FamilyGuy

Do you have any more sources to back that up? I would like to read about it. I'm not disputing you; I have no idea what the truth is. The kid part of me is hoping you're exaggerating the situation, but that's just because the revving of a big V-8 is music to my ears.

And which engines are the most balanced, then, besides our favorite the Wankel? Just curious.

Quick_lude

I would guess the flat 4's and 6's in Subaru and Porsche.. followed maybe by the inline 6's from BMW?

I'm surprised the Vigor was a fwd car.. especially since it had an inline 5 engine mounted longitudinally right? Just the layout of the engine lends itself to rwd.. How was the power transferred to the front wheels?

I'm very disappointed that Honda has chosen the "Toyota Camry" approach to their vehicles... and for whatever reason they do not bring over the hottest offerings like RSX typeR and Civic type R.. oh well, maybe in time things will change but unless I can live with the S2000 as my only car, looks like the 8 is a much more sensible and logical choice for my life.

pelucidor

I agree that HONDA are doing well for their price point (even though they screwed up the new Civic for the FF crowd). My point is ACURA are NOT doing well at all above $30k - the CL and RL are disasters, the NSX is now selling a few dozen a year and the TL is a lone FWD island in a sea of RWD and AWD luxury sports sedans at $30k-$40k. The only good selling $30k+ vehicle that Acura have is the MDX which is not FWD (it's predictive AWD - works brilliantly). I have one and love it, and I would like to consider getting another Acura but they don't do any RWD or even AWD sedans models (unlike Infiniti, BMW, Lexus, MB, Audi, Volvo, Mazda, Cadillac, Lincoln, Jaguar etc - i.e. every single one of their competitors has a non-FWD model somewhere for the enthusiast). The only reason someone would buy a TL is brand loyalty or content for the money, and the G35 offers almost as much content for the money and far more power/fun and I believe is eating their lunch (check freshalloy to see how many ex-TL/CL owners now have a G35).

To answer Quick_lude: the V12 (Ferrari, MB, BMW, Lambo etc) is the best balanced, followed by the I-6 (BMW and Lexus). I don't know how smooth the flat 12 in a Ferrari 512 BBi was, but nobody makes them anymore (gets ready to be corrected).

Schneegz

The funny thing is that the new Accord is actually slightly faster than the Mazda6. But according to all the reviews, the 6 is much more fun to drive. Even Honda motorcycles are said to be a little "too" refined. I don't know abou that. I think Honda's refinement makes up for my sloppyness, as far as motorcycles go. But, as far as cars go, I think they're dropping the ball.

The S2000 and RSX are fine. Honda needs to introduce the S2200 and an RSX Type R. That's in the works, I think.

The NSX needs the Dual Note's hybrid system, or a V-8, or an F1 isnpired V-10, or SOMETHING! But, for the love of all that is holy, she needs more power, Captain! And if she could drop a few pounds in the process, that would be swell. Oh, and keep the price the same. Ain't I a damanding bastard?

The Accord needs a Type S version. OK, it really needs a Type R version, like in Europe, but I'd settle for a Type S. It should handle better than the current Accord, be geared for better acceleration, have a 6-speed, and cost less than $30K.

And if Honda did everything I want, they'd be selling far fewer cars than they do now. But I would get my way. And that, ladies and gentlemen, is what really matters in life.

Rich

Bah, it doesn't need more power. Ok, hitting that 300 hp number is probably necessary for the price they ask for an NSX. The real thing they need to improve is weight. Adding power helps straight line performance, but the extra weight that usually accompanies increases in HP means the springs need to be heavier, the brakes need to be heavier, etc. which all hurts other areas of performance. Reducing weight is the only thing that improves all measures of performance. Did you know that the NSX weighs *more* than the RX-8? Yep. Edmunds lists it at 3153 pounds. If they got the power up to 300 (for marketing to power ******) and dropped the weight to - say 2600-2700, there would be little else they would need to do to have it be a true supercar. 2600 isn't out of reason, IMHO. The Miata is 2400, MR2 is 2215, and the Elise that is suppose to hit our shores sometime next year (and is on sale in Europe now, I believe) is close to 1700 pounds, I believe. The Ferrari F360 is 3064, and the already mentioned RX-8 is around 2900, I believe.

