Bucket Dyno

[koba]

I've been reading and daydreaming and would like to revisit the idea of a bucket dyno.

Someone please tell me why this wont work:

Make a crade for the engine, that bolts to a bigger frame either adjustable or just make a cradle for each engine type.

Add a shaft that can be chain driven from the engines sprocket and attach the other end of the shaft to a big old water pump like (not exactly but just as an idea) this one:
Waterpump Auction


Then draw water out of a big barrel into the pump inlet.
from the pump outlet run a pipe back into the water source.
Using lots of water may dampen effects of temp changes in the water.

Have a restiction (valve) in the inflexable line from the pump outlet to the water source that cound be adjusted to "tune" the meter for the appropriate motor.
Once tuned the restriction would remain fixed and then a pressure gauge before the restrictor could be used to determine the torque of the motor at a given rev range. pressure readings taken at different revs (after conditions stabalise) would be taken down, then changes made and another run made asap under as close conditions as possible to make a comparative reading.

Obviously it would only be comparative data and even conditions on different days would influence the results alot so a base run would have to be made each time to account for temp changes ect.

If you were hardout mathsy some conversion factors could probably be devised over time from keeping thorough, accurate records.

As far as I understand it is pretty much how an old style dyno works anyway...

I don't know if that makes sense but I WANT A DYNO DAMMIT!

Seems to me that altho not perfect such a system would be better than an arse dyno for pissing about with buckets and the like, also it wouldn't have to be 2 massive.



All feedback and debate encouraged and I may try to draw a picture.

[Skunk]

I'm thinking of something driven by the rear wheel for tuning purposes. More useful than remove the engine.

First up though is a bike starter. When I get the time and materials together.

[CookMySock]

it will be a lot tidier if you can put a sprocket on some electric motor and mount it in the rear axle area. The motor can be used as a generator and then it's quite trivial to use an electrical meter on it, or better still, interface it to some simple A-D converter to make a nice graph of it on your PC. Then you can compare graphs between runs etc and see where your improvements (or other) lie.

edit: you can probably use a legacy PC motherboard joystick controller. It's only 8bit (256 steps) but enough for a pretty graph.

edit: or make one of these http://www.sensorwiki.org/index.php/...nsor_interface

DB

[koba]

hmm, good thinking!
would u be able to put enough load on the bucket engine with a reasonably sized electric motor tho?

[CookMySock]

you might have to rewind it. Will have to have a think about that.

DB

[bungbung]

Use a series wound DC motor, you'd need to know the efficiency lets say around 70%. You need to dissipate 20Hp peak, which you can split between heat at the motor and a load. 20hp is around 15kW. You'd need some way of getting managing more than 10kw (after generating losses). It's not a continuous load though, maybe heat a drum of water.

[CookMySock]

what is the reason for the serious-wound DC motor ?

DB

[koba]

Use a series wound DC motor, you'd need to know the efficiency lets say around 70%. You need to dissipate 20Hp peak, which you can split between heat at the motor and a load. 20hp is around 15kW. You'd need some way of getting managing more than 10kw (after generating losses). It's not a continuous load though, maybe heat a drum of water.

Jeeze Im lost already!
Im still tring to think how an increased torque load at identical RPM would effect the generator. Is that kinda what you talking about bungbung?

[F5 Dave]

The big problem is where are you going to house this? Not in suburbia for sure, noise police will be around in seconds.

[cooneyr]

Have a read.

http://pages.quicksilver.net.nz/geoffm/dyno/dyno.htm

Cheers R

[bungbung]

what is the reason for the serious-wound DC motor ?

DB

It'll need to be pretty serious to cope.

The GL145 motor puts out serious power.

At least it did until Mr. Valve met Mr. Piston

[koba]

Have a read.

http://pages.quicksilver.net.nz/geoffm/dyno/dyno.htm

Cheers R

Awesome, I got some reading and dreaminig to do....

The big problem is where are you going to house this? Not in suburbia for sure, noise police will be around in seconds.

Fuck the po-lice!
Naa seriously that was one of the reasons I was thinking more along the lines of an engine dyno, inside a garage with very muffled fume extraction.
Timing would also be important. (not 7am sunday morning!)

[RantyDave]

I had pages of stuff written about making a dyno ... yesterday. I went to post it and discovered the site was dead due to some upgrade thing. Dah! You at the buckets this weekend?

Dave

[Skunk]

He better be.

[Mike748]

Have thought about the idea of a Dyno, but it just gets tooooo complicated for me to even attempt.
I considered water pumps but thought if you could get a generator and run that off a couple of rollers driven by the back wheel it would be simpler and space for me is a problem.
I want to be able to run the bike onto the dyno without taking things apart.