miatas. Putting the muffler in the right place can help you.

[Andy Bettencourt]

And so you know Jim, The MS header IS the Boig header.

[tnord]

+1 on the "not that big of a difference" observation.

[ddewhurst]

There is another E/F prod header out there that Jon Brakke/Terry Barnhart are involved with.

[ITABoy]

Hey Andy,

I called MazdaSpeed and they tell me that they no longer have the headers available for the 1.8l. I guess I gotta find a used one if I want to go that way.

I'm thinking of the Racing Beat unit. Probably a bit more pricey. I was kinda impressed with the way he described the development process on his web site.

Looking at pictures from the web, assuming I'm seeing the right MS header, it appears that the MS header has longer primary tubes than the Racing Beat unit. Is that your observation? Can't tell much about pipe diameters.

Have a friend who bought a header off Ebay. He had to open up the exhaust ports in the head a lot to match the header. That didn't look right to me, but who knows - without a lot of dyno testing.

Thanks again for your valuable insights.

Jim Epting

[IPRESS]

Jim, call Mike down at ISC (iscracing.net) he and his brother have done as much Mazda IT development as just about anybody in the country. The RB header is nice but I doubt it makes anymore power than cheaper headers. The RB header is marketed to the aftermarket mod crowd. First move I would make is to look up ISC website and start talking to them.

[Andy Bettencourt]

Jim, call Mike down at ISC (iscracing.net) he and his brother have done as much Mazda IT development as just about anybody in the country. The RB header is nice but I doubt it makes anymore power than cheaper headers. The RB header is marketed to the aftermarket mod crowd. First move I would make is to look up ISC website and start talking to them.

If you wanted to do it all in one call, go this route.

[TStiles]

I use the MS header. It's the FP/EP header. Exhaust ports are small so don't go too big if you try and source an over the counter one. The stock unit is as close to a factory header as you may see so there are little gains to be had.

Info I have gathered on testing a bunch of systems hasn't showed more than a 1-2hp difference so some aftermarket guys focus more on the flexibility of the system. We found some power in the placement of the muffler and the sizing of the exhaust tubing.

Care to expand on the pipe sizing issue ?

At some point I'm going to develop my SM based ITA via Header , Exhaust , Muffler , ECU and Tune. My current set up is the " Ara " exhaust.

I understand that ECU and Tune is where it's at , but if I'm going to the trouble of doing that , I might as well start the process with the header / exhaust question answered.

Any significant gains to be made ?