How much power can a DP-A handle?

[j_cizzo]

I'm building a new chevy 350 for my boat. it's a grady white 241 offshore. the old 305 is done. the new one will be home-grown with vortec heads and all the trimmings. i've already spec'd out the cam, it's going to be a
hydraulic-roller from compcams, for marine use, and the heads will be built up too, i'm going to port them a bit, and use bronze guides and seats with heavy-duty valves.

i have software from compcams that claims my design will make roughly 410hp (with a 9.0 compression).

i know the volvos are good, and i've been told it can handle it, but i just want verification. anyone know for sure? this engine could make more than 410, i am going to swap the firing order and perform a couple of tricks to the valves and what not, so 410 or more is almost conservative...

thanks in advance

 

[tommays]

Re: How much power can a DP-A handle?

That is a LOT of power at BELOW 5000 RPM when even a full MPI motor only puts out 300 HP


Tommays

 

[j_cizzo]

Re: How much power can a DP-A handle?

That is a LOT of power at BELOW 5000 RPM when even a full MPI motor only puts out 300 HP


Tommays

it's not below 5000, it's by about 5300rpm... but no, i don't plan on running it that hard. i've studied enough graphs and what not to know that this combo will produce about 230hp and about 375-400ft/lbs at about 3000rpm, which is where i want to cruise it at. i will prop it so that max rpm is between 4600-5000 rpm... it should be very doable even with stock vortec heads.

 

[Don S]

Re: How much power can a DP-A handle?

The only problem with the DP-A would be the shift cone. The A models had the steel cone. If you changed it to the newest style shift cone and a steel shift slide, then it would probably be ok. Volvo ran the 44 series diesels on the DP-E, which is the same gears, just the newer shift cone.

 

[John_S]

Re: How much power can a DP-A handle?

410 seems very optimistic. I could see about 10-20 for the light porting, and maybe 25 for a cam. That would put you at about 325 at prop, assuming a dual plane carb induction and thru prop exhaust. I am not sure you would want a 350 with an upper powerband to reach 410 in a grady white. It would seem that you could benefit more by going to a 383 with 325-330 hp.

 

[mtnrat]

Re: How much power can a DP-A handle?

410 is likely optimistic. I am building a 383 with engine quest 200cc heads, forged crank, rods and d-dish pistons. .039 quench. Have 9.1:1 compression and running a custom cam by Chris Straub. We figure it will have a quite flat 400lbs torque curve and put out 350hp.

 

[TilliamWe]

Re: How much power can a DP-A handle?

" i am going to swap the firing order and perform a couple of tricks to the valves"

How do you change the firing order on a small block Chevy? And what tricks can be done to valves?

Good reply DonS. How much would those modifications you wrote about, cost?

 

[Don S]

Re: How much power can a DP-A handle?

If you wanted to stick a lot of power in front of it, the parts (cone clutch, shoe, seal kit) would run about $500 probably take 2 to 3 hours labor to replace the parts and check all the shimming and gear patterns to make sure all is well in the upper gear box.

 

[rodbolt]

Re: How much power can a DP-A handle?

I am with DonS on the cone change.
we run the 425HP 8.1 in front of DP-E,s all the time with no drive issues.
but I also think 410 HP at 5000 is a bit optimistic for a 5.7 with a water cooled exhaust.
we have enough water reversion issues due to the aggresive cam with a 425 and even the 375 versions of the 8.1.

to just replace the cone and shoe will only require upper box removal and shimming of the shift shoe on reassembly. last cone and shoe kit I got there was a slight change in the shiming procedure but I cant remember the details.