JackNco
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| posted on 8/11/06 at 08:55 PM |
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Turbo spin speeds?
Hey does anyone out there know what kind of speed you would expect a turbo to spin at on a 2.0L engine at 7k RPM?
Just pulling over the idea posted on here a few weeks ago about using the compressor from a turbo as a Supercharger. probably not really a feasible
idea but anything beats revision!
thanx in advance
John
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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Simon
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| posted on 8/11/06 at 09:00 PM |
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Between 0 and 150,000rpm!
You'll need to gear it up slightly to use the compressor side only
ATB
Simon
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flak monkey
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| posted on 8/11/06 at 09:00 PM |
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Its possible to do. So says our ex-drag racer bloke.
You just need the cold side impeller from a decent size turbo and a bit of imagination...
David
Sera
http://www.motosera.com
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ed_crouch
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| posted on 8/11/06 at 09:03 PM |
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Yep, little tiny ones do anything up to 200kRPM, but something like a Garrett T4 probberly does 100kRPM.
You'd probably need 15:1 increase in speed to get anything sensible out of it when engine driven.
So run it of a pulley drive from the crank: that could give you 3:1 without to many problems, then youre after a 5:1 gearbox. Thats pushing it for a
single stage epicyclic, but dead easy for a 2 stage. You'd probably have to design the box yerself though!!
Ed.
[Edited on 8/11/06 by ed_crouch]
I-iii-iii-iii-ts ME!
Hurrah.
www.wings-and-wheels.net
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Ivan
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| posted on 8/11/06 at 09:12 PM |
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Anything between 30,000 and 80,000 or more RPM depending on the turbo size relative to engine capacity and boost.
You need the compressor map for your particular turbo to find out exactly what speed it spins at for what boost for your engine - can sometimes find
the maps on the internet if you have the compressor make, number and impellor size. Also gives efficiency curves that give you some idea of the amount
of charge heating that will occur and where the surge points are.
From this you can see that there are no simple answers to this. There are plenty of good books on Turbo selection available.
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Dale
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| posted on 8/11/06 at 09:49 PM |
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A t3 or t4 garret would be somewhere in the sub 100k range. I think they start having self destruck issues up past 120k.
I dont see it being able to use as a blower as the shafts are much to small to handle any pull from a belt or pully. I am using a t3 on my 2.4 l ford
but its the factory one and I would be happy to be able to run a sc on it if I could get the same power level for the $.
Dale
Thanks
Dale
my 14 and11 year old boys 22
and 19 now want to drive but have to be 25 before insurance will allow. Finally on the road
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JackNco
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| posted on 8/11/06 at 11:19 PM |
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Hey all cheers for all the responses, forgot 2 subscribe otherwise ide have replied sooner!
I was looking at the gearbox from a drill i have, or used 2 striped it all down to day.
Its got 6:1 gearing, and its all metal so no nylon gears. all the versions ive seen run off the Cam gears not the crank or separate pulley. so that
would give the turbo 168,000RPM at 7,000 Engine RPM.
ill have to do some research in to what turbo would suit me best. its still WAY off as i haven't even got my self a chassis yet but im just
playing with ideas.
Sounds like a small turbo would do the job better, maybe off a diesel?
John
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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Simon
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| posted on 9/11/06 at 12:21 AM |
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Drill sounds like a novel way to go, though I suspect it will be nowhere near strong enough. Might also overheat somewhat.
ATB
Simon
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JackNco
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| posted on 9/11/06 at 12:24 AM |
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Some one else mentioned over heating to me..... as for strength, i sheared the head on a decent sized nut before the battery died. and its all pretty
well put together. all im worried about i expansion due to heat. theres not alot of give in the thing.....
Are there any other options you can think of for a small gearbox?
John
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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JackNco
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| posted on 9/11/06 at 12:47 AM |
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maybe a gearbox from something like this ?
http://cgi.ebay.co.uk/24v-lift
-motor-and-gearbox_W0QQitemZ260049022242QQihZ016QQcategoryZ26209QQrdZ1QQcmdZViewItem
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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gazza285
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| posted on 9/11/06 at 04:24 AM |
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If you want to mechanically drive a turbo then I think you'll struggle to find a decent gearbox to cope with the speeds involved, and the
parasitic loses will be very high. More to the point, turbos work by spinning at a fairly constant rpm, controlled by the actuator to give even boost
across the rev range, by linking turbo rpm to engine rpm full boost will be achieved at the limit of engine revs. OK for a drag engine perhaps, but
the lack of boost at lower rpm when you need it, will not make the car fun to drive.
DO NOT PUT ON KNOB OR BOLLOCKS!
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JackNco
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| posted on 9/11/06 at 04:33 AM |
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as i say im just playing with ideas. i would like to go down some kind of forced induction route though.... and supper chargers are just massive to
be sticking in a 7. As for turbos the idea of boost kicking in half way round a corner puts me off them...
