Maximum Torque Per Litre
Discussion
Huff said:
The current Yamaha R1 has an inline 4 with a crossplane crank:
http://www.ashonbikes.com/cross-plane_crank
A great link there and very well explained, i have learned something today, thanks for posting that. Do any car manufacturers or engine builders do a cross plane crank for a 4 cylinder car engine?http://www.ashonbikes.com/cross-plane_crank
How was the crank in the Audi I5 (quattro turbo) configured, having 5 cylinders would throw the balance right out if it was a flat plane crank, shirley..?
There are two standout performers when talking about specific output (BMEP) for NA engines:
1) large (ok huge!) prime mover engines (ships!) They operate at low speeds (<800rpm) so have a very low level of friction for there size, and have a excellent thermal efficiency due to their optimum surface area to volume ratio. ~150Nm/litre (112 lb.ft/l) is not unheard of.
and at the other end of the rev spectrum
2) F1 engines, making peak torque at pretty much peak power rpm (18krpm) yet still putting out ~125Nm/litre (93 lb.ft/l)even at that speed (which when you consider that BMEP = IMEP - FMEP is impressive)
However both engines are optimised to run over a relatively narrow rev range. A typical modern NA passenger car engine is actually incredibly well optimised to perform over a much wider range of speeds, even if it can't quite make the absolute magnitude of BMEP delivered by those more specialist engines.
1) large (ok huge!) prime mover engines (ships!) They operate at low speeds (<800rpm) so have a very low level of friction for there size, and have a excellent thermal efficiency due to their optimum surface area to volume ratio. ~150Nm/litre (112 lb.ft/l) is not unheard of.
and at the other end of the rev spectrum
2) F1 engines, making peak torque at pretty much peak power rpm (18krpm) yet still putting out ~125Nm/litre (93 lb.ft/l)even at that speed (which when you consider that BMEP = IMEP - FMEP is impressive)
However both engines are optimised to run over a relatively narrow rev range. A typical modern NA passenger car engine is actually incredibly well optimised to perform over a much wider range of speeds, even if it can't quite make the absolute magnitude of BMEP delivered by those more specialist engines.
Pumaracing said:
Yeah well don't get me started on you bloody colonials and your reluctance to leave the 19th century and imperial measurements. It's high time we invaded you again, gave you a bloody good thrashing, annexed you back into the Queen's Commonwealth and dragged you kicking and screaming into the 21st century and stopped you being the only country in the world that can't cope with metric measurements.
While we're at it we could ban religion over there, abolish the Republican party which is near as dammit the same thing, release Sarah Palin back into the wild and then shoot the daft b1tch from a helicopter and stick a broom handle ten inches up Newt Gingrich's arse so he knows what his first two wives felt like after he shafted them.
So why do you talk about lb ft/litre? A true forward thinking European should be thinking purely in Nm/litre.While we're at it we could ban religion over there, abolish the Republican party which is near as dammit the same thing, release Sarah Palin back into the wild and then shoot the daft b1tch from a helicopter and stick a broom handle ten inches up Newt Gingrich's arse so he knows what his first two wives felt like after he shafted them.
Auto-scape covers it pretty well
http://www.auto-scape.com/?p=31
" 4 valve: The best example of this is in the BMW E36 Euro M3 3.2 litre S50 engine. Infact I would rate the E36 M3 3.2 litre way above in terms of achievement over the Honda S2000, no other car can achieve close to 14 bar BMEP at 3250 rpm and over 100 Bhp/litre at 7400 rpm-such incredible range. Also put into perspective that this was achieved in 1995. The newer CSL is even more impressive as it achieves 14.3 bar BMEP (113.8 Nm/litre or 83.9 lb ft/litre) and 360 Bhp from a 3.2 litre (110.9 Bhp/litre- but not the torque band or range) . The Porsche 911 (997) GT3 is a more recent example and it achieves: 415 Bhp@7600 rpm (113 Bhp/litre) and 299 lb ft at 5500 rpm from 3.6 litres or 14.15 bar BMEP (112.6 Nm/litre or 83 lb-ft/litre)....From a production and design for manufacture perspective it is extremely difficult to get 100 Bhp per litre from a 4 Valve . I would set down the yardstick at anything above 105 Nm/litre (77lb ft/litre) out of a 4 valve unit and quite hard to achieve in practice.
