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Acura RL



  • robertsmxrobertsmx Posts: 5,525
    SOHC versus DOHC is a matter of choice. DOHC offers more flexibility in terms of variable valve timing due to an additional pair of cams (a DOHC “V” uses four cams, compared to two in SOHC “V”). However, that also makes SOHC a smaller and lighter engine package.

    A typical SOHC layout is associated with either 2-valve per cylinder (BMW’s V12 in last generation 7-series, and from Honda, the Civic Hybrid’s 1.3-liter I-4), or 3-valve per cylinder (Mercedes). Honda has always used 4-valve/cylinder with SOHC layout for the V6, just like DOHC engines. The only six-cylinder engine from Honda that has 2-valve/cylinder is the 1.8-liter Flat-6 used in Honda Gold Wing/Valkyrie.

    In terms of output, the advantage of DOHC layout over SOHC is debatable. Honda could move to a 3.5-liter DOHC V6 for the RL, but given the way the “J-series” SOHC V6 engines perform with red line limited to 7000 rpm or less, it may not be necessary (Acura TL's 270 HP 3.2/V6 is a good example, as are the other variations). In the past, Honda has developed SOHC and DOHC versions of otherwise virtually identical engines, going with DOHC in high rpm applications.

    Regarding Dick Colliver’s statement: "new and our most powerful engine yet", I see two things here. One, with 300 HP, the 3.5/V6 will exceed the highest (rated) power output offered in any production Honda/Acura (i.e. the 290 HP 3.2/V6 in NSX). And “new” could imply use of J-series V6 (could still be DOHC though) instead of C-series V6 that the current RL uses.
  • robertsmxrobertsmx Posts: 5,525
    Having seen the numbers from you that match my guesstimate, I assume your concern regarding RL’s torque numbers being a pie in the sky (or not) has been addressed. My guesstimate is based on assumption that RL will use 3.5-liter version of the V6 used in TL.

    Going beyond the peak numbers, let us analyze the 3.5/V6 used in MDX using the official dynograph.

    In Japan, the engine is rated at 260 PS @ 5800 rpm / 345 Nm (about 255 lb.-ft) @ 3500 to 5000 rpm. North American version got a boost in peak power output to 265 HP for 2004 (but the Japanese version has stayed put to 2003 level).

    At about 1200 rpm, the engine is producing 300 Nm (87% of the peak torque). Between 2000 rpm and 5800 rpm, the engine’s torque output varies about 5-8% with near flat (peak) torque output from 3500 rpm to 5000 rpm. This is a classic example of a Flat AND Broad torque curve, and out to prove it doesn’t matter where the engine produces peak torque, because it is more about “a range”.

    At 10.0:1, the 3.5/V6 in MDX is far from being a “very high compression” engine. In fact, the compression ratio is identical to the 3.5/V6 used in Odyssey & Pilot. For RL, I suspect, the compression will be as high, if not higher, than in the TL (about 11.0:1). This will help boost the output beyond the MDX-levels.

    There are three stages in the output from MDX’s 3.5/V6. The first is the usual tuning, to maximize low-end torque output, the second stage gets a boost from the variable intake manifold, and finally, the third stage gets a boost from VTEC. This is not unlike the 260 HP/3.2-liter V6 we saw in last generation Acura TL (and CL) Type-S. The TL-S engine was rated at 260 HP at 6100 rpm, and 232 lb.-ft at 3500 rpm to 5500 rpm.

    In the end, I suspect Acura RL’s 3.5/V6 to deliver 235-240 lb.-ft at an engine speed, as low as 2000 rpm, and continue to develop within 5-8% of the peak torque between 2000 and 6500 rpm.
  • markcincinnatimarkcincinnati Posts: 5,343
    If you are correct, and I hope you are, the need for a V8 will be even further reduced, IMHO.
  • robertsmxrobertsmx Posts: 5,525
    To improve its acceleration, assuming my guess that the torque ratings will be "OK" or "good" but not "oh wow, impressive," Acura may have elected to lower the final drive ratio and made 5th gear a bit taller "overdrive" (in an effort to raise its combined MPG). A six speed transmission with both 5th and 6th being overdriven, but 5th only mildly so, would somewhat counter and "mask" the hunting that could have been engineered in if such an approach is actually taken.

