Tuning the 3 power outputs from the latest 2.4 motors
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PAJ
Re: Tuning the 3 power outputs from the latest 2.4 motors
I wonder, Does the new engine use the same gear box and ratios ?
Re: Tuning the 3 power outputs from the latest 2.4 motors
[quote="PhillipM"]
Unfortunately the longer stroke of the K24 means you have to bring rpms down to limit the piston speeds if you want to keep things reliable, which is why peak power remains similar (although it's still actually faster as the engine has more power everywhere in the rev range)
[/quote]
"Peak power similar" & "more power everywhere in the rev range" = confused.com
Being a longer stroke, larger capacity engine with different inlet and exhaust it is clearly tuned for more torque low down. BUT this means it will rev lower and produce less top end torque and power. Plus peaking at a lower rev limit you need to run higher gearing to achieve the same speed. This is not good for a fast track car.
High torque is useless at low revs for going quick as you need to run high gears! What you want is to keep producing torque high into the rev range (with a high rev limit) to enable low gearing for maximum acceleration. Race car engines produce low torque but high power at high revs. They are tuned that way specifically. That is noisy and in-efficient on the road, but the optimum for speed.
Unfortunately the longer stroke of the K24 means you have to bring rpms down to limit the piston speeds if you want to keep things reliable, which is why peak power remains similar (although it's still actually faster as the engine has more power everywhere in the rev range)
[/quote]
"Peak power similar" & "more power everywhere in the rev range" = confused.com
Being a longer stroke, larger capacity engine with different inlet and exhaust it is clearly tuned for more torque low down. BUT this means it will rev lower and produce less top end torque and power. Plus peaking at a lower rev limit you need to run higher gearing to achieve the same speed. This is not good for a fast track car.
High torque is useless at low revs for going quick as you need to run high gears! What you want is to keep producing torque high into the rev range (with a high rev limit) to enable low gearing for maximum acceleration. Race car engines produce low torque but high power at high revs. They are tuned that way specifically. That is noisy and in-efficient on the road, but the optimum for speed.
Last edited by Peter255 on Mon Sep 05, 2016 12:47 pm, edited 1 time in total.
Atom 4, Clio v6, & some other cars obviously.
Re: Tuning the 3 power outputs from the latest 2.4 motors
Example
My daily driver Alfa diesel produces a shed load more torque all across its limited rev range than my Clio v6 or my Atom. But it runs out of puff far earlier and has a lower rev limit.
However it has its @rse handed to it by both my Clio and Atom both with less torque but who rev higher and crucially produce more power at high revs. Both these cars can run lower gearing for any given road speed and accelerate much faster.
My daily driver Alfa diesel produces a shed load more torque all across its limited rev range than my Clio v6 or my Atom. But it runs out of puff far earlier and has a lower rev limit.
However it has its @rse handed to it by both my Clio and Atom both with less torque but who rev higher and crucially produce more power at high revs. Both these cars can run lower gearing for any given road speed and accelerate much faster.
Atom 4, Clio v6, & some other cars obviously.
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phil4
Re: Tuning the 3 power outputs from the latest 2.4 motors
[quote="Peter255"]
High torque is useless at low revs for going quick as you need to run high gears! What you want is to keep producing torque high into the rev range (with a high rev limit) to enable low gearing for maximum acceleration. Race car engines produce low torque but high power at high revs. They are tuned that way specifically. That is noisy and in-efficient on the road, but the optimum for speed.
[/quote]
Quite. And is why in the previous decade Honda and others with similar to VTEC (eg. VVTi/VVTLi) and similar had high revving engines, but pathetic torque... think previous generations of Civic Type R and the S2000. Often said they'd struggle to pull the skin of a rice pudding.
As you say, on a track if you're doing it right, you'll be at the top of the rev range most of the time, and indeed is why the VTEC kick in points are where they are, so if you change up at redline, you're still in the VTEC zone for the next onslaught.
Very different thinking to a nice surge of midrange torque for a smooth overtake on the road.
High torque is useless at low revs for going quick as you need to run high gears! What you want is to keep producing torque high into the rev range (with a high rev limit) to enable low gearing for maximum acceleration. Race car engines produce low torque but high power at high revs. They are tuned that way specifically. That is noisy and in-efficient on the road, but the optimum for speed.
