j999dpt Posted September 30, 2009 Share Posted September 30, 2009 the eaton m45 looks a good size on the eaton site it says good for 2-3L, suppose then its just a case of getting the pulley ratios right. sounds like a plan for off roading , ie quick bursts of power. BEng Sweet FA Quote Link to comment Share on other sites More sharing options...
Aragorn Posted September 30, 2009 Share Posted September 30, 2009 I really dont see the point of both. If we compare the figures posted for that 3.7L Volvo marinised diesel, 600nm between 1500 and 3000rpm with some normal car engines its not actually that special: Audi 3.0 V6 TDI - 500nm @ 1,750 rpm, 450nm between 1,400-3,250 rpm Audi 4.2 V8 TDI - 760nm (561 ft·lbf) @ 1,800-2,500 rpm (elec limited in A8 650nm @ 1,600-3,500 rpm) BMW N57D30OL - 520 Nm @ 1750-3000 All those car motors are running normal VGT turbos, with the BMW and smaller audi lump running one single blower, and the V8 running a pair. Ok the headline figures in the 6 cyl motors are lower, but they're smaller capacity, and the V8 has a slightly higher capacity, but produces its torque over a wider range of operation. You REALLY dont need power any lower than 1500rpm, you should not be down there, change down a gear and let the engine do its job. Quote Link to comment Share on other sites More sharing options...
flatback90 Posted September 30, 2009 Author Share Posted September 30, 2009 Flatbed, If you are going to the Three Peaks, look me up and we can chat, I will be in the "Dirty Buckers and Belgian Bennys" team, Will get there on Friday evening. Staying at the Hi-B. Is this your first time at the TP's? oh yeah i'm a virgin all right!!! not in the hi-b tho it was booked up, i'll find you though. this discussion is starting to degenerate into "i'm more qualified than you" thing so i will get the mods to keep an eye on it so we dont get upset with each other. its definately going to be something that i will look at in the near future but its going to be a 300tdi (coz i have one) Quote Link to comment Share on other sites More sharing options...
Happyoldgit Posted September 30, 2009 Share Posted September 30, 2009 <snip> ... this discussion is starting to degenerate into "i'm more qualified than you" thing so i will get the mods to keep an eye on it so we dont get upset with each other. <snip> We've been watching it from the off Quote Link to comment Share on other sites More sharing options...
Lara Posted September 30, 2009 Share Posted September 30, 2009 I think it has calmed down really, don't think anyone meant anything by it but it is one of those subjects that gets you quite hyper as there is so much to think about when you start comparing advantages / disadvantages etc, and to be honest it is fairly un-answerable as a lot of the time it is just down to personal preferences. I think a little banter is quite expected on this type of subject! Aragorn is quite right though that you only need to look above 1500 rpm, and there have been some extremely good points brought up! Look forward to seeing you at the bar! Mine is a Cola You will love this event!!! Lara Quote Link to comment Share on other sites More sharing options...
flatback90 Posted September 30, 2009 Author Share Posted September 30, 2009 cola with what?? dont realy want to go down the vgt route as its been done a few times as has propane. does anyone know of any supercharged diesels in mass production i THINK mazda did one but could be wrong.. anyhoo of to google we go... Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted September 30, 2009 Share Posted September 30, 2009 I've a Masters Honours degree in Automotive Engineering, and it taught me nothing which contributed to me VGTing my 300Tdi. After doing it, with the experience I've got now, I'd have a go at supercharging if I started again but probably more for interest's sake than for real performance. Bish - pressure waves + girders = Tacoma Narrows. You boys need us. Quote Link to comment Share on other sites More sharing options...
