New Merc 400hp 383 Scorpion Engine

[harbormaster]

Hello everyone.

I was in Las Vegas last week and got a peek at Mercruiser's latest offering.

It's a 400hp 383 scorpion. I comes decked out with billet valve covers and a flamed theme (see photos). It also comes with some nice internal components. It's currently only being offered as an inboard/transmission configuration for the skiers. The scoop is however that it will be available in a Bravo version in February. I have enclosed a pre-release brochure. (begin tasteless Plug) Oh yes and did I mention that I could sell them to you? Call me at Victory Marine 713-910-2000 if you have more questions. I am working on getting pricing.

[Ranman]

Looks like a nice motor. 400CSHP @ 6000RPM is interesting. I bet the Bravo version wil have to be tweaked since Bravo's don't like 6000RPM. Also the PSHP would be around 360. Still very solid, but I bet not far from the standard 6.2MX when tuned down to 5000RPMs.

[Lenny]

Is that a carb motor?

[harbormaster]

fuel injection

[RickSE]

The inboard guys get all the good motors. They've got the new GM small blocks.

[Trueser]

How much $$$$$

[Cuda]

What's the torque graph look like?

[Pismo]

What's the torque graph look like?

That could be a weak point. If it needs 6000rpm to get out 400cshp then 2500rpm torque may not be so hot. It sounds like a cool motor for a lighter fast boat, like an 18 classic, but I'm sure the low end torque numbers don't match up to a 454/496/502 which has about the same top end hp.

[BigGrizzly]

Merc isn't that stupid, it is a ski boat motor, so torque should be up there at low rpms.

[Cuda]

Merc isn't that stupid, it is a ski boat motor, so torque should be up there at low rpms.

They are probably geared down for ski boats, and run a small prop, I just don't see an engine that spins 6000 rpm for max hp, having much low end grunt.

[BigGrizzly]

On my Criterion the max torque is 700lbs @ 3,977 and max power is around 5,600, still climbing but I ran out of intestinal fortitude and shut it down. The Corsican with a 351 Ford 351 V4 big port,no less, has max torque at 3,200 anf hp at 6,100(which it never sees). That boat comes out of the hole real well. I have never tried to push the Criterion because it will lunch the transmission and or the outdrive. It has 500lbs at just over 2,200. Point is it can be done easily if the correct cam and piston combination is used. Things have changed in the past Decade. If I knew in the 1970's what I know now I could have won the Daytona 500 with one gas stop. when I was a kid one horse power per cubic inch was a radical engine. Today it is commonplace on regular gas!

[Cuda]

351 Ford 351 V4 big port,!

Big ports is an understatement! The intake valves were 2.19. I don't know how big the ports were, but you could drop a crescent wrench in it! They were huge!

My dad had a couple 351 C's, and they never would run as well as you would think. My buddy even had a Boss 351 he bought just to beat my other buddy's basically stock Nova 350, and still couildn't beat him.

I had a 69 Mach I with a 351W, and it was faster than any of the Clevelands.

I think the ports, and valves were just too big for a basically stock engine.

[BigGrizzly]

Cuda you are correct on the original stock versions. The engines were designed for sustained high speed operations ie. Lemans 24 hour. In the street versions the had two heads the big port open chambered and closed chambered head. I am not including the small port Clevelands, which are not too bad.
At this time the were down HP ing the auto industry. As a result the cams were poor to say the least. H&M put them in some boats. They had two configurations. One a bib port small valve (only a few made) amd big port big valves. Didk Edelbroc and Ed iskaderian and Babe Erson got together to make cams and intakes tor Dick's Pantera sports car. I have been friends with Babe since the mid 1970s, and he hooked me up. Took the stock cam out on my 71 MACHI and put in Babe's max 108, and a different car. BTW I still have the MACHI. If this motor can be made to work, I am sure that the Scorpion can. Also my fuel economy is a lot better than stock too.

[Pismo]

Merc isn't that stupid, it is a ski boat motor, so torque should be up there at low rpms.

I can't say it's a question of stupid or not, it's just tough to get the same torque curve out of a 383 as opposed to a 502.

[BigGrizzly]

The 351 Cleveland has more torque than a 350mag does the point is it is stwrting out for ski boats ie Mastercraft, ski Nautic etc. Can they do i-YESW- will they time will tell.