Dry Lakes Racers Australia

grumm441 wrote:

internetscooter wrote:hmmm...

so at the moment the only streamlining is the small hump on my leathers. Does that mean with an unblown engine (which is still a Vespa), no additional screen and no hump I can run as M/G 250cc? Current record 99.042?

edit: as far as I can tell from looking at the rules I do qualify in the Modified Production - 2014 just got more interesting

Modified Production?
Is this a new class?

G

7.F MODIFIED PRODUCTION !?

i.e. M/G 250 allows me to run a production frame with a modified exhaust

Am I misinterpreting the rules somehow?

BTW - you were the one that gave me the idea

I think you would have to take the legshield off to run M/G 250
because it might be considered streamlining ahead of the rider 7:F:11
And if you took it off it then be an A bike
G:-)

grumm441 wrote:I think you would have to take the legshield off to run M/G 250
because it might be considered streamlining ahead of the rider 7:F:11
And if you took it off it then be an A bike
G:-)

Bugger - if I took it off it would be a lump of scrap as it is a monocoque structure

I am already registered as M/G but I still have the MPS/G stickers on it, Is there anyway to get a ruling beforehand so I know what stickers to use?

Also my CFD stuff shows that the legshields followed by the gap is sucking the scoot back significantly, so could that be used to show that it is OEM and not actual streamlining?

No big dramas anyway, since I postponed the charger I am aiming for just having fun MPS/G saves me having to remove the hump from the leathers.

Ross would have to give the ruling, but I would say no

Streamlining is defined as any devices or objects forward of the rider that have the apparent effect of directing, limiting, or controlling airflow around the motorcycle or rider.

It sounds like you need to fill in the area behind the legshield so we can see your legs but the air can't get in
G

grumm441 wrote:Ross would have to give the ruling, but I would say no

Streamlining is defined as any devices or objects forward of the rider that have the apparent effect of directing, limiting, or controlling airflow around the motorcycle or rider.

It sounds like you need to fill in the area behind the legshield so we can see your legs but the air can't get in
G

No problems - I was wondering why not many production looking bikes were going in the class and thought I had missed "something".

MPS/G it is (again) and I saved the hump back

hay Paul, heres an opptunity, make up some skirts that run from the legshield back to the profile of your legs, run with, run without, moniter difference,

Stayt`ie wrote:hay Paul, heres an opptunity, make up some skirts that run from the legshield back to the profile of your legs, run with, run without, moniter difference,

Yes - I will be experimenting but unfortunately my power curve is such that even a really big drop in Cd would only translate to 1-2mph. The supercomputer I run is quiet during this period so I am developing some large scale simulations and when I get that running I can easily try a few things such as filling in the gap

strike out the word "unfortunate" mate,, the game your playing with the bike your running, (low power, shite aero), 1-2 mph gain is not to be sneezed at, ,, it is a 1-2% increase at speed, translate that to the 200 bikes, and its a even lesser %,,

trouble is that I have fixed gears, so 1-2 mph is optimistic. e.g. Say I do 100mph and then try something fancy with the aero to drop the Cd - I'd have to drop the Cd by huge 10% to do 1 mph faster If I could change the gearing I could do 105mph with no Cd change at all.

The above is based on my dyno data. I'd be interested to know is people have tried comparing an inertia dyno with an onboard dyno? If I do my run in 4th I get a lower reading than if I do it in 3rd, this suggests to me that the dyno curve might be different pushing different weights i.e. I'd be 220Kg on the salt but the dyno drum is 400Kg

Hi Paul

I had a look back through you're posts and I could not see any detail regarding your tune. I found a couple of things when doing the RGV that I found helpful.

Does the KDX Cylinder have Power Valves? and are you using the Ignitech Ignition? if you are then maybe you might be able to get the Power Curve you need. I know you're Rev Range is different but the idea might be transferable.

I am using a Zeeltronic to control the Igntion/Power Valves, after a number of Dyno runs I found leaving the PV's closed for longer and advancing the Ignition curve in the middle of the "Power Curve" I ended up gaining some mid range power and removing the RGV dip at 8000 rpm. The Green Curve is an optimised Pump Fuel set up, as I am using the Sunoco mine is closer to the Red Curve.



My Power Valve settings are 50%/8500 - 75%/9100 - 100%/10600.

I will be looking at getting some over rev on the next tune by retarding the ignition towards that Green Line after Peak HP/RPM.

Like I said, I don't know what you have done and might have tried this any way, keep at it, there will be a way to do this.

Pete

Thanks for the info Pete. Here is my last dyno result with the calculated aero drag at different speeds. I have a power valve but as you can see that there is no low down power dip to worry about, so I have it manually switched for power in the high rpm range. I don't have an adjustable ignition so it is also set to the maximum retard for high rpm.



There is a lot I could do to the port timing to push up the power in the high rpm range but as I was concentrating on the supercharger so I have not yet done that. If fact I could probably order a bolt on Eric Gorr 225cc kit (this is a tricked KDX 220) ported exactly to suit... however I spent all my money If I get desperate for a few extra mph I will probably try some porting at the lake;)

Ah the old $$/Gearing Limitation, I think a few of us on here know that one,

The Dip on the RGV was like that 50 mph to 70 mph part of your curve, when you go Super Charged it will be a very different thing.

Is an Ignitech on the Future List ?

Pete

Paul something about your graph looks wrong to me , think your comments earlier about hp/gear are showing here
is there another factor that should be included in the calculation to make the hp read the same no matter what gear your in
My old interia dyno needed calibrating for the gearing each pull that it was changed ie if you used 3rd instead of 4th or put the bike on after a sprocket change

Pete - I have a Jaycar electronic ignition 90% done, so if I need it I can finish that off

Greg - I helped a mate set up a dyno for his scooter shop so I have access to that and can get at the raw data. As I am only concerned with top speed the data I have is the measured drum speed. Your's would be converting the drum speed to the engine RPM and would have to be calibrated each time there is a change in gearing. 110 mph is 9000RPM so it is very conservatively ported and I have a lot of room to move

Hey Paul
You said that you cannot change the gearing -- you said fixed gears.
How is the blower going to help you go faster? You can have all the power you like but if you cannot change the gearing to use it you will
not go any faster.
Are you not better to make the engine rev higher for more speed?
Maybe I've missed something

Bones