What are the advantages and disadvantages? Why does the TL only have SOHC?

 

single overhead cam (SOHC)
double overhead cam (DOHC)


The TL has two heads, each head has one cam, if the car was DOCH then you would have two cams per head.

 

Kinda like the Corvettes and why they do what they do === COST!! The cost of a SOHC is less than a DOHC. If Honda can get amazing horsepower and performance out of a SOHC why put the DOHC and pass the extra money onto the consumer. Although I would be a proponant of DOHC if they offered it, I think the masses would opt for the cheaper car, I may be wrong??
I think alot of peoples grips about the TL all boil down to cost.
If the car had more it would cost more.

 

DOHC would also require more room to take advantage of its best air flow possibilities. SOHC can approximate DOHC (without the fun of selective intake/exhaust cam timing control) with long rockers.

Look at the size of most DOHC heads, then look at the SOHC equivalents...

Who knows...

 

Have you ever looked at all the extra room the engine compartment has? I am thinking there is probally enough room in there to fit the larger DOHC heads in. Look at how small the NSX engine compartment is and how that engine fits snuggly in tere.

I really think it all boild down to cost.

 

From what I heard besides costs, DOHC uses more gas has more power but on the higher RPM with less torque. A truck per say would likely use a SOHC but a sport car would definitely benefit from DOHC. Integra and Accord 4-cylinders all have DOHC except for the V-6's. Imagine what horsepower output if you put aside mpg if our TL-s has DOHC Can't be that much more expensive.

 

Perhaps -- that is one reason. Your “probably enough room…” statement gives me pause as well. Perhaps it would “fit” but are we talking about jacking-up the engine to do various maintenance tasks? THERE is a key word that engineers and designers forget AND they do write a number of books on the subject, it is called – MAINTAINABILITY!

But without getting into the variable timing for two cams, it comes down to allowing a more "direct" air flow into the engine. If you look at the 4-cylinder DOHC, the intake velocity stacks (on a race engine) are sitting at 90 degrees to the cylinders, and the exhaust is pretty much the same (except for the number of cylinders etc).

I would love to look at the actual NSX engine and if we are talking about variable valve timing in addition to the VTEC, then there is no question that the advantages are quite extreme.

But when you talk about the amount of "room" that the engine has -- I really start to wonder...

BTW -- the NSX makes 290 HP, but it is also revving another 1000 RPMs higher. Did you know that the early BMW 2002/320 had such a wide set of rocker arms, that its intake flow approximated the look (from an air-flow standpoint) of a DOHC engine. When the variable timing stuff comes around, then I'll be expecting a DOHC.

 

I could make a DOHC work exactly like a SOHC! The converse would not necessarily be true. And when I sue the turn "make a DOHC work", I'm refering to making an engine with the DOHC replacement have the exact same specs as the SOHC (in every respect)!


With the advent of variable timing in the Honda/Acura familly the advantage of DOHC will become much more important...

See if I'm wrong...

 

Well, I decided to do a "REAL" check on the fitment issue to see if I was full of it.

The NSX has a 90-degree V6 -- this means that 2 banks of 3-cylinders are at right angles to each other. If someone could put this in the TLS or CLS -- without serious body mangling, I give them my best wishes and want to hear from them!

The 90 degrees gives the engine enough room in the middle to take advantage of the DOHC (other reasons too, but a DOHC isn't to valuable if the gas has to make a stiff turn right at the intake!

OUR CLS/TLS/CL/TL engines are "J" series engines and are 60-degree V6 engines. This means that only 60 degrees of arc separate the two banks of cylinders. This means the engine takes up less room!!!!

Check out NSX prime for more details -- If you like...