Bottlehead Racing's CB77 land speed racer - first nitrous run, BMST 2019

The first trial run of my AMA 2018 national record making 350 M-CG Honda CB77 landspeed racer with a new-this-year progressive wet nitrous system running in 350 M-CF, on August, 28, 2019 . I got about a 9 mph gain with about a 10 hp shot programmed into the progressive controller built by my lead technician, Paul Birkeland, using my well worn 305cc backup motor. Shot hits at 1:13. If you listen very closely you can hear me say WOW! at 1:15. Ended up being my personal best run of 95.612 mph avg. I took time to visualize - every shift, arming the nitrous system at the 1-1/2 marker, and hitting the nitrous button at the 1-3/4 marker - as I waited for my run. That really paid off with probably my cleanest run ever. Next run I set the controller for a 12hp shot. An intake valve adjuster backed off and punched a hole thru the valve cover before I got on the bottle, so I turned out. Going to try to work up to a 24hp shot in 2020.

[@frankie5341]

That was impressive, we used to grind and smooth a little off the base of the cams so it gave a little more lift, alloy or plastic carb to head extensions help with low down pull and a cb72 gearbox sprocket helped it rev out, 340 cc bore with pistons from the 750 made a big change. The heads are ok on these so we would reduce the barrel height (skim the top) to give more piston lift, (a little) and file down the edge of piston crown, takes it to 9.1/ 10.1. The ultimate is 450 head. Are you adding more petrol with the nitro shot?, Thanks for the vid and good luck.

[@danschmalle136]

Thanks much for the suggestions! After analysis of gearing charts and this vid it appears I still had a clutch slippage issue as the nitrous came on. That seems to have cost me about 6 mph. A new Barnett clutch and heavier springs will be fitted for 2021 (2020 event cancelled). Thanks for the tip about the cams, will look into that. The nitrous bumps up the compression and the torque nicely. It's pretty much about tuning for top end hp, getting the gearing right, and figuring out how to get all that extra charge from the nitrous out of the cylinder efficiently. I was using 16/30 gearing on this run. Next year I will probably change to the 250M-CF class and run CB72 jugs and head. The nitrous system is indeed a wet shot (fuel was ERC A-8D with one step cooler plugs and electronic ignition), using a fuel pump at 3psi and a 1lb. bottle, which is good for a couple of runs. This run was with the progressive controller pulsing the solenoids 20Hz at a 50% duty cycle with jetting for a 12hp shot, so there should be a lot more potential with bigger jets and a 100% duty cycle. More pics scattered thru my IG @bottleheadaudio