HabanaJoe

The props on the Skater don't work well, spoke on the phone with them. 18" 4 blades is all you'll need.

Your question is Hp and you are a realist, you brought a less expensive boat and don't sound like you want to spend $100k on engines for an older boat - you want to make an affordable package that won't break the bank with repairs.

Hp - you don't want 5.9 or 6.7's you want the older "C" 8.3 engine, bigger cubes a little slower speed, 2,600-2,800 rpm's.

SeaMaster in Palm Beach $16,000 each rebuilt 450hp CTA's.

You can find used ones out there as well, they are sleeved engines you buy pistons, rings, liners & bearings drop them in and good as new. They will take the Nippendso pumps from the old 300hp B's, if you turn them allll the up you can make 500hp out of them.

If you get the Boosch P7100 series there are many hop-up kits out there for them 500-750 hp no problem.

Aftercoolers be smart get two old sq box 300B's cut off one side of each weld them together so you get almost a double delta drop in temperature or take 2-400C coolers that have cores in them and again cut and weld the two together and use the double cores.

There area several ways to get reliable engines on the cheap if you don't mind some smoke coming up on plane, exhaust totally under water into the prop vent tube and the smoke can't be seen.

Again your question regarding Hp all I can do is relate past boats we've built and ran - 17-18,000 lbs 40' V hull with 2-380hp 3,100 rpm engines and a 1.15:1 reduection gear a little over 60 mph. Take out 4,000lbs of lead ballast of the same boat and use bigger props and go 65-68 mph.

If you had those 450hp C's with 1:1 you should run 70 mph, you will cruise at 60mph. I know it won't be less, if I'm wrong it will be faster!

lotopa.com

where does the after cooler mount? I have a Inner cooler on my turbo drag bike that we built ourselves ( actually my buddy was the mastermind, I just polished it lol ) and when does it cool the charge? or does it work the same as my bike inner cooler ( after the cold side of the turbo and before the intake plenum)

lotopa.com

also thank you for the names and resources to acquire the parts and pieces

HabanaJoe

Both inner & aftercoolers mount after the turbocharger just like on your bike. In the older diesel days when Detroit Diesels were all 2 stroke, Detroit would call their coolers "intercoolers" because they mounted "inbetween" the turbocharger and the roots type blower that was needed for the 2 stroke to run hence a 6-71TI (turbo-intercooled). All the other brands called theirs aftercoolers as in 3408TA (turbo-afttercooled).

Just some useless history!

You really need to start with used marine engines, just because they'll have most of the parts you need like manifolds, gear drive water pump, heat exchanger, aftercoolers etc and all you need to add is upgraded fuel and turbo's.

Here's a project we built and it's not hard if you can find the right part? The old "C" exhaust manifolds were like the old "B" where the turbo could be mounted either at the end of or on top of the manifold (for different configurations).

We did this with both B & C series as tests but never in a boat, but dyno worked well. We would take 2 of the turbos for either a 300 "B" or 400 "C" and mount them on the manifold at the same time so you have a "twin turbo" set-up. The trick to that was you need to make a valve for lack of a better word to block off the exhaust to one turbo so you have boost at lower engine speeds otherwise the boat would never be able to get on plane. The other part is to build a valve to block boost on the same turbo so the intake manifold pressure does not blow out the turbo that is not spinning.

This set-up is exactly how the SeaTek engines work, I've used them, installed them and took them apart in detail to copy years ago. We were trying to do the same thing using mostly stock parts rather than make "new" casting to keep costs down. We are talking 23 years ago so there were not many people with lots of turbo experience to help us make parts that were small, long lasting and looked good. Today with all the import and diesel people making custom parts I'm sure you could fab the needed valves or sliding block-off plates you would need to make this would.

The big plus is you use all of the shelf Cummins water cooled turbos so should something break it's easy to find parts and fix it.

As for performance you have never felt anything like it in your life the jolt when you open the second turbo (on the SeaTeks in a boat) was actually like turning the nitrous bottle on!!! On the dyno it was uncontrollable, you could not add load fast enough with a waterbreak, it ran away!!!!

If you ever wanted to talk it out, you can call me, I love to talk old school shop!