Lara Posted October 1, 2009 Share Posted October 1, 2009 Actually loads of diesel engines are supercharged but mostly the 2 stroke type used in stationary engines etc, when I did my engineering apprenticeship, the firm I was contracted to, specialized in pumps of all types you could imagine, some of these were driven by Diesel engines of varying size from 8Cyl 8litre Cummins upward, some of the smaller V8 2 strokes had Superchargers between the banks and a single turbo blowing into that. I think they were rated for our application at 300bhp but can't remember too much about them except they were F-in Heavy! The GMC Type superchargers that you see on all the dragsters in the states were derived from a line of Diesel Supercharged 2 Stroke engines produced by GMC, (I think still do?) these were rated and cataloged as 471 671 871 etc and referred to cylinder displacement X cylinder number, hence the popular 6-71 blower name came from the 6 cylinder 71ci/cyl GMC Diesel engine. Keep us informed! sounds like an interesting project, whatever the outcome, it will be a big experience! Lara. P.S. Cola and Ice then Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted October 1, 2009 Share Posted October 1, 2009 <snip> The GMC Type superchargers that you see on all the dragsters in the states were derived from a line of Diesel Supercharged 2 Stroke engines produced by GMC, (I think still do?) these were rated and cataloged as 471 671 871 etc and referred to cylinder displacement X cylinder number, hence the popular 6-71 blower name came from the 6 cylinder 71ci/cyl GMC Diesel engine. </snip> Detroit Diesels aka GM diesel still produce supercharged / turbocharged engines for marine use. It has been my misfortune to work with the whizz bangy things for 13 years. In this installation, the superchargers were mounted in the vee, with a charge air cooler on top. Two turbos blow in to each charge air cooler, and then the supercharger. These engines were totally mechanical. Each cylinder has its own combined fuel pump/injector driven from the camshaft, so no fancy control for the boost, but they ran at constant speed. Now thinking outside the box, but if the diaphragm air supply is still taken from the inlet manifold, this should take care of the fueling as the boost rises. With the correct gearing, you should be able to achieve positive boost from 1200 rpm, but I agree that you really want to stay above 1500, if only for lubrication issues on the bottom ends. You might need some sort of relief valve on the inlet manifold to limit boost to something close to the original setting in the first instance while you fiddle with the fueling. Sounds an interesting project. Quote Link to comment Share on other sites More sharing options...
nicks90 Posted October 1, 2009 Share Posted October 1, 2009 doesnt the maddison lot use a supercharger on their diesel challenge motor? OK, they killed it in the Oz outback challenge, but they obviously have some knowledge and experience in this area. If you're really interested in doing it, maybe worth speaking to them for advise. as for fuelling, calm me simple if you want - but whats the big issue? The standard tdi fuelling is increased according to boost pressure acting on a diaphram in the I/P. So as long as the supercharger delivers approximately the same boost and you can get a feed off that boost onto that diaphram, then it'll fuel the same? Boost delivered at lower revs - so what? Still getting boost which will still act on the diaphram, just earlier...... Quote Link to comment Share on other sites More sharing options...
Guest otchie1 Posted October 2, 2009 Share Posted October 2, 2009 McInnes quote you added says very clearly that in his opinion if the exhaust outlet pressure at the valve is twice that of the manifold, then exhaust back-pressure has very little effect, quite possibly true! but think for how long this "Critical pressure" goes on for. Experience experiment. Many years ago, I was doing development of a 1.4 litre 8 valve turbo engine, this engine was production based NA engine, Turboed and modified by me, and was giving 296bhp @ 6800 rpm, @ 2.2bar boost. I made a fixture out of a Yamaha FZ750 engine and transmission brake to power a separate turbo to test exactly what we are discussing. When hooked up (and this was no mean feat I can tell you) to run next to, and boost the other engine on the dyno we got 316bhp at the same revs with 2bar boost as this was all we could achieve from the Yam engine. Now where did that extra power come from? I think I was right in presuming it was mostly due to back-pressure and driving the Turbo! You won't read that in a book though. So your point here is (ignoring the 10% boost deviation) that an 8 valve 1.4l engine giving 296bhp@6800rpm could, if you took away all that horrible exhaust restriction caused by the turbo, generate a massive extra 20bhp. Only it wouldn't have 296bhp as it wouldn't have the turbo unless you have a spare 750cc high speed engine to act as a turbo in it's place. 