TRE rebuilt. Cooler isn't installed yet because of reasons I posted above.

 

Agree! This line of thought served me well with my last car and so far so good on my Evo. My hope is to be as fast as possible while being as smooth as I can be. I may beat out a few 1/10ths by being more aggressive but my biggest gains are without question is other areas where I need to improve.

As such I hope to keep my car strong and healthy so it can get me as much seat time as possible.

 

It's basically useless. It raises your octane by one "point." In other words, you'll go from 93 octane to 93.1 octane. Nothing to write home about.

Since you're running stock engine management (no tune) and stock boost controller (19 psi peak with high-rpm boost taper) you'll be fine. Remember the stock fuel maps and boost profile are tuned for 91 octane...otherwise Mitsu wouldn't have been able to sell the car in The People's Republik of Kalifornia. If you run 93 octane, you're already way above the level where you'll run into knocking.

Emre

 

Not to mention the stock tune dips into the 9s for AFRs. Last thing you should be worried about on a stock boost / stock tune Evo is detonation, imo. I'd be more worried about EGT than anything.

 

Wide band, if th eengine is dropping in the 9's should you be worried about being too rich?

 

I was just looking at the stock dyno runs on my car. The damn thing was going to about 9.8:1 AFR. The car wasn't very happy with the timing or fuel. I never ran it with the stock tune, but I've put on quite a few miles with revised fueling (a sensible number richening up to about 11:1) and a bit less timing for our crappy 91 octane.

If I can ever get a downpipe to stay on my car (shop development vehicle), then I could get some bungs in place and see what the car does under the harsh conditions at the track.

-Jon

 

Interesting. I used to run 27PSI with it on my subaru, with no knock, while without it I would get the occasional ping without it at 22-23psi.

I agree that most fuel additive is useless and raise octane by like 0.1. Ive had good results with Torco and NOS brand (the two that contain MMT). one odd side effect is that it turns your plugs orange...

not contradicting or anything, just sharing my anecdotal evidence.

 

so people with the taper removed (yet still on stock boost control hardware) have more to worry about?

 

Even if a 12oz. bottle of NOS Octane Booster contains MMT, it's a very small dose. Will such a small amount of MMT make a difference? Wth the Torco stuff, have to add a significant volume to your tank. I wonder if a small bottle of NOS will make much difference considering how small the dose it.

According to the NOS ad copy, one 12oz. bottle "increases octane effect as much as 3 points." So that will take you from 93 to "as much as" 93.3 ... which means it'll probably be a bit less than that (otherwise they wouldn't have said "as much as"). Again, it's not such a dramatic effect unless you add lots of it.

EDITED TO ADD: I've just noticed that NOS offers a "Racing Formula," which they claim increases your octane by "as much as 7 points." I guess that's the one you guys were referring to. A 5-7 point increase actually might be significant. I stand corrected

Emre

 

Sure. As the engine runs at high rpm, it runs hotter and is more prone to knocking. It's safer to richen the mixture at higher rpms to help solve both problems. Adding more air at high rpms without increasing fuel delivery may lead to a lean running condition, which is quite dangerous for a turbo engine running the sustained high revs you see on the track.

Stock engine management is on the rich side to start with. The rich fueling plus the stock boost taper keeps the engine running relatively cool and has very little tendency to knock. As you'd expect, the OEM "tune" trades performance for engine longevity. Simply turning up the boost (without addressing fueling) is a cheap way to make more power, but you cut deeply into your safety margin.

Emre

 

Who has such a thing? I've never seen a MAP sensor log showing anyone with no taper on the stock BCS especially without a flash. Are you saying you have stock boost and 0 taper?

 

This is actually the text I read before I started using it:

NOS® Octane Booster Racing Formula

NOS performance for the serious enthusiast. Developed to increase octane effect up to 60 points or 6 full octane numbers. Blended with MMT and our performance-enhancing Powertane, along with Nitro Methane and unique lubricants specially developed for high performance engines.

could still be just marketing bull...

 

6 full numbers huh... I wonder how much you have to toss in to get that?

 

I think it's a 12 or 16 oz bottle, and treats up to 16 gals

we have 14 gal tanks, so not sure how that works out.

 

MMT is used in several countries, Canada being one -- though there's a move to ban it, for octane trimming at the refinery. There's a standard formula used to estimate the octane increase with MMT. MMT very quickly hits a point of diminishing returns and also has less of an effect when you start with higher octane gas. Off the top of my head, trying to remember the formula, I don't think you're likely to get better than 95 AKI no matter how much you use.

Dave