ESE's works engine tuner

[adegnes]

Ambient temp can't be hurting. I've spent about 5hrs today in warm muggy dyno room chasing missing power, how much due to atmospheric. . also trying to fuel map (sorry its my foulstroke 675) in a room that needs ventilation. Getting the curve/map even, but needs so clean runs to verify baselines.

So you calculate like 5hp loss in the variator thingy. That would make it get very hot in short order.

I'm very uncertain about the transmission loss numbers. The variator/belt/clutch will burn you after a run tho.
I am also trying to draw attention from scooter kids...

[jasonu]

I've had a good look at them. Lots of good points including magnetically coupled so no seal to leak.

Finally given up on thermosiphon Mike?

[mr bucketracer]

Ambient temp can't be hurting. I've spent about 5hrs today in warm muggy dyno room chasing missing power, how much due to atmospheric. . also trying to fuel map (sorry its my foulstroke 675) in a room that needs ventilation. Getting the curve/map even, but needs so clean runs to verify baselines.

So you calculate like 5hp loss in the variator thingy. That would make it get very hot in short order.

why would you worry about dynoing some road bike?

[husaberg]

why would you worry about dynoing some road bike?

I heard it was making strange farty noises.

[peewee]

hi frits I have a question regarding your power range idea but its late so ill save that for tomorrow. for today I have something else to ask. in a effort to minimize or maybe eliminate piston cracks on the inlet side, ive been reading some research papers on stress concentration of various window shapes. ive included a photo that represents some what of a pyramid from terrible shapes to better shapes. youll see where I think the original window belongs and I circled the window shape which I think would be better. also ill radius all the sharp edges. what do you think ?

[husaberg]

hi frits I have a question regarding your power range idea but its late so ill save that for tomorrow. for today I have something else to ask. in a effort to minimize or maybe eliminate piston cracks on the inlet side, ive been reading some research papers on stress concentration of various window shapes. ive included a photo that represents some what of a pyramid from terrible shapes to better shapes. youll see where I think the original window belongs and I circled the window shape which I think would be better. also ill radius all the sharp edges. what do you think ?

Peewee have a read up on the De Havilland DH 106 Comet.
One of the first, if not the first jet airliners.
They had some issues with the windows too.
http://www.dailymail.co.uk/travel/tr...ft-safety.html

[Frits Overmars]

in a effort to minimize or maybe eliminate piston cracks on the inlet side, ive been reading some research papers on stress concentration of various window shapes. ive included a photo that represents some what of a pyramid from terrible shapes to better shapes. youll see where I think the original window belongs and I circled the window shape which I think would be better. also ill radius all the sharp edges. what do you think ?

I think there should not be any windows in pistons at all, Peewee. I'd rather bring the inlet port down and shorten the piston. Apart from this, Husas Comet-link is worth reading.
Radiusing all sharp edges is good. Not only for stress concentration avoidance, but also because radiused edges won't scrape as much oil off the bore as sharp edges would.

[adegnes]

Manual powerjet shutoff valve.



Will attach a wire and use a handlebar lever to operate it.
As my bike is only supposed to be above peak power rpm when it's fully geared out and rpm starts climbing I think it'll work fine.

[Magnus676]

Which power range is best for a drag bike, largely depends on the amount of power itself, and on the clutch and gearbox.
For example, a Top Fuel car with thousands of HP needs a damn good clutch and only two gears; a 50 cc drag bike doing a quarter mile will need all of its six gears.

Guys,and Frits my bike is a 5-speed 250cc drag bike, max power @ 11000rpm(Too much?I know but it's drag racing,you need as much power as you can get and as much rpm as possible,or at least I think so )
What I can't understand,a bike with,say 70hp and 1.25 power range will have power from aprox 9000-11000.Even with a close-ratio gearbox,you'll need a very tall primary and final gear ratio in order to reach max speed in 400 m and not say,300m.
So I guess little less power but with a ~1.38 power range would be better.
What's your opinion guys?

[Frits Overmars]

Guys,and Frits my bike is a 5-speed 250cc drag bike, max power @ 11000rpm(Too much?I know but it's drag racing,you need as much power as you can get and as much rpm as possible,or at least I think so ) What I can't understand,a bike with,say 70hp and 1.25 power range will have power from aprox 9000-11000.Even with a close-ratio gearbox,you'll need a very tall primary and final gear ratio in order to reach max speed in 400 m and not say,300m. So I guess little less power but with a ~1.38 power range would be better. What's your opinion guys?