2 valve:The very best two valve I’ve seen approach perhaps 80/Bhp/litre from the 911/993 Porsche RS. It makes 300 Bhp from a 3.8 and produces 262 lb ft. That is 11.8 bar BMEP or 69lb ft / litre 93.5 Nm/litre....."
http://www.auto-scape.com/?p=31
" 4 valve: The best example of this is in the BMW E36 Euro M3 3.2 litre S50 engine. Infact I would rate the E36 M3 3.2 litre way above in terms of achievement over the Honda S2000, no other car can achieve close to 14 bar BMEP at 3250 rpm and over 100 Bhp/litre at 7400 rpm-such incredible range. Also put into perspective that this was achieved in 1995. The newer CSL is even more impressive as it achieves 14.3 bar BMEP (113.8 Nm/litre or 83.9 lb ft/litre) and 360 Bhp from a 3.2 litre (110.9 Bhp/litre- but not the torque band or range) . The Porsche 911 (997) GT3 is a more recent example and it achieves: 415 Bhp@7600 rpm (113 Bhp/litre) and 299 lb ft at 5500 rpm from 3.6 litres or 14.15 bar BMEP (112.6 Nm/litre or 83 lb-ft/litre)....From a production and design for manufacture perspective it is extremely difficult to get 100 Bhp per litre from a 4 Valve . I would set down the yardstick at anything above 105 Nm/litre (77lb ft/litre) out of a 4 valve unit and quite hard to achieve in practice.
2 valve:The very best two valve I’ve seen approach perhaps 80/Bhp/litre from the 911/993 Porsche RS. It makes 300 Bhp from a 3.8 and produces 262 lb ft. That is 11.8 bar BMEP or 69lb ft / litre 93.5 Nm/litre....."
Huff said:
The current Yamaha R1 has an inline 4 with a crossplane crank:
http://www.ashonbikes.com/cross-plane_crank
Wow! What a fantastic article. That's an avenue of engine theory I'd never thought about before.http://www.ashonbikes.com/cross-plane_crank
What I would like to know is the magnitude of the variation in instantaneous crank speed during a single revolution at a nominal steady rpm. I suspect there's also a further factor involved and that's piston ring friction. With a flat plane crank when all four pistons are at TDC or BDC not only have they transferred all their kinetic energy to the crank but also the friction levels are zero because they momentarily stationary. So when they accelerate up to maximum velocity again at half stroke not only do they have to absorb kinetic energy from the crank they also have to absorb whatever force it takes to overcome the rapidly rising ring friction which will slow the crank even further.
What the magnitude of the friction element of this is in terms of crank velocity variation per cycle I also have no idea.
Brilliant food for thought though. Thanks very much for posting this.
Pumaracing said:
Huff said:
The current Yamaha R1 has an inline 4 with a crossplane crank:
http://www.ashonbikes.com/cross-plane_crank
Wow! What a fantastic article. That's an avenue of engine theory I'd never thought about before.http://www.ashonbikes.com/cross-plane_crank
What I would like to know is the magnitude of the variation in instantaneous crank speed during a single revolution at a nominal steady rpm. I suspect there's also a further factor involved and that's piston ring friction. With a flat plane crank when all four pistons are at TDC or BDC not only have they transferred all their kinetic energy to the crank but also the friction levels are zero because they momentarily stationary. So when they accelerate up to maximum velocity again at half stroke not only do they have to absorb kinetic energy from the crank they also have to absorb whatever force it takes to overcome the rapidly rising ring friction which will slow the crank even further.
What the magnitude of the friction element of this is in terms of crank velocity variation per cycle I also have no idea.
Brilliant food for thought though. Thanks very much for posting this.
1st major mistake: the force applied to the crankshaft in order to accelerate or deccelerate the piston does not act exactly on the crank radius
You need to integrate the entire crank revolution in the crank angle domain to come up with the actual values.
2nd mistake: Comparing the (incorrect) inertial torque with the "mean" crank torque. BMEP is typically in the order of ~12bar, whereas Pmax (peak cylinder pressure) is typically a decade larger (120bar)
The Flexibility required in the drivetrain (or the acting inertia of the flywheel) is largely as a result of damping the firing loads to a smooth output value.