    Acura went 5-speed auto with 2000 TL (1999 TL had 4-speed, which was the norm back then), and something I noticed didn’t sit well with me and that had to do with the added weight. The new TL gained about 50 lb.

    I can still see some improvement of going up from 4 to 5 speeds, especially given that the gear ratio spread (between first and final gear ratios) is virtually unchanged meaning the addition gear actually helped close down the spacing. But if every cog ends up adding 50 lb. with diminishing returns, I don’t know if I would like the idea of going to six or seven speeds. Why not just go CVT instead and for those who care, use a preset 7-speed ratios from it?

    In Acura/Honda 5-sp auto, the transition from cruising in the tall overdrive mode to acceleration mode forces an upshift from fifth to third. If it were a six speed auto, “sixth” could replace “fifth” and “fourth” could replace “third”. But since the gearing is going to be closer, there will be times when an additional shift will occur during acceleration.

    So, pros and cons of 5-sp versus 6-sp versus 7-sp is very debatable. It is probably more about academics than practicality.

    As far as RL is concerned, Acura will probably stick with the existing 5-speed gear ratios. In the first, RL will likely carry an overall drive ratio of 11.35-11.55:1 (like it does in TL and MDX). The net thrust at the wheels will likely stay the same because although the car gains in torque by about 10% (compared to TL) it will also gain weight by about 10% (compared to TL). The maximum thrust in RL in first gear is likely to be about 0.60-0.62g, which is quite good. So, it is not going to feel like a muscle car off the line.

    Somewhere I have read (a long time ago) that in a front driver, 0.60g can be considered a limit for traction purposes (both, Accord V6 6-speed Manual and TL 6-speed manual exceed that). With AWD, in RL, “launch traction” is unlikely to be an issue. And then, AWD will be engaged everytime the throttle is depressed the way it works in MDX’s VTM-4 system (somewhere between 30-70% of the torque may be routed to the rear wheels).
  • robertsmxrobertsmx Posts: 5,525
    I think the “need a V8” argument will be handled by Honda in its own way, and using a hybrid. If observations are true, with V8 available as an option, the eight banger woos few buyers compared to its six-cylinder counterpart. This gives little incentive to develop a V8 unless it is to be shared with some other vehicles in the lineup.

    This is purely a guess, but a V8 option typically adds a premium of about $4-5K. That’s enough for reasonably powerful and advanced hybrid system. So, with a base engine that can share bits and pieces with others, and a hybrid system that can be shared as well, it makes sense to go the hybrid way.

    The 3.5/V6 in the new RL could simply be the J35A tweaked for 300 HP (tweaks similar to those in TL’s 3.2/V6 will help accomplish that). Or, it could be an all-new 3.5-liter DOHC I-VTEC V6, something Honda showcased three years ago (2001 Honda Dual Note). The Dual Note’s 3.5/V6 was also rated at 300 HP.

    Both engines are compatible with Honda’s IMA (knowing that Honda Accord’s J30A is being mated to IMA for launch this Fall, unless it happens to be an “all-new” engine as well which I doubt given the development efforts on J30A in Japanese market).

    A “twice as powerful” version of the ultra-thin brushless DC motor used in Civic Hybrid could add 70-80 lb.-ft at low-low engine speeds, more than compensating for the low end torque that would come from a 4.0-4.5 liter V8 when compared to a 3.5- liter V6. Even if there is no gain in the top end, if the peak torque hovers around 310-325 lb.-ft @ 2000 rpm, it is sure to make a “must have V8” argument moot (this is not to say that it won’t be brought up).
  • markcincinnatimarkcincinnati Posts: 5,343
    The 6 speed tiptronic, steptronic, positronic, or whatever the big three German manufacturers call it, weighed in at 44 pounds less than the outgoing 5 speed tiptronic. The supposed benefit to the 6speed was to keep the engine in the torque sweet spot mostly during gears 1 - 5 with 6th being more overdriven.

    BMW's 7 speed and Audis Multitronic both offer some interesting aruments to the "how many speeds are enough" debate.