Magnus, I'm a guy too. And no, I'm not going to prove it by posting some eludicating picture here. You'll have to take my word for it.
11000 rpm is rather high for the max.power of a 250 cc single (at least, I'm assuming it's a single). I would not be surprised if you could find more power at lower revs.
I agree that for a drag bike you need as much power as you can get, but why would you want as much rpm as you can get?
As I wrote in my previous post, my experience with dragracing is limited, but I would think that a close-ratio gearbox, roadracing style, is not the optimum. You will problably need a lower first gear and a wider spread from first to top.
A few more words about the power range concept may be in order. The power range of an engine, or rather the power range of a dyno graph is its maximum rpm divided by its minimum rpm. For example, an engine may have a total power range of 4, from 3000 to 12000 rpm, and a power band of 1,3 , from 9000 to 11700 rpm.
The power range that you need, depends on the form of motorsport that you wish to take part in.
Like I said, you will have to build your own database about the best power range for a certain combination of engine, transmission, tire, track conditions etc.

[Michael Moore]

At one time drag bikes had only one gear, they just spun the rear wheel off the line until they were going fast enough to hook up solidly.

A CVT seems like it would be good for a small engine but you may need even more power to offset losses in the CVT (it sounds like they get hot from belt slip). But it would let you keep the engine at the full power RPM. There's been a lot of CVT tuning research done by the snowmobile crowd.

cheers,
Michael

[Frits Overmars]

At one time drag bikes had only one gear, they just spun the rear wheel off the line until they were going fast enough to hook up solidly.

Today Top Fuel cars spin their rear wheels to get heat in the tires. Subsequently they try to get off the line on the border of wheel spin, and as the speed and the wheel rpm rise, so does the tire diameter, automatically adjusting the transmission ratio.

A CVT seems like it would be good for a small engine but you may need even more power to offset losses in the CVT (it sounds like they get hot from belt slip). But it would let you keep the engine at the full power RPM. There's been a lot of CVT tuning research done by the snowmobile crowd.

Keeping the revs always at max.power rpm is one big advantage of a CVT. But it's not their only advantage. Apart from dragsters that can shift up under full power,
a gearshift usually requires that you take the torque off the shift dogs for a moment in order to be able to axially move them to the next insertion posititon.
But cutting the torque, even for a fraction of a second, means interrupting the combustion. And no combustion, no exhaust gas energy. A four-stroke can live with that, but for a competition two-stroke it's disastrous. The exhaust pipe dynamics collapse and although the combustion sound returns as soon as there is combustion again,
it may take a whole second before the pipe dynamics have fully recovered and all the power is available again.
CVTs are clearly less efficient than gearboxes, but at least they don't require combustion interruptions and power collapses, so they may come out on top after all.

[jonny quest]

Isn't that why you never let off the throttle and just stab the clutch?

[cotswold]

[QUOTE=TZ350;1131025445].
Back to working on the EFI project.

Attachment 328055

I kept having problems with the original 12Volt water pump and eventually it burnt out. So I found this little beauty lying around the workshop and plumbed it in for a temporary fix. The unkind suggested I put a skate board under it and ride the outfit in the side car class. The up side with the 12V pump being temperamental was that I found the engine boils up nicely without any damage, did it quite a few times.

Have you tried the Mercedes Aux pump, the lads in the uk swear by them
this is possibly a bit heavy http://www.xylemflowcontrol.com/mari...fugal-pump.htm
range rover one does 4 yankie gallons per minute http://www.ebay.com/itm/BOSCH-AUXILL...5T~gH0&vxp=mtr

[wobbly]

In karting the 250 engines rev to 11,000 all day with no issues,apart from needing regular big end bearings.
Using speedshifters that have ignition cut for say 50 msecs the loss of combustion and pipe effect is minimal, and on the dyno the power drop delta
between gears using this gives setup about a bike length advantage per change ( using the Dynojet time/distance histogram output ).
Most late model MX have only 5 speeds with big gear drops, but many also originally had a 6 speed that still fits straight in.
Full throttle staging with a rev limiter gets heat in the pipe real quick, and also means consistent launch technique.
Drag racers now also use seamless shift gearboxes in Banshees, with a very simple fork/dog mod, Google that.
You want to get the thing reving to its mechanical limit the whole time, as this affects the speed/rev ratio and thus the torque multiplication of short drive ratios.