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MG TD TF 1500 - supercharging and turbocharging

For some reason I got caught up on reading about the difference between supercharging and turbocharging. I know nothing about it, but from what I've read, there is a long history of supercharging TD's - but nothing about turbocharging them. Has anybody done this? From what I understand, the difference is turbocharging takes its power from waste gases, not directly from the engine. This has some advantages, but also disadvantages including more heat.
Then there's a third variety : electric turbocharging, where battery power is used to drive a fan to compress intake.
I'm curious to hear what others may have found researching this; has anybody actually turbocharged or electrically turbocharged a MGTD?
Geoffrey M Baker

Not knowing what your looking for in use, turbo chargers have a lag period coming on line compared to direct drive superchargers. The turbos on my tractors work very well, they just require running the engines at idle for 30 seconds before shut down, which cools them a bit and gives the turbo vanes a chance to slow down, as once the engine is shut down no oil is going to the hot bearings. PJ
Paul S Jennings

I can't imagine an electric fan doing anything of value. There is a trade off for the other two variaty. With the super charger you have parisitic drag..in other words it take horsepower to turn the unit that would otherwise be going to the rear wheels. The turbo on the other hand take the already wasted energy of the exhaust flow and uses it to spin a compresser vane. The vane gets up to around 100000 rpm at max out put. So it takes a little time to get it to build up pressure. The supercharger on the other hand builds pressure at engine rpms and thus the boost is available must quicker.

The compression of air in either case will generate heat and in addition the mechanical bits of a turbo will create their own heat...which is why the those rapidly spining bearings are usually fed with an oil supply and the advice to allow the engine to idle several minutes before shutting it down. For an electric fan to do any good it would require an alternator with a huge capacity which would be as much of a drain as a supercharger.

If you are talking about the "electric turbo's" as fleeced on feebay... they would be about as effective as farting in the general direction of the carb....with my apologies to the cast and crew of The Holy Grail.
MG LaVerne

There's that long history of MGs and superchargers, older than most of us geezers. A match made in heaven. There were no automotive turbos back in the good-old-days.

The roots type & vane superchargers we relate to, are a "fixed displacement" air compressor driven off the crank, so it goes up to a predictable boost/horsepower, and no more, which is fairly conservative for good reasons. Boost must be limited in these blowers because of the heat from compression (turbo aren't ). Add-on performance parts, like cams and headers, will promote exta power, too, but seldom will street driven XPAG engines exceed 100hp. (Yeah, the factory was pumping 200+ hp in full race on 72 octane "petroleum distilate"!).

Turbochargers are driven by exhaust gas, and can go crazy high in boost, since they don't have the heat limitation of the our style of superchargers. The more high performance parts, the more exhaust, the more boost, and more boost makes more exhaust,.... you get the idea. Take a little Jap car, throw on a cheap turbo & cam kit off of ebay and the sky's the limit.

There are some examples of mechanically drive turbine superchargers, but none for our MGs. The electric superchargers on ebay are a sad joke just to take some sucker's money.
JRN JIM

Geoffrey - it would be an expensive effort to design and cast a new exhaust manifold and machine it to accept a turbo in the exhaust flow. Not at all worth it. A supercharger has immediate response, and has proven to give a solid 45% increase of HP at the wheels. My blower required no service for 100,000 miles, which is more than most T-series cars will run in this century. Not all, but most - and some of those cars driven hard and long already use my blower (cf. LaVerne)!

Tom Lange
MGT Repair
t lange

Don't sluff-off the electric supercharger. They have a specific use.

Despite significant improvement in turbocharger spool-up times and manifold pressure increase, it still takes a few moments to get any significant pressure into a manifold with a turbo; enter the electric supercharger.

An electric supercharger can be at full speed in less than a second meaning the manifold is fully pressurized in less than a second too.

Once exhaust pressure has spooled-up, the turbo comes on and the electric supercharger disconnects.

Audi is using this technology on their TD5RS, a V8 monster that can get to 60 in less than 4 seconds using an electric supercharger and 2 turbos!

Gord Clark
Rockburn,Qué.

Gordon A Clark

Gorden, Your saying that the electric supercharger is used merely in the system to spool up the turbos for more instantaneous boost and then shuts down, correct? I can understand that. That's not what the ones on ebay are being presented as. Not in so many words, their being presented as a regular "electric" supercharger. Not good! PJ
Paul S Jennings

This thread was discussed between 05/06/2014 and 06/06/2014

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