A excel spreadsheet, with an appropriate lookup table for cylinder pressure, and the mass/inertia/geometry of the engine rotating and recoprocating parts makes plotting the crank accleration in the crank angle domain simple ;-)
Marquis Rex said:
Auto-scape covers it pretty well
http://www.auto-scape.com/?p=31
" 4 valve: The best example of this is in the BMW E36 Euro M3 3.2 litre S50 engine. Infact I would rate the E36 M3 3.2 litre way above in terms of achievement over the Honda S2000, no other car can achieve close to 14 bar BMEP at 3250 rpm and over 100 Bhp/litre at 7400 rpm-such incredible range. Also put into perspective that this was achieved in 1995. The newer CSL is even more impressive as it achieves 14.3 bar BMEP (113.8 Nm/litre or 83.9 lb ft/litre) and 360 Bhp from a 3.2 litre (110.9 Bhp/litre- but not the torque band or range) . The Porsche 911 (997) GT3 is a more recent example and it achieves: 415 Bhp@7600 rpm (113 Bhp/litre) and 299 lb ft at 5500 rpm from 3.6 litres or 14.15 bar BMEP (112.6 Nm/litre or 83 lb-ft/litre)....From a production and design for manufacture perspective it is extremely difficult to get 100 Bhp per litre from a 4 Valve . I would set down the yardstick at anything above 105 Nm/litre (77lb ft/litre) out of a 4 valve unit and quite hard to achieve in practice.
2 valve:The very best two valve I’ve seen approach perhaps 80/Bhp/litre from the 911/993 Porsche RS. It makes 300 Bhp from a 3.8 and produces 262 lb ft. That is 11.8 bar BMEP or 69lb ft / litre 93.5 Nm/litre....."
I wanted to post on Auto-scape and could find no way to register - any suggestions?http://www.auto-scape.com/?p=31
" 4 valve: The best example of this is in the BMW E36 Euro M3 3.2 litre S50 engine. Infact I would rate the E36 M3 3.2 litre way above in terms of achievement over the Honda S2000, no other car can achieve close to 14 bar BMEP at 3250 rpm and over 100 Bhp/litre at 7400 rpm-such incredible range. Also put into perspective that this was achieved in 1995. The newer CSL is even more impressive as it achieves 14.3 bar BMEP (113.8 Nm/litre or 83.9 lb ft/litre) and 360 Bhp from a 3.2 litre (110.9 Bhp/litre- but not the torque band or range) . The Porsche 911 (997) GT3 is a more recent example and it achieves: 415 Bhp@7600 rpm (113 Bhp/litre) and 299 lb ft at 5500 rpm from 3.6 litres or 14.15 bar BMEP (112.6 Nm/litre or 83 lb-ft/litre)....From a production and design for manufacture perspective it is extremely difficult to get 100 Bhp per litre from a 4 Valve . I would set down the yardstick at anything above 105 Nm/litre (77lb ft/litre) out of a 4 valve unit and quite hard to achieve in practice.
2 valve:The very best two valve I’ve seen approach perhaps 80/Bhp/litre from the 911/993 Porsche RS. It makes 300 Bhp from a 3.8 and produces 262 lb ft. That is 11.8 bar BMEP or 69lb ft / litre 93.5 Nm/litre....."
DV
It's been years since I looked at them - but would I be right to recall that 800ish rpm is "medium speed" in ship terms? I'm sure I recall some of the very big engines running <100rpm. Mostly turbocharged 2 strokes, too, I think.
Max_Torque said:
1) large (ok huge!) prime mover engines (ships!) They operate at low speeds (<800rpm) so have a very low level of friction for there size, and have a excellent thermal efficiency due to their optimum surface area to volume ratio. ~150Nm/litre (112 lb.ft/l) is not unheard of.
