coyoteboy
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| posted on 20/1/12 at 02:51 AM |
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If you want relatively low boost and a linear power band from low revs get yourself a SMALL compressor turbo with a relatively large turbine housing
and a BIG intercooler. IT'll spool quickly, probably just off idle with something suitably small, and it'll be right out of its efficient
envelope at high revs, probably choking the engine a bit, but through the IC you should be able to keep the heat bearable.
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gazza285
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| posted on 20/1/12 at 05:45 AM |
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Use an electric supercharger
DO NOT PUT ON KNOB OR BOLLOCKS!
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coyoteboy
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| posted on 20/1/12 at 11:32 AM |
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You might laugh, there is actually someone developing one that effectively uses a fairly large compressor housing and a powerful brushless DC motor in
the kW size range which does actually work a treat, I'll see if I can find it.
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MikeRJ
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| posted on 20/1/12 at 01:00 PM |
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quote:
Originally posted by coyoteboy
You might laugh, there is actually someone developing one that effectively uses a fairly large compressor housing and a powerful brushless DC motor in
the kW size range which does actually work a treat, I'll see if I can find it.
Only for very brief, intermittent operation though.
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coyoteboy
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| posted on 20/1/12 at 01:41 PM |
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quote:
Only for very brief, intermittent operation though.
Limited by battery capacity and alt charge rate I suppose! But when you look at a normal road-use car, the turbo use is only intermittent high
intensity or long duration low intensity.
Quick calcs: Power required (hp) to run the supercharger to boost an engine from shaft power:
hp=(0.0043*boost psi*cfm)/compressor efficiency.
i.e. you could boost a small bike engine to 1bar at 14Krpm for about 6kW, requiring 500A from your battery. Clearly this might take a bit of
re-charging 
[Edited on 20/1/12 by coyoteboy]
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hypersonic
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| posted on 20/1/12 at 07:17 PM |
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My mate fitted an eaton from a mini to an mi16 engine in his 205. Did it all himself and it made an impressive 252bhp at the wheels.
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madflow
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| posted on 25/1/12 at 04:18 PM |
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on the ppc supercharged xflow , did it ever get going--i stopped getting the mag , and it always puzzled me to see the dummy /mock build which showed
the twin side draft manifold with throttle bodies on it--how was that going to work out ?
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NeilP
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| posted on 25/1/12 at 05:54 PM |
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quote:
Originally posted by coyoteboy
Quick calcs: Power required (hp) to run the supercharger to boost an engine from shaft power:
hp=(0.0043*boost psi*cfm)/compressor efficiency.
i.e. you could boost a small bike engine to 1bar at 14Krpm for about 6kW, requiring 500A from your battery. Clearly this might take a bit of
re-charging
Separate high voltage battery system - weight penalty and a fairly sophisticated ECU / alternator setup...
Had too much sugar today 
If you pay peanuts...
Mentale, yar? Yar, mentale!
Drive it like you stole it!
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coyoteboy
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| posted on 25/1/12 at 06:33 PM |
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Personally I'd just make space for a supercharger
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AntonUK
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| posted on 25/1/12 at 07:37 PM |
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I cant see the problem with finding a properly spec'ed turbo for your engine... got to be cheaper and less hassle?
That's what i'm planning to do eventually.
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bi22le
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| posted on 5/11/13 at 07:24 PM |
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And the dream rumbles on. . . . . . .
Even more so now as its time I dont have, well and money. I am full of ideas though.
I have acquired the turbo and dismantled it. Its a big Holset so I am currently on the hunt to find the effeceincy map for it.
I am thinking I can gain about 2 or 3:1 at least via the pulley set up. I am also thinking that I can gain approx 4:1 from a home made gearbox. Thats
nocking on the door of 80,000 RPM. Well within the expected efficency range of a large turbo.
Gears will be sourced from somewhere. I can get metal gears from work which look quite strong but if not ill see whats available from gear companies
or scrap gearboxes.
Shafts I can turn up or get turn up or get turned up at work.
Bearings ill source from a bearing company, they will be oil cooled.
Casing will be made from CAD cut plates, possibly water \ laser but probablt not due to numbers req. Design will include internal bearing carriers.
These layers can be nice and intricate and then welded together. This allows for cheapish manufacture, idealistic design and and oil ins and out, or I
might seal it. so it just has a front piece.
The more I think about it the more I think I can do it.
Thoughts?
I know people have resivations on large turbo compressors being used but the high volume and cool compression from low RPM is appealing.
I also know that people ask "why bother?".
This forum is called locostBUILDERS not low costBUYERS. The fun is in the thinker and tinker not the deliver and believer.
[Edited on 5/11/13 by bi22le]
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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sky12042
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| posted on 5/11/13 at 08:24 PM |
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To get the required rotational speed for the turbo why not use a coupe of pulleys so if you need a 20:1 ratio use two 10:1 pulleys
That way it will keep the size down and allow you to mount it in a suitable position. I think it could be possible with some good bearings and strong
belts.
Agree that a turbo used as intended might be easier. But worth playing about with just so you can say that it's been done.
Andy.
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bi22le
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| posted on 5/11/13 at 08:40 PM |
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quote:
Originally posted by sky12042
To get the required rotational speed for the turbo why not use a coupe of pulleys so if you need a 20:1 ratio use two 10:1 pulleys
That way it will keep the size down and allow you to mount it in a suitable position. I think it could be possible with some good bearings and strong
belts.