20bhp vs the entire output of a separate engine...hmmmmm. The point being that although the turbo itself can get in the way its benefits far outweigh its cost - hence it is free as in you get more that you lose. Technically putting fuel the tank costs power as it increase weight but you get a lot more power with it than with out You read that back-pressure tuning is good for power, Semi true, but what you are actually doing is "pressure wave tuning" and although back-pressure is one of the ingredients, it is not the trigger for power, it is an unavoidable sufferance, the pressure wave if tuned correctly will actually "Suck" at the valve area as in "Negative pressure" not back-pressure, you may also believe the advertising blurb in the "super trap" adverts, Testing shows this to be absolute bull, and they do not tune any power except all of it down!! Back-pressure on it's own is bad for power! Unless driving a Turbo or exploited in other ways. No, I didn't say back pressure was good for power. That would be a stupid thing to say. What I said was 'explain the need for exhaust pipes'. To be clearer I should have referenced 'restriction' rather than 'back-pressure' but heat-of-the-moment and all that. Clearly hammering a header pipe closed will be bad for power. Less clearly, even on a single, ripping the thing off is also bad for power (unless it's a useless design of course). I don't know what a 'super trap exhaust' is but I do know what an expansion chamber is, why it is where it is and why it features so heavily in high rpm 2-stroke exhaust design. I also know why those trick individual pipe exhaust manifolds are tuned to length for a given (usually very high) rpm. These 'pressure waves' of which you speak...they are propagating through what media exactly? Not the exhaust gas that we are desperately trying to bung out the back of the pipe by any chance? Surely a low pressure behind an exiting exhaust slug will slow it down as it goes? Pressure acting equally in all directions and all that, no? Exhaust temp is, what, 800C and up? with a pressure of 5-10 bar. Something like that IIRC but I'm sure you'll have measured it for the entire length of the exhaust tract and can correct me from your experience. And then you open the big valve to good old 1 bar and away it goes. Unless your back pressure is over 5 bar what's the problem? I'll give you a clue about the exhaust pipe thing - high rpm means less time; Boyle's Law is useful; Bernoulli was a clever fella; and inertia doesn't take promises. You only understand something truly when you have "done it your self" No other way in my experience! There are many more experienced people on here I am sure who can laugh at yours and my experience put together and P quite happily on us both, so no point into pissing in the wind! No. You've learned a given physical skill like riding a bike or bolting on an Edlebrook head after you've done it a few times. You only truly understand something when you have studied it, can predict how it will behave and explain it with reference to known phenomenaaaaa that you also understand. Study != read about in a book. Study means attempt to understand from other people's experience. Learning by experience on the other hand is slow, expensive, inefficient and frequently means re-inventing someone else's wheel. Experience on its own is great when it comes to doing it-or-something-similar again but not so much otherwise. Of course, knowledge AND experience are unbeatable, it's just that you seem to favour unqualified experience whereas I prefer education and then experience on top. In my experience professors usually are very experienced in their field. The early part of the PhD process is to catch up with everything that has gone before in, say, the field of efficient exhaust gas management, allowing the student to learn from the distilled wisdom and experience of other researchers in the field. Or should we insist they waste 3 years welding bits of pipe together so that they have 'experience'? I'm taking about engineers, not fitters (and I'm both). Aristotle thought his experience of gravity was sufficient; Galileo proved Aristotle wrong by experiment; Newton was able to make predictions with his new understanding but it wasn't until Einstein came along that it all fitted together. Einstein is the odd one out as he didn't do any experiments at all and had absolutely no experience. He was also right - well, so far. Lastly, and I mean that as I'm bored now and haven't dabbled in engine design theory for a couple of decades or so, your design of a blower looks a lot like a copy of someone else's design of a blower adapted to fit a certain engine configuration. Well done for making it work and everything and I'm sure it won you a lot of races but you could at least reference the original that you based it on. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 2, 2009 Share Posted October 2, 2009 20bhp vs the entire output of a separate engine...hmmmmm. The point being that although the turbo itself can get in the way its benefits far outweigh its cost - hence it is free as in you get more that you lose. Sorry if I am being a bit thick here, but isn't this EXACTLY the same situation as a supercharger? Something lost to drive it, but massive gains in power? Free = get something for nothing, and we all know in this world that never happens. Bowie (BEng, just not related to this ) Quote Link to comment Share on other sites More sharing options...