[/quote]
Quite. And is why in the previous decade Honda and others with similar to VTEC (eg. VVTi/VVTLi) and similar had high revving engines, but pathetic torque... think previous generations of Civic Type R and the S2000. Often said they'd struggle to pull the skin of a rice pudding.
As you say, on a track if you're doing it right, you'll be at the top of the rev range most of the time, and indeed is why the VTEC kick in points are where they are, so if you change up at redline, you're still in the VTEC zone for the next onslaught.
Very different thinking to a nice surge of midrange torque for a smooth overtake on the road.
Re: Tuning the 3 power outputs from the latest 2.4 motors
Agreed.
The 2.4 on the road is probably better 99% of the time, but on track the 2ltr should be better.
I am also interested if the 2 engines run the same gear ratios. The unfortunate acceleration sapping change to 6th would be even more of an issue on track with the lower rev limit on a 2.4 with the same gearing.
I am trying to remember the redline speed in 5th in my Atom. I think its about 125ish (on the speedo).
Assuming 2.4 7600 red line & 2.0 8250 red line
Shift to 6th for the 2.4 would be 115 mph. That'd be much more of an issue on track. You'd have to change into 6th much more often.
And if they ran longer gears to address this it'd be slower. Not ideal.
The 2.4 on the road is probably better 99% of the time, but on track the 2ltr should be better.
I am also interested if the 2 engines run the same gear ratios. The unfortunate acceleration sapping change to 6th would be even more of an issue on track with the lower rev limit on a 2.4 with the same gearing.
I am trying to remember the redline speed in 5th in my Atom. I think its about 125ish (on the speedo).
Assuming 2.4 7600 red line & 2.0 8250 red line
Shift to 6th for the 2.4 would be 115 mph. That'd be much more of an issue on track. You'd have to change into 6th much more often.
And if they ran longer gears to address this it'd be slower. Not ideal.
Atom 4, Clio v6, & some other cars obviously.
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import_trung
Re: Tuning the 3 power outputs from the latest 2.4 motors
From my experience and research, the k20 uses NPR3 lsd gearbox.
The k24 uses sm5m gearbox
Sm5m ratios
gear: no of teeth: ratio
1st - 15:49 = 3.2667
2nd - 26:49 = 1.8846
3rd - 36:49 = 1.3611
4th - 42:43 = 1.0238
5th - 47:39 = 0.8298
6th - 51:35 = 0.6863
FD - 17:81 = 4.765
Npr3 ratios
1st: 3.266
2nd: 2.13
3rd: 1.517
4th: 1.212
5th: 0.972
6th: 0.78
FD: 4.764
There are also differences between the k24z engine and k20a/z that makes the k20 much better suited to power upgrades
The k24 uses sm5m gearbox
Sm5m ratios
gear: no of teeth: ratio
1st - 15:49 = 3.2667
2nd - 26:49 = 1.8846
3rd - 36:49 = 1.3611
4th - 42:43 = 1.0238
5th - 47:39 = 0.8298
6th - 51:35 = 0.6863
FD - 17:81 = 4.765
Npr3 ratios
1st: 3.266
2nd: 2.13
3rd: 1.517
4th: 1.212
5th: 0.972
6th: 0.78
FD: 4.764
There are also differences between the k24z engine and k20a/z that makes the k20 much better suited to power upgrades
Re: Tuning the 3 power outputs from the latest 2.4 motors
If I read that the correct way the k24 has the same final drive to make things easy, and the same first gear (not used when pressing on). However the rest of the ratios are all higher on the k24 to match the lower rev limit.
Indeed 4th gear on a k24 engined Atom is almost identical to 5th on a K20 car!
This is not good news for acceleration and top speed (but good for economy and general road use).
Torque is multiplied by the gearing used so this higher gearing reduces the output (useable) torque to the wheels. This will act to reduce the extra torque from the 2.4 engine at most rpm.
Look at 2nd gear (for launch). The ratios are quite different. The k24 is 13% higher gearing. Thus torque is reduced by this factor (in comparison to a engine using the other box with a lower gear).
Interesting....
Indeed 4th gear on a k24 engined Atom is almost identical to 5th on a K20 car!
This is not good news for acceleration and top speed (but good for economy and general road use).
