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Old 10-16-2016, 07:13 PM   #1
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Gas power choices

Times change, life goes on. We sold our Gulstar 36 last September in Sheboygan, WI, having decided that living aboard full time wasn't for us. By the way, the boat is for sale on Yachtworld in St. Petersburg Fl. Overpriced for what it is. We now live in New Bern, N.C. We miss the cruising, and want to get back to it on a smaller scale. One of the big drawbacks of the Gulfstar was the 7 kt cruising speed, 9 kt top speed. You can run a fast boat slow, but can't run a slow boat fast.

We're looking at Trojan F32s, early to mid 1980 models. My question is which engine is the best for power/economy/durability. The choices are 350 Mercruiser, 454 Crusader (350 hp), or 318 Chrysler (225 hp). Running the ICW will be at slower cruising speeds, even single engine, but it will be nice to have the power to speed up when possible or necessary.

I bow to the collective wisdom of the forum. It's good to be back.
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Old 10-16-2016, 07:30 PM   #2
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Mercruiser should be ok, but I'd prefer Crusader
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Old 10-16-2016, 07:39 PM   #3
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I liked my 305 Crusaders in a 28 ft Carver - sometimes wished I had 350's but that was before going to a single Mainship 34HT and learning that slower wasn't all that bad.

Never had 454's but friends seem to always to be complaining about fuel burn rates.
I would think that if you were talking twins 350's would be plenty of HP for a 32 ft even if you intend to get up on plane to go fast.
Just my opinion
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Old 10-16-2016, 07:39 PM   #4
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the 454 block engines I have dealt with in the assistance towing business are near indestructible.

I think they are better off being used and abused than lightly used.

my old Tow boat has a GM block 454 with over 5000 very abusive hours on it.

still powers up and doesn't burn oil. it has more time in the red line for temp than most boaters put on an engine in years.
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Old 10-16-2016, 08:20 PM   #5
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Get an electronic fuel injected (EFI) engine, whatever you do. EFI maintains a tighter fuel air ratio than a carburetor and if it is port injected, it will provide a more consistent fuel air ratio across the cylinders.


More displacement usually means worse fuel economy, unless you are really using the hp it can generate, but in that case nothing will help. So if you don't need the hp look at the small block V8s or even the newer V6s.


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Old 10-16-2016, 08:29 PM   #6
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If I remember right the T/318ci Chryslers were very popular in the F32. They cruised in the 18-20 mph range. If you are going to repower, new fuel injected 5.7L Crusaders would be my choice.
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Old 10-17-2016, 01:13 PM   #7
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Quote:
Originally Posted by psneeld View Post
the 454 block engines I have dealt with in the assistance towing business are near indestructible.

I think they are better off being used and abused than lightly used.

my old Tow boat has a GM block 454 with over 5000 very abusive hours on it.

still powers up and doesn't burn oil. it has more time in the red line for temp than most boaters put on an engine in years.
454 was one of the standby workhorse engines for those needing high performance. We had quite a few of them on the lake and they were certainly the most abused engines there but kept on going.

Now, to the OP's question, depends on the performance he wants and the condition of the specific engine. All could be good or bad. The 454 is going to provide the most speed and use the most fuel.

To the OP, how much speed do you want? That's a key question. You figured out that below 10 knots was not for you. Yet you still talk about running a good bit at slow speeds. So, is the magic number to be able to cruise at 15, 20, 25, or 30 knots?
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Old 10-17-2016, 01:35 PM   #8
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No small part of this project is adaptability of the powerplant you choose to the conditions existing in the boat, ie engine room space, mounting footprint, transmission adaptability, and running gear compatibility. Changes in weight distribution, fuel capacity, noise, and more will factor in here too.
And BTW, some fast boats do not like to run slow at all, and will keep the helmsman very busy.
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Old 10-17-2016, 02:20 PM   #9
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Not sure some of the good suggestions are going to be available unless those mid 80s boats were repowered or are going to be,
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Old 10-17-2016, 03:21 PM   #10
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In the early 80's the owner of the marina I was keeping my boat at had
a 34' Silverton. The original engines were 318 Chryslers. Said they had
to work too hard for cruising speed.
He replaced them with the GM based 454's. Engines loafed at cruise.
But get a mayday call and that boat went down the channel at a blistering
54 knots, made a good welcoming committee for the Coasties.

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Old 10-17-2016, 05:57 PM   #11
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Some Trojan owners report cruising at 15 to 18 kts and burning 18 to 20 gph. That gets close to 1mpg, which seems to be a goal for gas engines. I would think running at 10 kts would improve efficiency, but only if you're not wallowing along bow high. I still have to learn about trim tabs and semi-planing hulls. A 10 kt cruise would be acceptable if the ride was comfortable.
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Old 10-17-2016, 06:15 PM   #12
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Quote:
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Some Trojan owners report cruising at 15 to 18 kts and burning 18 to 20 gph. That gets close to 1mpg, which seems to be a goal for gas engines. I would think running at 10 kts would improve efficiency, but only if you're not wallowing along bow high. I still have to learn about trim tabs and semi-planing hulls. A 10 kt cruise would be acceptable if the ride was comfortable.
Is 15 knots or 18 knots at 1 nmpg not acceptable or not a speed you'd want to go?

You said, "One of the big drawbacks of the Gulfstar was the 7 kt cruising speed, 9 kt top speed." Is 10 knots enough to change things? I'm not sure 10 knots dramatically changes the fuel per mile, might have to go to 7 or 8 knots to get that impact.

The boat you're talking about should cruise at 20 knots, have a WOT of at least 25.
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Old 10-17-2016, 07:24 PM   #13
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454s are great engines but so are all the old school small block Chevys except for the 400 cu inchers. They had siamesed cylinders and therefore cooling problems. It will depend on what size/weight boat you have what you will want. I had a 27' Chris Craft Constellation with twin 283 ci Chevys it was okay but the same boat with 350 ci engines was way faster and when run on one engine got about the same mileage at displacement speeds. A loafing 454 will not do as well at slow speed.

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Old 10-17-2016, 07:36 PM   #14
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I've run a bunch of boats with both 454's and 350's. My take on it is the 454, while a bulletproof beast, does not seem to make that much more power than a 350 for the extra gas it burns.

If boat runs well with the 350's, that's what I'd go for. If you need to keep 350's hammered to plane, then go 454.

Better yet are the modern EFI's, should you find one with a recent repower.

And if you find one with Chryslers, they did a real good job marinizing. There is a boat on my dock with a 318 installed in 1986. Still runs fine, never had any major problems. That's 30yrs in salt water. Pretty dang good for a gasser. Find a Mercruiser with that service history!!
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