Discussion
Take the WRC for instance they limit capacity and restrict air intake. The race teams tune their cars to produce lots of torque as max power is not what they are after. Remember the pugs with only 4 speeds worked very well.
So why not run a top flight team using a diesel? It can make the same power give the money they spend plus it's only 275-300hp so a 2ltr would do it but the torque that unit would put out would be notable higher than the petrol. And they want low end torque??
Basically why isn't diesel a popular choice for rallying?
To me if within budget they can get the diesel to produce the same power but loads more torque and the delivery of the torque low down which is how they seem to be tuning their petrol cars - due to the restriction on max power. Seems a no brainer better torque and slightly less fuel over the stage.
Sensible responses please. The question arose watching Dakar with those carzy lorries drifting
So why not run a top flight team using a diesel? It can make the same power give the money they spend plus it's only 275-300hp so a 2ltr would do it but the torque that unit would put out would be notable higher than the petrol. And they want low end torque??
Basically why isn't diesel a popular choice for rallying?
To me if within budget they can get the diesel to produce the same power but loads more torque and the delivery of the torque low down which is how they seem to be tuning their petrol cars - due to the restriction on max power. Seems a no brainer better torque and slightly less fuel over the stage.
Sensible responses please. The question arose watching Dakar with those carzy lorries drifting
As far as i remember from when a mate of mine was in discussion with skoda about running a fabia vrs, for him to run it in the 2 litre class there was a problem calculating the equivalency ratios. basically you multiply the engine capacity by (i think) 0.7 because it is diesel and then by 1.4 because it has a turbo and it would have been just over the 2litre limit forcing him to run in with the 4wd boys.
As far as the wrc goes they already get 5-600lbft of torque and more revs from the petrol engine with a more progressive power delivery which makes it easier to drive, with the diesel everything would happen all at once over about 1500rpm and it would have been a b
h to drive
As far as the wrc goes they already get 5-600lbft of torque and more revs from the petrol engine with a more progressive power delivery which makes it easier to drive, with the diesel everything would happen all at once over about 1500rpm and it would have been a b
h to driveThere have been plenty (ok, plenty is an exageration!) of clubman and semi-pro diesel rally cars, especially when the initial rules allowed them to run with a larger diameter inlet restrictor than the gasoline engined cars!
For several years VW campaigned a series of Golf Tdi cars that did very well indeed.
At top level (WRC) the rules are not nearly so favourable and do not really suit compression ignition engines (remember wrc cars make about 340bhp, and thats actually quite hard to do at only 4500rpm) The gasoline wrc cars easily put out 650+Nm at approx 1000rpm with antilag enabled so diesel is no advantage there!
For several years VW campaigned a series of Golf Tdi cars that did very well indeed.
At top level (WRC) the rules are not nearly so favourable and do not really suit compression ignition engines (remember wrc cars make about 340bhp, and thats actually quite hard to do at only 4500rpm) The gasoline wrc cars easily put out 650+Nm at approx 1000rpm with antilag enabled so diesel is no advantage there!
Edited by anonymous-user on Wednesday 5th January 22:44
Welshbeef said:
Remember the pugs with only 4 speeds worked very well.
They didn't, actually. The gearbox being their main problem.Wikipedia says:
The Peugeot 307 WRC, a World Rally Car based on the 307 CC, replaced the multiple manufacturers' and drivers' championship-winning 206 WRC in the World Rally Championship for the 2004 season. The vehicle, nicknamed "The Flying Frog" and "The Whale", was plagued by transmission problems and only began to come into its element in competition towards the end of its factory-supported participation in the WRC.
I think they switched to a 5-speeder in the end too.
There was a Golf TDi racing in the F2 series, and it did quite well if you forget that it was racing against NA 1.6 petrol powered cars.
http://homepage.virgin.net/shalco.com/golf_tdi.htm
EDLT said:
vrooom said:
noone want to drive a diesel rally car.
They will if it gives them a massive advantage over the competition *cough* Le Mans *cough*In rallying the same advantage would not exist (unless we are talking about the Dakar rally). The main downside for the diesels being that the petrols make as much torque, and have a linear and instant power delivery, and rev freely, making it easier to drive the cars smoothly.
Also, who wants to listen to a diesel engine with all those lovely petrol rally noises?
XitUp said:
Useable power band.
Thats the key issue IMO - there is a diesel Skoda rallying down here, but it struggles a bit because the power band is so narrow - it'll bog down on corner exit, lag lag then boost followed by a brief flurry of wheelspin before it bogs down again with the next gearshift.For noise I agree the spectators prefer petrol but drivers petrol race cars are very loyd and transmission I guess to them whatever is best for the job will do.
