SteVTEC

Since you're an engineer also, here's a good SAE paper that you might want to check out on the topic.

SAE 2002-01-887: Listening to the Voice of the Customer: Inertia Dyno Horsepower Versus Oem-Rated Net Horsepower

It's pretty well understood how cars behave on dynos, although there are a zillion variables also which is why you see so much variability in the real world. The numbers here should be "about average" for the car (not high or low). One Avalon on one dyno on one day is not necessarily going to give you the golden dyno numbers for a car. Just like one magazine report isn't likely to give you the golden representative 1/4 mile time for a car either.

doug_999

I don't understand - If a dyno number for a given car could be different from the next car (and it is), is it less reliable than your estimate?

RON430

This thread is really a bit baffling. I personally think the Avalon is going to be a very good vehicle and do well for Toyota. But does anyone actually think many Avalons are going to ever get close to that 280 hp at 6200 let alone the 260 lb ft at 4700? Unless that thing is going to come with one stout final gear ( and lower numerical final gear ratio is a great way the auto makers use to increase hp peaks), the Avalons transmission ECU is going to keep it well away from either peak. And using a modelled dyno curve to surmise the superiority of Toyota engines over Honda or Nissan seems like a poor use of bandwidth.

If the sophistication of the motor is driven by the hp and torque peaks where do you put Chryslers hemi with 340 hp at 5000 and 390 lb ft at 4000? Does anyone figure we are going to rank it as superior to the Japanese motors? Especially here - no way. But the ChryCo hemi will be much more satisfying to real word drive from a performance standpoint then anything mentioned here. I guess I am just content with my belief that the Avalon will be the best car at its price point by a lot. The room, pricing, build quality, and yes, performance, are going to be very difficult for any other sedan to match. There are going to be a lot of lucky grandpas driving those things. And maybe a few smart youngsters as well. I would have absolutely no reservations in recommending it to anyone.

I have owned motors made by Toyota, Nissan, Mazda, and Mitsubishi and think they are all pretty good pieces. I have also owned motors made by the big three as well as most of the European makers. But the hemi, SRT or not, is the one that I think I most want to own next. Having the hp and torque peaks closer and at more realistic rpm ranges makes for a much more satisfying driver experience. At least if you are driving a real car in the real world rather then a spec chart on a Playstation.

SteVTEC

No, I just wanted to compare the two since I'm considering both. You're reading into it way too much. And based on the curves (the Acura is a real dyno plot, not estimated), neither of these cars will have trouble staying in their powerbands. The peak torque may be at a high RPM, but remember these are gizmoed out import engines with variable valve timing and variable intake manifolds. Both of them maintain 90% of peak torque over practically the entire range of the engine.

Personally I find the Hemi motor fascinating. It makes more HP/L than Nissan's VK56DE "Endurance" engine despite only having a 2-valve head, pushrods, no variable valve timing, and no variable intake manifold. And that's just the lowly 340hp version. The SRT-8 is nuts.

LOL, well call it what you will, but it's just a different way of analyzing the relative performance of cars, and a pretty accurate one at that. Race engineers use techniques not unlike these. Find me a good stock 300C dyno (dynojet 248c, SAE corrected), and I'll plot the 300C against the Avalon just for kicks.

SteVTEC

The hard numbers are what count. But due to lack of any hard numbers, the estimate I put together is based on a 22% total intertial and parasitic loss for FWD automatic tranny cars on a dynojet 248c chassis intertia dyno as described in that paper. If it were AWD, turbo or supercharged, or a really big engine in a tiny little car (C55 AMG), or Toyota had a history of playing numbers games with their power ratings (like Nissan these days on their VQ35DE engines) then all bets would be off. But none of that is the case here, so this estimate should be accurate to within +/- 1-2%

RON430

Uh, compare what exactly? A made up plot of engine performance to a real one? And if you are interested in both models why don't you just go drive them?

