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Eleanor, sounds like supercharging is better? Why are there so few made?
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Supercharger draws power at all speeds, supercharging by Turbo only when you need to use boost. Turbo is driven by exhaust gasses which would otherwise be largely wasted, Supercharger by power take-off from engine.
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Quite a few manufacturers have cars with superchargers these days. The components have improved and prices are dropping so we will probably see more in the near future.
Eleanor, who drives a Toyota Landcruiser with a TRD Superchager
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Eleanor,
Whatever improvements are being made to superchargers, I cannot see any way they can get around the problem of the pumping losses that turbochargers avoid.
I believe that turbos will remain in the forefront, especially with benefits like the variable vane geometry that we already have plus the possibility of 'free' electric or hydraulic power obtained off the back of the turbo (and which could be reversed to give electrical or hydraulic powering of the turbo under very low engine speed conditions).
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For absolute maximum power output superchargers are superior right now to turbo's, in drag racing for example in Top Fuel superchargers are widely used and if turbo's were superior beleive me they would be used.
Eleanor
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We agree on one thing (and one thing only) -- that superchargers are ideal for drag-racing. I was heavily involved in introducing drag racing to the UK in the early '60s, at which time top-mounted superchargers were to be found on all top fuellers, so I do know a bit about this.
As it happens, the first dragster I came across was a Chrysler-hemi monster built by Sidney Allard who was a big name behind the Shorrock supercharger. He was racing it in a sprint meeting, i.e. a single car against the stopwatch, on Debden Airfield in Essex, UK, in about 1961. I was so impressed that I joined up with others to build the Santa Pod Raceway and invite US racers over here. We held discussions with with such greats as Mickey Thompson, Don Garlits and Tommy Ivo, and hosted a lot of incredible machines and drivers.
My favourite was Ed Potter, the 'Michigan Madman', who became a regular visitor and a good friend. He raced a Royal Enfield motorcycle fitted with a fuel-injected Chevy V8 running on methanol. He would get through a rear tire every three 1/4-mile runs!
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Blimey David. Drag racing to steam trains. We'll never match your after dinner topics.
David
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Dragsters, steam locos -- they're all the same really. You can fix them both with a hammer and a spanner. :-)
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I remember the early days also, 70's when Denis Priddle, Allan Herrige, Clive Skilton etc were doing their stuff. My favourite was Peter Crane in the Stormbringer Top Fueler. Also Tom Christenson on the double Norton engine "Hogslayer" was magical to watch. So you mush have known the Phelps boys?
Eleanor
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Eleanor, yes I remember Priddle, Herridge and Skelton. You may know that Alan Herridge had a tragic early death from an accident.
I also knew the Phelps - the fibreglass kings. Can't remember their first names now, but we all worked together in building Santa Pod, five of us I think. We had a diesel-powered generator and, because I worked in engine design, I was expected to know what had gone wrong on the many times that it broke down -- but diagnosis is far removed from design and I didn't usually have a clue!
The construction team was led by John Bennett who had a business in North London specialising in American and Bubble cars! He put up the money and declared that the entrance fee for the public should be no more than 2/6d (12.5 new pence!), which it was for the first couple of race days.
John's wife Ann was very fast down the strip in their Pontiac, much faster than he was. He blamed his weight but it was more than that since she was far quicker off the line.
John paid for a new tarmac surface to be laid down after a few months and Ed Potter was the first to run down it, on his Chevy-powered Royal Enfield. It was a beautiful June day without a cloud in sight. I was on marshalling duty on the start line and, when Ed dropped the rear wheel down to take off, I was hit by masses of what seemed like bits of tarmac and the sky turned black. John came running across, most upset because he also thought the bits were from his precious new tarmac -- but they were in fact bits of rubber from Ed's rear tyre!
We couldn't get planning permission for the control tower so we built a temporary, free-standing, three-storey structure with the top storey for the commentators, etc, the second floor for the timing equipment and the bottom floor for the tons of concrete lumps that were needed to stop the tower falling over!
I was the only one on the committee who didn't want the name Santa Pod (based on the name of the nearby village of Podington). I thought it wouldn't attract the rather reserved UK public, but it seems I was wrong. I haven't been there for many years, not since the top speeds were hovering around 200 mph with elapsed times of 8 seconds or so. I think its around 300 mph and 5 seconds nowadays, isn't it? Oh, and the drivers no longer sit with the diff between their legs -- very dodgy!
David.
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David
I'd agree the turbo has some benefits, but it's not quite 'free'. The Turbo will increase exhaust back pressure, so has some downside. You never get something for nothing!
Regards
John
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John,
Yes, I did exaggerate slightly! Not only will the turbo have an affect on the exhaust back-pressure but, of course, the turbo will require pumping and cooling of the lubricating oil and this all impacts on the base engine efficiency.
By the way: Emissions legislation is easier to meet with turbocharged diesels than with naturally aspirated (i.e. non-turbo) diesels. For this reason, it is becoming increasingly likely that diesel engine manufacturers will need to drop non-turbo engines from their ranges in due course.
David.
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Hmnnnn......sorry to bring you all back to the question but there are a few small points.....
Whether you call it a turbo or a supercharger it takes power to drive and that power is thus unavailable for anything else,like a jet thrust tailpipe.This is,in fact perfectly feasible.
But none of this matters since the task they both need to perform,and both woefully fail to perform,is maintaining constant manifold pressure throughout the operating range of the engine.
If they were the pressure generators for a spray gun we would solve the problem with a simple pressure tank.Since the manifold pressures in question are derisory,and there to do little more than avoid pumping losses in the cylinders,and friction losses in the downright tortuous induction systems,then some sort of underwing plastic reservoir ought to suffice.If you couple this to a supercharger with a simple variable drive ratio then adequate pressure is easy to maintain.With turbos I see no option to a double arrangement,although if someone wanted to do some work on the variable geometry,otherwise known as variable inlet guide vanes,they might surprise me.After all,the things have only been around for half a century,but perhaps its a bit soon yet.
Someone mentioned auxiliary drives,and I have to say that the arrangement on both my XUD and HDI engines leaves me speechless,but they are all as awful.
As you say,they can be driven off the turbine,or off a jackshaft driven like a camshaft.The main thing is,no exposed drive belts and instant removeability.
It just needs someone to sit down for a few days and design it.I realise that this means that the new door trims may be delayed for perhaps as long as 10 days,we could live with that.
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