Hello, Im from germany and plan on building a turbine from a K37 I have.
I read some threads on here, but still have some questions
I tried to find some data for the K37 but sadly couldnt find anything (I even contacted Borgwarner, but they couldnt or wouldnt help me) flowchartlike, or A/R, if anyone has some info on the turbo, I would appreciate it.
So I only have the data i can measure:
Comp inducer 85 mm
comp exd 117 mm
Turb inducer 112 mm
turb exducer 101 mm
I cant find anything useful written down on the turbo, but I will attach some pics.
I want to do this project just for fun, I dont want to put it in a vehicle or something like that, I just want to have fun and learn something.
I will post more tomorrow, its getting kinda late now. I had a lot longer post written before but accidently hit the back button in the browser and lost everything........
Edit: Sry, I posted this in the wrong sub, can someone put this thread in the DIY Turbine sub?
Last Edit: Jan 30, 2020 15:58:11 GMT -5 by hans611
Yeh , not much info around , but don't be concerned , the compressor and turbine wheel sizes are a reasonable match for each other so you shouldn't run into problems getting the engine to operate .
The turb wheel exducer has been heavily clipped , but still shouldn't prevent the engine working , just be cautious about turb stage temperatures , don't install a jet nozzle until you have the engine operating satisfactorily and verify that the temperatures are OK , ~500 C jetpipe temps without a jetnozzle , and up to ~650 C once the nozzle is fitted and sized correctly for full power/RPM, probably ~75-77 mm dia jetnozzle required .
Sry, but I dont understand, what do you mean by "The turb wheel exducer has been heavily clipped" ?
Edit: I think I know what you mean, but how does it affect the turbine? Shouldn´t it be abe to flow more gases with the clipped wheel?
I´m planning to inject the diesel with a variflo nozzle, but since I dont have a flowchart and no experience, I´m wondering how much fuel the turbine will take, I would suspect somethig around 16-18 gph (around 1,1L/min), is this an ok estimate? Or should I try to get a, lets say 20gph nozzle and not use the full potential of the nozzle?
Also, I read that a lot of you guys start on propane, I did not find a post/thread where someone started the turbine with diesel/kerosene, is it that hard to get running? Or did I not look hard enough?
One more thing, when calculating your flametube with jetspecs, it throws out a max rpm of 77000rpm, which is around 440m/s on the turbine wheel.
I know that automotive turbocharger with normal cast aluminium can run sustained at around 520-550m/s (520m/s would be 85000 rpm for me) so is the 77000 rpm just a "super safe" estimate or is there a different reason for that?
Thanks in advance for letting me learn something!
Last Edit: Jan 31, 2020 14:04:51 GMT -5 by hans611
Yep , the clipping of the exducer will increase its flow capability , perhaps a tad too much considering your turb exducer has ~40% greater area than your comp inducer , an "idea" ratio is ~20% greater.
The potential for geater flow will mean theres a possibility your compressor wheel will run more to the choke side of the map in a less efficient region , this can increase your turbine temperatures .
Your fuel nozzle sizing will depend on your fuel pressure , but aim for ~1 lpm flow at the pressure drop you have .
Propane simply makes starting/ignition easier , whereas kero starts needs a higher energy ignition for them to be reliable ignitors.
RPM/tip speeeds are best kept modest with an old turbo of unknown heritage , the accepted "safe" tip speed is ~1450 ft/sec which for a 117mm comp is ~72,000 rpm .............with a new turbo of reputable manufacture those speeds can be increased , but a old turbo might already have passed its "cycles" limit , or had an overspeed at some time so could be weakened ...............play it safe and keep below 72,000 , often theres not a lot of extra power potential above that tip speed limit with older design turbos as the comp efficiency is falling off so any potential extra power from the higher pressure ratio is wasted by having to drive the ever more less efficient comp .