Lara Posted October 2, 2009 Share Posted October 2, 2009 You have so many back steps in your last post that you just overtook Usain bolt Having a very large spade, And Digging very deep holes seems to spring to mind here Lara PS. Lastly, and I mean that as I'm bored now and haven't dabbled in engine design theory for a couple of decades or so, your design of a blower looks a lot like a copy of someone else's design of a blower adapted to fit a certain engine configuration. Well done for making it work and everything and I'm sure it won you a lot of races but you could at least reference the original that you based it on. Well, you are wrong yet again! Seems to be getting a habit. Quote Link to comment Share on other sites More sharing options...
Daan Posted October 2, 2009 Share Posted October 2, 2009 it wasn't until Einstein came along that it all fitted together Is he on this forum? Sounds like the right guy to sort out our issues. Daan (realist ENG, which is an optimistic engineer with experience) Quote Link to comment Share on other sites More sharing options...
flatback90 Posted October 2, 2009 Author Share Posted October 2, 2009 play nicely boys or i'll get the mods to lock the topic. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted October 3, 2009 Share Posted October 3, 2009 Driving along today in our A4 with its slightly broken oil pump (half a bar at idle anyone?) made me think of something that would be relevant to this thread. As it stands a good VNT will have you on boost by 1500rpm, have you considered that even at 1500rpm the oil pressure in your engine is quite likely to be less than ideal for massive boost/torque? If your aim of supercharging the engine was to get the boost in earlier (which it seems to be?), then i think you might have the distinct possibility of ending up spinning some shells trying to put MegaTorque thru a crankshaft thats floating on not much more than a bar of oil pressure.... Quote Link to comment Share on other sites More sharing options...
flatback90 Posted October 3, 2009 Author Share Posted October 3, 2009 ooh hadnt considered that... will check what my oil pressure is doing at 1500rpm when i out in it tommorow Quote Link to comment Share on other sites More sharing options...
ajh Posted October 5, 2009 Share Posted October 5, 2009 Sounds like the best option would be to fit inline turbos, a very small light fast (bearing spun) primary followed by a bigger VNT/VVT unit with more mass and higher peak output. Having tuned straightpipes (up?) would drop the backpressure enough to likely make the first transparent in power loss. Also the backpressure issue is more a hold-over from 2-stroke technology where there is no exhaust valve and scavenging depends on the bounce back off the silencer (ever notice running without a silencer on one is just it done) and this is known as the Schnurl Loop Effect (I challenge everyone to use that in conversation at least once a year ) On the turbo 4-stroke diesels it has little effect and you really do not want pulse waves coming at the vanes from the wrong side anyway. In reality though if money is not unlimited just do the normal upgrades, fit a single hybrid or VNT and propane injection and you should get the best bang/buck anyway. IMHO at least, but then I have never been know for subtle sensible solutions when something radicalamd experimental and likely explosive is an option Quote Link to comment Share on other sites More sharing options...
vagrent Posted May 24, 2012 Share Posted May 24, 2012 Spotted this video and thought I'd post it, we were discussing this very item the other week on Landy Zone Quote Link to comment Share on other sites More sharing options...
cackshifter Posted May 29, 2012 Share Posted May 29, 2012 ooh hadnt considered that... will check what my oil pressure is doing at 1500rpm when i out in it tommorow Don't worry too much- the pressure that the crankshaft floats on is not the oil pressure generated by the pump. It's caused by the action of the crank. The oil pump is there to get the oil round, more pressure = greater throughput (and more power consumed and hotter oil). It needs to be 'enough' (for piston and turbo) cooling and to get to the various distant places and really not much more. Otherwise 2 strokes would seize immediately, 'cause they have no oil pressure. If you have a cooler it can be advantageous to have higher pressure to circulate it through that to keep it cooler. Quote Link to comment Share on other sites More sharing options...
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