Hello all. I was wondering if autocrossers that have shift lights (that they can see) would chime in (or better yet show a picture) and discuss and share their placement of the shift light. I currently have mine stuffed into one of the two gauge side pillar holder but plan to use that spot for an oil pressure gauge so the shift light will be moving out.

 

Here's my old setup. Bright as hell. Easily caught my eye in bright daylight track racing.

 

Thats really fantastic , but how did you do that?

 

Thats really fantastic , but how did you do that?

 

I use a 10mm LED that I have poking out between the dash and the cluster housing. The legs allows for aiming the LED so it hits my eyes though reflections in the windshield.

Shiftlight HUD, no need to look at the instrument cluster.

 

How often do you plan to shift during an autocross.

 

That's a funny question. Would you prefer i call it a motor redline warning light? LOL

 

Can't you hear the motor hitting the redline? Honestly whenever I did autox, I launched in first and then went to second pretty quickly, then normally stayed in second for the run. On a few courses I had to shift to third, but it was rare.

 

It depends a lot on the car and the course.

Back when I used to autox regularly, most courses only had one straight long enough to use 3rd with the 6-speed + 3.636. I briefly had a 6-speed + 3.9 in the car, that was a disaster as far as autox was concerned because most courses would have 3 or 4 shifts to 3rd. This was with 270 rwhp and a 7200 RPM rev limiter.

That said, I never felt the need for a shift light.

--Ian

 

I can indeed hear the car hit the rev limiter but i would prefer to begin letting off as i approach the rev limit instead of just shutting off fuel on boost. With 260RWHP on 107,000 mile stock internals, i am attempting to help the motor run longer.

 

this would make a great shirt light for this application

 

that's the point of the rev limiter...

 

I like this one. Bet this dude autocrosses his Miata pretty hard.......

 

Arduino, LEDs, wiring, and youtube arduino videos.

 

I've always heard that leaning out (aka no more fuel for you mister) a boosted engine is like playing Russian Roulette, but you add another bullet or two.

 

There's "lean" and then there's "no fuel".

Lean is bad because lean mixtures burn hotter and are more likely to detonate. If you turn the fuel off all the way, though, there's nothing *to* burn. Yes, hitting a fuel cut feels violent to the driver, but it's really not hard on the engine.

--Ian

 

a rev limiter is no different than staying in gear and lifting off the fast pedal.

 

My Miata has never had a fast pedal. A "slightly faster, if you give me a couple seconds" pedal, but that's about it.

 

The hydra in my car has a "soft" and "hard" rev limit. According to the manual upon arriving at the "soft" limit, it begins cutting back on fuel in proportion to it's distance to the "hard" (no fuel) rev limit. On the dyno it looks like a double tier waterfall beginning at the first "soft" limit and then crashing hard over at the hard one. I guess the thought process of the soft/hard limiter is to begin lifting when the car starts losing power, but in effect what is happening the car is running very lean because it's cutting back on the fuel supplied increasingly until the hard limit is reached. Would it be "nicer" on the motor to just set the two limiters at the same number to accomplish a NO fuel limiter?

 

AIUI, the soft limiter doesn't cut a percentage of fuel out of injection cycle, instead it starts cutting out entire injection cycles, so individual cylinders are seeing no fuel.

That is, say you want to cut 1/4 of the fuel. Rather than doing four squirts of 75% of the normal fuel (which would take you from a nice safe 12:1 to a very dangerous 16:1), you get three squirts of 100% fuel and then one squirt missed entirely.

--Ian