Modifying the exhaust from an expert
 

For those who have not had a chance to read this, you should take a look. Mike Kojima is one of the top modifiers in the US and he relates some of the problems in installing new exhaust parts on this engine. Seems that the ecu is the root of most of the problems.

http://www.motoiq.com/magazine_artic...strations.aspx

Sure sounds like the ECU in this car is the source of many headaches - stock or modded.

i think this confirms what we all know but only some accept: that tuning this car na is pretty much pissing in the wind. a couple grand for mods that may or may not make any real power (that lasts).

it's becoming clearer and clearer that if you want to go fast in an 86, you want boost.

The same can be said of most 4 cylinder engines.

It seems like they attributed the difficulties primarily to the poor fuel. Sure, the ecu contributed to the troubles, but 93 or e85 would have allowed the ecu to cooperate. Not exactly pissing in the wind if you have better fuel...

that's one theory...

One theory that's been confirmed by others not in CA

Just give it time boys. I remember when the GTR first came out, it was supposed to be "untuneable" and the ecu was supposed to be totally locked down. 3x the horsepower later, i think the tuners have cracked it.

Given the twins have only been available for about a year now, I'm sure things will get better.

Or a tune. Just like every other car, you'll get marginal power gains from bolt on parts. On a factory turbo car it's as easy as turning up the boost. In an NA car you can throw on a turbo or build the motor. At 12.5:1 compression we're already pretty high strung. No idea why anyone would think it would "respond well to mods."

i disagree. a tune is good for 10-15whp. this thing needs more than 10-15whp to keep up with minivans, much less be 'fast' by any reasonable standard.

i can never figure out why people throw thousands of dollars at exhausts and tunes and intakes just chasing a few hp from an already fairly well optimized engine. by the time you have full exhaust, a tune, an intake and some pretty wheels you could have gone FI and actually be working with something substantial.

it's baffling to me, but it's not unique to the 86. miata guys will throw thousands into built 2.0 strokers to make less power than the most basic bolt on FM kit. just doesn't make much sense i guess.

but hey, the wheels are pretty :bonk:

I just said you aren't going to see a ton of power from bolt ons. How do you disagree?

i guess i don't. i read your post wrong i suppose.

Basically either you're going to be happy with the power with very minor gains or you need to spend a lot of money either on FI or a build, like any other NA car.

Seems to me to be awfully speculative.

He claimed they got 5HP from the mods, right? That's 3%. Temperature changes in the differential and trans could account for more error than that; a change that small is well within the range of measurement error.

EDIT - 5HP was the exhaust; I guess it was 13-14HP altogether. That's still less than 10%, and chassis dynos in general have a lot of variables.