    I am not as concerned, now, about the 3.5L in the new RL based on the recent posts pertaining to torque. 5spds will be fine, 6spds will be eventually required for marketing purposes (not that six speeds will be limited to marketing purposes, however).
  • robertsmxrobertsmx Posts: 5,525
    It is possible that the old trannies were quite heavy compared to the new to start with. So, weight gain or loss is still debatable compared to perceived (or real) benefits.

    I have participated in some debates that pertain to counts, albeit not just when it comes to cylinders (and in this case, cogs), but also number of valves...

    5-valve per cylinder layout that Audi/VW (and Ferrari) seem to prefer over the usual 4-valve per cylinder.

    Advantage to having 5 versus 4 has been very debatable.
  • steveaccordsteveaccord Posts: 108
    As always an excellent contribution. I look at all the numbers and try to interpret them and yet right now I long to drive this car more than anything else.

    Perhaps it is because yesterday I drove back and forth to Indianapolis to see the US GP race and I enjoyed enormously my Accord EX-L. It was the first 'long haul' trip I took in it (~185 miles) along with a couple of friends.
    Not only keeping it at avertage of 75-80 mph was a breeze (and kept us below 3 hrs, including stops, to reach destination) but it was delightfully responsive when I had to overtake at 90-100 mph.
    Indeed the car behaviour was such that my passenger in the back (owner of a >200 HP FWD american vehicle equipped with a V6) kept commenting that the car behaved as it was powered by a V6 (and this even after I told him that indeed it was a lowly I-4 engine that was carrying us around).

    So I guess my point is that for as much we love to see 'nice numbers' I still believe that nothing can 'do justice' to how a vevhicle really drives. I guess is another facet of the same recurring topic of 'how great' european RWD cars feel when you are behind their steering wheel.

    Anyway to add to the pleasant experience the car consumed far less than the stated 28 mpg (~31 mpg) and with few exceptions road noise was limited such that we could enjoy my CD mixes with volume set at 13 (those who have the new digital panels know this is in the level kept for city driving).

    Now if I can get so much from the Accord I do not see how the RL is going to fail to be a pleaser. I can understand that there are lots of very good cars out there but I feel that at the proposed price (and the present day knowledge of tech spec) this Car is going to 'kick butts'.

    Just my thougths, kudos to whoever will think differently and buy something else!!
  • steveaccordsteveaccord Posts: 108
    By the way as soon as I will download pictures from yesterda I'll see if I can post some here. It was a great present for father's day to have a podium with 2 Ferrrari and Honda on it. I plan to go there again next year so let me hear from you if you are interested!
  • lexusguylexusguy Posts: 6,419
    I have heard that Mercedes is retiring its 3 valve SOHC design. Is this true?
  • robertsmxrobertsmx Posts: 5,525
    Seeing that 2005 C-Class will have the C55 AMG in its lineup, I doubt the 3-valve SOHC layout is being retired anytime soon. The C55 will use 5.5 liter 24-valve SOHC V8.
  • markcincinnatimarkcincinnati Posts: 5,343
    The "new" Hemi from Chryco has 2 valves per cylinder, Mercedes uses two spark plugs with three valves, the new FSI engines from Audi/VW are back to 4 valves, GM's northstar prefers the 4 valve layout, etc.

    I completely agree, the "proof" will be in the driving. I applaud the 300HP bragging rights w/aV6 approach, if for no other reason, for the potential for better fuel economy.

    As I said before, the "I shoulda had a V8" crowd will be mostly silent if whatever is under the bonnet performs at or above expectations and/or class standards.

    The new A6 has both a V6 and a V8 offered. The net dif is 1 second in the dash to 60 mph. The cost, attempting to equate like for like is over $5K more for the V8 plus a loss of miles per gallon.

    Here in this "big town" of Cincinnati, the ability to regularly and frequently use the extra grunt isn't "worth" the premium in price and longer term fuel upcharge.

    Now, this is not to say that if the price differential were much closer, that I wouldn't at least consider the V8.

