Why don't we have a DOHC???

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Old Jul 17, 2001 | 05:04 PM
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Why don't we have a DOHC???

Does anyone know? This is starting to piss me off
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Old Jul 17, 2001 | 05:09 PM
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great question - can someone answer this? Is there any logic to it? or just a holdover in that the 3.2 liter engine never had one in the past?
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Old Jul 17, 2001 | 05:11 PM
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I wish our cars had DOHC. Regular Nissan Altimas,Maximas have DOHC standard on their vehicles. Im surprised Honda doesnt put DOHC in their higher model vehicles.
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Old Jul 17, 2001 | 05:13 PM
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The NSX 3.2 has the DOHC!!!!
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Old Jul 17, 2001 | 05:14 PM
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My guess is to make the NSX more elite. Why buy the NSX when the CL/TL have a similar engine? I know there are a A LOT of differences between the two motors, but think of it from a marketing standpoint. The average buyers looks at HP, cylinders, and valves when comparing. The NSX needs to stand apart from other Acuras.

Also: The SOHC is competitive in its market and cost less than DOHC to build.

Originally posted by CL-SPS:
<STRONG>Does anyone know? This is starting to piss me off </STRONG>
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Old Jul 17, 2001 | 05:38 PM
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Cost...
Size and additional weight...
Nessesity....

I'm not too concerned about it. I like how mine revs but don't need 8k - 9k. I look at the NSX and its DOHC and then my CL-S with a more usable torque curve and it makes me feel fine and actually more impressed with the J32A2.

Manual NSX:
NSX 3.2: 290 @ 7100
NSX 3.2: 224 @ 5500

Auto NSX:
NSX 3.0: 252 @ 6600
NSX 3.0: 210 @ 5300

CL Type S:
Type S - 260 hp @ 6100
Type S - 232 lb.-ft. @ 3500-5500

The CL-S has more torque earlier than the NSX which is certainly a plus in traffic. Add headers and intake to the CL-S and the HP numbers are greater than the NSX. Then look at the Auto. version of the NSX, but in defense of it it is 0.2 Liters down.

What the NSX has over the CL-S (besides the obvious styling issues, etc.) is much less weight and more agressive gearing. But the engine, to me, isn't the highlight of the car...
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Old Jul 17, 2001 | 05:54 PM
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Originally posted by scalbert:
<STRONG>Cost...
Size and additional weight...
Nessesity....

I'm not too concerned about it. I like how mine revs but don't need 8k - 9k. I look at the NSX and its DOHC and then my CL-S with a more usable torque curve and it makes me feel fine and actually more impressed with the J32A2.

Manual NSX:
NSX 3.2: 290 @ 7100
NSX 3.2: 224 @ 5500

Auto NSX:
NSX 3.0: 252 @ 6600
NSX 3.0: 210 @ 5300

CL Type S:
Type S - 260 hp @ 6100
Type S - 232 lb.-ft. @ 3500-5500

The CL-S has more torque earlier than the NSX which is certainly a plus in traffic. Add headers and intake to the CL-S and the HP numbers are greater than the NSX. Then look at the Auto. version of the NSX, but in defense of it it is 0.2 Liters down.

What the NSX has over the CL-S (besides the obvious styling issues, etc.) is much less weight and more agressive gearing. But the engine, to me, isn't the highlight of the car...</STRONG>
Excellent answer!!! Thanks I feel better now
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Old Jul 17, 2001 | 05:58 PM
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Don't forget mid-engine design.

There are many reasons why we have a SOHC. I'm sure only Honda of America knows all of them.

Originally posted by scalbert:
<STRONG>Cost...
Size and additional weight...
Nessesity....

I'm not too concerned about it. I like how mine revs but don't need 8k - 9k. I look at the NSX and its DOHC and then my CL-S with a more usable torque curve and it makes me feel fine and actually more impressed with the J32A2.

Manual NSX:
NSX 3.2: 290 @ 7100
NSX 3.2: 224 @ 5500

Auto NSX:
NSX 3.0: 252 @ 6600
NSX 3.0: 210 @ 5300

CL Type S:
Type S - 260 hp @ 6100
Type S - 232 lb.-ft. @ 3500-5500

The CL-S has more torque earlier than the NSX which is certainly a plus in traffic. Add headers and intake to the CL-S and the HP numbers are greater than the NSX. Then look at the Auto. version of the NSX, but in defense of it it is 0.2 Liters down.

