Dry Lakes Racers Australia

Enzo Ferrari said "Aerodynamics is for those who can't build horsepower"

With respect to everybody; this frontal area is quite differant to other pics posted by green hornet...(we all kwnow the the v formula)

Yes - I need to hit the dyno - from last measurement if I put my engine in JP's bike it should have done 100mph

dplecko I'll also be blowing the dust off my homemade data logging kit (shelved after a long long exercise in discovering how to accurately measure wheel rotation speed). You have a pretty good set-up - all you need to do to work out the forces you are fighting is to pull the clutch in The only thing that will change your velocity is the air and rolling resistance and therefore your measuring deceleration and mass will enable it to be measure the forces.

Ferraris are for those who can't build horsepower

One of my team came back in the office yesterday grinning and then told us about how he was walking back to the office via the Ferrari/Lamborghini dealership in Fortitude Valley. Some clown out front was revving up his Faz ready to make a scenic departure and pulled off with intent - only to run into a bus....

Bus 1 - Ferrari 0

Lynchy wrote:One of my team came back in the office yesterday grinning and then told us about how he was walking back to the office via the Ferrari/Lamborghini dealership in Fortitude Valley. Some clown out front was revving up his Faz ready to make a scenic departure and pulled off with intent - only to run into a bus....

Bus 1 - Ferrari 0

Where's the LIKE button?

Dave

I cobbled together some electronics for an intertial dyno over 20 years ago (quite an achievment at the time - took minutes to compute then draw the graph), it is trully amazing how accurate they can be.

I was talking to a guy at the canteen one night about dyno's. He had built one using a load cell like this. Easy conversion from ft/lbs to HP.

http://www.ebay.com.au/itm/221386078007 ... 1423.l2649

RGV wrote:I was talking to a guy at the canteen one night about dyno's. He had built one using a load cell like this. Easy conversion from ft/lbs to HP.

http://www.ebay.com.au/itm/221386078007 ... 1423.l2649

Very nice! - just added to my list of sensors to include - I can read any value so I will go for a more sensitive one without the display. Thanks!

I did spend a lunch break looking at torque sensors, that would be very very nice to read the Hp straight from the wheel strain!

A quick google gives one overview:
http://www.testing-expo.com/europe/12tx ... _Novak.pdf

AEM have an interesting load cell in the tailshaft:
http://www.google.com.au/search?q=AEM+t ... s&tbm=isch

Actually I just found that I noted down my googling result and found a motorcycle version http://www.vespalabs.org/Projects/Scoot ... que_Sensor but that is about as far as I got. Don't know where you get them or how much: http://www.gtme.co.uk/Torque.aspx?id=14 but it wouldn't fit on my Vespa anyway Someone else can try

I am concentrating on a hall effect sensor for accurate wheel rotation measurement - should be able to achieve the same result Will try an get it working this week so I can compare it to the dyno result (booked in for Sat).

Good news?! The dyno run today shows me quite a few horses have bolted and I only have 22Hp (down from 32Hp) - this explains a lot!

1-2Hp is due to the side panel alone! This is probably even more at higher speeds due to even more restricted air flow - though I tried measuring a pressure drop on my road scoot and couldn't see anything of note.

I suspect the other Hp's may be due to seals not handling the intermittent starting (i.e. many months sitting still and then being thrashed - I did note oil after the first few starts but then it stopped).

Next step rebuild the engine without changing anything and see if I can get back to 32Hp (there were a few splutters which might indicate electrical problems also).

I'll process the dyno graphs for more detailed info.

Lesson learnt - if my mates dyno is not functioning before the salt, pay for a dyno beforehand and get 100mph+ rather than pay for one after to work out what went wrong!

edit: adding dyno result...

You might need this Paul

How does the lower hp look with your achieved speeds , does it correct the calculations ?

Greg Watters wrote:How does the lower hp look with your achieved speeds , does it correct the calculations ?

I'll need to do some more scribbling on the chalk board - I suspect the RPM on the chart is wrong as it is based on my rev counter and I don't trust it to be correct. The rear wheel speedometer reading showed max speed of just under 100mph, which suggests that I am not only fighting with lost power but short RPM range.

My mates dyno should be online in another few weeks so I can do further testing and compare. I have dyno'd the scoot on this other dyno before so I am comparing apples with apples (just the rpm has always be suss due to the way he runs the dyno).

I'll keep the thread updated.

Tiny I'll try the power band out in your private race track

OK more info...

Added the "Bad" Hp results (mapped against the 4 gears) and left the old good results (dotted lines) and then tweaked the Hp to overcome drag (red line) to emulate what happened at the lake. To fit the Hp to overcome drag I just added more frontal area (as I was not sitting as low) and guesstimated the rest in Cd till 4th maxed out at 90mph (red became more than green). The Cd should be lower but rolling resistance would account for some of the extra I had to add.

So I have to get the red line down and regain my power. I will redo the dyno on my mates one (where the good results were taken) so I have an additional data reference to go by. I'll also redo the CFD simulations with me sitting in a more upright position.

http://files.internetscooter.com/dlra/2 ... alysis.jpg (click here is the image is too big for your forum view)