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.

I like the lil bump in power, but especially love its look, sound, and feel. :wub:

Mr Kojima has a lot to learn about 32 bit subaru ecu's. It's no mystery. It's fuel trims and learned knock correction. Simple as that. If he bothered to buy and Ecutek cable from JV and actually use it to datalog while they were doing all the parts swapping and dynoing, he would have very clearly seen what was going on.

Just sayin, dude ain't all that.

Because I can afford to build my own turbo kit, but its the stuff you need to go with it that is the problem. (brakes, wider tires, injectors, gauges, tuning software, new clutch, etc.)

Exactly my thoughts. I'm not planning on modding my car too much, but if I do it, will be in a couple years when the tuning is perfected. I have no doubt, it'll get better with time and experience.

Sad time to live with California gas.. sigh. I'm assuming octane boosters don't really help either.

Reliability. We have no idea how the engine will hold up to boost. I would rather have less power and increased longevity and reliability than more power at the expense of either.

yeah i see where some can feel that way. to me a blown engine is just an excuse to build a monster. if the car is broken, it's easier to justify fixing it to the wife :party0030:

Torco Fuel Accelerator fuel additive works very well. It uses MMT as a detonation suppressant. My tuner said one bottle of Torco in a tank was able to produce the same power as running straight 104 octane gas on his dyno.

^^THIS. That's the other reason why I'm okay with just the simple things like intake and exhaust. I'll eventually want a tune, too, but wheels and tires first. I don't know if I'll ever want to do FI, but maybe after a few years and 100,000+ miles proven, that $5000-ish price tag will be worth it.

But, I'll prolly have kids by then and $5k on my car as opposed to something on the kids isn't gonna be the most prudent expenditure. :(

DING DING DING!!! correct answer!

Don't you think John did that when he was there tuning it?

If JV spent several weeks doing the logging and adjustments, then yes. But I did not get that from this story.

I'd like to add that i don't think this car was designed "to be fast" in the street racer sense of the word.... more so "Fast" like the ae86 was...

Yep definitely it helps. Haven't seen it mentioned on this forum too much yet though. Surprised people without access to e85 aren't using it more.

First I've ever heard of it, but it has definitely piqued my interest.

That said not surprising since this is my first tuning car.

This was one of the first production Nameless headers and the review date is very outdated. In defense to Mike Kojima, I think he is more of a suspension tuner and less of an engine tuner. And we havent really seen anything going on with this project so hopefully some works is getting done with said FRS....

What would be the best brand or type of octane booster? I saw some on amazon for like 7$ a bottle...

I've never used octane booster before but it seems like a pretty good product to use before some spirited driving :thumbsup:

Like sw20kosh said, Torco is best additive IMHO. Unless something new has come out in past couple years that is better (if so I haven't heard of it, though I wasn't messing with performance cars past coupla years due to "family" vehicle obligations). Torco is designed/bottled and marketed as fuel octane additive. It does work. However, most fuel additive is no good and barely raises octane if at all. I never use any other brands besides Torco.

There are "home made" brews you can do like Toluene... It is toxic (as is Torco) so don't breath it or get it on your skin. But if you add a gallon or two each fill up it can raise 93 octane up to 94-95.
[ame="http://en.wikipedia.org/wiki/Toluene"]Toluene - Wikipedia, the free encyclopedia[/ame]

If you add homemade brew like Toluene only add a gallon or two to each fill up.

Check out the owner's manual. Im pretty sure I read that you shouldnt use octane booster with mmt... could damage the engine.

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I not 2 stressed on the money I spent on bolt on's. It's gonna just breathe that much better when we go fi. I do care about longevity, but if it breaks or fails it will be an excuse to upgrade. If it means replacing a whole motor so be it. Everything I have seen is just giving me more reason to use e85.