What the NSX has over the CL-S (besides the obvious styling issues, etc.) is much less weight and more agressive gearing. But the engine, to me, isn't the highlight of the car...</STRONG>
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Old Jul 17, 2001 | 06:24 PM
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I would guess to that having DOHC bumps up the cost for the entire VTEC system.
More cams and lobes = more manufacturing.
Good breakdown above in regards to the CLS engine T- curves to the NSX .
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Old Jul 17, 2001 | 06:40 PM
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If you'll notice...the DOHC design is saved for the Racing versions of Acura/Honda..remember, this is a sport luxury coupe with more than enough power from a SOHC...I wouldn't mind a DOHC...as that would make it that much more formidable on the freeway..but I think the SOHC produces better low end torque...
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Old Jul 17, 2001 | 06:44 PM
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Originally posted by moomaster_99:
<STRONG>If you'll notice...the DOHC design is saved for the Racing versions of Acura/Honda..remember, this is a sport luxury coupe with more than enough power from a SOHC...I wouldn't mind a DOHC...as that would make it that much more formidable on the freeway..but I think the SOHC produces better low end torque...</STRONG>
That's what I was thinking. Isn't DOHC usually used on their Type-R vehicles? I think I had seen some Type-R DOHC Accord in a magazine before, but it'sonly sold in Japan like everything else.
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Old Jul 17, 2001 | 06:48 PM
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sohc gives you more torque....dohc allows the engine to breath easier and rev higher, but it is harder to maintain and produce. Not to mention weighs abot 20lbs more im guessin.
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Old Jul 17, 2001 | 06:54 PM
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What is DOHC anyway ? I know it stands for "Double Overhead Cam" but what purpose does it server ? It might sound like a stupid question to some but I don't know much about engines.

Thanks.
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Old Jul 17, 2001 | 06:58 PM
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Scalbert's answer is 100% complete. As he stated, cost is the #1 factor here. The #2 is torque at "low" rpm.
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Old Jul 17, 2001 | 07:01 PM
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Originally posted by batra:
[QB]What is DOHC anyway ? I know it stands for "Double Overhead Cam" but what purpose does it server ?QB]
In OHC engines you have either a belt or chain attached from the crank pulley to the cam pulleys on the heads. These drive the camshafts that in turn actuate the valves.

In SOHC we have only one camshaft per head. Meaning that a single cam actuates both the exhaust and intake valves.

In DOHC there are two camshafts per head. One that actuates the exhaust valves and one that actuates the intake valves.

That pretty much sums up the mechanics of it. The concept is really about efficiencies. Although this could be debated, it is general thought that by using individual cams on the intakes and exhaust valves allows for lighter valve train components and greater implementation flexibility. In the end it comes down to allowing the engine to breathe better particularly at higher RPMs.
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Old Jul 17, 2001 | 07:49 PM
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Enough room in the engine bay to take advantage of the "original" reason for DOHC -- a very straight flow into the cylinders, and cost. Acura didn't have the variable timing ready for production...

This has now changed with all of the variable timing.
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Old Jul 19, 2001 | 06:45 AM
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A final thought -- I got some more data from the NSX prime forum. I was curious if the blocks had different configurations (60 degrees, 90 degrees, etc) -- something that would impact the ability to fit the DOHC engine into our engine bay.

The NSX engine with its DOHC, is a 90 degree V6 and takes up more room than our 60 degree V6 SOHC engine.

In the case of the NSX, the banks are at right angles -- can you say, "TAKE UP MORE ROOM".

Our engine is a relatively compact design at 60 degrees. The banks are closer by a 30-degree angle. This makes for less room requirements from side-to-side, and it also makes the straight airflow that would really help the DOHC make the good power (minus the future advantage of dual camshaft independent control [separate intake and exhaust cam timing is nice!!!]).

Here is a link to the NSX Prime engine spec page for anyone interested...
http://www.nsxprime.com/FAQ/Reference/1991_svcman/5.pdf
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Old Jul 19, 2001 | 01:54 PM
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Eric this is a cool PDF. Why cant we find one for our car?
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Old Jul 19, 2001 | 03:50 PM
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DOHC would not affect our torque one bit.

It's all about cam profile. If the profile of the DOHC and SOHC is the same (before vtec is engaged) then the output will be the same.

The only reason we don't have DOHC is cost. They know that the average consumer of this vehicle isn't interested in pushing their family to 8000 rpms. Only the crazy ones like us are.
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Old Jul 19, 2001 | 04:02 PM
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Originally posted by Closer:
<STRONG>The only reason we don't have DOHC is cost. They know that the average consumer of this vehicle isn't interested in pushing their family to 8000 rpms. Only the crazy ones like us are. </STRONG>
We need a 3.5L DOHC CL Type R.
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Old Jul 19, 2001 | 10:21 PM
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Originally posted by gavriil:
<STRONG>Eric this is a cool PDF. Why cant we find one for our car?</STRONG>
Funny, I printed out a few of the .pdfs (for the NSX engine stuff) last night, and wondered why the pics and info in the Helms (for the CL/CLS) wasn't as good as the NSX stuff.

There are a TON of .pdfs over there -- it looks like they scanned everything they could get their hands on!
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