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sixth gear tune suggestions welcomed

Howard Coleman

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i will be running the Texas Mile March 22. i hope to finish at 7000 rpm in 6th gear/200 mph.

i did attempt this a number of years ago and was running just over 160 a bit before the 3/8th mile marker when my fuel pump fuse melted. a week prior i ran 330 KM/Hr-205 on the dyno. at the time i had a T56 which had the .5 6th so i was running in 5th at 8650.

i now have a Magnum F with a really nice 6th.

the finish line, for my Mazda RX7 running around 575/600 rwhp, is 30 seconds from start. that's lots of time for my 2 rotor to be running near the 600 level. 

there is a very interesting lengthy post by someone working for Cadillac that tuned the Northstar engine. he programmed in various changes in the map if the engine had been running flat out for X amount of time.

i like the idea for my needs. when i did run the Mile previously i had boost by gear enabled so i ran off the spring in first and second and then curved into 27 psi (GT4094r) as i moved towards higher gears. 

i have a ViPEC log of the 205 dyno run. we ran thru 5 gears and of course i know it isn't the real thing but it was a start. all the engine metrics were fine at 9 degrees advance, 27 psi and 77% ethanol.

i will be using 6th this March.

what would be my options and how would i enable..... as to timing, AFR and boost give my G4X Extreme?

i am primarily interested in what if anything i could do in 6th.

thanks for any help. 


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Use the race timer function, I would probably trigger the timer at a specific speed rather than at the start line to eliminate some of the acceleration variables.  You can use that to trim fuel ignition, boost, throttle, etc. 

What you choose to trim as the strategy will depend on what adverse condition you are trying to improve, combustion chamber temps? Exhaust gas temps? Water jacket temps? IAT temps?  You may be able to cool combustion and EGT by adding more fuel, but with a rotary at high boost you may already be pretty rich with not a lot of headroom for that.  Water injection may be an option or possibly reducing boost & increasing advance as RPM and time increases.

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