    Unless Acrua really "blows it" with the performance (that the automags will harp on) figures with the 3.5, I think, to repeat, they have chosen wisely.
  • shotgunshotgun Posts: 184
    Yes, Honda will handle the V8 argument in it's own way by not offering one until it goes in the "real truck" business! For what it's worth, and listening to Dick Colliver, I got the impression, and don't ask me why, other than the emphasis he put on the word "new", it somehow implied to me that he was alluding to a "new" not "recycled" 3.5-liter DOHC I-VTEC V6.
  • ksomanksoman Posts: 593
    hmmm, which brings us to why in hell is CVT bad then?
  • steveaccordsteveaccord Posts: 108
    In my 2 item list of desirable features to be suggested to Acura's president I listed the "integration' of iPod in the RL stereo system.
    I had the queue from an article suggesting collaboration between Apple Computers Inc. and undisclosed car manufacturers. Well it turns out that BMW will be the first to score in that departement. The glove box installed 'craddle' will be operated via the sterring wheel commands! It will also be made available for Mini (& Roll Royce?) models.

    I still wish Acura will follow!!
  • markcincinnatimarkcincinnati Posts: 5,343
    I, for one, don't think CVT is a bad thing. Audi has been unable to offer if for sale in its quattro cars (although they promise it "soon") and it apparently isn't ready for the higher torque of the V8 engine either.

    Other than that, I found the CVT that I have driven as a loaner to be almost eerily smooth and able to accelerate briskly.
  • saugataksaugatak Posts: 488
    Having seen the numbers from you that match my guesstimate, I assume your concern regarding RL’s torque numbers being a pie in the sky (or not) has been addressed. My guesstimate is based on assumption that RL will use 3.5-liter version of the V6 used in TL.

    They weren't MY numbers. I was posting numbers from another site, which is also pure speculation.

    We'll see which 3.5L version they use but I don't think they can use the TL's 3.2L v6 and bore it out even more. The TL's 3.2L v6 is itself a bored out version of the Accord 3.0L v6. Getting an extra .3L of displacement out of an already bored out block sounds unrealistic to me.

    My guess is that the RL engine will be based off the MDX's 3.5L v6. Despite your statement that you think the RL's engine will be based off the TL's engine, you draw your numbers from the MDX's 3.5L v6, so I'm not sure what you think.

    North American version got a boost in peak power output to 265 HP for 2004 (but the Japanese version has stayed put to 2003 level).

    I don't think the North American version of the engine changed from 2003 to 2004. I had read that Acura placed a dual exhaust system in the 2004 MDX (2003 MDX had single exhaust system) to get the extra 5HP. Maybe you know more about this.

    At 10.0:1, the 3.5/V6 in MDX is far from being a “very high compression” engine. In fact, the compression ratio is identical to the 3.5/V6 used in Odyssey & Pilot. For RL, I suspect, the compression will be as high, if not higher, than in the TL (about 11.0:1). This will help boost the output beyond the MDX-levels.

    The 2003 TL type-S 3.2L SOHC v6 produced 260HP with a compression ratio of 10.5:1. By raising the compression ratio by 0.5 to 11:1, Honda squeezed out an extra 10 HP for the 2004 TL so that it got 270HP.

    To get the MDX 3.5L engine from 265HP to 300HP by raising the compression ratio, Honda would have to get a compression rato of 13.5:1 (assuming about 10HP per each 0.5 increase in compression ratio).

    I just don't see how Honda could do that. The 3.2L I6 in the BMW M3 has a compression ratio of 11.5:1 and that is VERY high, so high in fact that the M3 engine has had reliability issues because that kind of pressure puts a lot of stress on the internals of an engine.

    I'm curious to see the final details on this engine. Frankly, I don't see an easy way for Honda to get to 300HP out of either the 3.2L v6 in the TL or the 3.5L v6 in the MDX. Honda will have to do more than just raise the compression ratio or bore out the blocks.
  • merc1merc1 Posts: 6,081
    Actually the SOHC 3-valve Mercedes engines are on their way out. The new generation DOHC 32v V8 doesn't arrive until the next generation C-Class, due out in 2007. The CLS, E, SL, next S/CL and CLK will all get new DOHC 32v V8s for either 2006 or 2007.

  • saugataksaugatak Posts: 488
    Robertsmx, post #1416 was excellent.

    Merc, you got details on the new DOHC 4 valves per cylinder MB engines?

