Over 100bhp per 1000cc...
Discussion
Without access to the mass airflow before and after, transmission loss fudge factor etc, in isolation it's quite misleading as I understand it. You only have to factor a few % difference to make the figures look much more appealing Factory racing cars can only produce 420bhp (ish) from the 4.3 litre engine, it has been posted why this is the limit. It's not a Bamford Rose fanboy issue, it's a matter of fact. If they have done some headwork to this car, then fair enough, but on standard internals, 420bhp (ish!) is the maximum.
I remember Tony's old green meanie went on the dyno as standard and kicked out a reading, after the fudge factors were applied of 509bhp. Needless to say...
I remember Tony's old green meanie went on the dyno as standard and kicked out a reading, after the fudge factors were applied of 509bhp. Needless to say...
These dyno results are also over 4 years old!
Also, is it usual for the transmission losses to be so high? (103bhp of a total of 442bhp. That's 'only' 339 horses finding their way to the tarmac).
(BTW, BMW have been producing '100bhp per litre' engines for their M3s since 1996. The first was the 3.2l e36 Evo engine that produced 321bhp).
Also, is it usual for the transmission losses to be so high? (103bhp of a total of 442bhp. That's 'only' 339 horses finding their way to the tarmac).
(BTW, BMW have been producing '100bhp per litre' engines for their M3s since 1996. The first was the 3.2l e36 Evo engine that produced 321bhp).
Edited by Bravo73 on Saturday 25th May 17:39
toohuge said:
The dyno sheet states this to be: Aston Martin race car......
Either way, 100bhp/litre is not unheard of on a properly designed and optimized na engine - especially if it has been optimized for the trace track.
Chris
Either way, 100bhp/litre is not unheard of on a properly designed and optimized na engine - especially if it has been optimized for the trace track.
Chris
both dyno sheets hint at a race car (dog box)Really surprised they reckon they are losing ~100BHP (23.2%) through the drive train on each run! (goes to Yeti's point)
I notice they did the runs in 5th as well, more often it is 3rd or 4th.
It would be interesting to know the WHOLE story.
When I was developing the SC package on my Honda S2000 we always worked 18% drive train loses.
The F20C in the Honda produce 120 BHP/litre from the factory (held the NA record for a fair while)
I managed to get 212BHP/litre out if it
Correct, there is no reason why a modern day engine should not achieve 100BHP per litre, care points here with the AMV8 is that it came from Jaguar at well below that power output from basic engine design from late 90’s / early 2000’s, and in mid 2000’s for both 4.3 and 4.7L that magic specific power output ideal the factory also did not achieve.
The base engine is possible of making that power output, but when EU5 or EU6 emissions hardware that fits within package constraints (very difficult) is bolted to the engine, the power drops significantly.
Importantly here, the race car spec mentioned does not have air induction system fitted AT ALL, it has foam airfilters fixed straight onto air pipes which go to the throttles, it also has a motorsport cat fitted to a silencer which is basically a straight through pipe and fully blue printed and ported motor. All of which would not just fail emissions standards, but would fail noise drive-by and annoy the hell out of the driver because the package could not be switched ‘silent’ when spirited driving is desired. The biggest issue with the foam air filters is that there is no real protection to stop water ingress, meaning it is not a wise update to carry across to the road, I have also found the foam filters promote stall at return to idle (motorsport cars run 900/1000 rpm idle (not 750rpm) to stop this), and when fitted to Sportshift gearbox this condition is yet further aggravated.
Anyway…. Onto the dyno analysis…
The first question any engineer or person looking at data should ask themselves is… “what is wrong here”, only then when all the possible errors to give an incorrect reading are removed can we be certain the result is good enough to inform others. So, what is wrong here…. well, lots as it happens..!
The first 4.3L race car engines and power output was developed by me and released by the factory to the first 17 customers, then along came prodrive to took over the program, but the first spec N24 @ 4.3L was a factory delivered project. The engines were all handmade (blueprinted and ported) and dyno tested and the batch of 27 engines we made, from memory (I did all the tests!), dyno’d at between 410 and 425’ishBHP flywheel power. I don’t believe there is any difference to those engines and the engine that generated the data here which would affect flywheel power, so this raises an eyebrow for me to delve deeper….
The data reports peak power at 7760 rpm – what road car revs to this? So for correlation to what the road car would deliver at this engine spec we need to look at the data at 7300 rpm – and that is the figure which the road car would return if it had all the engine spec changes applied – first bit of misleading data…
The data reports wheel BHP as being 339BHP and CALCULATES a flywheel BHP of 442BHP meaning over 100BHP transmission losses – Really..! the road car gearboxes don’t have this frictional power loss and the title of the graph states that the cars is “Aston Martin with dog box”, so I would guess somebody has built a special gearbox for the car, and one would assume this special box returns less frictional power loss than a standard road car gearbox (or why else build it??) so its frictional power loss result of over 100 BHP I don’t believe meaning the back calculated flywheel power result is VERY compromised – 2 strikes and out for me, I would throw the graph in the bin at this point… BUT….
