RE: 'Beyond 400hp' Mercedes-AMG A45 caught testing
Discussion
TwinExit said:
Knock control REDUCES torque/HP at the onset of knock in efforts to protect the engine. Direct injection (fuel ingress further into the combustion chamber) does not increase the gas mixture's resistance to knock, in fact it increases the likelyhood of pre-ignition due to contamination of oil additives 'washed' into the fuel mixture.
It reduces power at the knock limit sure but you can, as a result of the accuracy of the knock sensors, run a lot closer to the knock limit and run a higher compression ratio than an old school ‘analogue’ turbo engine....or indeed considerably more boost as required when extracting 200hp/l out of an engine (that doesn’t rev to 15,000 rpm).Nanook said:
big_rob_sydney said:
Dude, why don't they count? Technology is technology, and materials science is materials science. If engineers have found solutions in the past, do you not think technology is transferable?
More to the point, why do you feel achieving this today is news, when they are more than 30 years late to the party?
2 stroke engines and 4 stroke engines are inherently different.More to the point, why do you feel achieving this today is news, when they are more than 30 years late to the party?
If there are 4 stroke engines out there from 30 years ago, that make this sort of power from this sort of capacity, whilst realising this sort of fuel economy, and these emissions figures, then yes, they're 30 years late to the party.
If someone built a rotary engine with a turbo on it, and a capacity of 2.0L, and it made more power again, would that still be comparable?
We're talking apples and oranges here.
Generally, bike engines and car engines are different. Bore/stroke, max engine speeds as a result, torque produced as a result, etc.
ked within a couple of thousand miles and need a full top end rebuild probably every 2years on moderate use.TwinExit said:
We don't have the factual torque numbers yet, I am almost certain it will be significantly lower than 400 lbs/ft, more along 280-300 lbs/ft. The headline 400+ horses will be achieved at the top-end of its rev range, so we'll see a relatively peaky powerband.
I've just looked at the old Amg 45 dyno graph, it in no way looks peaky with regards to power or torque, and making a hell of a lot more than 300 lbs/ft.Nanook said:
big_rob_sydney said:
Dude, why don't they count? Technology is technology, and materials science is materials science. If engineers have found solutions in the past, do you not think technology is transferable?
More to the point, why do you feel achieving this today is news, when they are more than 30 years late to the party?
2 stroke engines and 4 stroke engines are inherently different.More to the point, why do you feel achieving this today is news, when they are more than 30 years late to the party?
If there are 4 stroke engines out there from 30 years ago, that make this sort of power from this sort of capacity, whilst realising this sort of fuel economy, and these emissions figures, then yes, they're 30 years late to the party.
If someone built a rotary engine with a turbo on it, and a capacity of 2.0L, and it made more power again, would that still be comparable?
We're talking apples and oranges here.
Generally, bike engines and car engines are different. Bore/stroke, max engine speeds as a result, torque produced as a result, etc.
Brooking10 said:
I think the current MB 9 speeds are designed and built in house as were the 7 speeds before them.
May be wrong but I don’t think it is a third party box.
Yeah, the old thing about 'Mercedes being an engineering company which happens to make cars' means they don't buy in major parts like gearboxes, it's all in-house AFAIK.May be wrong but I don’t think it is a third party box.
clarki said:
Really?? Mine had no trouble making over the claimed power, 425 and 377 lbft. The gearbox would happily back that up too. I destroyed 3 in 20,000miles!!
Reading failure?A STOCK/STANDARD FQ400 when put on a dyno with commercially available pump fuel would typically fall shy of the claimed 400 HP.
Mitsubishi boxes, transfer cases and output shafts are notorious for breaking at hard launches, so your '3 destroyed gearbox' antidote does not prove anything other than you ran the risk of modifying your car and running it hard.
Edited by TwinExit on Tuesday 6th November 13:50
RemyMartin81D said:
Nanook said:
big_rob_sydney said:
Dude, why don't they count? Technology is technology, and materials science is materials science. If engineers have found solutions in the past, do you not think technology is transferable?
More to the point, why do you feel achieving this today is news, when they are more than 30 years late to the party?
2 stroke engines and 4 stroke engines are inherently different.More to the point, why do you feel achieving this today is news, when they are more than 30 years late to the party?
If there are 4 stroke engines out there from 30 years ago, that make this sort of power from this sort of capacity, whilst realising this sort of fuel economy, and these emissions figures, then yes, they're 30 years late to the party.
If someone built a rotary engine with a turbo on it, and a capacity of 2.0L, and it made more power again, would that still be comparable?
We're talking apples and oranges here.
Generally, bike engines and car engines are different. Bore/stroke, max engine speeds as a result, torque produced as a result, etc.
ked within a couple of thousand miles and need a full top end rebuild probably every 2years on moderate use.No comparison and all the better for it...
Olivera said:
I've just looked at the old Amg 45 dyno graph, it in no way looks peaky with regards to power or torque, and making a hell of a lot more than 300 lbs/ft.
I mean at 400 HP/PS, it will be making around 300 lbs/ft @ 7000 RPM.Nearly all the standard A45 AMG graphs show peak power at 6000-6250 RPM with around 300 lbs/ft
This is the only knock-safe way to produce big numbers per litre without needing race fuel or charge cooling, however it is a peaky powerband so it needs 9 short gear ratios to make it work.
markcoznottz said:
TwinExit said:
Silverbullet767 said:
Absolutely mad, I love it.
No doubt someone will have a 500bhp remap ready to go a week after release. Who will take one for the team and find out the engines limit I wonder?
Not without water/alcohol injection or race fuel it wont.No doubt someone will have a 500bhp remap ready to go a week after release. Who will take one for the team and find out the engines limit I wonder?
