Engine power measurements

*Plaz* · 04-02-2005, 11:45 AM

I was thinking. (Always dangerous)

Instead of engines always being measured in terms of peak torque and peak horsepower, wouldn't it be more indicative of real-world performance to compare the average power delivered across the entire rev band?

It seems to me the current norm favors those engines with very peaky powerbands, to the disadvantage of better engines with smooth, linear torque and power curves.

Am I wrong? Am I missing something?

lemming · 04-02-2005, 01:16 PM

nah.

you're right.

peak power is meaningless and this is what i was trying to allude to, unless you see how effective it is in accelerating from a standstill and acclerating in various gears while on the move (as measured by autoweek in various gears at different speeds).

there is no question that the BMW "small" N52 while rated at 215hp/185ft#'s will have a flat power curve --that used to be the BMW owner's response to the japanese peaky powerplants.

all i'm pointing out is: the japanese have learned and now have the same breathing tricks and also have flat powerbands --this may not automatically apply to honda motors which are still peaky, but take for example the vq35 engine or subaru's new 3.0 litre flat six. both have very flat power curves and meet/exceed the "big" N52 output.

in theory, gearing can help with acceleration, but the vq35 will always be faster and the subaru will always be hobbled by gearing and AWD frictional losses. the point being, compared to the upcoming IS250 or IS350 or the current G35, either BMW left themselves plenty of room to tune up (unlikely) or they're going to keep selling cars with excellent marketing.

in time, marketing cannot cover mechanical underperformance and there is this trend where auto magazines drive enthusiasts who are counted on by their friends as being relied upon for automotive advice. "we" as a group won't always be pushing BMW's anymore if we know quantitatively that they are more expensive and underperforming.

this has always been the case with the 325 which outsells the 330 3:1 and almost 4:1 but the competition has gotten a lot better about benchmarking the e46 and the upcoming vehicles are a lot more palatable. whereas it used to simply be the I30, the ES300 and the TL3.2 (225hp first gen. car) it's now the G35 (298hp), the same stupid ES330, the IS250 and IS350 (likely 225hp and 300hp) and the still FWD TL (270hp). and this is assuming that cadillac doesn't improve on the CTS for the next generation because it, too, with the 3.6litre engine (260hp) if mated to a manual be great competition.

people who drive the 325 with company money will make it easy. the extra cost is lost on them. but for people who want the 330 but can in reality mostly afford the 325 and are paying with their own money, the competition looks enticing, doesn't it?

it's the same logic that drove the fx35 purchase. the x5 is a decent dynamic benchmark. but the x5 4.4 is ludicrous as a primary commuter vehicle due to fuel economy and price --but the x5 3.0 isn't even an option: 214ft#'s to drive 4600 pounds of weight? for $43-45k. you're kidding, right?

choice is a good thing as it benefits the buyer and pushes BMW harder to stay "ahead". i can already tell you that the "big" N52 is barely staying ahead. we already know on paper in a shootout the G35 is going to smoke the e90 330 --the question is whether the intangibles are going to be enough to keep us interested.

JetBlack330i · 04-02-2005, 03:06 PM

Peak power and torque are meaningfull because you don't have to drive the entire rev band.
Sure you may use the entire rev band to get to a desired speed, but once there, you choose the appropriate gear such that you maximize torque. You spend a lot more time in a certain rev than others. Single weighted average wouldn't make sense.
Think of a CVT where the rev is constant (at least it tries to maintain that).

lemming · 04-02-2005, 07:42 PM

Quote:

Originally Posted by JetBlack330i

Peak power and torque are meaningfull because you don't have to drive the entire rev band.
Sure you may use the entire rev band to get to a desired speed, but once there, you choose the appropriate gear such that you maximize torque. You spend a lot more time in a certain rev than others. Single weighted average wouldn't make sense.
Think of a CVT where the rev is constant (at least it tries to maintain that).

if you ask a BMW executive about the dearth of torque in the 3.0 litre straight six, they'll look you in the face and tell you that although 214ft#'s doesn't seem like a lot, it's available down "low" and is relatively flat.

to that i say: whupdedoo. so is the case for the 3.2 FSI from audi, the vq3.5 from nissan, the all new 3.5 v6 from toyota, the flat six from subaru, the 3.5 v6 from MB.....