The best is saved for last. Power correction figures…..
If an engine is tested at very high altitude and high ambient air temp the flywheel power will be lower than an engine tested at below sea level with very cold ambient. For this reason a correction factor was created to return a calculated normaliser result at somewhere in the middle for when engines are tested at these extremes – the correction factor returns results at ambient pressure of 1013.25mbar @ 25 degrees C by taking away power or adding it on for engines above or below the normalised references.
The data here does not tell us it if has been corrected to this standard, we assume so, we are told the data was collected @ 1014mbar and 20degrees C. This would mean the correction factor would remove a little power for the ambient pressure but would take some considerable power away because the air temp was too low – but because we cannot see the raw data, we just don’t know. Then, on searching for the correction factor we see that the datasheet reports standard ‘DIN 70020’ – WTF..! This is a German correction standard linked to PS (often called metric horsepower) which has a different calculation to get from Kilowatts to PS, and should not ever be called BHP. In the trade, normally if we talk of power using DIN, its often metric (PS) and if we talk of ISO standards we talk in Kilowatts and calculate (British) BHP – this is the norm within the industry.
For example 4.3L V8 is 283.3 KiloWatts or (*1.341) 380 BHP or (*1.36) 385.28 PS (but this should not ever be termed BHP) – the datasheet reports DIN, so one normally in the trade would expect to see the result in PS here not BHP when the word DIN is used.
Long story short, there are some errors in this data to rule it of very limited use for my eyes, but, if the gearbox losses seemed normal, raw data was corrected for ISO1585 and not DIN 70020, BHP was not metric, the test speed was 7500 rpm, then about 420BHP flywheel power would be the scores on the doors.
Dyno power testing is a very precise science which needs to be undertaken by folk who don’t believe a figure which is reported until they have crossed all potential errors off the list. In the world of aftermarket I have yet to come across a facility which truly understands all these factors and calibrate their facility robustly. This is why I record the airflow data from the mass airflow meter from engine management system, because aside from engine friction, flywheel power is a result of airflow in.
Like cigarettes, dyno reports should come with massive health warning..! and this one needs it..!
The base engine is possible of making that power output, but when EU5 or EU6 emissions hardware that fits within package constraints (very difficult) is bolted to the engine, the power drops significantly.
Importantly here, the race car spec mentioned does not have air induction system fitted AT ALL, it has foam airfilters fixed straight onto air pipes which go to the throttles, it also has a motorsport cat fitted to a silencer which is basically a straight through pipe and fully blue printed and ported motor. All of which would not just fail emissions standards, but would fail noise drive-by and annoy the hell out of the driver because the package could not be switched ‘silent’ when spirited driving is desired. The biggest issue with the foam air filters is that there is no real protection to stop water ingress, meaning it is not a wise update to carry across to the road, I have also found the foam filters promote stall at return to idle (motorsport cars run 900/1000 rpm idle (not 750rpm) to stop this), and when fitted to Sportshift gearbox this condition is yet further aggravated.
Anyway…. Onto the dyno analysis…
The first question any engineer or person looking at data should ask themselves is… “what is wrong here”, only then when all the possible errors to give an incorrect reading are removed can we be certain the result is good enough to inform others. So, what is wrong here…. well, lots as it happens..!
The first 4.3L race car engines and power output was developed by me and released by the factory to the first 17 customers, then along came prodrive to took over the program, but the first spec N24 @ 4.3L was a factory delivered project. The engines were all handmade (blueprinted and ported) and dyno tested and the batch of 27 engines we made, from memory (I did all the tests!), dyno’d at between 410 and 425’ishBHP flywheel power. I don’t believe there is any difference to those engines and the engine that generated the data here which would affect flywheel power, so this raises an eyebrow for me to delve deeper….
The data reports peak power at 7760 rpm – what road car revs to this? So for correlation to what the road car would deliver at this engine spec we need to look at the data at 7300 rpm – and that is the figure which the road car would return if it had all the engine spec changes applied – first bit of misleading data…
The data reports wheel BHP as being 339BHP and CALCULATES a flywheel BHP of 442BHP meaning over 100BHP transmission losses – Really..! the road car gearboxes don’t have this frictional power loss and the title of the graph states that the cars is “Aston Martin with dog box”, so I would guess somebody has built a special gearbox for the car, and one would assume this special box returns less frictional power loss than a standard road car gearbox (or why else build it??) so its frictional power loss result of over 100 BHP I don’t believe meaning the back calculated flywheel power result is VERY compromised – 2 strikes and out for me, I would throw the graph in the bin at this point… BUT….
The best is saved for last. Power correction figures…..