The ability to maintain greater than 90% of torque over given ranges has existed for many, many years by many, many engines - that's almost a given nowadays. And just imagine how it complicates putting more gears in the transmission when you have such a broad power band available. My GS430 has impressive specs in that regard as many engines do. But I can tell you that my GS430 was particularly disappointing at Laguna Seca putting power down. The combination of the engine ECU, the transmission ECU, and the final drive just make it not much fun coming out of slow turns. I was probably very foolish spending the time I did out there but it just showed in the real world what the GS was engineered for.

Racers absolutely use dyno information comparatively. But dynos do not simulate real world conditions very well. Theory generating equations to correct dyno data are usually very simplistic rarely accounting for more than air density and maybe a simple temperature, and the corrections are often disappointing, even for just comparing dyno runs on different days. In any system you develop theory which allows you to model. Models are useful but then you move on to experimentation, in this case a real car on a real dyno. If the model prediction doesn't match the experiment, you figure out where your differences are at - the basic theory, the model, or the experiment. I am glad that creatively grafting minimal information on the Avalon motor to the Acura's performance curve has helped you decide what car to buy. As I recall, a similar process worked very well with prehistoric mosquitoes and frog DNA in Jurassic Park but I would rather just go drive the things and see which one I like better. But then I probably have never driven a mathematically average engine in a mathematically average car on a mathematically average day. As for dyno results of an actual car coming in within 1 to 2% of your model, that would be great. That would also be a lot closer than I have seen for corrected dyno data just comparing a car to itself on different days or in different locations. Seems I recall that SAE recommends the auto makers select hp and torque numbers that will not vary more than +/- 7% across the production run.

Good luck with your choice, both cars should be very satisfying for their intended purpose.

Bean

iTrader: (1)

As an engineer, you should know better than that... getting one dyno vs one estimate isnt any better... it'd have to be a bunch... which he gave his reasoning for it just a minute ago

now if you want to go find 10 near-identical avalons and ask their owners to dyno their cars on the same day in the same weather, etc... be my guest...

one can only speculate here and i think the mere fanboys are reading into this thread just a tad too much...

thanks for the in-depth info SteVtec!!! its nice reading good data from someone that actually knows what they are talking about with regards to gearing, torque, horsepower, rpm and resulting acceleration...

SteVTEC

Ron, you're still missing the point.

doug_999

I guess you are not an engineer.....yet

RON430

I think we both are.

SteVTEC

Not really. I'd explain more, but this isn't the right medium for it. I'm working on a little something for another site. When it's completed I'll link it here at CL and then you can say whatever you want. For now I'll just agree to disagree though.

Celicamaro

Very good point. I've already told StevTEC before at Maxima.org to stop looking at graphs and start livin in the real world. It's like looking at **** online vs actually courtin the chick and doin her. There's just too many variables involve. But as I've said before, StevTEC's intention is Honda bashing, He has no intention of DECIDING between a TL or Avalon, if you know him from his own site Maxima.org. He admits he hates being associated with a brand name make and consistantly knock Acura for torque steer and it's recent quality issues(tranny recall). This whole thread is to show that Honda's 3.2 Liter SOHC with a slightly outdated variable valve timing system is inferior to a brand new Toyota DOHC 3.5 liter with a more sofisticated variable valve timing system. It's not even a fair comparison to begin with, but he knows that.

Fair (IMO) would be more like Nissan's 3.5 DOHC vs Merc's 3.5 DOHC vs Toyota's 3.5 DOHC or Hondas 3.2 DOHC(nsx) vs e36 BWM M3's 3.2 DOHC. Even then each motor would still respond, feel, and sound different because they were design for different purposes.

