n55 vs n55HP - How do we get that extra power and torque?

Originally Posted by K-A

Actually the Mustang comparo I was using is a 2003 GT which I find is a very accurate basis of HP/Weight/RWHP/Trap Speed aligning. It gets 225 RWHP with a 5 Speed Manual which equated to 260 crank HP.

It does EXACT times the 535i does, 14.0 @ 100 as a solid basis. Sometimes under, sometimes (but rarely) over. The 535i on the other hand has trapped OVER 100 MPH.

The GT is almost 3200 lbs, the 535i almost 4100 lbs. So you can quickly figure the 535i needs an extra 80 crank HP to simply tie it. Now, you can make the argument that the 535i has more gears, etc., but IMO that would be matched or even overshadowed by the GT's lack of drivetrain loss, comparatively speaking, with a Manual.

About the drag times website. First off, to make it accurate, since it's determining numbers based on race weight, you have to add a human being to the car, taking the 535i's weight easily over 4200 lbs. Then, we all can come to a conclusion that the Edmunds time was in a lousy environmental condition rendering its time freakishly low, considering we have several stats of 99-101 MPH.

Again, every single way I can look at this, be it on a "VS 2003 Mustang GT who puts out identical numbers in an 800 lb less frame and less drivetrain loss due to being a Manual", 20% HP addition over the 277-280+ RWHP we've seen from N55's, using that 'Calculator", comparing to a G37 which traps similarly with 330 HP AND less weight.... it all draws to the same crank HP figure required to make the average 535i stat (including documented trap speeds and RWHP), which is 325-340 HP.

What does a 2003 Mustang with V8 and a 5 speed manual transmission have to do with modern car with turbochargers and a highly efficient 8 speed auto? The 535's torque converter physically locks at 1,500rpm, which at that point it has similar losses to a manual transmission, but with today's much lighter/efficient components. The 2003 Ford most likely has more drivetrain loss than the 2011 BMW. In a race over a specific distance, the BMW's 0.2 second shifts are far superior to the 1+ second manual shifts, during which time the car does not accelerate and does not contribute to an improved trap speed. The BMW also enjoys a huge gearing advantge over the soon to be antique Mustang. Also with respect to your race weight claim, a car's curb weight includes a full tank of gas, so the 535 is carrying an extra 110lbs of gas. The weather conditions looked to be fine for the Edmunds 95mph test, unless you consider a 2mph crosswind to be horrible. Edmunds also tested another 535i in a comparo with the A6 and that one trapped at 97mph. So, I count three 535i data points under 100mph and two above in this thread.

Now the G37 (or the heavier M37 which traps at 102hp with a 7spd auto) has a normally aspirated engine. Your formula does not take into account the different shape of the horsepower and torque curves of turbo vs. NA engines. Supercharged engines also have different shapes than the turbo engines. The area under the curve is what determines how much work a motor can do, not the peak horsepower. With identical peak horsepower, a turbo motor will perform more work (the integral of power over time) than a NA engine. The Infiniti has more peak horsepower, but it also has much less torque throughout the curve. Without torque the wheels don't turn and the car doesn't move. Horsepower is just a measure of the rate at which torque is applied. Thus work is the total torque applied. The Infiniti's lack of torque at the lower rpms hurts the trap speed. Note the Infiniti's peak horsepower doesn't happen until 7,000rpm, a full 1,200rpm later the the N55. The N55 also reaches its peak torque at 1,200rpm and maintains that value until 5,000rpm. The M37 doesn't reach it's peak until 5,200rpm. Since you know the formula, you should be able to calculate the massive difference in power at low- to mid-range rpms between the two motors. Thus the M37 is incapable of doing as much work as the 535 during acceleration despite having a higher peak horsepower.

Now if you are still collecting data to "prove" your point, do a search on N55's on Mustang dynos and don't be too surprised if you see results in the 240s. I wasn't.

@D.
Stop debating basic mechanics.
Pack the lederhosen instead.
And go enjoy the bierfesten!