Huff said:
The current Yamaha R1 has an inline 4 with a crossplane crank:
http://www.ashonbikes.com/cross-plane_crank
I am not sure what formulas he used to come up with his numbers. Maybe it is an American trying to use metric. http://www.ashonbikes.com/cross-plane_crank
Stan
Bore = 90.0 Stroke = 57.3 Rod Length = 114.6 RPM = 12000
Piston Speed is 75.19685 Feet per Second 22.92000 Meters per Second
Piston Speed is 4511.81102 Feet per Minute 1375.20000 Meters per Minute
Maximum Piston Velocity 2226.870651 MPM @ 76.72097791861 Degrees
Piston Travel from TDC 1.00446 Inches 25.51334 mm
Bore Rod Angle 14.08232
Cylinder Volume 9.90470 CI 162.30887 cc
Crankshaft Degrees at which Rod and Crank are 90 Degrees 75.96375
Piston Travel from TDC 0.98910 Inches 25.12302 mm
Bore Rod Angle 14.03624
Cylinder Volume 9.75317 CI 159.82577 cc
Piston Piston Piston
Crank Angle Velocity Acceleration Flow @ 28"
Degree-ATDC M/Sec M/Sec/Sec M^3/S
.000 .000 56552.833 0.00000
5.000 3.919 56216.818 0.01247
10.000 7.792 55214.152 0.02479
15.000 11.573 53560.942 0.03681
20.000 15.217 51283.896 0.04840
25.000 18.682 48420.101 0.05943
30.000 21.930 45016.656 0.06975
35.000 24.923 41130.126 0.07928
40.000 27.632 36825.766 0.08789
45.000 30.030 32176.461 0.09552
50.000 32.095 27261.349 0.10209
55.000 33.812 22164.107 0.10755
60.000 35.171 16970.898 0.11188
65.000 36.169 11768.030 0.11505
70.000 36.807 6639.416 0.11708
75.000 37.095 1663.944 0.11799
80.000 37.044 -3087.062 0.11783
85.000 36.673 -7552.133 0.11665
90.000 36.003 -11681.503 0.11452
95.000 35.059 -15438.380 0.11152
100.000 33.868 -18799.537 0.10773
Bore = 90.0 Stroke = 57.3 Rod Length = 114.6 RPM = 12000
Piston Weight = 200.0 Rod Weight = 500.0
Small End Rod Weight = 166.6666 Big End Rod Weight = 333.3333
Rod CG / Distance from Small End = 76.4 GAS PRESSURE = 0
Reciprocating Total Piston Side Piston
Crank Angle Force Force Force Inertia Force
Degree Newtons Newtons Newtons Newtons
.000 20736.039 35816.795 .000 11310.567
5.000 20612.833 35660.433 449.238 11243.364
10.000 20245.189 35194.398 879.714 11042.830
15.000 19639.012 34427.877 1273.406 10712.188
20.000 18804.095 33376.327 1613.755 10256.779
25.000 17754.037 32061.699 1886.353 9684.020
30.000 16506.107 30512.797 2079.574 9003.331
35.000 15081.046 28765.822 2185.115 8226.025
40.000 13502.781 26865.161 2198.426 7365.153
45.000 11798.036 24864.521 2118.990 6435.292
50.000 9995.828 22828.477 1950.413 5452.270
55.000 8126.839 20834.311 1700.315 4432.821
60.000 6222.662 18973.486 1379.977 3394.180
65.000 4314.944 17350.784 1003.772 2353.606
70.000 2434.453 16076.977 588.376 1327.883
75.000 610.113 15250.056 151.824 332.789
80.000 -1131.923 14925.884 -287.532 -617.412
85.000 -2769.116 15093.638 -712.082 -1510.427
90.000 -4283.218 15677.218 -1105.922 -2336.301
95.000 -5660.739 16563.630 -1455.666 -3087.676
Edited by Stan Weiss on Monday 6th February 13:04
Edited by Stan Weiss on Monday 6th February 13:07
It's "maths" not math. Duh!
Anyway
SAN FRANCISCO MAN BECOMES FIRST AMERICAN TO GRASP THE SIGNIFICANCE OF IRONY - Jay Fullmer, 38, yesterday became the first American to get to grips with the concept of irony. "It was weird" Fullmer said. "I was in London for the first time and like, talking to this guy and it was raining and he pulled a face and said, "great weather, eh?" and I thought "wait a minute, no way is this great weather". Fullmer then finally realised that the other man's 'mistake' was in fact deliberate.