Torque is multiplied by the gearing used so this higher gearing reduces the output (useable) torque to the wheels. This will act to reduce the extra torque from the 2.4 engine at most rpm.
Look at 2nd gear (for launch). The ratios are quite different. The k24 is 13% higher gearing. Thus torque is reduced by this factor (in comparison to a engine using the other box with a lower gear).
Interesting....
Atom 4, Clio v6, & some other cars obviously.
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import_trung
Re: Tuning the 3 power outputs from the latest 2.4 motors
the ratios in the k20 atoms are far from ideal for such a lightweight car.
if anything, the longer ratios from the sm5m box coupled with the higher redline of the k20 engine makes for an excellent upgrade.
i've carried out this gear swap on a few cars now including ian's turbo atom, and the car is much better to drive with the added bonus of a longer 6th gear for cruising.
if anything, the longer ratios from the sm5m box coupled with the higher redline of the k20 engine makes for an excellent upgrade.
i've carried out this gear swap on a few cars now including ian's turbo atom, and the car is much better to drive with the added bonus of a longer 6th gear for cruising.
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PhillipM
Re: Tuning the 3 power outputs from the latest 2.4 motors
[quote="Peter255"]
[quote="PhillipM"]
Unfortunately the longer stroke of the K24 means you have to bring rpms down to limit the piston speeds if you want to keep things reliable, which is why peak power remains similar (although it's still actually faster as the engine has more power everywhere in the rev range)
[/quote]
"Peak power similar" & "more power everywhere in the rev range" = confused.com
Being a longer stroke, larger capacity engine with different inlet and exhaust it is clearly tuned for more torque low down. BUT this means it will rev lower and produce less top end torque and power. Plus peaking at a lower rev limit you need to run higher gearing to achieve the same speed. This is not good for a fast track car.
High torque is useless at low revs for going quick as you need to run high gears! What you want is to keep producing torque high into the rev range (with a high rev limit) to enable low gearing for maximum acceleration. Race car engines produce low torque but high power at high revs. They are tuned that way specifically. That is noisy and in-efficient on the road, but the optimum for speed.
[/quote]
Eh? That might be the case if you're comparing two engines of the same size, but you're not, you're comparing one with 20% more displacement that makes the same power at the top of it's rev range as the 2.0L and more power everywhere else through it.
[quote="PhillipM"]
Unfortunately the longer stroke of the K24 means you have to bring rpms down to limit the piston speeds if you want to keep things reliable, which is why peak power remains similar (although it's still actually faster as the engine has more power everywhere in the rev range)
[/quote]
"Peak power similar" & "more power everywhere in the rev range" = confused.com
Being a longer stroke, larger capacity engine with different inlet and exhaust it is clearly tuned for more torque low down. BUT this means it will rev lower and produce less top end torque and power. Plus peaking at a lower rev limit you need to run higher gearing to achieve the same speed. This is not good for a fast track car.
High torque is useless at low revs for going quick as you need to run high gears! What you want is to keep producing torque high into the rev range (with a high rev limit) to enable low gearing for maximum acceleration. Race car engines produce low torque but high power at high revs. They are tuned that way specifically. That is noisy and in-efficient on the road, but the optimum for speed.
[/quote]
Eh? That might be the case if you're comparing two engines of the same size, but you're not, you're comparing one with 20% more displacement that makes the same power at the top of it's rev range as the 2.0L and more power everywhere else through it.
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PhillipM
Re: Tuning the 3 power outputs from the latest 2.4 motors
[quote="phil4"]
Quite. And is why in the previous decade Honda and others with similar to VTEC (eg. VVTi/VVTLi) and similar had high revving engines, but pathetic torque... think previous generations of Civic Type R and the S2000. Often said they'd struggle to pull the skin of a rice pudding.
As you say, on a track if you're doing it right, you'll be at the top of the rev range most of the time, and indeed is why the VTEC kick in points are where they are, so if you change up at redline, you're still in the VTEC zone for the next onslaught.
Very different thinking to a nice surge of midrange torque for a smooth overtake on the road.
[/quote]
That's disingenious too, the ENTIRE point of the VTEC system is that it allows you to have both - the decent torque low down as well as the better breathing to hold the torque to high rpms.
