What would you pay for a dohc 4 valve head

[JimmyZ]

If someone made a head like OS Giken used to what would you be willing to pay?

Yes, it's a hypothetical question and the performance gains are disproportionate to the money spent vs other ways BUT it is something to brag about.

What would it be worth and would you want a N/A head or one designed for forced induction? Any special features you'd like to see on such a head?

I imagine many people would hop on it if were between $1500-$3000,00 for a bare head. By bare head I mean a casting minus valvetrain having seats and guides installed. It would utilize the stock rockers which would not be included. (All major machining operations completed) Herringbone gears for the cams would be included and the stock chain could still be utilized.

On Z-car.com there was a fellow who built up such a head and there have been a few places doing variations of that over the years. It seems to have generated some interest.

Jim

[Carl Beck]

How about a cross flow rotary valve head for the Z?

http://www.coatesengine.com/csrv.html

CSRV Cylinderhead

FWIW

Carl B.

[carrott]

Just by an RB series engine, hell there's plenty of variations to choose from , pretty cheap and stronger than an L series.

[JimmyZ]

I'm sure there is SOME interest in reviving the idea of a 4 valve head for our L-series.

Sure, it would be easier to bolt in a V-8 or other engine but I'm talking about a certain coolness factor here.

Carl, If I knew some specifics about the ease of construction of the rotary valve head I'd definitely mention that as a possibility. I imagine there is some sealing going on between the cam and the head... More than could be had by just machining to close tolerances. Such a head would be way cool though.

So far I'm getting the impression that there is no real interest in reviving the 4 valve but I imagine there might be if someone made one.

The real question is how much could someone justify spending for the aforementioned "bare" head.

Maybe I need to make a poll.

[Nota280]

Bryan's DOHC head may have a chance of being produced in small numbers. This is the one from Zcar you referenced right?

http://forums.hybridz.org/showthread.php?t=120659

[JimmyZ]

Yes that's it!

I cast aluminum as part of a hobby. Talking with Norm Simpers about this head got me wondering about taking a swing at casting such a head. Of course I'd have to make a much larger furnace and crucible but it could "easily" be done with a lost foam casting. I also have some light machine shop equipment which could tackle some aspects of the rough machining of said casting. I'd want to entrust the rest to someone with a Serdi machine and other high end equipment.

After looking at the simplicity of the OS Giken cam towers and hearing the gripes about the thinness of the OSG ports I'm just trying to get a feel of what changes would be needed to make a better 4 valve head. I've cut up a few 4valve heads and observed the thickness/cross sections of the parts. Having that knowlege make the task a bit easier. Designing the ports would prob find me just copying a similar heads ports.

If I were to be able to test and produce such heads I'm just trying to see what kind of interest there is.

Jim

[red_dog007]

Some people would buy into it no doubt.

Performance gains I would see wouldn't be worth the cost. Though other modifications would take advantage over DOHC like a turbocharger.

But for that price, people would rather just keep their SOHC L motor, or get a V8 or RB/SR motor.

Hell, you can get a 4800 Vortec motor with everything except a tranny for $500 almost brand new. That right there gives you 300/300 stock.

[JimmyZ]

Some people would buy into it no doubt.

Performance gains I would see wouldn't be worth the cost. Though other modifications would take advantage over DOHC like a turbocharger.

But for that price, people would rather just keep their SOHC L motor, or get a V8 or RB/SR motor.

.

I mentioned this at the beginning of the thread.

The question is... How many of us would be interested in slapping a DOHC head on our Z's and what would be the price range desired? If one day you found one on E-bay what would you be willing to spend? (Knowing that the head was a proven design of course) Remember, this is more of a bolt on type of thing rather than fitting a whole new powerplant/drivetrain.

[e_racer1999]

that's a tough question to follow. if i actually had $$, i'd be able to give you a guestimate, but not as of now. I am very interested, though.

[red_dog007]

Ummm.... I would say $2,000 tops.

Normal heads go up for $500, so I would say that $1,500 should cover labor, and parts. Though that includes everything.

Would I do this? I think that I would if I had money. I would have several different Z's tuned to much different specs.

[Mike]

How about a cross flow rotary valve head for the Z?

http://www.coatesengine.com/csrv.html

CSRV Cylinderhead

Carl, the rotary valve system looks VERY interesting. Are they building one for the L series?

[240znz]

From memory the OS Giken head out flowed the standard heads by only 15% or so.

For the money these days in building a DOHC head, I'd say that a good head specialist would provide way over the 15% increase from stock at a fraction of the price of a DOHC head.

Now, for coolness factor, a DOHC head would look awesome in my engine bay or anyone's for that matter. Go for it, I'd be watching the developement unfold if allowed.

The rotary valve idea is not new. I remember watching a TV program years ago (10-15 at least) that was on this very subject. The guy who did it was a old chap from Italy who was trying to make one for the F1 industry. He had it working to a point but he was a privateer who had run out of funds to develop it further. I wonder if these guys picked up his ideas and ran with it. Red line was a huge 19,000 plus. That's what they doing now with valves anyway.....mind boggling isn't. If my maths is correct, that's a valve opening 158 times per second. 19000/60 = 316.66sec divided by 2 (four stroke engine) = 158