Fullmer, who is 39 next month and married with two children, aged 8 and 3, plans to use irony himself regularly in future. "I'm like using it all the time" he said. "Last weekend I was grilling steaks on the bar-b-cue outside and I burned them to sh!t and I said "great weather, eh?".
Anyway
SAN FRANCISCO MAN BECOMES FIRST AMERICAN TO GRASP THE SIGNIFICANCE OF IRONY - Jay Fullmer, 38, yesterday became the first American to get to grips with the concept of irony. "It was weird" Fullmer said. "I was in London for the first time and like, talking to this guy and it was raining and he pulled a face and said, "great weather, eh?" and I thought "wait a minute, no way is this great weather". Fullmer then finally realised that the other man's 'mistake' was in fact deliberate.
Fullmer, who is 39 next month and married with two children, aged 8 and 3, plans to use irony himself regularly in future. "I'm like using it all the time" he said. "Last weekend I was grilling steaks on the bar-b-cue outside and I burned them to sh!t and I said "great weather, eh?".
Stan Weiss said:
Semi on this topic. My software was written in 1986 under MD-DOS and then some years later converted to Windows. I only calculated BMEP in PSI and just added BARS also. I have metric torque in Kgm is this still used? If so when is Nm used?
Stan
Nm & kg·m are both used (at the same time) regularly in Japan on their specifications sheets.Stan
Dave's Baker and Andrews,
Just want to back up what you are saying about exaggerated torque numbers. My push rod 10.5/1 motors consistently make 85 -86 lbs-ft per litre and getting them over that while still having a pump fueled street driver is a ton of hard work.
It is not until we start pushing the CR up that it is a practical issue to break the 90 lbs-ft per litre.
To get much past 90 per litre with a two valve engine you have to resort to such things as crank case vacuum (and plenty at that) low tension rings, hi - compression, optimal valve events in conjunction with matching tuned intake and exhaust etc.
The 712 inch BB Chevy I am currently working on with my friend Terry Walters is hovering around the 1110 lbs-ft mark at present giving some 95 lbs-ft per litre. We are expecting when all adjustments are done that this will very closely approach the 100 lbs-ft per litre.
But this is a motor that sports a 16/1 CR and all the trick stuff within the class rules allowed for its application. The big advantage here to making that near 100 per litre is the 16/1 CR. Take that out of the equation and everything gets really difficult to achieve.
That said I do know that in the days of the N/A BTCC super tourers that a top engine builder friend of mine was making 103 lbs-ft per liter from a 12.8/1 CR. Needless to say this was not a cheap engine!!!!
It is interesting that few, if any, magazine articles (other than the 2 -3 of mine) have ever directly addressed the means of maximizing torque output. If any of you guys are really keen to find out my Swansea seminar will cover it in micro-detail (www.davidvizardseminars.com)
David Vizard
Just want to back up what you are saying about exaggerated torque numbers. My push rod 10.5/1 motors consistently make 85 -86 lbs-ft per litre and getting them over that while still having a pump fueled street driver is a ton of hard work.
It is not until we start pushing the CR up that it is a practical issue to break the 90 lbs-ft per litre.
To get much past 90 per litre with a two valve engine you have to resort to such things as crank case vacuum (and plenty at that) low tension rings, hi - compression, optimal valve events in conjunction with matching tuned intake and exhaust etc.
The 712 inch BB Chevy I am currently working on with my friend Terry Walters is hovering around the 1110 lbs-ft mark at present giving some 95 lbs-ft per litre. We are expecting when all adjustments are done that this will very closely approach the 100 lbs-ft per litre.
But this is a motor that sports a 16/1 CR and all the trick stuff within the class rules allowed for its application. The big advantage here to making that near 100 per litre is the 16/1 CR. Take that out of the equation and everything gets really difficult to achieve.
That said I do know that in the days of the N/A BTCC super tourers that a top engine builder friend of mine was making 103 lbs-ft per liter from a 12.8/1 CR. Needless to say this was not a cheap engine!!!!
It is interesting that few, if any, magazine articles (other than the 2 -3 of mine) have ever directly addressed the means of maximizing torque output. If any of you guys are really keen to find out my Swansea seminar will cover it in micro-detail (www.davidvizardseminars.com)
David Vizard
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