    I always admired MB's creativity for going against the flow and coming up with SOHC 3 valve per cylinder dual spark plug v6's and v8's. I'd love to see if MB has come up with another twist or if they're just going to play the same DOHC game as everyone else.
  • merc1merc1 Posts: 6,081
    Well I'm afraid they're going to play basically the same DOHC game as everyone else. You can checkout under the Mercedes news archive for the details. There are few new tricks like direct-injection (for a gas V6), but they're playing it safe with these engines by incorporating things they've done before (pre-1998) and some newer things others have done since.

  • lexusguylexusguy Posts: 6,419
    There's no reason Honda couldn't further enlarge their 3.2L V6. Nissan has pushed its 3.5L VQ to 4.0L for the upcoming North American built Pathfinder (in order for it to deliver 280+ lb.ft of torque). I dont see why Honda couldnt throw on another .3L.
  • saugataksaugatak Posts: 488
    We'll have to see. At some point you can't bore out the block any more. You have to build a new and bigger block. I don't know whether Honda has reached that point yet with the 3.2L v6 block.

    I'm eager to see how Honda does it b/c as long as the engine isn't too peaky, 300HP out of a 3.5L v6 is pretty impressive.
  • sirdarbysirdarby Posts: 20
    I too am considering a 99 RL. This one is listed for $15,995 from a private owner. It has heated seats and nav. White with grey leather in pretty good condition. The transmission fluid was clear but a little low. Otherwise it drove fine.

    The owner lost his job and wants a quick sale.

    It was a certified car when he bought it and has the remaining warranty on the Powertrain and engine till 100K miles. It currently has 75K miles. Is this a good deal?

    I noticed some rust around the silver back windshield trim; under the hood, some of the bolts had a little rust or corrosion. Looked as if someone up north or near the ocean had it before he got it. Other than a good cleaning, I don't see many problems. We live in the South so winters or water is not a problem.

    What do you guys advise other than the obvious -- getting it checked out etc. Is the price good. I know they will be falling with new body style coming out soon.
  • markcincinnatimarkcincinnati Posts: 5,343
    . . .present were 97 cars with VW/Audi 1.8T engines, several were "tuned" to 350HP and very high torque at relatively low rpm.

    These mods to a basic 225HP engine all seemed to be concentrated on breathing modifications (and, remember, they were all turbo charged.)

    Getting a 3.5L V6 to 300HP should NOT involve herculean efforts or Einstein's intellect. Not that this much HP is not impressive (it is).

    And if torque is as the posters are honing in on, well, that bodes well too. There are several, perhaps "many" engineering solutions to the "how did they get 300HP from the 3.5L engine?" riddle.

    I have not, yet, bothered to search the web for possible Acura/Honda approaches, but perhaps someone here has.

    So, how are they doing the HP without forced induction (which would be about the easiest method)? Anyone? Anyone?

    I assume it is not "the Acura way," but imagine what two very small, very light turbos could do for this engine?
  • robertsmxrobertsmx Posts: 5,525
    With the exception of NSX and current RL, Honda is using a single family of V6 engines (J-series), and the basic version is the 3.0/V6 in Accord (the J30A).

    The J30A is a square engine (bore: 86 mm, stroke: 86 mm). To develop J32A (3.2/V6 in TL), the bore was increased to 89 mm while the stroke stayed at 86 mm. So, J32A is an undersquare engine. To develop J35A, the bore was increased to 89 mm (same as J32A) and the stroke was increased to 93 mm, making it an oversquare engine.

    The J-series engines are technically similar except in terms of tuning and displacement. There was a fourth displacement for the Japanese market until last year (the J25A) that had replaced the old 2.5-liter Inline-5 in 1999.

    Regarding the 5 HP bump in MDX, the point wasn’t important, only to reduce confusion that might arise from looking at the dyno (from Japanese website) which still has 260 HP version compared to 265 HP in the MDX. I’ve not looked into how the output was increased.

    J35A is also the perfect example to illustrate that output isn’t necessarily dependent only on compression. There are more ways to getting it done. Odyssey & Pilot have the 3.5/V6 rated at 240 HP, and while using same compression (10.0:1), the version in MDX is rated at 265 HP. That’s using simple tweaks to the intake and the valve heads.

