I did all the testing on 91 octane fuel. I only had 29-30 total timing in the ecu. The combustion chamber is so efficent in the head it did not need much timing.

Tyler,

Will you also have a package less exhaust for those who have already purchased CMI's?

Keith

Thanks for the information. Would 87 octane work or not?

Keith yes I will I am looking into some other ex for the people that cannot spend 4600.00 for ex. It may cost a little power but that's were the saying you get what you pay for came from.

Yes you can run on 87 octane.

ttt

Show Me!, Make us Believe!
 

Hi Again Tyler :

I am kind of curious here. By my measurements the stock 496 iron head has 119cc's stock with no milling or changes. The stock 496 is 9.1 to 1 with this head and stock.059" head gaskets.
If the new Dart iron head has a 108CC combustion chamber as listed in their spec., how do you get back to 9.1 to 1 compression with the stock flat top piston and a head gasket of .060" or less?

We all know the stock 496 flattop hyper-eutectic piston is on the edge with an iron head and any raise in compression so the cc's of the new Dart head could be an issue and confuse me.

As for the stock intake, we tried everything on a stock manifold on our dyno testing with our aluminum heads and we could not get the stock intake to flow enough air to even make quite 525HP.
Believe me when I say Raylar would never have made a new expensive intake manifold if we did not believe we had to, especially to keep the costs to users on upgrades down.
Maybe our dyno is just stingy, but we were using CFM intake measurements on the dyno and with our heads above 4800 rpms and we started pulling vacuum of nearly 3-5 inches when we were at 5100 rpms. When we put the manifold on a head on a flow bench the manifold would only flow about 80% of head flow on the intake side at .580 lift. So we new we had to make a manifold, especially if we wanted to go above 525HP with 496's.

This was also the results Tom at Flagship got in his extensive 496 upgrade research and packages and I saw real dyno outputs and figures from Innovation and they never got above 535HP with stock cnc'd heads with their giant cam and piston mods that they used in the factory class GMC sponsored engines they distributed.
I know Rage thinks or has been told otherwise, but I have persoanlly had two Innovation 496's in our shop and on the dyno and believe me they did not make anywhere near 575HP calibrated with proper correction factors!
It just seems amazing now that someone is getting 575HP with just heads and cams and headers and a stock intake manifold. I know any good cylinder head will help this engine, thats why ours have been working so well for over 7 years now. I guess I must have some MISSOURI blood in my veins, as I am still skeptical of these initial results.

I was also told by Dart that the new 8.1L block is only available in a bore size and their website shows also that the block will only support the same over-bores as the stock block. so how do you get to 540 cubic inches and up with that.

As for the crankshafts, I understand that Richard at Dart wants to move the crank sensor up to the front of the motor with special add on reluctors, so how does this set up integrate for stock 496 Merc owners and if they run a MEFI they would have to change all the engine wiring and harness like the setup Arizona Speed and Marine used to market.

As for cooling and oiling issues on the stock block, that's kinda news to me, we have built hundreds of them from 525HP to 800HP supercharged and never had a heating or oiling issue in any of them with a good oil pump, bearings and clearances.

I am glad to hear Dart is going to make some cast carburated and EFI single plane manifolds as they will be helpful in some applications , but in general it would be very difficult, complicated and expensive to modify a stock Merc 496 package to run this set up in most cases. Obviously these manifolds are cheaper to make and that's the biggest incentive to use one but to be honest you've got to consider that of nearly 40,000 to 50,000 marine 496 engines out there 90% or more are Mercury packages and we all know how difficult they are to modify externally to accept major mods.
This is where I hope Dart has paid careful attention to all the dimensions and accessories mountings so that if a Mercury,
Volvo 496 owner wants to upgrade his block and engine , it will be a bolt in ,no mess, no fuss type of install, otherwise I can hear the crying , *****ing and screaming already!

Its hard as you know to come out with systems and kits that average performance boaters can buy, install, afford, and get reliable results with. Sometimes manufacturers, large ones especially kinda sometimes puff out their chests, make great claims and promises and usually don't hit their release dates or deliveries. I hope these new offerings from Dart are great additions to the marine performance industry and they establish themselves as being what they claim to be. Everyone with great product and reputation should be successful in any industry!

Not trying to be negative or a nay say'er here, but the old saying still holds true that the "Devil's In the Details" Lets hope that when a OSO'er who's going to upgrade his 496 that after he buys all the new Dart aftermarket products for the engine that everything fits, goes together painlessly and works. Cause if Richard thinks drag racers and such can ***** when something doesn't work or fit, He ain't heard nothing yet until a few disgruntled performance boaters get a hold of his huevos on the internet!

Best of Luck to anyone trying to grow and succeed in this damaged industry!

Just my usual 2 cents here mixed with a few questions and some findings.


Best Regards,
Ray @ Raylar

I'm glad to see more options for the 496 platform. I love competition though.

Ray I took the time yesterday to CC a bone stock head right off a Mercury 375 and it CCed out to 111cc's so you may have some heads from Texas (everythings bigger in texas) lol. I put a forged flat top piston in this motor with a little deeper intake valve relief so I could use several different camshafts in the motor for testing. I also used a .060 Gasket we had made for this motor the stock gaskets are .054. I also worked on the HP3 engine project for GM back when they started it and they were only looking to make 525HP. Tom at Flagship had Champion Heads port some heads and their were heads from Linenfelter and I had my head porter do some and we made the most power but the cost was to much and a lot of work and the ex ports got to thin. I know Innovation has gotten 565HP with the stock intake maybe you had some of their earlier versions. Their are a couple Super V light boats still running them. As far as the block Dart puts the hole in the back of the block for the stock crank sencor and everything bolts right on. They also will give you any bore or configeration you want because they control all the machining. And the stock water and oiling system work we just made it better !! That intake manifold is just like a restritor plate in Nascar if your good enough you can still make power there are ways around it. I don't know much about Missouri blood other than that's where Toto was from but I am from Detroit The Motor City !!!!

:popcorn: