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Apr 24, 2012 22:50:43 GMT
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So I've been thinking about ripping the turbo off my tdi Disco and replacing it with a m45 supercharger fom the new 'mini'.
Problem is I have no idea about supercharges wht so ever.
Would the m45 be big enough for a 2.5 diesel, at around 17psi and 150 ish bhp?
Is there some clever Maths I can do to work out what pulleys I'd need?
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Koos
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Apr 24, 2012 22:53:39 GMT
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Think it would be long out of puff, TBH. I'm sure someone that knows these things will be along soon enough. In the meantime, perhaps look at the M60 as used on Jags and Mercs?
How about compound charging it? Whacking great turbo for high(-ish) revs, M45 to fill the gap until the turbo spools up?
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Apr 25, 2012 12:17:44 GMT
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I'm sure m45's are for 2 lt and under
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Apr 25, 2012 21:24:22 GMT
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Is that 2litre petrol and under? On a Bini they make up to 200bhp with the right pulleys.
Wouldnt that be enough airflow to make 140 ish from a slow revving oil burner?
Turbos are so much easier!
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Koos
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froggy
Posted a lot
Posts: 1,099
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Apr 25, 2012 22:33:11 GMT
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don't think the m45 will stand 17k without damage .
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Apr 25, 2012 23:25:37 GMT
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17k meaning 17psi?
So an m62 might be better?
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Koos
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The op asked for 17psi, but I think 17k is referring to rpm. The m45 tops out at about 13krpm, though I don't know how that relates to output pressure on a 2.5l diesel.
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I've got Rovers.
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Apr 26, 2012 12:43:57 GMT
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I did indeed!
With a turbo I can calculate the CFM of the engine and look at pressure maps to see which will suit.
Is there nothing like that for superchargers?
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Koos
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Apr 26, 2012 13:34:07 GMT
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Eaton names are pretty handy, the 45 from 'M45' means it displaces 45ci (about 740cc) per revolution.
With a top end of 13krpm, quick maths suggests a max flow rate of about 9.5k litres per minute, or 160 litres per second.
*this information may be inaccurate, 160 litres / sec sounds a lot!
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I've got Rovers.
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Apr 26, 2012 13:42:51 GMT
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Fairly sure there are some pressure maps out there on the internet for Eaton blowers - or there were about 5 years ago.
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Apr 26, 2012 16:01:05 GMT
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fit an M60 supercharger, along with a slightly larger turbo. Set it up to go: air filter > turbo > supercharger > chargecooler > intake Select a turbo that will flow for around 2Bar at the required cfm, and set the supercharger up for a couple of psi at idle. To make sure you don't lose ALL your mpg, setup a bypass butterfly around the supercharger (some m60's and m90's have them built-in, you just need to modify the control mechanism to do what you want) Since airflow at idle doesn't really change much, having a bit of boost at idle will REALLY make it accelerate, and have minimum smoke too. Dropping the CR a tad closer to the theoretical "ideal" 15:1 (for direct injection dervs, IDI devs are around 16:1) will also help reduce pumping losses, and gain you a tad more mpg back - along with helping the engine survive the extreme boost levels  For this setup, a chargecooler would be better, to help keep it small |
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You're like a crazy backyard genius! |
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Apr 26, 2012 19:52:25 GMT
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^^ This man speaks truth. It's exactly the setup I'm building for my tdi ibiza. Use the supercharger to get the engine generating enough exhaust gas to spool a large turbo from low down....... In a word. WINNING.
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1994 Rover Metro
1994 Peugeot 405 Estate
1991 Rover Metro Gti 16v
2001 Fiat Seicento Sporting
1999 Fiat Punto 1.2
1994 Peugeot 106 Xnd (x3)
1991 Westfield 7
2004 Landrover 110 SW
2003 Seat Ibiza 1.9Tdi Sport
1959 Ford 107e Prefect
1992 Suzuki Vitara
2008 Skoda Fabia
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Apr 26, 2012 20:04:50 GMT
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Last Edit: Apr 26, 2012 20:05:34 GMT by SamR380
I've got Rovers.
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Apr 26, 2012 23:17:24 GMT
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Wow thanks chaps!
I'm not keen on compound charging, but a blower that gives boost from just off idle would be ideal.
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Koos
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Apr 27, 2012 10:11:59 GMT
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tbh, just running a supercharger as the only means of boost, would leave you with a car that feels MUCH slower, and would be getting less mpg!
The boost rises purely with rpm, not load/fuelling, so to get boost, it HAS to be revving, meaning you're trying to drive it like a petrol... it aint gonna work how you'd like it, trust me.
the mpg will drop when cruising along, as the supercharger will still be taking large amounts of power to run - you can get away without too much of an mpg penalty on the compound setup, as the turbo will still be supplying a small amount of boost when the supercharger is bypassed
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You're like a crazy backyard genius!
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kerrly
Part of things
Posts: 266
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Apr 27, 2012 11:42:59 GMT
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Surely a smaller pulley on the charger will be suitable for a diesel application since the engine revs will not be so high but additional boost at low revs would be very advantageous.
As an example on a VW G60 charger the stock pulley is 78mm, reducing it to 68mm increases boost pressure from a stock level of 8-9PSI to nearly 14PSI and is still well within the superchargers gearing limits at full revs.
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Apr 27, 2012 12:36:19 GMT
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I get it - as I use a higher gear, the revs will drop, so will the boost/power so I'd end up using more revs to get the torque I need.
What I'm looking for is boost from idle, rather than 2500 rpm at current. Maybe I'd be better of twin turbo'ing it with the first turbo being a weeny little thing from a 1litre or something...
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Koos
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