RON430

I think it is probably pretty obvious to everyone that whatever he is doing, he is not comparing two cars with an intention to purchase. I am not saying he may not purchase one or both of the TL or Avalon, both of which I think are very good cars (OK, maybe I lean toward the Avalon but it isn't because of the engine). But to me, if you are seriously interested in buying a car, get your head out of the brochures and go drive the things. Dyno's don't account for additional factors like vehicle weight, unsprung weight, engine and transmission control programming, chassis dynamics, brakes, seats, visibility, cup holder location, and on and on and on.

Now if you have some other agenda or want to demonstrate your expertise with somebody's software, that's fine. It just isn't the way I evaluate cars to spend my money on. People who model reality can get a little too wound up in their models. But when you get to the point where Doug999 recommends getting an Avalon on a dyno and seeing what it does and you tell him he doesn't understand and the model is more relevant, well, I guess baffling is just the best answer I can come up with. I think that the vast majority of people visiting here understand that a specific dyno curve on a specific car is probably not representative of any other car but the model may not be representative of any car that you actually buy. Probably quite a few of us here have experience with dyno results, either for the street or racing applications (or both), and they are valuable. But they rarely tell you what the car will actually do on the street (or track). Which is why you get your butt into the thing and see what it does. I spent a maddening amount of time trying to improve an engine dyno model with increased sensing but finally gave up. We instrumented outside air temperature, air temperature at three points in the intake manifolding, coolant temperature, lubricant temperature, cylinder head temperature (multiple spots), block temperature (multiple spots), fuel temperature, temperature deltas, barometric pressure, and on and on and on. When we were doing an engine in a car we tried to record additional lubricant temperatures, gearing, tire info, and on and on and on. All we got to was a never ending path of other parameters that seemed to be needed to be input and I can't say that the data was anymore useful. It was just useful in comparing options on the specific package we were putting together at that time. The driver had to get in the seat on a specific track on a specific day and see what it was like. So when I made the point about why don't you just go drive the two things and got the comment back that I was missing the point, I guess I could agree, especially if there is something other going on here then really evaluating for a purchase. But he obviously also missed my point. I am still baffled about making a purchasing decision from a dyno curve, real or imagined. As for which engine (or manufacturer) is "better" by looking at the dyno curve, real or imagined, that's really pushing IMO. Engines, especially street engines, are tradeoffs. Every manufacturer does it. And in all honesty, engines today are all very good, with the exception of the occasional oil drinking grenades from bimmer (sorry Doug). But then I guess I do miss the point. Some car salesman will light a candle the day a customer comes in with a made up dyno curve of a new model and say that was the deciding factor in his purchase. Whodathunk.

SteVTEC

Ron, you and I are on different tangents and you're just not seeing my angle. And I never said I was making a car buying decision just based on this. That's absurd and you know it. If power was all I was interested in then I would just go buy a 300C, but I'm not even interested in that car in the first place for many other reasons besides power. This is merely a tool to help understand the relative performance of the cars better. For all I know the Acura might have had gearing short enough to make up the torque deficit as some other Hondas can (Acura CL-S 6spd vs Maxima 6spd), but not in this case. The 5AT gearing isn't quite aggressive enough. It would need a 4.80-5.00 final drive to pull that off. The reviewers of the TL would not be complaining about lack of torque anymore if it had gears like that. They'd be complaining about lack of fuel mileage.

Will link an article I'm working on right now here at CL when I'm done, hopefully in a few weeks. And this will totally baffle Celicamaro, but the article actually shows a "torqueless" Honda getting the upper hand on a "world class torque" Nissan. I come off as a "honda hater" to most Honda folks because I dare to be critical of legit shortcomings in those cars. But I'm the same way with Nissans, Toyotas, and pretty much every car make too. Nissan quality control flat out stinks these days, and Toyotas are still incredibly boring although mechanically near flawless. I guess that makes me a Nissan fanboy?

BTW Celicamaro, why don't you tell everybody here what kind of car you drive? Like I've said countless times on the Maxima.org site, the Acura TL is a great car. Just drop a 3.5L and a sturdy Jatco or Aisin automatic in it and I would probably buy one tomorrow and would probably not even bother test driving a new Maxima. So I guess that makes me a Honda hater?

geez....