Quick_lude

So what makes a V12 the best "balanced" engine? Why not the flat 4 or 6? I'm just curious..

wakeech

as far as firing order and exhaust pulse timing, the 6 cylinder configuration (in either a straight line, V, or Vx2 (V12)) is the best.

Quick_lude

Cool thanks.

wakeech

...as a side note, the two rotor'd wanekl type engine has the same exhaust pulse timing as a 6 cylinder engine (per full rotor rotation)...

pelucidor

Horizontally opposed boxer engines (as used by Subaru and Porsche) are also inherently perfectly smooth (I didn't know that before...)

Here is a quote on the I-6 engine: The inherent smoothness of an inline 6-cylinder design is because it has both primary and secondary balance. Primary balance is when the crankshaft counterweights offset the weight of the piston and rod. Secondary balance is when the movement of one piston balances the movement of another. V6's have a secondary imbalance that causes engine vibration. Adding a counter balance shaft can reduce this imbalance, but that adds weight and complexity.


Here is an great article on smoothness of various engines: http://autozine.kyul.net/technical_s...ne/smooth3.htm

Inline 6-cylinder engines
...straight-6 engine is simply two 3-cylinder engines mated symmetrically together, thus piston 1 is always in the same position as piston 6, piston 2 the same as piston 5 .... in other words, the engine is balanced end-to-end and requires no balancer shaft, unlike 3-cylinder engines.
What about vertical / transverse forces? like 3-cylinder engines, the vertical and transverse forces generated by individual cylinders, no matter first order or second order, are completely balanced by one another. The resultant vibration is nearly zero, thus inline-6 is virtually a perfect configuration...

V12 engines
Theoretically the best balanced configuration for practical use. It is simply a duplication of inline-6 (therefore achieve the same perfect balance), with corresponding cylinders in both banks joined at the same crank pins. V12 is better than inline-6 just because it has more cylinders, thus doubling the firing frequency and smoothen power delivery.
Of course, the disadvantages are cost, size and weight.

There's no structural differences in crankshaft for all V12s, no matter for luxurious cars or supercars. Most employ 60°, although Ferrari prefers 65°.

Quick_lude

I'm really surprised not many other manufacturers went with the Inline 6 configuration.. I remember the 240Z had one correct? The 3 series BMW, IS300, Supras, Ford F150 trucks.... Actually I think some of the new GM Jimmy's have an inline6?

FamilyGuy

Well, in the linked article it says that inline sixes take up a lot of space... you have to really play around to get it to work with FWD. Otherwise, you have to make your vehicle wide, or have a lot of length under the hood.

For pickups, and the new GM Envoy/Chevy Trailblazer, the space isn't really an issue.


Cool article though. First good points I've read why an I4 and I6 are more balanced than a V6 or V8. It also explains why high-revving 4's and 6's are more common than high revving 8's.

I had read somewhere that the Toyota Supra, which had an I6, could be heavily turbo'd with relatively low risk of screwing up the engine. I wonder if that's related to the whole balanced engine thing.

Quick_lude

I don't think so.. The Supra inline 6 engine was just built with VERY strong internals from the factory which enabled it to take a lot of turbo boost. The Twin Turbo 6 will easly make 500 whp with turbo and other external upgrades.. on STOCK internals.