Agree that a turbo used as intended might be easier. But worth playing about with just so you can say that it's been done.
Andy.
Thoughts on this peeps?!?!
[Edited on 5/11/13 by bi22le]
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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scimjim
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| posted on 5/11/13 at 09:17 PM |
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quote:
I am thinking I can gain about 2 or 3:1 at least via the pulley set up. I am also thinking that I can gain approx 4:1 from a home made
gearbox. Thats nocking on the door of 80,000 RPM. Thoughts?
The efficiency map is based on an rpm that's controlled by the shape of the turbine blades (hence variable vane are so much more efficient).
your belt driven design with large pulley and gearbox may be nearly as effective as a conventional turbo between 7 and 9,000 rpm (engine) - but just
extra weight and restriction to the airflow in every other part of the rev range?
from an engineering point of view you're losing all of the advantages of a turbo (weight, cost, simplicity) but from a "built it in my
shed" view you could be up for massive man points as long as it sticks out of the bonnet and has a loud dump valve
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owelly
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| posted on 5/11/13 at 09:17 PM |
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Take a drive off the flywheel. Big gearwheel driving a starter motor gearwheel and then step that up to whatever you need.
http://www.ppcmag.co.uk
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scudderfish
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| posted on 5/11/13 at 09:53 PM |
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quote:
Originally posted by sky12042
To get the required rotational speed for the turbo why not use a coupe of pulleys so if you need a 20:1 ratio use two 10:1 pulleys
That'll give you 100:1! Two 4.5:1 will give 20.25:1
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sky12042
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| posted on 5/11/13 at 10:29 PM |
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Scudderfish your right didn't quite think it through correctly, but you get what I mean two smaller belts will give you a more compact belt
driven install.
Andy.
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mark chandler
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| posted on 5/11/13 at 11:34 PM |
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You need to consider the power involved in spinning it up, my db7 has a 10 rib wide belt on a 3" pulley, it must be able to absorb maybe 40bhp
without overheating.
Getting the speed in theory is fine, actually translating this into reality is another thing, at the speeds mentioned you really need a mechanical
solution on the final drive.
Cog off the flywheel sounds good, I bet the gears will howl when running!
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scudderfish
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| posted on 6/11/13 at 07:18 AM |
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What is the effective ratio between the flywheel and the starter motor?
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mcerd1
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| posted on 6/11/13 at 09:41 AM |
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quote:
Originally posted by scudderfish
What is the effective ratio between the flywheel and the starter motor?
count the teeth on each.....
I don't think most starters will have less than 13 teeth, but I've no idea what the average ring gear has...
[Edited on 6/11/2013 by mcerd1]
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mcerd1
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| posted on 6/11/13 at 09:52 AM |
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quote:
Originally posted by bi22leI also know that people ask "why bother?"
I'd guess your going to have more than a few issues with the ratio's, cooling, lubrication and the strength of any gears/gearbox etc...
but it sounds like a good project to keep yourself amused with and it'll be really satisfying when it works
and if you ever change your mind there are ways to make an eaton fit
(thats on an RV8, so no space at all in the engine bay )
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MikeRJ
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| posted on 6/11/13 at 10:57 AM |
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quote:
Originally posted by scudderfish
What is the effective ratio between the flywheel and the starter motor?
A Ford Crossflow, for example, has 135 teeth on the ring gear, and 9 on the starter, so a 15:1 ratio. It wouldn't be useable to power anything
continuously though since the teeth aren't lubricated, so would wear away to nothing in short order.
I suspect some kind of geared final drive would be needed though, probably an epicyclic gearbox which would minimise any radial forces on the
compressor shaft bearings.
[Edited on 6/11/13 by MikeRJ]
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sky12042
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| posted on 19/11/13 at 11:22 PM |
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Found this on the net. Thought it might help with any ideas or problems you might come across, Andy
http://www.cachassisworks.com/Attachments/DataSheets/CDS_DS_WEB.pdf
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flak monkey
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| posted on 24/11/13 at 08:03 PM |
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quote:
Originally posted by bi22le
Thoughts on this peeps?!?!
Dont bother 
High shaft speeds needed for the turbine need very precise manufacturing tolerances for alignments and bearing housings.
Belt drives have belt speed limits be sure to check them too as a lot of belts aren't capable of running anywhere near the speeds you are
thinking about. Also remember they will be carrying huge loads at those speeds to make 10psi of boost.
There's good reason people don't do this sort of thing. Procharger do make gear driven chargers, there's some tech on their site.
Even they only run an internal ratio of 4.1:1 You are into specialist gears at those speeds too.
http://www.procharger.com/supercharger-cutaway.shtml
They do higher ratio ones for big boost (20-50psi).
Post up a video the first time you run it up....
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stevio73
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| posted on 24/11/13 at 10:13 PM |
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Seems like a whole bunch of hassle that will effect reliability IF it works. Don't get me wrong, I love a challenge. If your going to all the
trouble of machining mounts, bearing housings and stuff like that, why not scratch build a rootes type blower?
Ultimatly what size are we talking? Sounds like you need someone who can cast aluminium. (Nudge, nudge)
Quick as a flash...... Nothing happens!
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