RacerMike said:
It reduces power at the knock limit sure but you can, as a result of the accuracy of the knock sensors, run a lot closer to the knock limit and run a higher compression ratio than an old school ‘analogue’ turbo engine....or indeed considerably more boost as required when extracting 200hp/l out of an engine (that doesn’t rev to 15,000 rpm).
I am sorry, but that just an ideological statement and wishful thinking.Knock control is a 'reactive' system, it only starts to dial back on boost, ignition timing and change injector pulse width when knock occurs, it cannot anticipate knock. No system can.
Fuel quality and additive content will vary pump to pump, day to day, and its sensitivity to knock will certainly increase on a hot /hard run engine - especially at high speed runs. If you run a motor with ignition and fuel maps just under the threshold of knock on day 1, day 2 or day 3-4-5-6 the motor may knock and damage could be done.
Charge cooling increases knock resistance, or using higher additive fuel (race fuel) ensures proper consistent fueling to meet desired power and torque numbers from a given displacement.
The other remaining trick for high HP/L is high revs with a limit to torque or make a one-off glory run dyno to fool the punters (Ala TVR Cerbera, BMW M3 E36).
Ford and Mercedes have called for higher octane fuels due to the current trend of high HP/L motors, there is only so much existing EFI systems and engine design can do with conventional unleaded fuel, and this has been studied in countless papers.
Edited by TwinExit on Tuesday 6th November 14:14
Olivera said:
Again I've looked at the A45 dyno graph, I wouldn't describe it as peaky in any way.
That is peaky for a turbocharged motor, it resembles a Honda or BMW NA motor, however this is a knock limited power band rather than of VE.The green line represents power, it only makes its headline power near redline.
The torque 'curve' is flat by the mapping, and is kerbed to 310-330 lbs/ft mark, hardly earth shattering yet deliberately kept this way so the 2 litre motor doesn't operate too close to conditions that invite knock.
TwinExit said:
That is peaky for a turbocharged motor, it resembles a Honda or BMW NA motor, however this is a knock limited power band rather than of VE.
The green line represents power, it only makes its headline power near redline.
The torque 'curve' is flat by the mapping, and is kerbed to 310-330 lbs/ft mark, hardly earth shattering yet deliberately kept this way so the 2 litre motor doesn't operate too close to conditions that invite knock.
Peaky in my understanding is a torque curve that peaks at one rpm, like the FQ400 where everything happened in a very narrow rpm band and which would need many gears to make the most of it. This on the other hand is a very nice power delivery, yes more NA than turbo and for the better for it. I don't like engines where the whole experience is determined by the max flow of the turbo, I rather like this. Torque is limited not just for knock, but also to keep cylinder pressure and blow by under control, to preserve the whole driveline from excessive twist, basically to keep the whole thing whole. Nothing new, and nothing wrong with delivering power up high, it is the same with other good turboed sports cars, e.g. Ferrari 488 and the 720s, and this is actually higher specific torque already (longer stroke engine though) so don't see the issue...The green line represents power, it only makes its headline power near redline.
The torque 'curve' is flat by the mapping, and is kerbed to 310-330 lbs/ft mark, hardly earth shattering yet deliberately kept this way so the 2 litre motor doesn't operate too close to conditions that invite knock.
Edited by Onehp on Tuesday 6th November 15:02
TwinExit said:
I am sorry, but that just an ideological statement and wishful thinking.
Knock control is a 'reactive' system, it only starts to dial back on boost, ignition timing and change injector pulse width when knock occurs, it cannot anticipate knock. No system can.
Fuel quality and additive content will vary pump to pump, day to day, and its sensitivity to knock will certainly increase on a hot /hard run engine - especially at high speed runs. If you run a motor with ignition and fuel maps just under the threshold of knock on day 1, day 2 or day 3-4-5-6 the motor may knock and damage could be done.
Charge cooling increases knock resistance, or using higher additive fuel (race fuel) ensures proper consistent fueling to meet desired power and torque numbers from a given displacement.
The other remaining trick for high HP/L is high revs with a limit to torque or make a one-off glory run dyno to fool the punters (Ala TVR Cerbera, BMW M3 E36).
Ford and Mercedes have called for higher octane fuels due to the current trend of high HP/L motors, there is only so much existing EFI systems and engine design can do with conventional unleaded fuel, and this has been studied in countless papers.
First a note on the diluting and lower knock resistance. GDI with modern high pressure fuel systems will atomise the fuel and inject it so late that it basically burns before hitting the walls and diluting with oil remains there is possible, this is only an issue with early DI and indirect injection methinks.Knock control is a 'reactive' system, it only starts to dial back on boost, ignition timing and change injector pulse width when knock occurs, it cannot anticipate knock. No system can.
Fuel quality and additive content will vary pump to pump, day to day, and its sensitivity to knock will certainly increase on a hot /hard run engine - especially at high speed runs. If you run a motor with ignition and fuel maps just under the threshold of knock on day 1, day 2 or day 3-4-5-6 the motor may knock and damage could be done.
Charge cooling increases knock resistance, or using higher additive fuel (race fuel) ensures proper consistent fueling to meet desired power and torque numbers from a given displacement.
The other remaining trick for high HP/L is high revs with a limit to torque or make a one-off glory run dyno to fool the punters (Ala TVR Cerbera, BMW M3 E36).
Ford and Mercedes have called for higher octane fuels due to the current trend of high HP/L motors, there is only so much existing EFI systems and engine design can do with conventional unleaded fuel, and this has been studied in countless papers.
Edited by TwinExit on Tuesday 6th November 14:14
On the above, the point is that modern knock sensor enabled ECU will prevent knock to become a massive problem, not to prevent all of it. Big difference.
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