Geek thread - What's your specific torque?
Discussion
Nerdy friday afternoon thread, and a spot of PH top trumps!
Everyone is familiar with specific power, i.e. the Ferrari 458 is the current top dog with 127bhp/litre. What you may not be so familiar with is the fact that this is an easily cheated figure, you simply rev the piss out of an engine and voila, you've got motorbike engines producing 140bhp/litre. Impressive no doubt, but not really a useful comparison.
What is not so easy to cheat is specific torque, most naturally aspirated engines will top out at around 75-80lbft/litre. The aforementioned 458 again tops this chart with I believe 88.5lbft/litre. It is certainly possible to get more, but it's in the realms of serious engine tuning...
What interests me is the specific torque of turbocharged cars, and how closely linked it is to boost pressure. My thinking here is that 1 bar of boost is effectively 200% VE, or double the engine size, so the specific torque of a turbocharged engines effective capacity should still be around 75lbft a litre.
I'm interested to hear what the vast array of cars on PH put out in this respect, wether they be NASP, forced inudction or heavily modified.
I'll start off with two of mine
1600cc 118lbft = 73.8lbft/litre
2200cc 159lbft = 72.3lbft/litre
Both Honda engines, renowned for being good on specific power but are also pretty good in terms of specific torque.
Everyone is familiar with specific power, i.e. the Ferrari 458 is the current top dog with 127bhp/litre. What you may not be so familiar with is the fact that this is an easily cheated figure, you simply rev the piss out of an engine and voila, you've got motorbike engines producing 140bhp/litre. Impressive no doubt, but not really a useful comparison.
What is not so easy to cheat is specific torque, most naturally aspirated engines will top out at around 75-80lbft/litre. The aforementioned 458 again tops this chart with I believe 88.5lbft/litre. It is certainly possible to get more, but it's in the realms of serious engine tuning...
What interests me is the specific torque of turbocharged cars, and how closely linked it is to boost pressure. My thinking here is that 1 bar of boost is effectively 200% VE, or double the engine size, so the specific torque of a turbocharged engines effective capacity should still be around 75lbft a litre.
I'm interested to hear what the vast array of cars on PH put out in this respect, wether they be NASP, forced inudction or heavily modified.
I'll start off with two of mine
1600cc 118lbft = 73.8lbft/litre
2200cc 159lbft = 72.3lbft/litre
Both Honda engines, renowned for being good on specific power but are also pretty good in terms of specific torque.
Edited by Kozy on Friday 27th July 16:25
Edited by Kozy on Friday 27th July 16:31
Edited by Kozy on Friday 27th July 16:39
V88Dicky said:
Torque per ton much more telling, surely?
Anyway, mine's 65lb/ft per litre
but....
220lbs/ft per ton
No it's pure as a comparison of engine efficiency. It's linked to BMEP which is a sort of industry standard, but specific torque is a lot easier to understand.Anyway, mine's 65lb/ft per litre
but....
220lbs/ft per ton
Torque to weight is no use compared to power to weight.
'90 BMW 750i: 330 lb ft / 4,988 cc = 66.16 lb ft/litre
'98 BMW 323i: 181 lb ft / 2,494 cc = 72.57 lb ft/litre
'12 Focus 1.6i: 111 lb ft / 1,596 cc = 69.55 lb ft/litre
All naturally aspirated petrol engines. The Focus will be replaced in due course with the new 1.0 EcoBoost engine and having now driven it, can't wait:
'12 Focus 1.0T: 125 lb ft / 999 cc = 125.13 lb ft/litre.
It also has "transient overboost" for 30 sec spurts of overtaking, which makes for:
'12 Focus 1.0T: 148 lb ft / 999 cc = 148.15 lb ft/litre.
Evo review of the Ecoboost 1.0. which provides some technical insights:
'98 BMW 323i: 181 lb ft / 2,494 cc = 72.57 lb ft/litre
'12 Focus 1.6i: 111 lb ft / 1,596 cc = 69.55 lb ft/litre
All naturally aspirated petrol engines. The Focus will be replaced in due course with the new 1.0 EcoBoost engine and having now driven it, can't wait:
'12 Focus 1.0T: 125 lb ft / 999 cc = 125.13 lb ft/litre.
It also has "transient overboost" for 30 sec spurts of overtaking, which makes for:
'12 Focus 1.0T: 148 lb ft / 999 cc = 148.15 lb ft/litre.
Evo review of the Ecoboost 1.0. which provides some technical insights:
article said:
The engine is a long-stroke three-cylinder, with direct injection, variable timing for both inlet and exhaust camshafts, and a tiny turbocharger that’s able to spin at up to an incredible 248,000rpm.
...
The 'brake mean effective pressure' is the ultimate measure of engine efficiency. A naturally-aspirated engine usually measures around 150psi here (that's the peak pressure on the piston crown), a good turbo well over 200psi. This tiny EcoBoost scores an extraordinary 348psi, all from an engine whose cast-iron block is small enough to sit on a sheet of A4 paper.
...
The 'brake mean effective pressure' is the ultimate measure of engine efficiency. A naturally-aspirated engine usually measures around 150psi here (that's the peak pressure on the piston crown), a good turbo well over 200psi. This tiny EcoBoost scores an extraordinary 348psi, all from an engine whose cast-iron block is small enough to sit on a sheet of A4 paper.
Edited by Zwolf on Friday 27th July 17:32
Zwolf said:
All naturally aspirated petrol engines. The Focus will be replaced in due course with the new 1.0 EcoBoost engine and having now driven it, can't wait:
'12 Focus 1.0T: 125 lb ft / 999 cc = 125.13 lb ft/litre.
It also has "transient overboost" for 30 sec spurts of overtaking, which makes for:
'12 Focus 1.0T: 148 lb ft / 999 cc = 148.15 lb ft/litre.
Evo review of the Ecoboost 1.0. which provides some technical insights:
Impressive - the bmep figures are often very hard to find, but that sounds good (assuming it's not inflated, erroneous marketing numbers). Hopefully there will be some data soon on real-world economy for the 1.0Ecoboost, early reports suggest much better than the Fiat TwinAir but it's still too early to know.'12 Focus 1.0T: 125 lb ft / 999 cc = 125.13 lb ft/litre.
It also has "transient overboost" for 30 sec spurts of overtaking, which makes for:
'12 Focus 1.0T: 148 lb ft / 999 cc = 148.15 lb ft/litre.
Evo review of the Ecoboost 1.0. which provides some technical insights:
article said:
The 'brake mean effective pressure' is the ultimate measure of engine efficiency. A naturally-aspirated engine usually measures around 150psi here (that's the peak pressure on the piston crown), a good turbo well over 200psi. This tiny EcoBoost scores an extraordinary 348psi, all from an engine whose cast-iron block is small enough to sit on a sheet of A4 paper.
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