....it's like what ross perot said when bill clinton said that he took arkansas public schools from near the bottom of the 50 states to something like 25th: "you got one penny in your pocket and you find a penny on the street --you get excited because you've just doubled your net worth --but you still only worth 2 pennies".

04-02-2005, 11:45 AM	#1
Plaz ••••••• Join Date: Oct 2003 Carmudgeonly Ride: '11 1M Location: Churzee Posts: 17,741	Engine power measurements I was thinking. (Always dangerous) Instead of engines always being measured in terms of peak torque and peak horsepower, wouldn't it be more indicative of real-world performance to compare the average power delivered across the entire rev band? It seems to me the current norm favors those engines with very peaky powerbands, to the disadvantage of better engines with smooth, linear torque and power curves. Am I wrong? Am I missing something? __________________ 2011 1M

04-02-2005, 01:16 PM	#2
lemming Western Anomaly Join Date: Oct 2003 Carmudgeonly Ride: White Orca Posts: 16,612	nah. you're right. peak power is meaningless and this is what i was trying to allude to, unless you see how effective it is in accelerating from a standstill and acclerating in various gears while on the move (as measured by autoweek in various gears at different speeds). there is no question that the BMW "small" N52 while rated at 215hp/185ft#'s will have a flat power curve --that used to be the BMW owner's response to the japanese peaky powerplants. all i'm pointing out is: the japanese have learned and now have the same breathing tricks and also have flat powerbands --this may not automatically apply to honda motors which are still peaky, but take for example the vq35 engine or subaru's new 3.0 litre flat six. both have very flat power curves and meet/exceed the "big" N52 output. in theory, gearing can help with acceleration, but the vq35 will always be faster and the subaru will always be hobbled by gearing and AWD frictional losses. the point being, compared to the upcoming IS250 or IS350 or the current G35, either BMW left themselves plenty of room to tune up (unlikely) or they're going to keep selling cars with excellent marketing. in time, marketing cannot cover mechanical underperformance and there is this trend where auto magazines drive enthusiasts who are counted on by their friends as being relied upon for automotive advice. "we" as a group won't always be pushing BMW's anymore if we know quantitatively that they are more expensive and underperforming. this has always been the case with the 325 which outsells the 330 3:1 and almost 4:1 but the competition has gotten a lot better about benchmarking the e46 and the upcoming vehicles are a lot more palatable. whereas it used to simply be the I30, the ES300 and the TL3.2 (225hp first gen. car) it's now the G35 (298hp), the same stupid ES330, the IS250 and IS350 (likely 225hp and 300hp) and the still FWD TL (270hp). and this is assuming that cadillac doesn't improve on the CTS for the next generation because it, too, with the 3.6litre engine (260hp) if mated to a manual be great competition. people who drive the 325 with company money will make it easy. the extra cost is lost on them. but for people who want the 330 but can in reality mostly afford the 325 and are paying with their own money, the competition looks enticing, doesn't it? it's the same logic that drove the fx35 purchase. the x5 is a decent dynamic benchmark. but the x5 4.4 is ludicrous as a primary commuter vehicle due to fuel economy and price --but the x5 3.0 isn't even an option: 214ft#'s to drive 4600 pounds of weight? for $43-45k. you're kidding, right? choice is a good thing as it benefits the buyer and pushes BMW harder to stay "ahead". i can already tell you that the "big" N52 is barely staying ahead. we already know on paper in a shootout the G35 is going to smoke the e90 330 --the question is whether the intangibles are going to be enough to keep us interested. __________________

04-02-2005, 03:06 PM	#3
JetBlack330i Jaded Join Date: Oct 2003 Location: Austin, TX Posts: 647	Re: Engine power measurements Peak power and torque are meaningfull because you don't have to drive the entire rev band. Sure you may use the entire rev band to get to a desired speed, but once there, you choose the appropriate gear such that you maximize torque. You spend a lot more time in a certain rev than others. Single weighted average wouldn't make sense. Think of a CVT where the rev is constant (at least it tries to maintain that). __________________ SP, black leather, xenon, myrtle Window tint (35% front, 30% rears) Custom Raised clutch stop (DIY) Custom Badge (good for 5 HP) Custom Homelink (DIY) 225/45/17 and 255/40/17 Pilot Sport (non-square)