Highest Revving Road Car?

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Not with FI it doesn't. Turbos are useless past a certain RPM as they cant spin fast enough and "puff out".

True, although I was always under the impression that this was the reason Diesels never gave terribly accurate BHP figures, because they can't rev high enough? Is that right or have I been living a lie?
 
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True, although I was always under the impression that this was the reason Diesels never gave terribly accurate BHP figures, because they can't rev high enough? Is that right or have I been living a lie?

Not quite sure what you mean by giving accurate BHP figures; do you mean the manufacturers stated power is often optimistic or that it's difficult to measure the power because of the limited RPM range? If the former, then that's just down to manufacturers artistic licence (lying scumbags!), but power is no more difficult to measure simply because the engine runs out of puff at ~4500RPM.
 
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Not with FI it doesn't. Turbos are useless past a certain RPM as they cant spin fast enough and "puff out".

Thats not really true.

Turbo speed is not linked to engine rpm its governed by the gas flow against the turbine housing and wheel size.

For anything that would remain efficient at that sort of gas flow both in terms of turbvine inlet pressure and compressor adiabatic efficiency would give a very high boost threshold and not a particularly torquey low rpm range.

Its all about sizing to get what you want and no OEM really wants a turbo with a peaky power delivery. My Turbo Honda revved fine to 8400rpm.
 
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I must say my VX220 is definately perkier past 5,000 rpm but I was also under the impression that Turbo's were for midrang torque and not the upper range - the vRS was diabolical past 5,000rpm but between 2k and 5k it was immense...remap for you I suppose.

I just remember being told at an early age that Diesels will never produce high bhp figures because they can't rev as high as petrol cars, but the torque increase more than makes up for it...?!
 
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I just remember being told at an early age that Diesels will never produce high bhp figures because they can't rev as high as petrol cars, but the torque increase more than makes up for it...?!

The key thing to remember is that at any given speed power = torque * rpm

Therefore there are 2 ways to get power, either high revs or high torque. In a diesel engine the combustion event happens so slowly that the short time available for combustion to occur becomes the factor which limits engine speed. In contrast petrol burns very quickly and so engine speed is generally limited by either the volume of air which can be fed to the combustion chamber or by the mechanical limitations of the conrods/valvetrain etc.
 
Soldato
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Not with FI it doesn't. Turbos are useless past a certain RPM as they cant spin fast enough and "puff out".

So how do you explain the 12000rpm capable turbo F1 cars?

Classic Impreza STis and the R32/33/34 Skylines had turbos and 8000rpm red lines.

If you want topend power at high rpm then the turbo just needs to be sized correctly to allow this without choking.
 

Zip

Zip

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He drives a giant dump truck i think

More of a Small dump truck.

Mine is 35 ton unloaded and 70 ton loaded.

The one hes talking of would probably be around 500 ton:p

And there is no clutch pedal if its like mine. you have the gears you select but no clutch. Bloody jerky thing in my truck =/

I had a the arse slidding out with full lock of the steering in the mud the other day in it:cool:
 
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Not with FI it doesn't. Turbos are useless past a certain RPM as they cant spin fast enough and "puff out".

That depends on how well matched the turbo is to your level of tune. With the correct turbo and cams and good mapping its quite easy to have a reasonably quick spooling car that pulls all the way to the red line (7500rpm)
 
Soldato
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Not with FI it doesn't. Turbos are useless past a certain RPM as they cant spin fast enough and "puff out".

Is this a good or bad example of that?
RR.jpg

Torque drops off after 5k but it makes max power after 7k
 
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I remember when I had an RX8 for about 6 months. Weird engine (sounds like a washing machine at times) however I often got it up to around the 9'000 mark before the rev's cut and you have to change gear...

Was good fun but lack of torque a bit of a problem along with its enthusiasm for petrol as well as oil...
 
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On another note...am I seeing this right?

05-veyron-dials-det.jpg


Veyron redlines at 6.5k? I know it has 4 Turbo's but how the hell do you produce 1000 horse power without the extra 2k in revs that most performance cars squeeze out? That's where horsepower comes from?!?

NA engines need to rev high to get BHP, Turbo engines can make peak power low down if needed.

the power in a Veyron comes from its W16 + turbos. im sure if you bolted bigger turbos on which wont run out of puff, upgraded the internals to take 9k rpm you could hit more power... but why would u want to?
 
Soldato
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i know its no record for this page but i have seen a landrover t5 tdi lump hit 6500rpm.

thats what happens when turbo oil seals fail and the engine decides it likes running off engine oil.
 
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