Ok, if the modern DOHC is marinized and we saw a movement to this style would it not overcome the ethanol issue? Ie, running E85 in the motors? Granted everyone would need 30% larger fuel tanks but hey, would do wonders for FI applications.

Merc had them back in the late 70's early 80's. Here's a couple pics of my 1980 38 flatdeck Scarab that i sold a while back. I loved those engines. I could cruise all day and stay out of the turbos (under 4 grand) but when I needed them they were there. Put you back in your seat. Merc 454s 12lbs boost.

http://i1150.photobucket.com/albums/...2/CIMG0465.jpg

http://i1150.photobucket.com/albums/...2/CIMG0464.jpg

http://i1150.photobucket.com/albums/...2/CIMG0469.jpg

CrownLPX in answer to your question about ethanol in DOHC engines in marien use the answer is NO! please study the rpoblems and issues with E85 ethanl and you will see the problem is not solved or cured with an engine valve actuation change.

As for Mercury Racings develoment of a DOHC marine engine it was pretty much to get away from one of the most difficult problems to solve on endurance BBC marine high performance engines -valve train stability on larger cubic inch higher horsepower versions at higher operating rpms.
Mercury already had a lot of somewhat publically unknown expierence with this type of engine with the LT5 DOHC engine they cast and hepled develop and assemble for GM starting back in the late 80's.

If you are going to develop a new DOHC big block engine it isn't engineering wise efficient, practicle or reasonable to do it on the standard GM type OHV pushrod block PERIOD!
Don't try, start with a c;ean sheet of paper!

As for turbos, I think the driving force here was to create bigger power in a smaller tighter package that would have some reasonable intervals between refreshening and rebuild and could re-establish Mercury Racing as the premier big power, high tech marine racing engine builder. Kinda think that they accomplished all their action points right on the money. By the way with a lot of money for a product that costs a lot of money! They did however at the same time raise the bar to a very high level!

JMO

Best Regards,
Ray @ Raylar

Mercury 460 Cyclones.

Daytona Marines 427c.i. GM based Scarab engine at 600-1050 h.p. single turbo 1965-66 others followed later on.

That was in the British Surfury Raceboat at the time which won practically everything.

That boat had so much pulling power that it's avarage race winning speed 45 yrs ago at CTC even puts Apaches that has raced the same race even to shame...

Did you Forget the Olds W43 455 DOHC Street Hemi ?

Would be easier to convert a Cummins N11/14 to Gas and make it work than use SS as a turbo manifold ;)

Now on a serious note.
In a pushrod engine especially a 2v there's one advantage and that's low bottom torque, therefore in a marine engine slap a Turbo keep the RPM's under 5000 and use high boost and even nowadays with the ignition controls we have you could run a sequential mechanical fuel injection even, ( a diesel pump basically), just saying.
But the days of the Gasoline engines are numbered.. .even though the Soviets fell in their own nuisance (general lazyness) one thing is for sure Russians sure as hell still can build big power and high tech diesels....with Turbos and superchargers in the same package ;)

Here's one I have fell in love with lately: Zvezda M504:
56cyl. Turbo&centrifugallly charged, multivalve and aftercooled radial engine at 11680 c.i. and 5000 h.p @2000rpm constant rating (read nonstop ) Tops has been in a "boat" close to 8000 at classified r.p.m. These were the mothers the Ruskies targeted to level the whole world with in bombers some 70yrs ago... so much for "Modern DOHCs":cartman:
http://www.shipyard.lv/images/galery...030a0b0c74.jpg

Is there anyone making a turbo kit for marine engines ??????????



Jim

Does anyone have a marine blower/supercharger preferably Pro Charger or Whipple for a 502 engine?? I am looking get some more power out of my 1998 formula 252.