MikeW

Keeping the cylinder count under a bakers dozen, these are fundamentally balanced.
V12-60 & 180 degree (Ferrari Testarossa, not a boxing engine-only 7 main bearing and no crank journal splay angle) & other odd angle V12s
Inline 6's-nuf said
Boxing 6'-Porsche/Subaru
Inline 8 as two Inline 4s-pre WWII
Boxing 8 (has poor firing order L R L L R L R R, probably why Porsche/Subaru haven't made it, yet)
Boxing 4-2nd order moment imbalance, L L R R firing order, hard to turbocharge well.
Boxing 2-BMW motorcycles
V8 flat plane crankshaft-two balance shafts flanking the crank-see VW W8 Passat, (Lotus Esprit Ferrari-lots, skipped balance shafts for more power at expense of refinement-side to side shaking of engine)
V8 crossplane crankshaft-2nd order moment/counterweights on crank
V10 72/90 and other 1&2 order moments, uses counterweight and/or balance shaft
V6's 60/90 and other 1&2 order moment, uses counterweights and/or balance shaft
Inline5-1/2 order moment-see V10
Inline 4-2nd order force imbalance-Lancaster balance shafts
Inline 3-see V6
Inline 2 same imbalance model as 1 cylinder engine
(V2 and V4) on motorcycles

1/2/3/4 rotor wankel-1st order moment-counterweights

Supercharger

The Corvette Z06 is faster and costs less than the Acura NSX.

Back on topic:
http://www.pumaracing.co.uk/power2.htm

wakeech

...that's not saying much, the FD was faster and WAY cheaper than the NSX too...

Schneegz

Rich:

Yes, the NSX NEEDS more power. The Corvette Z06 is FAR more powerful (405Hp, 400ft-lb), lighter (3116lb), faster, quicker, handles better and costs less than the NSX. Check Edmunds again.

I say if Honda can't build a car that is lighter, quicker and handles better than a Chevy for the same price, they need to fire their entire engineering staff.

And yes, it still needs to be as reliable as an Accord. :D

Quick_lude

Yeah but have you seen the interior on the Corvette? :o Looks like a $80K Cnd luxurious Cavalier.. yuck.. It certainly is very quick though.

FamilyGuy

While I'm getting ejumacated here...

Thanks for the info on balanced engines, MikeW. Here's my next question for you (or anyone else that feels like answering):

If you wanted an engine that displaced 4 liters in your car and generated lots of power, why couldn't you just put in a huge inline 4? Why do larger engines typically have more cylinders, instead of just larger cylinders?

Anybody? Anybody? Bueller?

wakeech

well, that is almost what Chevy does with their big-*** LS engines (well, all big-*** American engines) that are 7.1L and have 8 cylinders or something...

but basically put, the larger your pistons get, the greater your filling efficiencies become with more rpm, but more cylinders you have the greater the complexity, the greater the size of the engine (length of the crank is very important here), the more reciprocating mass, the more internal friction, etc... this is why F1 decided to go (for the most part: Toyota was prevented from building a V12 2 years ago now that the rules have stated "no more than ten") with the V10 unit for 3.0L as opposed to the V12 configuration: less moving bits, smaller package, although harder to get it to breathe right at 18.5k rpm...

FamilyGuy

What do you mean by filling efficiencies? I would think that if bigger cylinders give you better efficiency, then you would want larger cylinders.

I understand that having more cylinders adds a lot of complexity. That's why I am confused... what advantage does it offer?

Rich

Comparing the NSX to the Corvette is apples and oranges. The NSX is an ancient design, in automotive terms. I don't see why I need to check Edmunds again, since I never made any comparison to the Vette. Besides, the question isn't simply one of pure speed. When the NSX was released, it revolutionized the Exotic market. Every review for years afterwords (and still today, even) talked about the fact that it was the first car with exotic performance while maintaining the ability to be a daily driver. That means an unprecedented level of civility in daily driving in addition to reliability. It quite simply revolutionized the market. It was also considered the best handling car of the day by many. Of course, it's not competitive now in terms of performance, and that's why it only sells in the tiny numbers that it does. I never claimed that the NSX was faster (or better in any way) than a Vette, or any other car anywhere close to its price range. The '80s Ferraris did 0-60 in about 6 seconds. Will you claim that Ferrari needs to fire its staff of engineers because lots of cars can do it faster now? Of course not, because that's not a relevant comparison.

