Mondeo 2 Litre Zetec
- Thread starter wotan
- Start date
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around 3000rpm, it all depends on the length of the conrods
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Just as Davedasave wrote probably about 3000 but I think he meant the track rods
I don't think track rods would make much difference either, final drive ratio or wheel size are the deciding factors.
All sorted now, was daughters car she said it was using 4,000 revs to do 70MPH?
she was right......in fourth gear.
I drove it on a test drive, changed up to fifth gear revs 3,000 problem solved.
Wotan
http://en.wikipedia.org/wiki/Angular_velocity
i spent 4 years learning this stuff, so yes i am serious, the length of the con rod will effect the speed of an engine
edit - when i said length of con rods, i of course meant the length of the stroke which would then relate to the length of the con rods
i spent 4 years learning this stuff, so yes i am serious, the length of the con rod will effect the speed of an engine
edit - when i said length of con rods, i of course meant the length of the stroke which would then relate to the length of the con rods
and the problem was ?
surely con rod length is neither here no there ? Its either a short stroke engine or long stroke
its fine having long but not so durable as short, but short ok in a diesel tractor but not that fast in a racing car
you need a happy medium
surely con rod length is neither here no there ? Its either a short stroke engine or long stroke
its fine having long but not so durable as short, but short ok in a diesel tractor but not that fast in a racing car
you need a happy medium
a short stroke engine will be rotating quicker than a long stroke at a given speed and gear ratio, if a range rover and ford ka both have a 5th gear ratio of 0.8:1 and are both doing 70mph, the long stroke in the rover may be revving at 2500rpm while the ka with the short stroke could be revving at 3500rpm
but what was the original problem ?
I like short stroke for durability, but I like diesel
I like short stroke for durability, but I like diesel
which i said was about 3000rpm but said the length of the con rod affects it, but confused people by not mentioning the stroke
Sorry but that does not ring true, one revolution is one revolution, you could have a con rod six feet long and a crankshaft throw of only 2 inches this would then give a stroke of 4 "
Conversley if the conrod was 1 foot long and the throw was still 2 inches it would still have a stroke of 4 inches per revolution.
Final gearing and wheel size (rolling circumeference) are the deciding factors.
Wotan
trust me, it does
While I conceed that there is an optimum length for the conrod in engine design, long rods for long oversquare engines, which tend to be slow running designs.
And very short conrods for high reving engines, this is a design consideration to keep the revolving masses low, there by permitting a high reving engine.
One revolution is still one revolution, and if geared via a final drive ratio of one to one, then the rolling circumfrence of that tyre that is fitted will advance the distance of the car travelled by that amout, the length of the conrod or stroke of the engine makes no difference.
Wotan
And very short conrods for high reving engines, this is a design consideration to keep the revolving masses low, there by permitting a high reving engine.
One revolution is still one revolution, and if geared via a final drive ratio of one to one, then the rolling circumfrence of that tyre that is fitted will advance the distance of the car travelled by that amout, the length of the conrod or stroke of the engine makes no difference.
Wotan
a long stroke and short stroke both turning at 3000rpm will indeed both be turning at the same speed - well done, the part you have missed is that a long stroke engine will produce more torque than a short stroke, meaning that the long stroke will be doing 70mph while the short stroke 60mph
i'm not saying that long strokes are better because they aren't, i would much rather have an engine that can rev up to 8000rpm, i was just stating that the stroke of an engine has an effect on the speed of the vehicle assuming they are both geared the same
i'm not saying that long strokes are better because they aren't, i would much rather have an engine that can rev up to 8000rpm, i was just stating that the stroke of an engine has an effect on the speed of the vehicle assuming they are both geared the same
utter nonsense. torque only effects acceleration and top speed.
if an engine turns at say 3000rpm then it will produce say 70mph at the wheels (assuming correct gear ratios).
allow a long stroke engine turning at 3000 rpm - same speed. just not working so hard. high torque less effort.
allow a short stroke screamer turning at 3000 rpm - same speed (may struggle to maintain it) but working hard. less torque more effort.
its all down to gearing. put one speed into a shaft (gearbox input shaft) then you get a different speed out (wheel rpm) engine torque has no relevance (except ability to maintain given rpm)
if an engine turns at say 3000rpm then it will produce say 70mph at the wheels (assuming correct gear ratios).
allow a long stroke engine turning at 3000 rpm - same speed. just not working so hard. high torque less effort.
allow a short stroke screamer turning at 3000 rpm - same speed (may struggle to maintain it) but working hard. less torque more effort.
its all down to gearing. put one speed into a shaft (gearbox input shaft) then you get a different speed out (wheel rpm) engine torque has no relevance (except ability to maintain given rpm)
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