New projects for this year.

[dwilfong]

Great work Dave!

"It was very interesting in how the spray bar acted. It started making a noise as you moved it to different point on the boar. a real high pitched vibration as the air mixed in the spray bar with the liquid.

Moving the hole to different locations in the boar changed the frequency of the vibration and the mist.

You can tell when it is perfect."

I'm curious to know if the behaviour changes if you alter the fuel pressure - just like if the stinger diameter on the pipe was changed. Is the spray bar config still optimised at the same position if the fuel pressure was changed? I guess I'm trying to say - does the carb optimisation have to be re-done if the pipe stinger is changed.

It seams the velocity of the air stream in the boar is the key I think.

when you go to the out side and get into the boundary layer it slow down the song.

You only have a minute or two to check as the tank runs dry. then you have to fill it up and start over.

Also as the tank goes down the song changes.

Float chamber will be next test.

 

[Tom Foley]

BIG BORE CARB !!! Looking good David !!! It's BEEN a while since I've seen one this big !!!!

 

[dwilfong]

BIG BORE CARB !!! Looking good David !!! It's BEEN a while since I've seen one this big !!!!

I'm going to see if I can get Dale to put it on his VAC .91 at the next race to test it.

 

[dwilfong]

I did some more testing tonight and it seams the sweet spot is the sweet spot.

Tank pressure dose not change that.

I also tested my oval boar carb and it seams it likes the bar with no hole in it.

Also it likes the end right in the middle where the round likes it close to the edge.

the oval boar seams to not have a dead spot behind the bar wear the round dose.

these two different shapes pull the fuel different out of the bar and have different wet flow patterns.

The oval seams to spread the fuel out better and is less fussy with the bar placement.

This may be due to the VAC intake is long and confined and the RS opens up to the case real quick and spreads out quickly.

It seams the expansion of the mix changes the way it suspends in the flow.

Disk is GOOD long hole is BAD. that is what I am seeing.

 

[Tim_Duggan]

I did some more testing tonight and it seams the sweet spot is the sweet spot.

Tank pressure dose not change that.

Good to know - Thanks for sharing, Dave!

 

[Michael Caruso]

Found this on another site ( http://www.eng-tips....d.cfm?qid=84432) and thought you may find it useful;

A very easy way to build an eddy current brake is to just use any ac induction motor, and feed dc current through the windings. It only works for low power engines though, because the solid steel (squirrel cage) rotor does not dissipate heat well.

But if you are experimenting at home with very small engines, it is a very practical ultra low cost way to do it.

A three phase motor will have three terminals, just feed a dc current into any two terminals, and ignore the third. The rating plate will have a current rating for the motor, which should not be exceeded.

Only a low dc voltage is required because the resistance of the windings will be quite low. Also the braking torque will be extremely high, even at currents far below the maximum on the nameplate.

With a given braking current, the required torque to turn the motor increases very rapidly with speed. A given motor will brake full rated torque at its slip rate, which might be only 150 RPM.

Just to explain this, if the mains frequency is 50Hz, the magnetic field inside the motor rotates at 50 x 60 = 3000 RPM. The motor speed might be rated at 2850 RPM, so the slip will be 150 RPM.

If you try to spin it faster than 150 RPM with full field current, it will readily sink far more torque, so a small electric motor can easily hold almost internal combustion engine. But the big problem is heat buildup in the rotor. It will get very hot very fast, so that is what limits the power absorption, not torque sinking ability.

So, a single or three phase induction motor would make a nice home chassis dyno for a cart or small bike, provided you were careful not to cook it. A large external blower or submerging the whole thing in oil might also work.

It is all a bit Mickey Mouse, but some of us are not that wealthy. Short power runs are all you really need with long cool down periods for home use. Also, excessive RPM and heat might cause it to fly apart, so a bit of caution is required.

Try it yourself, get a quarter horse or larger single phase motor, and while turning the shaft by hand, apply 12v dc and see what happens.

Tim you are the man.

This looks like the answer to the problem in a very simple solution.

The motor will have a very big water cooling jacket.

Tyler posted a pick of a Dino that he uses and it has the motor built in to the cradle with water cooling to it.

I am planing on basing my build on this design.

This kind of build will pull lots of heat from the motor with a closed loop heat transfer coil running in ice water.

Hi David,

You are really on the way to learning with your wet-bench. Much better than what I tried in the 70's by using droplets of Dykem Blue into the intake port. Kind of messy but it did show what I thought was going on in there. Would you please send me a list of parts and suppliers I would like to learn some more. Also which Tyler can I contact about the Dyno in the picture? I really like the simple design. But an inertia is a great tool as Lohring said simple it just flat works! if you ever get a chance to hear a full size one you will never forget it. I will call Kevin at www.PerformanceTrends.com has a great Mini data recorder with a weather station inside it. He has been one of the leaders in HP software.

Mike

 

[dwilfong]

Mike there is not real a parts list. every thing was picked up at the local hardware store.

The most important piece if you want to calibrate the box is the flow plate.

I got it here http://flowbenchtech.com/

The container was a cheep $6 storage container. It works ok but in low flow conditions it will suck the sides in.

I would recommend a lexan fish tank to make a better setup.

The fittings are just PVC and come in any size you need to make the mounts and hook up for the vacuum.

the black piece the plate mounts to is a 6" floor drain.

The lid is a piece of 1/4" lexan but this has warped with use. Would recommend some thing thicker. the seal around the lid is self sticking rubber drawer liner.

I do not think I will go thew the hassle of making the tubes with water in them to calibrate the box. I do not need to know the exact flow number. That means nothing to me.

I am going to put a simple vacuum gage on the box. this will tell me if what I do makes a difference. that is all I am concerned about.

I will hook up the eng by the ex port with the piston BDC and remove the intake system. This will tell me how much vacuum the case will make on the box. then hook up the carb and intake system and see what the vacuum is.

This is how I will size the carb to the eng. if the case flowers the same as the carb that is what I will consider ideal.

This way I can tell if the carb is to big for the eng.

Relationships is what matters not the exact flow numbers.

Tyler is on IW as RaceMechaniX

 

[Michael Caruso]

Mike there is not real a parts list. every thing was picked up at the local hardware store.

The most important piece if you want to calibrate the box is the flow plate.

I got it here http://flowbenchtech.com/

The container was a cheep $6 storage container. It works ok but in low flow conditions it will suck the sides in.

I would recommend a lexan fish tank to make a better setup.

The fittings are just PVC and come in any size you need to make the mounts and hook up for the vacuum.

the black piece the plate mounts to is a 6" floor drain.

The lid is a piece of 1/4" lexan but this has warped with use. Would recommend some thing thicker. the seal around the lid is self sticking rubber drawer liner.

I do not think I will go thew the hassle of making the tubes with water in them to calibrate the box. I do not need to know the exact flow number. That means nothing to me.

I am going to put a simple vacuum gage on the box. this will tell me if what I do makes a difference. that is all I am concerned about.

I will hook up the eng by the ex port with the piston BDC and remove the intake system. This will tell me how much vacuum the case will make on the box. then hook up the carb and intake system and see what the vacuum is.

This is how I will size the carb to the eng. if the case flowers the same as the carb that is what I will consider ideal.

This way I can tell if the carb is to big for the eng.

Relationships is what matters not the exact flow numbers.

Tyler is on IW as RaceMechaniX

Thank you very much these answers as they are better that any parts list.

Race MechaniX I have talked with him and very helpful like yourself. Great bunch of Folk's here.

Mike