zilspeed
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| posted on 17/10/09 at 12:09 PM |
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Power / Torque / Weight
Currently driving a Golf GTI MK3 with the 8V engine. It has 122lbs/ft of torque @ 3200rpm and 115bhp @ 5400rpm.
It weighs about 1100kg
Nothing startling in other words, but quite a torquey little bugger and easy to drive and make progress without rowing the gears. Both power and
torque appear pretty early.
For the last week or so I have also been driving an Alfa 156 Sportwagon which has a variable valve timing 16V engine with 120lbs/ft of torque @
3,900rpm and 140bhp @ 6,500rpm. It weighs around 1300kg.
I haven't seen any graphs for either car so can't really talk about the curves for either. Whatever the case, the Alfa feels utterly
gutless in comparison with the Golf.
It may be much keener once you manage to wind the crank up to the bigger numbers, but otherwise it's just not interested.
You can't beat easily accessible low down grunt for a road car and although the Alfa may have 35bhp more at peak, it also has 200kg extra to
haul around.
I don't exactly know what I'm saying here, but it shows to go you. Peak power numbers aren't everything.
I was convinced I would be buying the Alfa, but now I'm not so sure. It looks very very cool, but I really don't like gutless cars.
(I'm saying all of this, but please rest assured that the Kawasaki in the Sylva will kiss the 10,500rpm rev limiter with every gearchange.)
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Volvorsport
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| posted on 17/10/09 at 12:18 PM |
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turbo , turbo , turbo .
area under the curve is always more important than peak numbers .
im aware neither of your motors are turboed , but the point is the torque curve is always flat and broad when in boost .
www.dbsmotorsport.co.uk
getting dirty under a bus
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zilspeed
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| posted on 17/10/09 at 12:26 PM |
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quote:
Originally posted by Volvorsport
turbo , turbo , turbo .
area under the curve is always more important than peak numbers .
im aware neither of your motors are turboed , but the point is the torque curve is always flat and broad when in boost .
That's what I was aluding to when I said I hadn't seen a curve for either.
I suspect that the area under the curve is fatter with the Golf when you consider the rev range that I tend to use, especially down at the every day
end of the rev counter.
When I'm going to work and wafting along the M73 at an indicated 58mph in fifth, I don't tend to trouble the dusty end of the rev counter
very much.
I get what you're saying about turbocharging though.
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liam.mccaffrey
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| posted on 17/10/09 at 12:51 PM |
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my two daily drivers are worlds apart.
Volvo v70 AWD 2.5 turbo 193HP
MGZR 160 HP
Obviously the volvo feels a lot more wallowy but is no slouch in a straight line despite its extra weight. The turbos power delivery is very smooth,
helped by the torque converter and auto box no doubt.
The MG is a lot more stressful to drive as its power delivery is more abrupt and high in the rev range. But it handles very well and feels very
tight.
[Edited on 17/10/09 by liam.mccaffrey]
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snapper
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| posted on 17/10/09 at 12:59 PM |
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BHP sells engines, Torque wins races......
Doing loads of research on the Pinto and am starting to read between the lines of the Tuning books, mid range torque is the key to a fast road car,
ultimate bhp is only seen higher up the rev range for a smaller period of time.
The under the curve area is a useful thing to look out for and i will keep that in mind as i formulate a cunning plan.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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mcerd1
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| posted on 17/10/09 at 01:55 PM |
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quote:
Originally posted by snapper
Doing loads of research on the Pinto and am starting to read between the lines of the Tuning books, mid range torque is the key to a fast road car,
ultimate bhp is only seen higher up the rev range for a smaller period of time.
thats what I'm thinking too (I'm building myself a 2.1 pinto on ZX9R carb's) - I must have read the same books as you 
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loggyboy
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| posted on 17/10/09 at 04:03 PM |
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simple fact is you cant have BHP without torque and vice versa. In my mind its always best to have a nice mix of both and ensure that they peak at
roughly the same place, theres not point in having them at opposite ends of the graph.
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britishtrident
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| posted on 17/10/09 at 08:03 PM |
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The 8v Golf engine always did punch above its weight when the 16v was introduced I remember everybody complaining that it didn't have the
grunt of the 8v.
With the Alfa it could be down to flywheel weight or some thing might be wrong such as the variator being up the spout or the catalysr being choked
or a valve or valve timing timing problem.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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craig1410
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| posted on 17/10/09 at 08:09 PM |
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What is actually important is average BHP between the RPM at which you change gear and the RPM at which the next gear engages. If you have a very
peaky engine then you might get 200BHP at peak but assuming you go beyond peak power RPM before changing gear and then drop below peak power RPM after
the gear change then the average BHP might only be 180BHP. With a less peaky engine you might get the same peak power (200BHP) but average closer to
190 or 195BHP due to the flatter power curve either side of peak power RPM.
Power is what wins races not torque, but it is average power which matters! Having said that, it is easier to drive a torquey car than it is to drive
a highly tuned screamer but a top driver will almost always get better results with more power regardless of how much torque is available.
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JoelP
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| posted on 17/10/09 at 08:21 PM |
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quote:
Originally posted by craig1410
What is actually important is average BHP between the RPM at which you change gear and the RPM at which the next gear engages. If you have a very
peaky engine then you might get 200BHP at peak but assuming you go beyond peak power RPM before changing gear and then drop below peak power RPM after
the gear change then the average BHP might only be 180BHP. With a less peaky engine you might get the same peak power (200BHP) but average closer to
190 or 195BHP due to the flatter power curve either side of peak power RPM.
Power is what wins races not torque, but it is average power which matters! Having said that, it is easier to drive a torquey car than it is to drive
a highly tuned screamer but a top driver will almost always get better results with more power regardless of how much torque is available.
Thats what ruins my 5 gear vivaro, you redline one gear and the next is off boost anyway, so it feel like a lame dog. Im guessing the 6 speed version
is better at keeping the turbo spinning.
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zilspeed
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| posted on 17/10/09 at 08:39 PM |
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quote:
Originally posted by craig1410
What is actually important is average BHP between the RPM at which you change gear and the RPM at which the next gear engages. If you have a very
peaky engine then you might get 200BHP at peak but assuming you go beyond peak power RPM before changing gear and then drop below peak power RPM after
the gear change then the average BHP might only be 180BHP. With a less peaky engine you might get the same peak power (200BHP) but average closer to
190 or 195BHP due to the flatter power curve either side of peak power RPM.
Power is what wins races not torque, but it is average power which matters! Having said that, it is easier to drive a torquey car than it is to drive
a highly tuned screamer but a top driver will almost always get better results with more power regardless of how much torque is available.
I don't have any doubt that in a competitive situation, I would cane the Alfa to within an inch of its life and do a better time than I would in
the Golf, purely by keeping it nearer peak more of the time.
Having said that though, slow corners where you need grunt to get you out of the corner or need to go all the way down to first to keep a peaky engine
lit can still kill things.
I don't know, but the Golf just seems more accessible, exactly as the road tests of the time said, as BT says above.
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