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Acura RL

7385 messages,  Last post on Apr 18, 2013 at 12:02 PM

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What is this discussion about? Acura RL, Sedan

Messages Page 288 of 739

#2869 of 7385 robertsmx by saugatak

Jun 21, 2004 (9:30 pm)

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.

#2870 of 7385 robertsmx by merc1

Jun 21, 2004 (9:43 pm)

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.
 
M

#2871 of 7385 robertsmx #1416 and Merc by saugatak

Jun 21, 2004 (9:55 pm)

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.

#2872 of 7385 saugatak by merc1

Jun 21, 2004 (10:26 pm)

Well I'm afraid they're going to play basically the same DOHC game as everyone else. You can checkout germancarfans.com 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.
 
M

#2873 of 7385 saugatak by lexusguy

Jun 21, 2004 (10:38 pm)

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.

#2874 of 7385 lexusguy by saugatak

Jun 21, 2004 (10:58 pm)

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.

#2876 of 7385 I went to an event last year. . . by markcincinnati

Jun 22, 2004 (7:56 am)

. . .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?

#2877 of 7385 Re: robertsmx [saugatak #1429] by robertsmx

Jun 22, 2004 (8:09 am)

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.

#2878 of 7385 Re: I went to an event last year. . . [markcincinnati #1436] by robertsmx

Jun 22, 2004 (8:18 am)

Replying to: markcincinnati (Jun 22, 2004 7:56 am)
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.

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