The One Man Turbofan

[CH3NO2]

Feb 8, 2019 10:04:50 GMT -5 monty said:

....

It would be nice if we could all post the inducer tip angles of the wheels we have in our possession and start a database!

....

Monty

Here's one for the data base.
85mm GTX5533R

[racket]

Hi Joe

Thanks , thats very helpful , every bit counts :-)

120 psi boost is >9:1 PR and probably needing ~250 hp/lb/sec , so possibly anything between 900-1,000 hp for the comp , but at 100,000 rpm that only represents ~50 ft lbs of torque on the quill

T I Ts are similar to ours so turb calcs can be similar

Thanks again

Cheers
John

[racket]

Hi Joe

Further to the above ..................I'm curious how they can extract that sort of power , the rpm are say 50% higher than "normal" , this will help with the blade speed part of the HP calcs , but the gas deflection part is still limited by choked sonic velocities which won't be any different to what we see , unless they've modified the scroll housing to produce supersonic gas velocities at the turb inducer , the turb exducer , if using normal wheels won't have any increase .

I've checked out Columbus Diesel Site columbusdieselsupply.com/images/prostockturbos.pdf and it looks like they're using 4.4" turb wheels , thats probably the standard 111.7 mm exducer , with scrolls of 32 or 36 somethings , probably square centimeters for the throat.

Even if they use small scroll throats with lotsa "backpressure" to get a low tangential angle for the gases , theres a limit to that as the gases still have to enter the wheel with some radial velocity .

LOL, I'd really like to know how they do it :-)

Cheers
John

[racket]

Hi Tony

Now thats a high flowing wheel , ~35 degree inducer, a ~2.6 : 1 in/out ratio and a low 41 Trim , gotta be good at very high PRs as well

Cheers
John

[CH3NO2]

Hi John,

Yeah, Garrett did some amazing work on the 5533R turbos. This is the map for it. Fantastic for a 85mm inducer.




And yes, I was wondering about the tractor pullers too. For pressures and flows that high, it seems like it would be better to use multiple turbos in a series/parallel configuration.

[turboron]

All, my understanding is that tractor pullers can have up to three turbochargers in series in some classes. However, some classes are limited to one turbocharger. The info is out there in some rule book I would think.

Thanks, Ron

[dieselguy86]

Hi John, Tony,

Yea i dont think they really use math, mostly all trial and error, if it works/holds together, they run it. At one point they limited the wheel to x.x”, so they started with a big turbo, machined the entire inducer shroud/map groove out. Then made a shroud with an i.d. To meet the x.x” rule with a reeeeally wide map groove and welded onto the housing. They would machine a step into the inducer of the wheel to the same limit, but after the step it would be the normal size. So technically the wheels inducer met the rule, but after the shroud the wheel was normal, so they were pulling air through the map groove as well to make up for the small inducer. Guess thats the definition of “bending the rules” lol. I would think/assume there is lots of wastegating being used, probably alot of clipping also. Theres alot you cant see, and even more they dont tell you lol.

Tony, they have all sorts of different classes all with their own rules. The most common class, pro-stock, is only allowed to run one charger. The super-stock are allowed to run up to 4 chargers of any size. Its not uncommon to see 300+psi of boost pressure, with no intercooling allowed (with 4 turbos there isnt enough room anyways). They’ve actually found out that if they extremely over-fuel, it decreases egts. Water injection is allowed, and they actually consume more water than fuel while going down the track. How anything holds together i have no clue. You cant even compete in the lower pro-stock class if you arent 2,500hp or above. And i think the super-stock’s are around 5-6,000hp.

[CH3NO2]

300+ PSI is insane.

They sure do detonate real nice. Whole blocks shattered with shrapnel, pistons and crank pieces flying in every direction. I dont know how the drivers have the balls to do it. They're sitting just feet away from a clay-more mine exploding.

[azwood]

It’s crazy how they get so much boost I’ve noticed there’s a lot of compound turbos for diesels out there.the pressures they run must be way off the compressor map of most turbos

[dieselguy86]

The theory with compounds is that instead of 1 turbo doing all the work, the “load” is split between 2 chargers. Properly done both turbos are running in their sweet spot. Its pretty hard to make 100psi of boost with a single turbo but if you split it up with 2 chargers: 100+14.7/14.7= 7.8pr. The square root of 7.8= 2.8pr. So now each turbo only has to do 2.8pr, much easier to do than one trying to hit 7.8. The reason why they’ll use 4 chargers, is because lets say they need 300lbs/min of air, there isnt a turbo big enough to move that much. So theyll run 2 or 3 moving 100-150lbs/min each and blow into another large turbo. 300psi is 21.4pr, but between 2 stages each turbo can run at 4.6pr and be able to move 300lbs/min at 300psi. The problem then becomes spooling up all those turbos, and if the engine bogs just a little bit while going down the track, there isnt enough energy to keep them all “on boost” and the engine falls flat on its face.

[monty]

After a lot of calculating and head scratching, I ordered a new compressor. I also ordered a spare turbine. The price from Andy's supplier is just too good, and I wanted to have a spare. Now I have to wait until the compressor arrives so I can measure the inlet angles and the throat area. Then I can proceed with the design of the diffuser. Fingers crossed!!!

I did make some concrete progress this past week. I drilled and reamed the planet gears for the brass bushing to be pressed in.

I used a collet to hold the hub, and was able to get all of these gears to less than two tenths run-out before I drilled and reamed them. Then I put them in the chuck and removed the hub. Once again, the run-out was non existent. This went better than expected. I was mentally prepared to mount the 4 jaw, use shims etc. Thankfully, none of that was necessary.

The ring gears showed up, and look really good. Next week I'll harden the gears and start working on the lapping fixture.

[racket]

Hi Monty

Gears look great :-)

LOL......You'll find making the rest of the engine much easier

Cheers
John

[monty]

I tried to harden one of the planet gears today. Unfortunately I was only able to get about 40ish RC hardness. I tried to upload some pics, but keep getting a 502 bad gateway error.... Don't know what that's about. I'll try again tomorrow.

Looks like I need some faster quench oil. I'm afraid to try water due to stress fracturing. Going to order some new quenchant....

Monty

[monty]

Pics working now...

Heating the gear:

Quench:

Test:

Regroup...

[monty]

My new compressor arrived from the UK....I still don't know how it is possible that it gets here so fast for only $25 shipping...I just sent a certified letter to Canada and it cost that much!

Here is a pic of the ideal inlet angle at max SL flow superimposed on the inducer. The inducer is still a bit too steep, maybe a degree or so. I may need to revise it depending on high altitude performance. Right now it should do the job:

This weekend the weather is going to be terrible so I'll measure the throat area and work on the diffuser/ngv.