#6

[speedpro]

60T on the back and 13T on the front. Still too high for a kart track. I will give it a go tomorrow on the HD club circuit. I have 14T and 15T sprockets if it's too low on HD

[diesel pig]

60T on the back and 13T on the front. Still too high for a kart track.

I am first to admit I know nothing about the engine you are working on. But that statement about the gearing on a it for a kart track, is doing things to my mind that I thought could only be achieved by vast amounts of illegal drugs

[F5 Dave]

It is 250 based gearbox spinning to silly revs.
We usually run like a 50 rear.

[Grumph]

Get the boost coming in at lower revs and then the question becomes "how many gears do you need for the track'?

Bit like the days of Foggy setting up the WSB Ducati to only use 5 of the 6 gears.

Our blown 500 Kawa could have used a 3speed gearbox. Rider wore out ankle getting to top quick enough.

[speedpro]

The motor wasn't really doing it's thing but the gearing was OKish with most of 6th gear still to go at the end of the straight. I was revving it to most of an indicated 18,000 but the logs showed it only going to about 16,000.
The intercooler made a huge difference. IAT was going to most of 100C when I ran it on the HD big track. Now it barely goes to 20C. Riding it was far easier with it pulling boost much earlier and quicker. When changing gears it still banged more often than not, and the turbo made a clearly audible "chirp". I figure it was flowing more with the much denser, cooler, air.

The problem was that much cooler IAT which resulted in much denser inlet air. Although the ECU should have calculated the required fuel taking account of the low IAT it didn't compensate enough. The engine was running leaner than the desired AF ratio. Lambda was around .9 versus a desired value of .78. The exhaust was so hot that the turbo outlet pipe was a nice blue to the tip and the exhaust collector wrap was making sizzling noises for over 10 minutes after I returned to the pits.

There was an odd cycling thing happening as well. The MAP was cycling at max boost, and at the same time so was the AFR. The AFR cycled between very lean and farkin lean. The MAP cycling might be because of how I have the ECU setup to control the boost. There is absolutely no control until MAP is at the desired boost. This causes a tendency to overshoot then over-correct.

There is big positives. The leanness can only be caused by a greater mass of inlet air due to the air being cooler and therefore denser. With the correct amount of fuel I can feel that it will be much quicker. I'll check the mixture/Lambda off boost but at 100% throttle. Changes to these values will determine the calculated fuel on boost. I think on the old setup even off boost the IAT was higher than 20C. Either way, adjusting the 100% throttle fuel map values will result in the desired changes on boost which is all I'm worried about. I'll finesse the boost control later.

[F5 Dave]

So let's say in the spare area above the empty cylinders, you rig up one of the old carburetors and feed petrol to the bowl. Then run small tubes to the throttle bodies with some brass tube into the airstream?

World first PowerJet into Fuel Injection ^tm

The innovation never stops.

[speedpro]

Way ahead of you. I had already thought of something similar. The issue is the air pressure at the TBs. I would use fuel from the injector pump through a control valve similar to what I have on my McIntosh. This can be tuned to open at any boost pressure. The initial flow can be tuned to be whatever amount I want, and then the flow varied by tapered needle, and springs, which control the movement, with different rates. On the McIntosh the fuel is delivered to the valve from the tank which is pressurised and the valve delivers the fuel plus leaked air as a froth to the inlet of the carb. The air is required to move the fuel quickly when required.

[speedpro]

The MB/FZR had issues as well unfortunately. It ran well and sounded crisp but every now and then it went off just for a very short moment. At the very end of the first race Cricket pulled in after it went off properly. I pulled the plug and found that it looked sort of OK but had specks on it. I surmised at the time that it was detonating now and again and the specs on the plug were from the centre of the piston. I was 100% correct. I have a box of pistons & rings and have a +.05mm set that should sort it out once honed. The question is why this is happening. There's a few possibilities. Recently I have used 98 octane, versus always using 100 octane Avgas in the past. I tuned it on the dyno but maybe I now have fuel from a dodgy batch. Another possibility is the frankenstein ignition system I put together which might be doing something odd. It's frustrating as I have bought one of those detonation detectors that Wobbly is keen on, and I ordered a new sensor from a guy here in NZ. This ass has my money but won't return calls and I haven't received the sensor. With it we might have seen the issue before it became a show-stopping problem.

[speedpro]

It is 250 based gearbox spinning to silly revs.
We usually run like a 50 rear.

The standard sprockets are 55T on the FZR250

[speedpro]

There are a few issues with the tuning now that I have the intercooler fitted. There are also huge positives. One major change is how easily and quickly it now builds boost, even down around 10,000rpm where previously it had real issues. Now the boost more or less follows throttle position(TP) and boost is held even with the throttle being part closed. There is an issue with oscillation but that is due to how I had the boost control configured in an effort to get it to build boost before I added the intercooler.

The turbo is clearly much happier now. Closing the throttle results in an audible "chirp" from the turbo.

As can be seen from the log the mixture is much leaner than desired. On boost the desired Lambda is .78 which is a nice safe rich mixture for a turbo. The log shows it oscillating between .87 and even as lean as 1.0. That's leaner than even a normally aspirated race engine would be run.

Hopefully I'll be able to get back on Kris's dyno and he'll be able to work his magic. There's different ways of getting more fuel into it. Simply turning up the fuel pressure would do it, but it's already seriously rich at the bottom. With the injector duty cycle only going to about 60% a proper adjustment of the fuel maps is the way to go, maybe even just a change to the 4D fuel map as it seems reasonably good off boost.