Hi Alex--------------There was a DOHC crossflow head produced by O.S. Geiken in Japan for the L series inline six engines. It is very rare, at least in this country, and co$tly at about $10,000 each. It's said to give only marginal increases in performance, and most builders try other methods of increasing hp.
on an L24. The LY head was good for about a 5% increase over the non-crossflow head, and that carried on to the top as it was able to be ported comparably to the standard head (non-crossflow). So if you could get 300hp from a N/A 2.8 with the non-crossflow head, the LY would give you maybe 315 comparably ported.
But is paying $5000 for a head that you need custom headers and intake for really worth only 15 hp? That's a lot to pay for only 15 HP...
The main question I always ask is "WHY?"
Why do you need a DOHC head? The cost is astronomical, and you won't make the power that you will get for a fraction of the outlay on the head as it exists on the vehicle today.
The DOHC head is a gee-wizz lookie me kinda accessory, and if you have all sorts of money at your disposal then by all means stimulate the sagging Japanese Economy, but just because Honda's need DOHC to make power, doesn't mean our cars do!
Check the archives, this one's been hit before.
Hi Tony, guys----------------I guess the only reason I can think of for a DOHC head would be the ease of working a hemispherical combustion chamber into the head design. This would be impractical and horribly expensive for a Z, but many, many years ago I owned a '58 MGA Twin Cam car that was set up this way. DOHC with a hemi combustion chamber, good for about 7500 rpm. That car was fast! There were only about 750 ever produced, for F Production racing against Porsches and Alfas. Close ratio 4-speed, about 70mph in second gear at redline. Great car for the "stoplight grand prix".
If the guy will part with it, I'm sure delivery can be arranged. It's just sitting in a box. He was dissapointed after running it and finding that it didn't make as much HP on the same block as the Non-Crossflow head he had done at JG Engines...
Just show a cashier's check for about 20K and I'm sure I could broker a deal for say, 10%...
Either that or twisted wedge. I forget, and don't want ot dig up the photos right now.
Oh, and to address the "rarity" issue, I still think O.S. has a stock of all parts and complete heads, so it's simply a phone call away!