John
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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zetec7
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| posted on 9/11/06 at 05:10 AM |
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Regardless what kind of gearbox you use, you'll have to supply some serious lubrication to it due to the speeds involved. As you know, turbos
commonly have a direct, pressurized oil feed from the engine...and a lack of high-pressure lubrication can turn a turbo into a hand grenade in
seconds!
http://www.freewebs.com/zetec7/
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Ivan
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| posted on 9/11/06 at 07:25 AM |
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You could save yourself a shed load of trouble going the exhaust driven turbo way. I would think if you still have to build the car it is better to go
the tried and tested path than delay your build trying to develop new systems. The costs involved would also be less than breaking up a turbo to
develop a supercharger.
With a sensibly sized turbo (smallish) and sane levels of boost (not more than 8 to 10 lbs and a compression ratio of around 9.2 - 9.5) there is
absolutely no reason why lag or sudden torque ramping up should cause any power control problems in a corner.
Most lag and sudden torque increases come from too large a turbo with too much boost and too low a compression ratio all slaughtering low rev
torque.
A standard turbo is also a lot more efficient throughout the rev range than a belt driven compressor and at normal cruising speeds draws almost no
power. It's also generaly a lot quieter.
I have driven enough well engineered turbo cars to know that they can be a delight and imminently controlable. Also very economical if the boost
isn't used.
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britishtrident
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| posted on 9/11/06 at 07:39 AM |
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The problem is because of the flywheel effect of the ex-turbo compressor spinning at such high RPM any crankshaft vibration places immense loads on
the gearing used to drive the compressor..
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NS Dev
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| posted on 9/11/06 at 08:09 AM |
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quote:
Originally posted by JackNco
Hey all cheers for all the responses, forgot 2 subscribe otherwise ide have replied sooner!
I was looking at the gearbox from a drill i have, or used 2 striped it all down to day.
Its got 6:1 gearing, and its all metal so no nylon gears. all the versions ive seen run off the Cam gears not the crank or separate pulley. so that
would give the turbo 168,000RPM at 7,000 Engine RPM.
ill have to do some research in to what turbo would suit me best. its still WAY off as i haven't even got my self a chassis yet but im just
playing with ideas.
Sounds like a small turbo would do the job better, maybe off a diesel?
John
How'd you work out those rpms, cos if you drive it off the cam I make that 21,000 rpm not 168,000..............bit of a difference!!
Remember the cams run at 1/2 crank speed!!!!
You would also overload the cam drive.
Remember your gearbox will need to be capable of transmitting 20hp reliably to work well.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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froggy
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| posted on 9/11/06 at 08:26 AM |
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vortech anyone ?
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JackNco
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| posted on 9/11/06 at 08:48 AM |
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ah thats my bad then, i was working thinking a cam was 1/4th the size of the crank pulley..... and thought they would spin faster ....
So i was doing 7k*4*6=168k
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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JackNco
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| posted on 9/11/06 at 09:04 AM |
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quote:
Originally posted by froggy
vortech anyone ?
The procharge superchargers was where i got the idea
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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NS Dev
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| posted on 9/11/06 at 09:16 AM |
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I think your best bet would be to look around for an off the shelf epicyclic box that can do the trick, I'm sure one exists somewhere.
I think turbo technics use a ball variator (similar to a Kopp variator, do a google and you'll see) to drive their centrifugal blower setup.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 9/11/06 at 09:24 AM |
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Here Ya go, ave a read of this, this is Turbo Technics DIY take on exactly what you are contemplating:
Turbo technics epicyclic roller drive centrifugal blower technical details
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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JackNco
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| posted on 9/11/06 at 09:31 AM |
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oh cheers!
Looks exactly like a bigger version of what i was looking at. except this is oil cooled
But at those prices i dont think ill be contacting them
Some people are worried about the difference between right and wrong. I'm worried about the difference between wrong and fun.
O'Rourke, P.J. (1989), Holidays in hell. London (Picador)
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NS Dev
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| posted on 9/11/06 at 10:25 AM |
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yes, but remember theirs is NOT geared, those are rollers and it is friction drive. They reckoned gears would fatigue too fast and break up, as well
as making huge noise.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Donners90
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| posted on 9/11/06 at 11:29 AM |
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Turbo Speeds
Not sure if it will help, but as an example, for a fairly low power 2.2L (common rail) diesel engine, at 3500RPM, with a MAF of 355kg/hr you can
expect a turbo speed in the region of 195,000RPM depending on your altitude and the type of manoevre! The diameter and material composition of the
compressor wheel would determine your maximum working speed. As mentionned above, poor lubrication and/or overspeed could result in a somewhat
catastrophic failure leading to the ingestion of metal into the engine!! Make sure you keep within the hardware limits!
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bigbravedave
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| posted on 9/11/06 at 12:23 PM |
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TTS do a hayabusa supercharger that looks just like half a turbo geared onto the crank, sorry no link!
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