    Honda has done this quite often, offering several outputs from tweaking the same engine block in a variety of ways. Another is the J30A. There are two variations of the 3.0/V6 in Japan, both running 11.0:1 compression. In this case, the peak power rating is identical (250 HP @ 6000 rpm), but one of the two engines develops peak torque of 228 lb.-ft (Elysion) compared to 218 lb.-ft (Inspire) in the other.

    I'm eager to see how Honda does it b/c as long as the engine isn't too peaky, 300HP out of a 3.5L v6 is pretty impressive.

    Aah, the benefits of variable valve timing & lift, and multi-stage intake! I’ve observed Honda engines enough to bet that it will deliver more than 90% of its peak torque from about 2000 rpm.
  • robertsmxrobertsmx Posts: 5,525
    A 5 psi supercharger could push the peak output to 400 HP/350 lb.-ft.

    Honda does use turbo-charging in production engines (couple of “minis” in Japanese market), and one of its watercrafts. Rumor/news item from a European magazine (who apparently drove the HSC) suggested that the car had a variable-vane turbo set up. Of course, the diesel engine uses a turbo charger.
  • varmintvarmint Posts: 6,326
    Geez, I go away for one weekend and come back to 113 unread posts! =)

    I'm more familiar with Honda's smaller engines (like the K24 and K20), but the speculation posted by Robertsmx isn't what I'd call far-fetched. 300 hp without going north of 7,000 rpms is very "doable". So does a reasonable amount of torque in the low end. It won't match the V8s of the class, but it shouldn't be required to if priced below $50K. At that price point, the competition is saddled with V6s offering fewer ponies and about the same torque.

    Just to add to the already voluminous conversation... The original 240 hp MDX engine was rated for something like 95% of peak torque from 2,000 through 5,500 rpms. When they tweaked the engine for higher hp output, the peak went up, but the curve changed very little. Technically, the curve did change and they could no longer make the same percentage claims. However, you need to have an extremely well-calibrated bum dynometer to feel the difference in thrust.

    Another example... There are three versions of the K24 sold in the US. The first was used in the CR-V, the second in the Accord and Element, and the third is in the Acura TSX. The same 4 cyl mill is used in each. They are just tuned differently using VTEC and compression variations.

    The Accord makes 161 lb-ft at 4,500 rpms, but only 160 hp. Conventional wisdom would suggest that making 200 hp using the same engine would require the torque peak to shift up higher on the rev band. It doesn't. The TSX makes 166 lb-ft at the same 4,500 rpms.

    The CR-V produces 162 lb-ft at a lower 3,600 rpms. Many people see the difference in rpms and assume that the CR-V has a stronger bottom end even though the peak output is slighter lower. That's not true, either. When you compare the dyno plots, the TSX's I4 is generating more thrust at 3,600 rpms. Of course the difference is negligible. If your bum-dyno is that sensitive, you must constantly be in danger of falling over as the Earth turns. =)

    Anyway, it would not surprise me to read that the RL's V6 produces 265 or 270 lb-ft of thrust at 4,500 rpms, or even 5,000 rpms. At the same time, it would not surprise me to read that 90% of that power is available by 2,000 rpms.
  • lexusguylexusguy Posts: 6,419
    BMW gets even more horsepower than the RL from a smaller displacement inline in their M3. Then of course there is the Porsche GT3 3.6L flat six, that makes 380 normally aspirated horsepower. It can definitely be done.
  • varmintvarmint Posts: 6,326
    There's a factory spec NSX in Japan that is offered exclusively for racing. IIRC, it puts out 350 hp in NA form.
  • habitat1habitat1 Posts: 4,282
    A 3.5 liter equivalent of the Honda S2000 engine (original 2.0 literversion) would produce 420 horsepower and about 275 ft lbs of torque. Not to mention a 9,000 rpm redline. Match that up with a short throw 6-speed and even I might turn in my TL 6-speed for an RL. It wouldn't be the quietest luxury sedan on the road, but it might be the most fun to drive.

    By the way, I'm not sure a 300 hp V6 is going to be all that fuel efficient. I am somewhat surprised that in 1,400 miles of moderately spirited driving, I've only averaged about 18 mpg in mixed driving with a 6-speed TL. That compares to about 23 with my Nissan Maxima and 22 with the S2000. My one long highway drive averaged about 28, but the mixed City / beltway driving isn't very impressive, at least not yet.
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