Re-powering 1972 SeaCraft 23'...F300?

[[email protected]]

I enclosed the transom and am running the same 30" Armstrong bracket with a 300 Yamaha 4 stroke. The boat runs 50 WOT and loaded burns 2.8 - 2.9 MPG. I ran it from Ft. Pierce to Walkers Cay / Rosie's Place in grand Bahamas this past weekend and had a glass crossing on the way over. I burned 42 gallons in 118 statute miles getting there = 2.81 MPG. On the way home the bank was windy and 2 - 4 where I could only run 20 knots. When I hit the stream it flattened out and ran 38 knots to make up for lost time and burned 50 gallons at the same distance = 2.36 MPG. Overall the boat is unreal! runs perfect and is very well balanced. The scuppers stay dry even with three guys standing on the bracket.

I have no idea about the etec. I am just happy that I do not have to buy the excessive oil at $40 a gallon.

[DonV]

Very nice numbers!!! 2.81 mpg is only double what I get, which if you do some Jethro inspired math that's half as much $$$$ as I would "burn"!!!

[fly4navy]

Right! You don't have to buy the $40 a gal. oil with the E-tec, but you give the same $$ and more to the dealer when you get the oil changed and after you have been burning dirty oil for 75% of the oil cycle. The E-Tec is always burning 100% virgin pure clean oil in the combustion cycle...and I like that!

Originally Posted by [email protected]

I enclosed the transom and am running the same 30" Armstrong bracket with a 300 Yamaha 4 stroke. The boat runs 50 WOT and loaded burns 2.8 - 2.9 MPG. I ran it from Ft. Pierce to Walkers Cay / Rosie's Place in grand Bahamas this past weekend and had a glass crossing on the way over. I burned 42 gallons in 118 statute miles getting there = 2.81 MPG. On the way home the bank was windy and 2 - 4 where I could only run 20 knots. When I hit the stream it flattened out and ran 38 knots to make up for lost time and burned 50 gallons at the same distance = 2.36 MPG. Overall the boat is unreal! runs perfect and is very well balanced. The scuppers stay dry even with three guys standing on the bracket.

I have no idea about the etec. I am just happy that I do not have to buy the excessive oil at $40 a gallon.

[DonV]

Ya know I've never thought about it in those terms. I've got a Yamaha four stroke and a Merc two stroke and even though I use Amsoil 100% synthetic in both I just never thought about the 75% of the engine oil life before in a 4S. Good point! FWIW.....I get my Amsoil HP 100% synthetic two stroke for $32 a gal delivered to my door. It can be used in the eTec at the same computer setting as the Evinrude 100XD.

[FishStretcher]

I don't know about the e-tec, but in normal 2 strokes the oil goes where the fuel is. Which breezes by some bearings.

In 4 strokes that dirty old oil goes to bearings and bearing surfaces like cam lobes, piston skirts, wrist pins, etc.

If it was a terrible idea, then 4 strokes wouldn't last hundreds of thousands or even a million miles.

The roots "supercharged" two strokes last a while, too. But those are also a different beast. YMMV. Literally.

So it might not be THAT cut and dried.

[Bushwacker]

Originally Posted by FishStretcher

I don't know about the e-tec, but in normal 2 strokes the oil goes where the fuel is. Which breezes by some bearings. . .

Unlike normal 2 strokes, the E-TEC's inject oil directly into the main bearings, crankcase and cylinder liners. Accumulated oil is recirculated from various locations in the powerhead via internal passages and external hoses, fittings and check valves.

The local dealer sells XD-100 full synthetic oil in bulk (bring your own jug) for $35/gal. On average I seem to use about 1 gal of oil for every 100 gallons of gas, which works out to about one gallon of oil for every 400-450 miles run, so the cost of oil doesn't seem to be much more than what I'd spend on changing the oil and filter every 6 months on a 4 stroke.

[jongolds]

My experience has been the same as Bushwacker's.

If you're going to have the dealer perform your service while under warranty, the cost to change the oil on a four stroke surpasses the cost to burn your oil in a two stroke, at least in my area.

I don't think there's a bad motor choice out there these days. I would go with your favorite local dealer. A good experience with the dealer is worth a lot of money in my opinion.

[DonV]

"A good experience with the dealer is worth a lot of money in my opinion"

How true!!

[bitsamonkey]

Just read this thread. If you had the low pressure pumps replaced and had one fail already make sure they aren't Mallory brand pumps. I made the mistake of buying a set and having them fail. Total POS Chinese crap that will fail. Save yourself a tow if that's what you've got and get some genuine Yamaha ones. By the way, they still have the Yamaha logo cast into the top plate so ask your vendor.

[Andy]

If I were to compare the weight of your 23 ft Secptre to a 1973 23" Center Console that I have recently cdone a complete restoration on using Divinacel and cloeed in the transom. I imagine the center console would be 300-500 lbs lighter. I am also going to use a 300 Yama and trying to guess the speed and fuel. Might be similar to yours accept for any weight difference.
What do you think.