Hello everyone,

What are the benefits of each application? I know that DOHC has more adjustability. Is it true that SOHC has better accelaration?

Let's compare FWD 2.4L supercharged SOHC and AWD 2.0 turbocharged DOHC. Assume both are manual.

 

To answer your questions:
SOHC can be cheaper but that is probably a case by case basis. DOHC can have more adjustability but is likely (but not always) a bit wider than a SOHC head.

There is no correlation between SOHC and "better acceleration".

I'm not even sure what you are asking with the last sentence. It looks like you have two cars in mind and you are trying to prove one is "better" than the other. I can't help you there.

 

Fully tuned a DOHC will almost always have a better power band. Yeah, you could put really big valves in a SOHC and get the same flow numbers as a DOHC, but the bottem end of the power band will suffer due to reduced air velocity. That doesn't matter as much if the car has some form of forced induction. In the end for all out performance just buy a DOHC.

 

Based on dragonacc's answer perhaps we should clarify are we talking about 4 valve heads in both cases?

 

I'll take stab at this one...

Let's assume both motors have comparable compression ratios or at least came from the factory with with forced induction. I say this to solidify that both motors are running equal boost.

Head to head, I will give the edge to the AWD 2.0L. The FWD (Front wheel drive I assume) car will struggle with traction as the supercharger will give power from idle. The AWD car will initially be slower to allow for spool-up, but traction won't be a problem.

As for SOHC and DOHC, the SOHC motor likely has fewer moving parts. If you are going to up the boost, it may last a tad longer than a DOHC, but that is just a guess.

 

Advantages of 4v DOHC?

Easier to get a central spark plug location, if that matters.

If you are using variable cam timing, you can vary the exhaust and intake separately.

May have some additional options for valve location.

If designed correctly it should be able to rev a little higher because you won't need rockers, the cams can act directly on the valves.

There's probably more stuff. I'm not very smart.

 

the only disadvantage of dohc is more friction and more parts.

otherwise, the central plug, adjustability, and chamber shape you get with DOHC si well worth that.

 

I'm sorry to change engines but consider the new RL engine...its the latest honda design and its SOHC, since its the top of the line Honda machine, why did honda not go DUAL cam with this one?

 

because they don't have a DOHC engine they can use. SOHC can do a really good job tuned right, as is in the RL. If they can get 300HP, why bother with tooling a DOHC head...that costs a lot of cash.

well, yea, they have the engine from the NSX, but i think honda politics just won't allow that one.

 

It's also easier to package an SOHC. The heads are smaller.