Don't confuse what people claim with their arse dynos when they try something with a flat torque curve as being truth.
An F20C cracks out 153lbft of torque from 2 litres. That's up with the best torque outputs in it's class. Better than most.
It's the same argument people use when they claim rotaries are torqueless - a Renesis has 80% of it's peak torque from about 2k to 8krpm - but because there's no 'kick' people relate it in their heads to 'no torque'.
It's also why they rave about turbo diesels that go nothing-everything-nothing. Even when they're driving a 110bhp Passat.
Quite. And is why in the previous decade Honda and others with similar to VTEC (eg. VVTi/VVTLi) and similar had high revving engines, but pathetic torque... think previous generations of Civic Type R and the S2000. Often said they'd struggle to pull the skin of a rice pudding.
As you say, on a track if you're doing it right, you'll be at the top of the rev range most of the time, and indeed is why the VTEC kick in points are where they are, so if you change up at redline, you're still in the VTEC zone for the next onslaught.
Very different thinking to a nice surge of midrange torque for a smooth overtake on the road.
[/quote]
That's disingenious too, the ENTIRE point of the VTEC system is that it allows you to have both - the decent torque low down as well as the better breathing to hold the torque to high rpms.
Don't confuse what people claim with their arse dynos when they try something with a flat torque curve as being truth.
An F20C cracks out 153lbft of torque from 2 litres. That's up with the best torque outputs in it's class. Better than most.
It's the same argument people use when they claim rotaries are torqueless - a Renesis has 80% of it's peak torque from about 2k to 8krpm - but because there's no 'kick' people relate it in their heads to 'no torque'.
It's also why they rave about turbo diesels that go nothing-everything-nothing. Even when they're driving a 110bhp Passat.
Re: Tuning the 3 power outputs from the latest 2.4 motors
Firstly the 2.4 does not (from what I have been told) make the same max power as the 2ltr. The 2.4 makes ~300, and the 2 makes ~310. Which is interesting as the long stroke engine even with 20% more displacement DOES NOT make 20% more power. If it was a true red top 2.4 (and not just a longer crank 2ltr) it should make circa 310*1.2=372BHP! So for its displacement advantage it is significantly down on max power output. If the engine got anywhere near 370BHP I wouldn't even question it!
Does anyone have any comparable independent DATA (not opinion) over the comparison between the torque from the 2lts and 2.4 from say ~6000 rpm upwards? On track that is where we need and use the full power. This is almost exclusively where a 2ltr is driven on track. On the high lift cams via VTEC. I suspect the 2.4 is comparable around 6000 rpm (at best), before dropping off to its lower limit. The 2ltr then screams on to its higher limit. This is exactly where the 2ltr car comes alive and really delivers. Hence the 2.4 is probably worse for track (6000-8250rpm). That's the point. Not once have I said the 2.4 is worse on the road. Indeed I completely agree for the Nomad off road, and on road in an Atom the 2.4 should be faster 99% of the time. That is not in question.
I am concerned if I buy a 2.4 next year (as I am considering) on track it will be slower. For me that's un-acceptable. To spend a LOT of extra cash and time selling my car to get a slower but newer model. And I get the new car might be faster until 6,000 rpm, or on road. But that's not the point! And the higher gearing is also a bad thing for me. I don't care about economy or relaxed cruising. I want speed and acceleration.
Plus if your running a s/c 2ltr Atom on the road do you really need more torque low down? Having driven mine for thousands of road miles both all across Europe and on occasional weekend drives IMO no. The thought never crossed my mind (unlike more top end power on track!!!!). I think the 2.4 makes sense for N/A cars, and for the Nomad. When s/c in an Atom I suspect its a backwards step... for me at least.
Anyways I want to get DATA to understand this not opinion. Hence a dyno day already arrange for a back to back comparison of 2ltr and 2.4s (in no way connected to Ariel).
Does anyone have any comparable independent DATA (not opinion) over the comparison between the torque from the 2lts and 2.4 from say ~6000 rpm upwards? On track that is where we need and use the full power. This is almost exclusively where a 2ltr is driven on track. On the high lift cams via VTEC. I suspect the 2.4 is comparable around 6000 rpm (at best), before dropping off to its lower limit. The 2ltr then screams on to its higher limit. This is exactly where the 2ltr car comes alive and really delivers. Hence the 2.4 is probably worse for track (6000-8250rpm). That's the point. Not once have I said the 2.4 is worse on the road. Indeed I completely agree for the Nomad off road, and on road in an Atom the 2.4 should be faster 99% of the time. That is not in question.