Again, I don't really know where this is coming from. Honda hasn't *tried* to build a car to compete with the Corvette. The NSX is a very old design; the Corvette is a fairly new design. No one is immune to the march of progress. Acura has clearly not had a real player in the performance market for the last few years. That doesn't mean they should stick a 450 HP engine in the NSX. That would be a horrible idea. Rumors have it that they are developing an all-new NSX, and that is the path they really need to take.

You did make one statement that was relevant, and that was that the NSX does need more power. Simply providing the numbers for another car doesn't provide any evidence for that claim. The Elise should have true supercar performance with a reported 190 HP engine. 0-60 estimates have been in the high 4s, but of course there isn't any test data to back that up yet. This shows that you can get supercar performance from low power engines if the total vehicle mass is low enough. The Elise also won the track portion of a comparison test one of the car magazines did a few months ago for the "best handling car in the world". It came in second overall to the Ferrari F360. It has incredible speed and is one of the best handling machines in the world, yet it doesn't have 200 HP. I'm not claiming that's the path Acura should take with the NSX, but to simply say that 290 is not enough for world class performance is simply and obviously false.

wakeech

WHOOPS!! early morning error, sorry guy... your volumetric efficiencies DECREASE as piston size increases, at any given rpm.
so, if you want to make a ton of power with a given displacement (as in racing you would), you need to make as much torque as you can at as many rpm as you can... to do this, you need somethin that will breathe at the very limits of the engine's capacity to spin, so, smaller pistons with big big valves, short runners, lots of timing overlap... when your goal is so simple, there are lots of tricks you can pull, but the basic architecture has a very very heavy influence on the fundamental performance characteristics of the engine.
small pistons are easier to fill very very fast, and thus lend themselves to high rpm application. if all you need is torque from idle, then you get big-*** pistons that operate between 250-3000 rpm, like a turbo-deisel you'd find in a semi-truck (lorry).

MikeW

Lets assume that the camshaft duration is only 180 degrees
and our engines are all running at 1000 rpm
So a 4 liter 1 cylinder engine has only 180 degrees of crank rotation to move 4 liters in 30 milliseconds
a 2 cylinder has 360 degrees of crankrotation, 60 milliseconds of valve opening
3 cyl 540 degrees, 90 ms
4 cyl 720 degrees, 120
5 cyl 900 degrees, 150
6 cyl 1080 degrees, 180
7 cyl 1260 degreees 210
8 cyl 1440, 240
9 cyl 1620, 270
10 cyl 1800, 300
12 cyl 2160, 360 ms
16 2880 degrees, 480 ms

Schneegz

Rich:

First of all, I'm saying that the NEXT redesign of the NSX will need much more power. At least 400hp.

Why? Refer back to your own quote.
Yes, Rich, we know that. But that is exactly the problem. The NSX has lost its claim to fame. It can no longer claim to be an exotic daily driver, because IT NO LONGER HAS EXOTIC CAR PERFORMANCE.

The NEXT REDESIGN will need exotoc car performance while maintaining its civility. And for that, it will need at least 400hp.

Actually, it isn't. Read reviews about the Z06. They all say what reviews of the NSX used to say. A Ferrari-killer that can be driven every day comfortably. Chevy achieved what Honda achieved years ago with a vastly different design. The Corvette, therefore, is the car the next NSX needs to aim for.

I never claimed that HP alone is the only way to achieve performance. Bringing up the Elise is irrelevant, because the Elise is not what one would call "civil". The Z06 is.

Besides, the reason I brought up the Z06 is that you said that adding HP to the NSX will add weight.

Not necessarily.

Once again LOOK at the Vette. 405hp, yet weighs LESS than the NSX. That is what Honda needs to shoot for...

IN THEIR NEXT REDESIGN.