Originally Posted by dunderhi

What does a 2003 Mustang with V8 and a 5 speed manual transmission have to do with modern car with turbochargers and a highly efficient 8 speed auto? The 535's torque converter physically locks at 1,500rpm, which at that point it has similar losses to a manual transmission, but with today's much lighter/efficient components. The 2003 Ford most likely has more drivetrain loss than the 2011 BMW. In a race over a specific distance, the BMW's 0.2 second shifts are far superior to the 1+ second manual shifts, during which time the car does not accelerate and does not contribute to an improved trap speed. The BMW also enjoys a huge gearing advantge over the soon to be antique Mustang. Also with respect to your race weight claim, a car's curb weight includes a full tank of gas, so the 535 is carrying an extra 110lbs of gas. The weather conditions looked to be fine for the Edmunds 95mph test, unless you consider a 2mph crosswind to be horrible. Edmunds also tested another 535i in a comparo with the A6 and that one trapped at 97mph. So, I count three 535i data points under 100mph and two above in this thread.

Now the G37 (or the heavier M37 which traps at 102hp with a 7spd auto) has a normally aspirated engine. Your formula does not take into account the different shape of the horsepower and torque curves of turbo vs. NA engines. Supercharged engines also have different shapes than the turbo engines. The area under the curve is what determines how much work a motor can do, not the peak horsepower. With identical peak horsepower, a turbo motor will perform more work (the integral of power over time) than a NA engine. The Infiniti has more peak horsepower, but it also has much less torque throughout the curve. Without torque the wheels don't turn and the car doesn't move. Horsepower is just a measure of the rate at which torque is applied. Thus work is the total torque applied. The Infiniti's lack of torque at the lower rpms hurts the trap speed. Note the Infiniti's peak horsepower doesn't happen until 7,000rpm, a full 1,200rpm later the the N55. The N55 also reaches its peak torque at 1,200rpm and maintains that value until 5,000rpm. The M37 doesn't reach it's peak until 5,200rpm. Since you know the formula, you should be able to calculate the massive difference in power at low- to mid-range rpms between the two motors. Thus the M37 is incapable of doing as much work as the 535 during acceleration despite having a higher peak horsepower.

Now if you are still collecting data to "prove" your point, do a search on N55's on Mustang dynos and don't be too surprised if you see results in the 240s. I wasn't.

Well, a Mustang dyno tends to read considerably lower than a Dynojet, and I've found Dynojet's to be more accurate in terms of reading crank HP.

All I know is that 280 RWHP, which we've seen from a 535i equals 336 HP if you consider 20% drivetrain loss, and if you want to consider 15% drivetrain loss (highly doubtful you'll see that little) you're still looking at 322 HP. What confirms this as realistic to me is the 101 MPH trap speeds the car has attained. Yes, there have been lower, but again, two different publications with two different cars got 101 MPH.... that's good enough for me to consider it a solid good trap for this car.

Therefore, if you do a power-weight-trap ratio of 4200 lbs, 325-340 HP, you arrive at around 100 MPH. Again, this matches up with the Dynojet readings.

Of course we can analyze the hell out of it, and maybe you're right, maybe you're wrong, but in my opinion, the most tangible facts add up to what has to be around a 330 HP rating on this car, unless it has a freakishly low drivetrain loss, or somehow defies odds in attaining a 101 Trap Speed on more than one occasion with a measly 240 RWHP.

Originally Posted by K-A

Well, a Mustang dyno tends to read considerably lower than a Dynojet, and I've found Dynojet's to be more accurate in terms of reading crank HP.

All I know is that 280 RWHP, which we've seen from a 535i equals 336 HP if you consider 20% drivetrain loss, and if you want to consider 15% drivetrain loss (highly doubtful you'll see that little) you're still looking at 322 HP. What confirms this as realistic to me is the 101 MPH trap speeds the car has attained. Yes, there have been lower, but again, two different publications with two different cars got 101 MPH.... that's good enough for me to consider it a solid good trap for this car.

Therefore, if you do a power-weight-trap ratio of 4200 lbs, 325-340 HP, you arrive at around 100 MPH. Again, this matches up with the Dynojet readings.

Of course we can analyze the hell out of it, and maybe you're right, maybe you're wrong, but in my opinion, the most tangible facts add up to what has to be around a 330 HP rating on this car, unless it has a freakishly low drivetrain loss, or somehow defies odds in attaining a 101 Trap Speed on more than one occasion with a measly 240 RWHP.

20% loss? What are you driving an 85 Buick? Sorry KA - you are reaching on this thread. I mean, I am glad you love your car (I do too) but your drinking the cool aid buddy.

