Hey guys, I know the Evo has a Dual while our RA's have a single.. What are some of the advantages of having a Single? When I talk to my buddy (drives a supra) he tells me that the supra is better simply because its a DOHC.

I know its a rookie question.. But any thoughts?

Edit:
Is it possible to drop a DOHC into our RAs ??

 

Cheaper to replace all the cams in the car?

 

There really isn't an advantage to SOHC, other than timing belt changes are easier ambystom01 is right, too, one shaft is cheaper than two, but not by much.

You could also argue that there's less weight for the engine to spin, but that's a pretty weak argument. DOHC really is the better option. Finally, no, you can't convert the RA to DOHC since there's not a DOHC head out there that'll work. Plus, it wouldn't be worth the cost, since most people wouldn't take advantage of the ability to independantly set the timing on the intake and exhaust lobes.

 

thanks otter. Someone mentioned dropping an Evo head.
whats the biggest advantage of DOHC?

 

It's more efficient since you have a separate cam for intake and exhaust. You can't swap an evo head in, completely different engine.

 

Don't you need DOHC to get 4 valves per cyl? I guess there a few SOHC with 24v, but I think it becomes more complicted. Also, DOHC can rev higher due to the valve/spring weights.

 

We have 4 valves per cylinder (we're 16v).

 

24v is for 6 cyl cars. But yes, we definitely have 4 per cylinder. If you pull the valve cover off you can see how it all works.

 

The advantage of SOHC is it's cheaper and makes for a more compact head.

Disadvantages:
--more complicated valvetrain, with lots of rockers and followers and such
--this means the engine cannot spin as high = lower redline
--can't have as wide an angle between the valves = less power from less spherical combustion chamber

Toyota had a DOHC two-valve engine for a while, I suppose for the third reason.

I think Honda had the first SOHC four-valve engine, in the first Legend. Since then Chrysler and Mitsubishi have also adopted the design, Chrysler only with the 3.5.

Honda appears to be the only company committed to SOHC four-valve engines, and its high performance engines remain DOHC.