New here/ Jet bike project

[turbob]

Hi guys I'm new to this forum. I happen to come across a link for it from a YouTube video. I have a Cummins turbo charger jet engine that I've been trying to get to afterburn but the nozzles I'm using keep melting. I've been using oil burner combustor heads as flame holders which seemed to work pretty well but I can never really get the afterburner dialed-in because I keep melting the nozzle. I'm curious as to what you guys are using for the afterburners as I cannot find anything online.

I moved the spray nozzle further down the exhaust nozzle and still no luck. I do have a stainless steel adapter but it seems too large and I wouldn't even know where to find another one. There is really not too many resources on the internet for these types of things. My goal is to make a jet mini bike with it, but really want to get the afterburner working before I move onto building it. Thank you.

Also is there a way I can post a picture or a video of it?   Figured out the picture part.  Have to use a desktop.

[racket]

Hi

Your A/B might be a tad small in diameter which won't help with combustion , also we don't tend to use spray nozzles simply because of the size required and the fact that its not the healthist environment for a nozzle to be in , we use spray tubes like this ibb.co/84scsDt with a multitude of small holes on the inner and outer edges of the ring , the high speed hot gas flow does a good enough job of atomising the spray , an all stainless steel spray nozzle might work OK , theres info here on a A/B fueling jetandturbineowners.proboards.com/thread/680/diy-turbines

Cheers
John

[turbob]

Hi, and thank you for your reply. The diameter is currently 5", by how much should I increase it by? is there a rule of thumb? When you say small holes, how small are we talking? 1/16, 1/8? I checked out the link you posted but I can't see any pictures. Are oil burner combuster heads an acceptable flame holder? I feel like I'm missing something. I have a few different exhaust nozzles with different diameter outlets to see which produces more thrust, but as simple as I thought this part of the build would be, it seems a little more involved. I apologize for all th questions, it just seems I solve one thing another issue arises.


  this is what I've been using for flame holders.  This is an f12, I also have an f22 which allows more airflow.  

[turbob]

Ok I switched browsers and now I can open the links you posted. I'm reading that "dump" style nozzles don't require a flameholder? Have I been overthinking this? Thankyou for the link, I have some reading to do.

[racket]

Hi bob

Your current flameholder will be restricting flow , I'd suggest going to the dump type A/B as its been found to be the easiest and most reliable system .

Yep , you need to hit the various icons in each section of that Link to bring up the info , the afterburner section should answer most of your questions but feel free to ask more :-)

What are the dimensions of your comp and turb wheels ??

Cheers
John

[turbob]

It is a cummins vt50 turbo. I don't have the exact specs at the moment but I will get them when I get home

[racket]

A lot of the info in that Link is appropriate for a VT/ST50 turbo

[turbob]

The size of the compressor and turbine wheels themselves I am unsure of. I had a spec sheet I printed but Idk what I did with it. Without getting out the vernier, The compressor inlet at its largest point is 4 1/4" and tapers to about 2 7/8" right where the compressor blades meet the housing. The turbine outlet is 4".

[racket]

OK thanks

RC Don did a nice build with a VT50 www.rcdon.com/html/experimental_projects.html

[turbob]

Wow! That bike he built was pretty awesome. The fact he got 69mph out of it considering combined weight was 530lbs is really impressive. I'd be ecstatic if I could get that out of mine. I feel there's so much to learn still. I do need to swap my oil pump as it's not putting out enough pressure at 20psi. I've read that 20psi was good pressure but here it says a minimum of 50. Everything is still tight in the turbo with no slack, but I'm not going to spin it up until I get a new pump. Happy I found this place. Lots to learn still.

[racket]

Yep , theres always plenty to learn ..........LOL, after 30 years I'm still learning :-(

The turbo bearing bushes need a fair bit of play so that theres plenty of oil getting through to keep them cool , lotsa heat generated in them at the RPM we use

[turbob]

Any advice on another oil pump. I'm currently using a 24v aviation pump from a helicopter but it only puts out 20psi. Also I read in the link you posted some turbos at full rpm you can increase to 100psi!!? Is that correct? So at a minimum idle it should be between 40-50psi, or is that acceptable for higher rpm's as well? Last thing I want to do is blow up the turbo.

[racket]

Yeh, there can be different pressure requirements between turbos depending on their bearing configurations , those with rotating bushes need more oil pressure whereas those with a "fixed" floating bearing can survive with less , but 20 psi is a bit low for any type , 40-50 psi is a happy medium which should be OK for you , high pressures can be a help if the thrust bearing is a bit "fragile" when using a turbo that normally only sees low boost on an IC engine is used at high boost/P2 in our applications

[turbob]

For a throttle would an electric dc speed controller or needle valve be better to idle up and idle down?

[racket]

For initial testing go with a simple needle valve, the less electronics the better until you get things sorted , then you can add some sophistication