RE: Audi diesel takes chequered flag
Discussion
victormeldrew said:
PS the four stroke vs two stroke comparison is not spurious. Two strokes can produce WAY more power - and torque - than four strokes for an equivalent capacity. In the bike world the two stroke was king until emissions regulations dictated its demise, otherwise the eighties would have seen GTXR Suzukis rather than GSXRs, and KHR's instead of ZZR's.
It'll be fuel efficiency rather that emmissions, but the four stroke petrol engine will give way to the more efficient diesel in time.
That may be true, but two strokes' power delivery, despite powervalves is leagues behind four strokes in terms of flexibility. That's what dictated their demise in road riding, along with emissions concerns. The same problem of narrow powerbands and flexibility exist in diesel racing cars and IMHO that's why four stroke petrol engines still have some weapons in their armoury.
>> Edited by runnersp on Thursday 23 March 11:22
runnersp said:No, the two stroke "peaky power" is a common misconception, but a misconception nevertheless. The zenith of two strokes in the seventies peaked with the GT750 Suzuki. In the model range at the same time was the GS750 four-stroke four. The stroker was more powerful and had masses more torque and flexibility than the GS. Was Hondas Superdream torquier than a Yam RD250LC? Not on your nelly, it was gutless. What about the tiddlers? Honda SS50 vs Yam FSie or Suzuki AP50? No contest, on power or torque, the little two strokes had the four stroke beat.
PS the four stroke vs two stroke comparison is not spurious. Two strokes can produce WAY more power - and torque - than four strokes for an equivalent capacity. In the bike world the two stroke was king until emissions regulations dictated its demise, otherwise the eighties would have seen GTXR Suzukis rather than GSXRs, and KHR's instead of ZZR's.
It'll be fuel efficiency rather that emmissions, but the four stroke petrol engine will give way to the more efficient diesel in time.
That may be true, but two strokes' power delivery, despite powervalves is leagues behind four strokes in terms of flexibility. That's what dictated their demise in road riding, along with emissions concerns. The same problem of narrow powerbands and flexibility exist in diesel racing cars and IMHO that's why four stroke petrol engines still have some weapons in their armoury.
Two stroked can be ported for huge top end power and peaky delivery. I know, I had a Yam RD400 which was converted to watercooling and ported to buggery. It revved to 12,000 or more, and didn't start making power until 8,000 rpm. Power wheelies in any gear off the throttle were a cinch. This was a full race engine, pure and simple, and yet it would still pootle about at tickover, and pulled away from those revs cleanly. The huge rise in power at 8,000 made it appear gutless below that, but in reality it wasn't.
I have never accepted that a fourstroke is inherently more torquey or flexible than a two stroke, because it's simply never been true. Even with a basic piston ported stroker like the GT750, let alone with reed valves, powervalves et al.
No, the stroker demise was purely emissions led.
PS I defy anyone to twist the throttle on a YZ490 Yam crosser and then tell me two strokes don't make torque!
>> Edited by victormeldrew on Thursday 23 March 11:42
victormeldrew said:
I have never accepted that a fourstroke is inherently more torquey or flexible than a two stroke, because it's simply never been true. Even with a basic piston ported stroker like the GT750, let alone with reed valves, powervalves et al.
No, the stroker demise was purely emissions led.
PS I defy anyone to twist the throttle on a YZ490 Yam crosser and then tell me two strokes don't make torque!
>> Edited by victormeldrew on Thursday 23 March 11:42
My personal experience has led me to think otherwise. However their demise also had something to do with fuel efficiency. However with relation to the diesel Audi IMHO its narrow powerband could count against it with relation to a petrol engined car, just like IMHO strokers are less flexible.
>> Edited by runnersp on Thursday 23 March 11:51
vetteheadracer said:
I read your posting yesterday about not competing at Le Mans.....I can't believe that they won't enter.
They aren't. It's as simple as that, they have already stated, in fact stated at the end of last year when they launched the car, that Le Mans 2006 was not on the agenda.
They are going to put a year's development on the Spyder before it is available to customers. They've also already admitted that its not a reliable endurance car yet (quick, but too fragile) and Sebring proved it.
I can see diesels taking over, as they are doing on the roads in the UK. I think its a bit of a shame, though on the roads you can't blame people as petrol is so ridiculously expensive. I agree with people when they said the sound of the Le Mans racers is a huge part of the enjoyment - what else sounds like those corvettes? It's magic. To eventually have just a load of diesels racing would seem very strange. I just hope that petrol cars don't become the next concorde and take a back seat, despite being bloody fantastic.
runnersp said:My personal experience, based on actually being there in the seventies when two strokes ruled the roost, is obviously slighly different. Nice website BTW, and impressive list of bikes for someone only 21!
I have never accepted that a fourstroke is inherently more torquey or flexible than a two stroke, because it's simply never been true. Even with a basic piston ported stroker like the GT750, let alone with reed valves, powervalves et al.
No, the stroker demise was purely emissions led.
PS I defy anyone to twist the throttle on a YZ490 Yam crosser and then tell me two strokes don't make torque!
>> Edited by victormeldrew on Thursday 23 March 11:42
My personal experience has led me to think otherwise. However their demise also had something to do with fuel efficiency. However with relation to the diesel Audi IMHO its narrow powerband could count against it with relation to a petrol engined car, just like IMHO strokers are less flexible.
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