11 replies to this topic

[mariner]

Keith Duckworth was famous in the 70's/80's for his strong opposition to the implied equivalency in the 3 litre NA and 1.5 litre turbo engine rules.

 

That was partially because the huge Renault investment in a turbo 1.5 V6 was threatening his very big DFV business but he also had an engineering objection and being Duckworth he pushed in vigorously.

 

His basic argument was that both NA and turbo were thermodynamic engines which converted heat energy into mechanical power.

 

For an NA engine all of that took place inside the measured cylinder displacement and nowhere else.

 

For a turbo engine heat is extracted from the exhaust in the external turbo to produce mechanical energy in the impeller shaft and then converted back into potential heat energy by the external compressor which is converted to the final crankshaft mechanical energy by adding fuel in the cylinders.

 

Duckworth's point was that you could only add cylinder fuel for more power as a result of the external turbo operations and unless the equivalency formula had very precise rules on the turbos design you cant have any real equivalency.

 

 

Was he right? 

 

Is there any way to write a”turbo size” rule which is as effective as a cylinder capacity or max revs rule?

 

does a restrictor rule as used so often now make his argument obselete ?

[ensign14]

Best I can say is that in preceding formulae the equivalency was a bit different.  750cc vs 2.5 litres, for instance, or 1.5 vs 4.5.  Indeed the latter formula seems to have come about because the 4.5l unsupercharged cars were nowhere against the 3l supercharged.

[gruntguru]

Duckworth was right of course. Power is restricted to the quantity of air and fuel that can be consumed in the right proportions. Adding excess of either does not increase yhe power further.

 

Under the NA formula, power was limited by volumetric efficiency and engine speed. The supercharged formula was limited only by thermal and pressure consideration (including detonation). There is essentially no limit to how much pressure and flow the turbomachinery can produce.

 

Any "turbo size" rule simply boils down to a restrictor rule. A restrictor places an absolute upper limit on airflow (Mach 1 at the smallest diameter of the restrictor). Restrictors are boring.

 

A better way would be to impose a fuel flow limit on an engine with essentially unlimited airflow. Power would the depend entirely on thermal and mechanical efficiency of the engine.

[Wuzak]

Best I can say is that in preceding formulae the equivalency was a bit different.  750cc vs 2.5 litres, for instance, or 1.5 vs 4.5.  Indeed the latter formula seems to have come about because the 4.5l unsupercharged cars were nowhere against the 3l supercharged.

 

The 1.5l/3l equivalence was because the FIA figured it would allow some of the manufacturers from the 1.5 era to compete in the new, from 1966, 3l era by simply supercharging what they had. Nobody took up the option until Renault in 1977.

[bigleagueslider]

Wasn't Duckworth pushing for a fuel restrictor to equalize performance?

[Catalina Park]

The FIA had a long history of stuffing up the turbo equivalency formula. It is probably the thing that killed Group A Touring cars.

[Nikski]

Keith Duckworth famously opposed the turbo-charging of the DFV, and made life pretty tricky for those who tried. However, John Barnard and the Parnelli team did it successfully, despite Duckworth telling them it was impossible. Their success was followed by Cosworth poaching Larry Slutter and others. It seems fair to say that the turbo-charged cosworth revolutionised IndyCar, and quite possibly contributed to its demise...

[ray b]

3 L of air would equal 1.5 L at 2 barr

 

now running at 4.5 barr would not be equal in any way

but was that what F-1 did at first

then tryed to reduce the pressure allowed in later years

 

but did they ever get to a 2 barr limit on turbo's ?

or has any other class tryed a equal air mass limit ?

[ray b]

Keith Duckworth famously opposed the turbo-charging of the DFV, and made life pretty tricky for those who tried. However, John Barnard and the Parnelli team did it successfully, despite Duckworth telling them it was impossible. Their success was followed by Cosworth poaching Larry Slutter and others. It seems fair to say that the turbo-charged cosworth revolutionised IndyCar, and quite possibly contributed to its demise...

 

indy yes but on methanol not gas

did anyone get a turbo gas DVF to work

or even try ?

[Lee Nicolle]

There is the problem. Fuel. 

They all will run on the same fuel but different fuels suit different engines far better.

The GpA Touring car fuel [at least here in Oz] was very suited to turbo engines and less usefull for n/a engines.

Avgas, is probably best for n/a engines and does not suit in particular rotaries.

Methanol probably suits forced aspiration too though it does suit very high compression n/a engines too.

Ethanol blend fuels too suit turbos though many are making good power with n/a engines too. Though economy is poor.

 

Obviously to run any engine on any of these fuels they have to be tuned and calibrated for the fuel.

[bigleagueslider]

Actually the DFX turbo Indy engine resulted in very competitive racing for many years. It was readily available to everyone at a reasonable cost and Cosworth provided excellent support and service. Each DFX engine supplied by Cosworth was dyno'd and calibrated to a produce an output within 1% of any other engine.

 

While the DFX engines ran on methanol while on the track, the fuel system had to be purged ("pickled") with gasoline to remove any methanol at the end of each day or before putting the engine in storage. Any methanol left in the fuel system would cause corrosion of magnesium engine parts.

[Greg Locock]

I suspect the answer to the following is obvious if you think about it the right way, but I'm not in the mood...

 

if you use an internal combustion engine/ turbo pair on gasoline, what is the maximum 'multiplier' you can get in terms of hp out/IC volume/rpm, assuming no mechanical connection or anything tricky between the turbo and the engine, and no fuel allowed after the engine. I imagine there are other constraints, use common sense to fill them in. We know 2 is too little, and 4 seems to be in the ball park.

Edited by Greg Locock, 26 September 2015 - 06:42.