cummins v gmc diesel v8

[regal cummins]

Bit of a question i bought a 24ft regal it was fitted with with a 6.2 gmc engine which was having starter probs.Also a DP-D1 volvo leg. But with a new starter it still has no life in it. So ive give up on it. Dont want to spend the money on it cause it is old.

Ive now a 5.9 cummins 6b but ive been told that it won't rev hard enough for that leg. The engine will have a lot of torque and if i up the pitch on the prop would it give me enough speed to get on to the plan. An help would be great on other engines i could fit.

THANKS STEPHEN

[captainrmw]

Looking at putting 2 GM 6.2L diesels in my 30' boat. looking at purchasing Velvet Drives with 2:0 to 1:0 ratios. to have counter-rotating props, is this done at the transmission or is this a modification of the rotation of the engine?

[marshmat]

Stephen - Welcome aboard! I don't think your proposed conversion is impossible, but it won't be simple either. You'll need proper torque and power curves for the new engine, which should be easy to get from Cummins. You might need to have the gear ratio in the drive changed and you will most likely need a new prop. Not to mention the modifications that may be needed to the engine beds, control systems, etc. As for what gear ratio and what prop, you'll need someone with experience in figuring that out- guesswork doesn't work here, and math isn't much better.

rmw - Most likely, your engines both spin the same direction; counter-rotation is a function of gearing. What Velvet Drive are you thinking of? That company has a pretty wide range, http://www.velvetdrive.com/productsm.html

[lazeyjack]

afraid the 6b torque WILL destroy that leg
Cummins and Mercruiser now have a leg that will take that torque
I put one of those 6l 4 strokes on a vOlvo leg once , was ok
you may be best look at alloy pod and 4 stroke outboard Suzuki

[regal cummins]

Have give up on fitting the cummins to much work involved in fitting it also that engine would only put out 2800rpm and the leg requires at least 3800rpm.
Im now on the look out for a volvo Tam41 a or b.
And now with the on set of the red diesel doubling price it might be better to go petrol.

[pasty63]

Stephen,

The 6.2 Diesel was introduced in the US in the early 80's as an option for light truck buyers (Chev/GMC). Most of the business I used to have for my small block chev hobby was converting those trucks to petrol at the 100K mile mark. Whatever one's opinion of the 6.2 Diesel, the easiest thing to replace it with is a volvo or mercruiser 5.7l or 7.4l V8 petrol engine. The big block (7.4l or 454 ci) would be a vast performance improvement - if fuel usage is discounted. Best of luck.

[regal cummins]

I can get my hands on a pair of these one which is a runner and the other for parts. Its all the ifs and buts. Now the government are supposed to be taxing the red diesel from 1st November .
Currently red is £.56p but if they tax it gonna be £1.16 against Petrol @ £1.12. Now i know you get more mile to the gal with the diesel but I'll be only using it at weekends so @ the most 20 hours a month.
Does any one how much fuel one these 5.7 would burn per hour @ cruising speed (keeping it on the plane)

[tuantom]

I had a 250 hp 5.8 engine in a 24'er for about 30 years. @ a 3300 rpm cruising we would average about 9 gallons/hour depending on load and conditions. It'd get on a plane much sooner; but it seemed to prefer that speed.

[captainrmw]

Thanks Marshmat for your reply.

My research found that using an automotive GM6.2L diesel, for twin engine set up, both engines will rotate in the same direction. Velvet Drive has two transmission: 1) Liberty 2) 5000. These allow you to reveerse direction in the transmission to provide the counter rotation.
GM 6.2l (non-turbo) uses the basic V8 marine exhaust manifolds making this an inexpensive conversion as compared to Cummins 5.9L

[tonylaventure]

Dear members,
i currently just joined and i'm seeking advice on finding what cummin engines i have in my moreland 38 i believe i have v8-185m's with twin discs m-506's but someone told me i have v-504's how can i tell. thaks tony