Racebits rolling road day vids and pics

Alan,

The engineering/physics definition of Torque is Force x Radius, so if you put a 1 foot long ring spanner on a horizontal nut so that the spanner is horizontal, then hang a 1lb bag of sugar from the other end of the spanner you're applying 1lb/ft of torque to the nut if you ignore the weight of the spanner itself. If you hang two bags of sugar, or make the spanner twice as long you've got 2lb/ft. If you make the spanner twice as long AND hang two bags of sugar you've got 4 lb/ft and so on.

Simply put, it's the engine's ability to twist the gearbox shaft.

Power (whether Horsepower, Kilowatts, or whatever) is how quickly the engine can turn the shaft with that torque, so immediately we can see that the peak BHP figure needs to involve an RPM somewhere high up the range. If peak BHP occurs some distance from the red line, then it implies that the torque falls off rapidly at higher RPM.

JJ and a big fat bloke can probably perform the same bicep curl once. Because JJ lives in the gym and only eats chickens though, he could get through 100 repetitions quicker than the fat bloke, so JJ would be more "powerful" even though their peak "torque" was the same.
 
Like that :LOL:

My 0 to 60times may show that my car is under powered, however that was because I was driving not because the car is slow, if I look in my mirror I see people following me struggling to keep up with me (even if I was going the wrong way) ;)
 
jamie_duff said:
JJ and a big fat bloke can probably perform the same bicep curl once. Because JJ lives in the gym and only eats chickens though, he could get through 100 repetitions quicker than the fat bloke, so JJ would be more "powerful" even though their peak "torque" was the same.
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Isn't that the same person?:LOL::LOL::LOL:

I learned something new today about the lbs/ft thing, it's just something that I have never thought of, a unit that I use to tighten nuts or bolts.
 
Richb said:
Isn't that the same person?:LOL::LOL::LOL:

I learned something new today about the lbs/ft thing, it's just something that I have never thought of, a unit that I use to tighten nuts or bolts.
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Same here but I would like to know how many lbs/ft were involved today when the spanner slipped trapping my finger against the framework on the rolls..........:sick::sick:
............I didn't measure how many feet away the spanner landed after I launched it though.o_Oo_O
 
Pid_16V said:
Have a look at my maps Matt, before and after. You can see whats been done to the torque, and that is what is noticable in the car on the road. Now if somebody asks me what the BHP is on my car, i'd just say, i have no idea, but it pulls like a train! There is a distinctive pulling power increase which is very noticable right along the rev range. (y)
Btw, "torque" is the term i understand, as basically its the force or power given/taken.
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Yeah looking back now at your map, I see your first reading shows the torque gradualy rising and peeking about the same revs as maximum power, then on the second run they have boosted the torque at the lower revs and also gained you an extra 6 BHP, plus peak Torque is now at a lower rev limit to maximum BHP.
On mine the power rises steadily with just a small blip at about 3500rpm when the secondaries open, however a large dip in torque happens at the same time, so the next time i'll have to ask if they can iron that out so the curve stays more constant (although anyone who has expereinced the secondaries kicking in will tell you it shoves you in the seat a bit more)
Your second Torque curve looks more like that of the V6 in my opinion (y) it is strange though that your max BHP is at a lower rev limit than the V6, here was me thinking you had to rev the Zetec to death to extract the power :oops:

(anyway this is slightly off topic as this is a pictures thread ;))
 
You have to rev the Zetec harder to get the same torque and thus horsepower to accelerate the Cougar at the same rate as you would with the V6, assuming the V6 is accelerating at part effort. The V6 with it's greater capacity will produce more torque at any RPM and thus more horsepower at any RPM than the Zetec.

Thus the observation that one has to work the Zetec harder to make the Cougar do the same thing, up to the maximum ability of the Zetec whereupon the V6 opens up a gap on it.

An 8valve such as the Ford OHV engine will produce peak torque lower still, but compared to the Zetec would have to be revved harder to achieve the same acceleration as a Zetec.

Obviously these comparisons are assuming "real world" driving where the guy with the more powerful car is just accelerating briskly and not thrashing it and the guy with the less powerful car is driving harder to keep up - e.g. coming off a dual carriageway roundabout.
 
I think Matt's saying that Al's engine is producing it's peak power lower down the rev range than a V6. It's true that because the Zetec engine is multi-valve (4 valves per cylinder) that it does need revving to extract the best out of it, because of the breathing characteristics of a multi-valve engine. With that being so, it's the same reason the V6 produces it's maximum power so far up the rev range, it's a multi-valve engine.
 
Stribo said:
With that being so, it's the same reason the V6 produces it's maximum power so far up the rev range, it's a multi-valve engine.
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That statement has confused me, i thought the whole idea of having the secondries was that under approx 3500rpm with the secondries shut the engine acted as a 2 valve /cylinder giving the extra torque that comes with that & it only acts as a multi valve in the higher rev range ?
 
Paul.P said:
That statement has confused me, i thought the whole idea of having the secondries was that under approx 3500rpm with the secondries shut the engine acted as a 2 valve /cylinder giving the extra torque that comes with that & it only acts as a multi valve in the higher rev range ?
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That's correct Paul, but peak power is still going to be up at the top of the rev range.
 
The multi-valve technology allows torque to be maintained at higher RPM than would otherwise be possible. Although PEAK BHP is kinda pub-talk, horsepower is what moves the car so multivalve engines will always deliver peak power high up. That's not to say they don't produce good torque mid range, but just that they still produce good torque high up so the torque x RPM results in a peak BHP higher up than a 2-valve engine can.

The IMRC is there because the cross sectional area of the inlet tracts on the Duratec is too big to actually develop any velocity at low RPM, hence one inlet valve is strangled on each cylinder to half the inlet tract cross sectional area.
 
Paul.P said:
That statement has confused me, i thought the whole idea of having the secondries was that under approx 3500rpm with the secondries shut the engine acted as a 2 valve /cylinder giving the extra torque that comes with that & it only acts as a multi valve in the higher rev range ?
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The valves are still 4 per cylinder aren't they? It's just that the incoming air supply is doubled isn't it?
 
That's right Rich. The exhaust valves remain unchanged throughout. The inlet valves both move, but the tube feeding one of them is blocked so that the air in the other one goes twice as fast (and thus has more momentum to keep flowing in after the piston reaches bottom dead centre and stops sucking the air in).
 
Not strictly true, Jamie, the secondaries close off the shorter tract in the UIM as the longer tract gives more torque at the lower end of the rev range, a shorter tract gives more power at the top end, its just they open the short one to give both feeding the cylinder, thus increasing the top end power, if they could have done it with both cost effectively, i'm sure they would have done, yamaha employ variable tracts on their bike engines whereby the tract is moved to the closed position at lower revs to give a longer inlet tract, which then opens higher up the range to effectively shorten the tract, giving more power at the top end
 
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