Again, the only benefit of a dyno measuring at the wheels is for before and after mods. With this you can see a % increase of previous number. Note I did not say hp/torque because they do not accurately measure them, in order to do that you need a baseline which anything other than crank testing can not do effectively.

Originally Posted by Sophisto

@D.
Stop debating basic mechanics.
Pack the lederhosen instead.
And go enjoy the bierfesten!

I just mentioned to Mrs D that I needed to start putting some clothing aside to start packing. I've also been watching the Munich snow forecasts, so far it's good.

Originally Posted by K-A

... or somehow defies odds in attaining a 101 Trap Speed...

It is called a turbocharger, but Sophisto is right; there is no neeed to for me to explain mechnics to you. So believe whatever you wish, but your car is only as fast as you can drive it and you won't actually know how fast it is until you take it to the track yourself. So, I'm done with the couch racing, my 6spd/3815lb/265hp 335d vs. your 8spd/4056lb/340hp 535i - let's do it! We can meet in Indiana, Iowa, or some place like that. Your calculators will show an easy win for you, I say it will come down to the driver.

+1 to miami

Just noticed you leave in a couple of days. Did mine in October and little green with envy - wish I was going back :-)

Mrs D going to let you open it up on the autobahn?

Interesting thread. I think measuring horsepower has its challenges even under current standards. Under new standards, as I understand it, all the belt driven accessories, emission controls etc. have to be engaged to capture the actual configuration of the motor. And this was different before 2004 because issues like the type of fuel, and the calibration of the engine controls were subject to interpretation.

Dynamometer readings at the wheels have their challenges because how much air is getting into the car with the hood up on a stationary basis, the air pressure in the tires all have an impact on the reported outcome. Considering Dunderhi's point, setting aside the actual numbers, K-A is merely capturing the impact of the turbo and other engine refinements to reported horsepower of an older Mustang. The new N55 engine performs like a NA car with more HP, recognizing that peak hp is not the sole indicator of performance.

If I can get the fun out of a car with a "reported" 100 hp and get to 60 mph in say 5.5 seconds I'm okay. Fact is the 535 performs quite well for a fairly heavy sedan. It's performance is comparable to a 1969 Mustang Mach 1 with a 428 Cobra Jet engine - shows you how far technology has come.

Originally Posted by miamiboyca

Just noticed you leave in a couple of days. Did mine in October and little green with envy - wish I was going back :-)

Mrs D going to let you open it up on the autobahn?

Mrs D decided it was too cold in Munich in February, so I'm on my own. As far as opening it up, I have been watching the weather forecasts closely, but the Coding Forum even closer. I really want to remove the top speed limiiter.

Originally Posted by dunderhi

Now the G37 (or the heavier M37 which traps at 102hp with a 7spd auto) has a normally aspirated engine. Your formula does not take into account the different shape of the horsepower and torque curves of turbo vs. NA engines. Supercharged engines also have different shapes than the turbo engines. The area under the curve is what determines how much work a motor can do, not the peak horsepower. With identical peak horsepower, a turbo motor will perform more work (the integral of power over time) than a NA engine. The Infiniti has more peak horsepower, but it also has much less torque throughout the curve. Without torque the wheels don't turn and the car doesn't move. Horsepower is just a measure of the rate at which torque is applied. Thus work is the total torque applied. The Infiniti's lack of torque at the lower rpms hurts the trap speed. Note the Infiniti's peak horsepower doesn't happen until 7,000rpm, a full 1,200rpm later the the N55. The N55 also reaches its peak torque at 1,200rpm and maintains that value until 5,000rpm. The M37 doesn't reach it's peak until 5,200rpm. Since you know the formula, you should be able to calculate the massive difference in power at low- to mid-range rpms between the two motors. Thus the M37 is incapable of doing as much work as the 535 during acceleration despite having a higher peak horsepower.

+1

This is a very good description of what is actually happening.

The 8 speed gives the 5er a nice advantage because:

1. The gear ratios are closer, so peak torque from 1,200 on up and the gear ratio of 1st gets the RPM's to the top of the curve quicker.

2. When up shifting, the RPM's drop less, so you stay nearer the top of the curve after an up shift.

As long as shifting takes place quickly, these two advantages are significant because you put more of your power to the pavement more of the time during a run.

