[Allch Chcar]

Originally Posted by serialk11r

Injection strategy is port injection, rpm cutoff is 12k (they didn't change the cams or anything to adapt to the restrictor), 14:1 compression ratio, 100 octane race gas (standard for FSAE, no additives allowed ). My guess is the 14:1 compression ratio has something to do with why they run so "lean".

If they were going for max power richer would be better, I know that much. Max power for Gasoline is at least .85-.90, it could change depending on the composition but realistically the Lambda sensor(I hate calling it an oxygen sensor) isn't reading completely accurate values. And the combustion chamber can also unevenly distribute the Air:fuel making lean and rich spots.

I remember a conversation with @WingsofWar that the Lamda sensor was almost worthless for tuning his Rotary, either due to bad placement or what have you, and so he would use exhaust temperatures for tuning. In his case the sensor would read far richer than what it actually was, like 10:1 on a turbocharged engine. Of course this isn't 1:1 with what we're talking, so take it for what it's worth.

Originally Posted by serialk11r

GSXR600

Might be an older one, since they mentioned being able to pick up blocks for 400 bucks. Not sure though.

I specifically asked, "I thought usually max power is at 0.9 or so?" The guy told me "well, depends on your setup". Yea not sure what's going on. Apparently a few years ago there was a guy on the team who was an expert at tuning, and the fuel maps he left behind were aiming for about 0.94.

Okay checked gixxer.com, they seem to agree on 13.2:1. Except pump gas is probably a little different from race gas... I think the pump gas stoichiometric ratio (with oxygenates) is like 14.1-14.3? In that case, 13.2 is about 0.93 lambda. Going by the usual 14.7, 13.2 is 0.90. Higher compression may work better on a leaner mix.

Stoichiometric is the same when reading Lambda sensors, 1.0, so don't let the different values confuse you. I'm suspecting that the new guy doesn't know what he's doing as much as this previous guy. You don't shoot for stoich except for emissions. Better power run rich and then lean it until fuel efficiency is adequate. A fuel economy competition would do the opposite. Lean it out until just before power becomes insufficient.

There is an argument for not reinventing the wheel, especially under time constraints, but I'd still test it out since goals change with time. Especially if the E85 rules leave them uncompetitive.

Originally Posted by Dimman

Fuck, I can't keep my numbers straight. Where did 14.3 come from ?

Stoich is 14.8 according to my bike engine book (2008). They hold to the 12 to 13 is optimal for Power on a typical performance bike of the era, but while race tuning it can adjusted leaner for better mixing/charge motion/combustion chamber shape. It's pretty involved, gets into fuel volatility curves and stuff. (Stuff I gloss over. ..)

Also is the fuel a spec fuel, or just can't exceed 100 octane?

Also the race fuel means leaner mixture. I would be tempted to run E85 even with the 19mm restrictor. But it would depend on the other requirements. If they're requiring running same fuel tank size or measuring fuel efficiency, the Race Gasoline might be better but if you're talking max power, better energy efficiency, or better emissions I'd go with E85 over Race Gas.

Originally Posted by boucher

Are internet memes becoming too popular and overused?

Are you a 4chan elitist? In all seriousness, I find the popularity of memes to be great IMHO. I use memes all the time to communicate with people of different ages. I can share memes with pre-teen siblings or even my 30 year old uncle and they can pick them up without a problem.