Would not a twin turbo setup eliminate the lag and pesky peakky delivery ie 123d style?
500-600nm at 1,500rpm wow and 350hp that would be a lovely drive how come the road going versions have a much narrower powerband?
Putstops on circuits really harm average speed so yep that's a big plus for diesel it takes a huge amount more speed to counter stopping.
With my commute it's a and m ways I get to the speed limit and it's hard to get any faster yet my average speed seems to range 30-35mph due to the stop start nature of congestion driving
Would not a twin turbo setup eliminate the lag and pesky peakky delivery ie 123d style?
500-600nm at 1,500rpm wow and 350hp that would be a lovely drive how come the road going versions have a much narrower powerband?
Putstops on circuits really harm average speed so yep that's a big plus for diesel it takes a huge amount more speed to counter stopping.
With my commute it's a and m ways I get to the speed limit and it's hard to get any faster yet my average speed seems to range 30-35mph due to the stop start nature of congestion driving
XitUp said:
They run out of puff at 5k.
Pit stops would favour hybrids much more than diesel, the reason they do better in LM is cos they are allowed 1.5(is that right?) litres more than the turbo petrol cars and a larger intake restrictor.
This goes for the LMP1-class.Pit stops would favour hybrids much more than diesel, the reason they do better in LM is cos they are allowed 1.5(is that right?) litres more than the turbo petrol cars and a larger intake restrictor.
Petrol engines can have a displacement upto 6000 cc in N/A trim.
For force induction engines petrol engines have a maximum of 4000 cc and for diesels 5000 cc.
vrooom said:
noone want to drive a diesel rally car.
I have competed (once) in a diesel rally car and it was useless (205 clubman rally car fitted with a 1,9 turbo diesel from a newer model citroen with the boost turned up.)First problem - massive weight at the front, nose heavy.
Next problem - noise, well the lack of engine noise.
You have no sounds to go on for gearchanges, with the sound of the stones hitting the floor of the car and no engine noise its a wierd sensation, made worse by having only a very narrow power band.
Made even worse by the rev counter not working on the car I was driving.
It turned out to be slow, heavy and it sounded like a tractor.
That was just my own experience of diesel rally cars. But as a spectator the last thing I want is some oil burner coming through the stage, with no engine noise to add to the show, just a cloud of black oil smoke after its gone - where's the fun in that? I want to see high revving cars that look fast AND sound fast - sounds like a BDA or a 6R4 or S2000, not some rep mobile giving good MPG.
Tell me which you would prefer to a) Drive, b) listen to?
http://www.youtube.com/watch?v=RyG7nesJo9E&fea...
v
http://www.youtube.com/watch?v=oFsEwVMItpk&fea...
If you answer the Golf you can be declared emotionally dead inside.
http://www.youtube.com/watch?v=RyG7nesJo9E&fea...
v
http://www.youtube.com/watch?v=oFsEwVMItpk&fea...
If you answer the Golf you can be declared emotionally dead inside.
Welshbeef said:
Take the WRC for instance they limit capacity and restrict air intake. The race teams tune their cars to produce lots of torque as max power is not what they are after.
I think this is down to regulations. They are all limited to something like 300bhp IIRC.To get "round" this, they tune the cars to produce close to 300bhp throughout the usable/driven rev range. I guess they wind down the boost at higher revs to stop the bhp going "over".
Welshbeef said:
500-600nm at 1,500rpm wow and 350hp that would be a lovely drive how come the road going versions have a much narrower powerband?
What/where do those figures come from? I'd be surprised if they're from a 2L engine! In overall performance 600nm @ 1500rpm isn't going to compete with 600nm @ 4000rpm from a (previous regs) WRC car though.It's just regulations.
At Le Mans the diesels are quicker because you're allowed a 5.5l Turbo, rather than a 4.0l Turbo or a 6.0l NA if it's a petrol.
In theory the idea of having both diesel and petrol fuels in motor sport is quite a good one, you get different styles of power delivery meaning that different cars are quicker in different areas. in practice they never get the equivalentcy right and as a result half the competitors end up wasting the season
At Le Mans the diesels are quicker because you're allowed a 5.5l Turbo, rather than a 4.0l Turbo or a 6.0l NA if it's a petrol.
In theory the idea of having both diesel and petrol fuels in motor sport is quite a good one, you get different styles of power delivery meaning that different cars are quicker in different areas. in practice they never get the equivalentcy right and as a result half the competitors end up wasting the season
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