1971 Donzi Classic 18 power....

[Classic18]

Talked a few hours last night about possible engine upgrades...in addition to redoing the rotating assembly (including a forged crank & lighter-weight pistons, the discussion of the flywheel surfaced. The flywheel I have seems VERY heavy and of course that's energy loss on acceleration and a hit on engine response time (from an inertia standpoint). Is there a lighter-weight flywheel that will fit in the Bravo One environment? If so, what coupler would be used?

[Classic18]

It was also recommended I pickup a hydraulic? balancer for the front of the engine....he said the production won't stay together. Any recommendations?

[Capt.Insane-o]

The stock balancers can spin the outer ring, a fluid dampr works fine.

[Greg G]

Talked a few hours last night about possible engine upgrades...

I know that you are leaning heavily toward a used option but here is a really good article you might want to check out on the 383 motor that comes with a warranty. You might want to see if Merc will offer 0 percent financing on it given your budget is limited. Sometimes this time of year they have some interesting options. Lot of motor for $10k and peace of mind. Maybe they would roll in the installation at a dealer and for no upfront money you could be into it for a 12 month note.

http://www.boattest.com/oem/497/engines/29500118/3

[blacktruck]

I know that you are leaning heavily toward a used option but here is a really good article you might want to check out on the 383 motor that comes with a warranty. You might want to see if Merc will offer 0 percent financing on it given your budget is limited. Sometimes this time of year they have some interesting options. Lot of motor for $10k and peace of mind. Maybe they would roll in the installation at a dealer and for no upfront money you could be into it for a 12 month note.

http://www.boattest.com/oem/497/engines/29500118/3

This is great advice from Greg. It would be a beast in an 18 Classic. Resale would be higher, bullet proof and cost less than rebuilding a used motor. If you can finance it, then you have money in your pocket longer.

[blacktruck]

Do you have pics of your boat?

[FMP]

That's still a very mild 377 with iron heads for 10k. No fuss, turn key.

[blacktruck]

That's still a very mild 377 with iron heads for 10k.

It's an amazing motor for $10k. With headers it's 370 HP. Couldn't build it for less than that to the same standard. More than enough for an 18 Classic too. Each to their own though.

[FMP]

Mild and reliable, but for 10 you could build a stroker with much more and still be turn key. Not saying that's better in this case, but 100% doable.

[blacktruck]

Mild and reliable, but for 10 you could build a stroker with much more and still be turn key. Not saying that's better in this case, but 100% doable.

Paying for someone else to do a 400 HP stroker, with a good block and really good marine marine parts for less than $10k? Maybe, I'd be surprised though. I haven't built an engine in a long time. Factor in the warranty, resale etc. Not even a contest to me. An extra 20 to 30 hp in that boat won't get you much speed either.

[FMP]

I'm frugal build your own with 75-100 more HP.

[Classic18]

I understand and very much appreciate all the comments on what to build, but I have very little money to put in this. I get the fact that $10,000 will get me there (maybe with a suspect motor), but I'm trying to do with much much less. Many of you have added information that has really pointed me in a different direction....and in some cases a safer direction! That's worth gold and my kids appreciate that!

My low-budget build starts with a 1991 2-bolt Mercruiser 350 pulled from a bow rider. $1000 for the whole boat and have sold $3400 worth of parts.....so I am partially funded. I kept the donor trailer and am modifying to lower the boat/trailer CG as I like to travel fast and the original trailer is a higher-CG unit.

The motor is down to the block now. I picked up a set of L31 5.7L Vortec heads, casting number 12558062. Based on what I've read, these are a very big enabler (for min cost engine development). I'd love to buy some Dart or other fast-burn heads, but they don't compare to the $75 I paid for these. I'll have the block checked, get some stronger/splayed mains, an affordable (?) forged crank and pistons and see what I have. I'll also do some of the recommendations to the heads and profile the CR....will see how it goes.

Regarding the boat: Its nick name is Eleanor since it is (was) yellow and wasa rat boat and reminded me of the original "Gone in 60 seconds" Mustang. . Paid a few thousand for it, but the hull was really gouged up from driving onto trailers sideways and over rocks. I have removed every scrap of wood in it, replacing with new, improved structure & new gelcoat. Before and after for the hull......more to come.

My wife want to know if she posted Donzi on my head if I'd pay more attention to her!

[Classic18]

The stock balancers can spin the outer ring, a fluid dampr works fine.

Capn, do you have a damper you'd recommend....maybe not the best, but a "good one"? Maybe that doesn't exist.

[FMP]

Can't remember right now about the L31 or cast # but you want the 1/2 ton heads not the 3/4 ton heavy truck heads. The 1/2 ton out flow and make more HP. Also check them for cracks.Ran them on a heavy K20 with great results just under 10:1,then went to aluminum .Just checked, those are the 1/2 ton heads.Either way they make great power, with less adv.

[Classic18]

Can't remember right now about the L31 or cast # but you want the 1/2 ton heads not the 3/4 ton heavy truck heads. The 1/2 ton out flow and make more HP. Also check them for cracks.Ran them on a heavy K20 with great results just under 10:1,then went to aluminum .Just checked, those are the 1/2 ton heads.Either way they make great power, with less adv.

Yeah, the ticket to have is PN 12558062.....I'm told for someone that doesn't want to spend a ton of money, these are the way to go for a big HP jump....adding the purchase price for my L31 heads, now have about $350 in it....but the machining hasn't started.