Anyways, back to my projects.

Celicamaro

The only thing that baffles me is when you complain that your torqueless accord sukk because you got beat by a minivan in a drag race. If you'd stop messin with graphs and learn to drive, you'd probably win that race. But who the heck gets a kick out of drag racing against minivans anyway? Don't you recall my NSX test drive? The torqueless Acura was faster than the 350Z and feels just as torquey eventho the numbers say otherwise. It didn't have the punch(torque) of my boosted Mr2 turbo, but it was easier and more consistant to drive. Your article will only baffle you when it fails to achieve it's intended purpose.

As Ron and I have said, get out into the real world and test drive the cars and buy the one that feels best to you. Graphs may say something about the engine and tranny, but it doesn't say anything about you, the driver.

The only problem I have is you coming to a Lexus forum to continue your Honda bashing. What is the point of comparing a Honda SOHC 3.2 L to a Toyota 3.5 L DOHC other than to bash Honda? You've already done this over at your site many times. Only difference is your homies got your back over there by agreeing with everything you say(mostly for fear of getting ban since you're one of the admin) All y'all gang up on anyone who defends Honda or say good things about Honda. And we all know winning in an internet forum arguement is all about playing the numbers game. If that doesn't work, you ban the dude who whooped everyones azzes.

While I agree most current Nissans do have quality issues(FX and Q45 are awesome IMO), but have you driven the MR2 spyder or even the Celica GT-S to make bold statements that Toyotas are incredibly boring? In my view, BMW doesn't have anything close to Mr2s driving dynamics eventho they maybe faster due to more HP/torque. I haven't driven anything over 100 grand yet, but under that only a 98k Porsche 996 carrera comes close to Mr2s in steering feel. Boxster S is also very sharp, so is S2000, but NSX is noticeably inferior to MR2.

If you're not a Nissan fanboy, why are you one of their fan site admin who also posts more than just about anyone else?

What does the kind of car I drive have to do with anything? You're going to argue with everyone anyway no matter what they drive. Look at how many pages this thread has gotten. Most of it is your posts, some of them telling people they're missing the point. People aren't missing the point, more like they're avoiding the point, that's why no ones engaging in your Honda bashing scheme.

I told you already, people here are more intelligent, mature and open minded than where you are from. The fact that you choose Hondas 3.2 SOHC instead of their DOHC and not BMW's 3.2 DOHC or Porsches 3.2 DOHC for comparison confirms that you are a Honda hater. You tried covering up your Nissan fan boy identity by using a Toyota engine instead of a Nissan VQ(they're both 3.5L DOHC) hoping folks here who are Toyota fans would take side with you. It's a neat trick but no ones buying it. If you had done a fairer apples to apples comparison, you'd hear no peeps from me.

If it's already a great car, why does it need a new tranny and engine? Why just drop in a 3.5 L when they could go out of their way and put in the Mugen 4.0L V8 developing over 580hp? While they're at it, why a weakazz Jatco or Aisin unit when the tranny from their own Civics would do better? Those little suckers have proven reliable at over 600whp on the tracks by import drag racers. SH-AWD wouldn't hurt either.

Point is why can't you accept the car for what it is? Model vs model, TL already outsells just about all other luxury sedans in the US even with those shortcomings you pointed out. People knock Honda for not having a V8 and predict Honda sales will suffer without it, yet just about every Honda model and Acura is at the top of their class in sales. You think HOnda is going to invest in millions only to hear you say you'll "probably" buy one? If a certain vehicle doesn't fit your need or satisfy your driving style, or has a reputation you don't feel comfortable parting your cash for, don't buy it! If enough of you vote with your pocket book, Honda will notice and make changes to their strategy. BMW is starting to see that now.