www.pulse-jets.com

That looked like a fun ride.

Bwahaha!! don't you just love never groing up?
That's awesome, can't wait until race-day!

Shit, now I've got to make a decent vid to

there's some serious red flames comming from the exhaust, is that excess fuel torching off?

CONGRATULATIONS very impressive ,

Most excellent indeed - well done!

Thanks guys!

The yellow flames in the first clip can be from gasoline pooled up inside the engine during the previous injector testing, but I imagine that gasoline will burn more yellow than propane so a completely blue exhaust is probably not going to be seen.

We will do another test on sunday so I will make a slightly larger injector for that run, you can hear it run harder for a split second before I take off on the kick so I know that there is more thrust to be found.

I made the new injector today, we´ll se how well it performs on sunday.

ha ha, that ride video is all-time classic! congratulations! I've been out of touch, but will go back through this thread. very nice. I'm sure it's somewhere here, but when is the race again?

The race is the last weekend this month, so there is not much time left for fuckups. I feel much less stressed now when I have a working engine, my friends on the other hand are starting to break a sweat...

Hopefully you will find the coming videos in this thread even more interesting.

Mike Everman wrote:ha ha, that ride video is all-time classic! congratulations! I've been out of touch, but will go back through this thread. very nice. I'm sure it's somewhere here, but when is the race again?

I ran it again today with mixed results, it runs much harder with the new and larger injector but the fuel pressure bounces around so much that the engine flames out immediately after it starts. I blame the fuel pump for this so before the next test I will fit a larger fuel pump to see if that cures the problem.

A bit more work to do and hopefully I will have time to test it again sometime next week.

Any way you can run a line from a pressure tap on the combustion chamber, through a one way valve, to the fuel tank? Not sure what kind of pump you are using or if it can handle pre-pump pressure.

Most automotive ones should be able to, most large trucks have in line booster pumps before the primary pump.

Hopefully that will help increase the fuel pressure enough so that it isnt bounced around at startup, since it should compensate for engine pressure.

Johansson wrote:I ran it again today with mixed results, it runs much harder with the new and larger injector but the fuel pressure bounces around so much that the engine flames out immediately after it starts. I blame the fuel pump for this so before the next test I will fit a larger fuel pump to see if that cures the problem.

A bit more work to do and hopefully I will have time to test it again sometime next week.

Hi Anders

It sounds like your vaporizer coil is flooding with liquid fuel due to the metering nozzle at its inlet being to big ( I assume you have a liquid metering nozzle fitted;-), that would fit with the surging you report.

Viv

Eric: My every remaining piece of common sense screams when I start to think about pressurising a plastic gasoline tank with the engine...

Viv: You might be on to something here, I will test flow the restrictor to see how much it flows before the next test. I owe you a beer if you are correct!

Hi Anders,
May try back flushing/purging the coil and see if there are little black flakes or particles developing within the coil.
Joe

PyroJoe wrote:Hi Anders,
May try back flushing/purging the coil and see if there are little black flakes or particles developing within the coil.
Joe

Good idea Joe, if the gasoline has overheated inside the coil and blocked it off partially it may very well cause problems. Will try to blow it through backwards with shop air when I have removed the coil restrictor.

The problem is solved, the coil was flooding from the 2mm restrictor.

I flow tested a couple of injectors at different pressures and found that a 1.3mm restrictor would flow enough fuel for the engine (1250ml/min) but since I only found a 1.2mm drill it had to do for the tests.
http://www.youtube.com/watch?v=z4n7G7j59ls

Fuel pressures reached 7 bar during the test so I can easily open the restrictor a couple of 0.1mm´s to get the fuel pressure down to around 4 bar to save the pump and battery.

I have to build a larger fuel tank since the 1 gallon tank I use now won´t last for the start and 2km run, a 10 liter tank should be better. The ejector haven´t been built yet either so I know what to do next weekend... =)

Great fun!