I am concerned if I buy a 2.4 next year (as I am considering) on track it will be slower. For me that's un-acceptable. To spend a LOT of extra cash and time selling my car to get a slower but newer model. And I get the new car might be faster until 6,000 rpm, or on road. But that's not the point! And the higher gearing is also a bad thing for me. I don't care about economy or relaxed cruising. I want speed and acceleration.
Plus if your running a s/c 2ltr Atom on the road do you really need more torque low down? Having driven mine for thousands of road miles both all across Europe and on occasional weekend drives IMO no. The thought never crossed my mind (unlike more top end power on track!!!!). I think the 2.4 makes sense for N/A cars, and for the Nomad. When s/c in an Atom I suspect its a backwards step... for me at least.
Anyways I want to get DATA to understand this not opinion. Hence a dyno day already arrange for a back to back comparison of 2ltr and 2.4s (in no way connected to Ariel).
Atom 4, Clio v6, & some other cars obviously.
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kelvin12382003
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Re: Tuning the 3 power outputs from the latest 2.4 motors
I just prefer k20Z engine. 
Re: Tuning the 3 power outputs from the latest 2.4 motors
[quote="kelvin12382003"]
I just prefer k20Z engine.
[/quote]
It does look better too! I love the red crackle finish, and that tubular manifold. Proper!
I just prefer k20Z engine.
[/quote]
It does look better too! I love the red crackle finish, and that tubular manifold. Proper!
Atom 4, Clio v6, & some other cars obviously.
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PhillipM
Re: Tuning the 3 power outputs from the latest 2.4 motors
Why do you need torque data?
You know it has more displacement, you know it makes more peak torque, you know it's a similar engine configuration, and you know it makes similar peak power at lower rpms. So you know it's holding more torque to it's redline. The thing holding the power back is piston speeds and head flow. Same as it is for the F20c vs the F24C.
The old engine is making (roughly) 310bhp@~8.4krpm, roughly, and about 225-230lbft of torque.
The new engine, given it's likely to be similar to the Nomad, should be making that 300 or so horsepower around 7000rpm. That means it's making 220lbft at peak power, or more, if that estimated 300 is conservative.
So if you plug that backwards then what you get is that from approximately 6800 to 7000rpm the new engine will be making a knats less power than the old one at peak power rpms. So for 200rpms you're loosing out on an extra 5bhp average (give or take, rule of thumb figures).
And everywhere else the new engine is making more power.
You know it has more displacement, you know it makes more peak torque, you know it's a similar engine configuration, and you know it makes similar peak power at lower rpms. So you know it's holding more torque to it's redline. The thing holding the power back is piston speeds and head flow. Same as it is for the F20c vs the F24C.
The old engine is making (roughly) 310bhp@~8.4krpm, roughly, and about 225-230lbft of torque.
The new engine, given it's likely to be similar to the Nomad, should be making that 300 or so horsepower around 7000rpm. That means it's making 220lbft at peak power, or more, if that estimated 300 is conservative.
So if you plug that backwards then what you get is that from approximately 6800 to 7000rpm the new engine will be making a knats less power than the old one at peak power rpms. So for 200rpms you're loosing out on an extra 5bhp average (give or take, rule of thumb figures).
And everywhere else the new engine is making more power.
Last edited by PhillipM on Fri Sep 09, 2016 9:36 am, edited 1 time in total.
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phil4
Re: Tuning the 3 power outputs from the latest 2.4 motors
[quote="Peter255"]
It does look better too! I love the red crackle finish, and that tubular manifold. Proper!
[/quote]
Can't help with the manifold (and 1-4-1 doesn't make sense), but for the cover: http://www.frost.co.uk/vht-red-wrinkle-finish-310ml.html
It does look better too! I love the red crackle finish, and that tubular manifold. Proper!
[/quote]
Can't help with the manifold (and 1-4-1 doesn't make sense), but for the cover: http://www.frost.co.uk/vht-red-wrinkle-finish-310ml.html
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