General Category > General Discussion
ORIGINAL VS MODERN POWERPLANT
rbay:
Good words about the small blocks, guys. I had ruled out the standard output 5.7L (250hp) since I have a psychological floor at 300hp. But now I see there were some high output 5.7L MPI ski boat engines up to 325 hp in the late 90's. Should be minimal electronics to integrate into the instrument panel.....I need to watch some videos or read some blogs or on-line articles related to the installation. Has anyone in this forum put a newer inboard engine into a GC?
The Olds 455 jet boat engine is largely a western US thing, the availability of a used 5.7L HO ski boat engine east of the Mississippi should be much higher. Biggest issue will probably be finding one with some hours left in it.....ski boats have a tendency to be used pulling towlines vs. sitting on sandbars.
My biggest temptation with a place diverter would be dousing an obnoxious stereo.
Plugcheck:
I suppose one aspect of your selection criteria should be cost. Ballpark what are you looking to spend?
rbay:
I'm hoping these are reasonable amounts to buy a used marine engine and get it running well:
- 455 Olds or 5.7 L $ 6-8K
- 6.2 L $ 8-10K
- 8.1 L $10-12K
(I don't think the marine 6.0L and 5.3L have been around long enough to get a deal on a used one)
I'll spend the extra money for the 6.2 L or 8.1 L to have a better boat, but feedback thus far has generally recommended newer, smaller displacement motors, suggesting stay at the low end of the scale. The boat came with two sets of logs & snails and a bellhousing, so the installation cost for the Olds would be almost zero, all other motors will be another $1-2K to get the gauges and controls working (?). I like the idea of a 1/2 closed-loop cooling system to avoid the high pressure problems when the jet pump feeds directly into the engine, so another $1000 there for the heat exchanger.
Plugcheck:
Exhaust costs can be considerable if you opt for non Olds, considering you have those. I have $3k in EMI thunders for BBC for comparison. Wondering how difficult a 455 in good shape would be to find? The dash gauges can work a variety of engines, so if you want to keep a classic dash, then there are ways to interface. As for water control, my friends 23, 460 jet, we simply used a gate valve and adjust water flow for desired temps. Wire it in the position that works best. Seems to have worked well for several years. Closed cooling has its good/bad. If I was in saltwater, id certainly consider it, but we travel mostly in fairly clean lakes. Missouri river is a bit muddy, but an end of the day flush seems to take care of that .
Plugcheck:
Found a 455 supplier out of Tyler TX that has a no core 455 offering for under $3k. By the time you get it installed and set up probably be around $6k. Would be a step towards period correct resto and all new. BTW, ever consider a Billy Bob copy?
https://www.mabbcomotors.com
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