If an engine is tested at very high altitude and high ambient air temp the flywheel power will be lower than an engine tested at below sea level with very cold ambient. For this reason a correction factor was created to return a calculated normaliser result at somewhere in the middle for when engines are tested at these extremes – the correction factor returns results at ambient pressure of 1013.25mbar @ 25 degrees C by taking away power or adding it on for engines above or below the normalised references.
The data here does not tell us it if has been corrected to this standard, we assume so, we are told the data was collected @ 1014mbar and 20degrees C. This would mean the correction factor would remove a little power for the ambient pressure but would take some considerable power away because the air temp was too low – but because we cannot see the raw data, we just don’t know. Then, on searching for the correction factor we see that the datasheet reports standard ‘DIN 70020’ – WTF..! This is a German correction standard linked to PS (often called metric horsepower) which has a different calculation to get from Kilowatts to PS, and should not ever be called BHP. In the trade, normally if we talk of power using DIN, its often metric (PS) and if we talk of ISO standards we talk in Kilowatts and calculate (British) BHP – this is the norm within the industry.
For example 4.3L V8 is 283.3 KiloWatts or (*1.341) 380 BHP or (*1.36) 385.28 PS (but this should not ever be termed BHP) – the datasheet reports DIN, so one normally in the trade would expect to see the result in PS here not BHP when the word DIN is used.
Long story short, there are some errors in this data to rule it of very limited use for my eyes, but, if the gearbox losses seemed normal, raw data was corrected for ISO1585 and not DIN 70020, BHP was not metric, the test speed was 7500 rpm, then about 420BHP flywheel power would be the scores on the doors.
Dyno power testing is a very precise science which needs to be undertaken by folk who don’t believe a figure which is reported until they have crossed all potential errors off the list. In the world of aftermarket I have yet to come across a facility which truly understands all these factors and calibrate their facility robustly. This is why I record the airflow data from the mass airflow meter from engine management system, because aside from engine friction, flywheel power is a result of airflow in.
Like cigarettes, dyno reports should come with massive health warning..! and this one needs it..!
BamfordMike said:
Dyno power testing is a very precise science which needs to be undertaken by folk who don’t believe a figure which is reported until they have crossed all potential errors off the list. In the world of aftermarket I have yet to come across a facility which truly understands all these factors and calibrate their facility robustly. This is why I record the airflow data from the mass airflow meter from engine management system
I think this is especially relevant right now and certain people should be reading carefully Good post, I asked earlier about the torque figure for the V8V is 310 a good figure as it seems a tad low to me. I realise that getting it to hold torque at higher revs is desirable for power given the direct link between the two but normal convention would be to rock the torque curve towards the higher end sacrificing low end but not ultimate peak torque.
A V8V is on my radar for a car to own but it seems that a much older and 'simpler' AJP8 in the Cerbera knocks it into a cocked hat, why?
A V8V is on my radar for a car to own but it seems that a much older and 'simpler' AJP8 in the Cerbera knocks it into a cocked hat, why?
scotpak said:
Lol. The fanboys live! You may now remove your lips from mike's behind Tony !
Bit confused by your remark 
I'm not a BR fanboy ( not even one of their customers!) as you put it. I was just saying that Mikes explanation of the dyno sheets was very well presented in a form that most on here would follow and fully understand. I don't think he was trying to baffle us or self promote - it was just an explaination in ,I feel, plain English from someone who is highly respected by many and quite obviously got huge knowledge of the development, both present and past, of AM powertrains.
So if you feel that makes me an arse kisser then I'm sorry you feel that way.
scotpak said:
Lol. The fanboys live! You may now remove your lips from mike's behind Tony !
You're just starting to sound like you have a major chip on your shoulder. Regardless of whether you or anyone else buys product from Mike, he takes the time to write detailed posts on technical aspects that he has a great understanding of. Unless you claim he doesn't? If so, please you or someone you trust could come on and take the time to explain things better.Tony V12V said:
Bit confused by your remark
I'm not a BR fanboy ( not even one of their customers!) as you put it. I was just saying that Mikes explanation of the dyno sheets was very well presented in a form that most on here would follow and fully understand. I don't think he was trying to baffle us or self promote - it was just an explaination in ,I feel, plain English from someone who is highly respected by many and quite obviously got huge knowledge of the development, both present and past, of AM powertrains.
So if you feel that makes me an arse kisser then I'm sorry you feel that way.
No need to explain yourself to little ol me. Im just a random guy on the net on this public forum.I'm not a BR fanboy ( not even one of their customers!) as you put it. I was just saying that Mikes explanation of the dyno sheets was very well presented in a form that most on here would follow and fully understand. I don't think he was trying to baffle us or self promote - it was just an explaination in ,I feel, plain English from someone who is highly respected by many and quite obviously got huge knowledge of the development, both present and past, of AM powertrains.
So if you feel that makes me an arse kisser then I'm sorry you feel that way.
Anyway you sound like an intelligent sensible guy and I have obviously upset you a wee bit and for that I apologise.
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