-Corey

Originally Posted by PeterC4

. Fact is the 535 performs quite well for a fairly heavy sedan. It's performance is comparable to a 1969 Mustang Mach 1 with a 428 Cobra Jet engine - shows you how far technology has come.

I actually was driven back then in one of those.
That car was spectacular, but in no way comparable to the well driveable F10.
These Mustangs were quite dangerous and hard to keep on the road.
Besides that, harsh as hell, very loud and rather uncomfortable, lacking any travelers space.
Nice cars though, for someone young and in that era.
I seldomly ever floor the accelerator of my F11 diesel, there is so much torque on a wide rev span the car is always faster than anything around. Flexibility is more of an interest in my driving than the first couple of seconds after a standstill. I hate standstills and try to forecome them as much as possible. Taking off is almost always in traffic, slower traffic, so the sprint capabilities of the car are seldomnly usable. Whilst flexibilty between 50-90 MPH is being used all the time. And at that the diesel is fabulous.
So far for this discusssion on the interesting but not very usable sprint capabilities of the F10 535.

Originally Posted by Sophisto

I actually was driven back then in one of those.
That car was spectacular, but in no way comparable to the well driveable F10.
These Mustangs were quite dangerous and hard to keep on the road.
Besides that, harsh as hell, very loud and rather uncomfortable, lacking any travelers space.
Nice cars though, for someone young and in that era.
I seldomly ever floor the accelerator of my F11 diesel, there is so much torque on a wide rev span the car is always faster than anything around. Flexibility is more of an interest in my driving than the first couple of seconds after a standstill. I hate standstills and try to forecome them as much as possible. Taking off is almost always in traffic, slower traffic, so the sprint capabilities of the car are seldomnly usable. Whilst flexibilty between 50-90 MPH is being used all the time. And at that the diesel is fabulous.
So far for this discusssion on the interesting but not very usable sprint capabilities of the F10 535.

If you really want to have some fun look at this test of a 396 Cubic In. 1969 Impala with a reported 265 hp

Originally Posted by dunderhi

but your car is only as fast as you can drive

Well then it's too fast cause I already got a speeding ticket .

So what do you guys think we're seeing for drivetrains loss on these cars? No way it'll be better than 15%? Either way, crank HP is for the marketing firms and what's most important is wheel HP and more so trap speeds. I really feels that if we saw an engine dyno of the N55 we'd see something significantly higher than what's advertised, but of course that won't change the performance figures we have on the car.

And I'm surprised nobody's come in here with times or dynos of their own, I know someone has to have some firsthand stats!

Maybe I should post s thread in the 3er forums to see if they've dynoed N55's.

Originally Posted by K-A

Well then it's too fast cause I already got a speeding ticket .

So what do you guys think we're seeing for drivetrains loss on these cars? No way it'll be better than 15%? Either way, crank HP is for the marketing firms and what's most important is wheel HP and more so trap speeds. I really feels that if we saw an engine dyno of the N55 we'd see something significantly higher than what's advertised, but of course that won't change the performance figures we have on the car.

And I'm surprised nobody's come in here with times or dynos of their own, I know someone has to have some firsthand stats!

Maybe I should post s thread in the 3er forums to see if they've dynoed N55's.

Automobile magazine did a Dyno comparison of the N54 and N55 September 10, 2010 for the 335 . Tells you quite a bit about both engines.

I'm sure Dinan has put one on the Engine dyno, and has true stock numbers, but they won't release what the N55 truly put down.

Dyno, crank hp, wheels hp, whatever.
Can't we just all agree for a car that weights as much as SUVs, the F10 535i is a pretty damn fast car?
It outruns many other competitor light or heavy in a straight line.

Originally Posted by smashhell

Dyno, crank hp, wheels hp, whatever.
Can't we just all agree for a car that weights as much as SUVs, the F10 535i is a pretty damn fast car?
It outruns many other competitor light or heavy in a straight line.

Agreed. The original question on this thread was an interesting one. I think BMW would do well to embrace tuning options. They are to a degree, and I think it gives enthusiasts lots of options and it's a bit of a throw back to the 60 s when you could get so many engine choices. I like the fact that the engines appear to have flexibility. If BMW gave me 2 additional factory options that could be installed at the dealer I think it would increase buyer interest. Then again maybe it's just most of us on this forum.