dieselguy86
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Post by dieselguy86 on Mar 2, 2019 20:36:02 GMT -5
Some turbos now have stainless or more commonly aluminum center housings, so the negative effects of running water would be reduced even more.
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dieselguy86
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Post by dieselguy86 on Feb 10, 2019 10:13:43 GMT -5
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.
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dieselguy86
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Post by dieselguy86 on Feb 9, 2019 21:33:08 GMT -5
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.
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dieselguy86
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Post by dieselguy86 on Feb 8, 2019 20:46:25 GMT -5
Hi John, My thoughts? Honestly i dont know how they do it. Most pullers are farmers that buy everything as assemblies, then just assemble it. They’ll buy a built engine from X company, Turbo comes from Y, frame from Z etc. the companys that build the turbos arent giving their secrets anytime soon. Very little is done by math, most of it is trial and error, build it, run it. I know they are getting so much power out of the turbines they are making larger quills, and keying them to keep the comp from slipping on the shaft. While im being honest, you guys are much, MUCH smarter than me! Im learning the equations, and slowly climbing the ladder of “turbo smarts”. I WISH i was at the level you guys are to be able to follow the math and understand it all alot better. Anyways, i do have some numbers for you if that helps. Good friend of mine pulls and has a data logger on his puller. I believe his charger is based off the Hx83, with a 4.5” inducer they are making 120psi at 100k rpms. I believe tit’s are around the 1,800°f mark. Ambient air temp during pulling season is usually between 75°-85°f, ~800’ elevation. I know they spray water into the comp to mostly control its speed. At 105k rpm they know it’ll only last 2-3 pulls before she lets go. I asked about airflow, and he said he doesnt have that working yet, so unfortunately its a guess. Wish i could be of more help you guys are a huge inspiration!
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dieselguy86
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Post by dieselguy86 on Feb 8, 2019 13:46:16 GMT -5
Hi Monty,
I deal alot with KTS, when they first started they use to do one-off customs. However now that they have been establish and have a large market, they no longer make one-off’s unless you order a quantity of 5 wheels, plus a $100 design fee.
My suggestion would be to find a wheel with the right exducer you need and larger inducer than you need, then go to a machine shop and have them trim the inducer/radius to your specs. Alot of places here do it, but im also in the heart of tractor-pulling country. As far as blade angles go, probably gonna be “slim-pickings”.
-Joe
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dieselguy86
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Post by dieselguy86 on Jan 31, 2019 17:56:44 GMT -5
PEEK is good for the cold side, not so great on the hotside. It works for awhile but seems to cook and seize the balls. GARRETT used phenolic in their first gen BB turbos, now they have switched to aluminum cages. PEEK would probably do ok with some air cooling, which isnt possible in a turbo application. Also i now remember the engineer saying to use the largest balls possible. Your bearing will have a bigger OD but the balls will travel slower, meaning more rpm potential. Sort of like a go cart tire vs car tire, both vehicles may be going 60mph/100kmh, but one wheel is spinning a whole lot faster than the other.
Depending on your oiling system/design, GMN and SKF are now making bearings that have oiling holes thru the outer race. You can get them in either thrust side, or non thrust side. I chose non thrust since i was already pushing the 61900 bearings to its limits, and i feared direct-oiling to the thrust side could help induce ball hydroplaning/skid. Have an o-ring on each side of the hole and kill the dampening and oiling problem in one shot.
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dieselguy86
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Post by dieselguy86 on Jan 31, 2019 16:50:08 GMT -5
When spec’ing bearings for a turbocharger project i was in direct contact with GMN engineers. They said full complement is the only option for high speed operation (190k rpms). Properly done there is very little rubbing if any once the bearings are up to speed. This is only what i was told. Cages rub the balls to. They sent me pics when i asked about the durability of ceramic. They smashed a ball into a 1” steel plate, and it dented it but the ball was unscathed. Usually the races wear out before the balls. And if you do full ceramic, they can operate up to 1000°c, but full ceramic is expensive.
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dieselguy86
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Post by dieselguy86 on Jan 30, 2019 11:47:06 GMT -5
What size are you after? I usually start with angular contact bearings, and then buy the balls i need from boca bearings. To assemble i put grease on the inner race so the balls stick to it. Press them together and wash the grease out with brake cleaner/gas/kerosene.
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dieselguy86
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Post by dieselguy86 on Dec 21, 2018 21:06:44 GMT -5
Monty,
My thought was something like a wing nut with really tall “wings” that threaded onto the shaft, with the wings being driven by the jaws. That would atleast provide some balance, and be easy to make.
Im still an amateur, and am really throughly enjoying all your pics. Studying ones experience is easier than learning it yourself. Keep the pics coming.
-Joe
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dieselguy86
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Post by dieselguy86 on Dec 20, 2018 22:39:57 GMT -5
Hi Monty,
I tried using a lathe dog when i attempted machining my shaft, and found that the weight of it was bending the shaft. Probably wouldnt have noticed with your size shaft, mine is .200”/5.08mm. I like your idea better.
-Joe
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dieselguy86
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Post by dieselguy86 on Dec 19, 2018 19:43:43 GMT -5
I emailed garrett a couple years back, and was told the shaft material is 4140 cr-mo. I tried machining a shaft for a project and had the same probs, carbide just wouldnt work. I didnt have any HSS tooling, but a nice sharp cutter was what i thought would work good. Glad to see my hunch was correct.
-Joe
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dieselguy86
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Post by dieselguy86 on Dec 9, 2018 19:34:40 GMT -5
My turbo guy here who builds tractor puller turbos, keys the wheels to the shafts.
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dieselguy86
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Post by dieselguy86 on Nov 22, 2018 17:43:45 GMT -5
Ron,
Im an amateur machinist so dont take what i say as gospel, but ive had the best luck with low spindle speed and high feed rate.
Very hard to machine after they’ve been “ran”, they seem to get hard and you have to get below the hardened layer. Once below that its workable, but none the less its a pain all over.
-Joe
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dieselguy86
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Post by dieselguy86 on Nov 20, 2018 8:33:10 GMT -5
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dieselguy86
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Post by dieselguy86 on Oct 24, 2018 20:27:52 GMT -5
John,
Just thought id point out, that turbo is a variable vane turbo. Also garrett has max rpm listed as 180,000rpms. Is there a difference in max rpms for turbo use vs turbo jet use?
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