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SANGER496
04-15-2002, 07:58 PM
I recentely completed an engine swap in a 73 Sanger flat. I built a blown 496 low boost motor to replace the stock 454. I also installed a turbo 400 trans. I ordered 1.37 gears to replace the 1.18 ratio to pick up more speed. Estimated h.p. is 850, about 400 more then I had. Will the new motor handle the 1.37s and how much more speed can I expect at the same rpm, about 5800? Also, what happens when a 11 1/4 x15 2 blade prop is replaced by a 12 1/2 x 15 3 blade prop in the same boat. I am new to this forum but have enjoyed reading your comments for quite a while. Thanks!

Costello
04-15-2002, 08:21 PM
I think your 12 1/2x 15 3 blade is a massive prop for what you're doing. If it's steel, and you want to sell it, let me know!! http://free.***boat.net/ubb/biggrin.gif, it sounds like a great daycruiser prop! Call Tom Bentley at Menkens he'll get you setup right. Phone # is at the top of the page.

V-Drive Tom
04-15-2002, 09:49 PM
SANGER496, I think you are going to find that the 37% gears are a bit too much. Are your props steel or brass? The 121/2 diameter is going to torque the boat around a bit. I think that a 12 inch dia. prop of any type is all your going to want. If you over gear the boat you will have to take off in second gear all the time. If you lower your gear ratio a little and raise your RPM up to about 65 or 6700 you will be going even faster. Right now, with a 15 pitch prop,5800 RPM and 37 gear,your MPH is only 90+ MPH.(at 20% slip factor) With a 16 pitch its about 100 MPH. What is it that you want the boat to be best at. Cruising around at low RPM or giong as fast as possible? As soon as you put too much gear in , it won't go fast it'll just kill it. Anyway come back with some info. http://free.***boat.net/ubb/smile.gif

058
04-16-2002, 08:20 AM
If you stepped up the boost of the blower you might be able to turn the 37s with the 11 x 15 prop. The boat won't leave like something with 12s or 15s but it will run good when the engine starts making boost. I'm with Costello and Tom on the 3 blade, ditch it. Run the 11 x 15 two blade.

SANGER496
04-16-2002, 07:35 PM
Thanks for the input, we do have a Sanger 21 foot mini daycruiser that uses a 12 by 15 prop. I thought I would try it but not anymore. My wife likes the daycruiser and beat me in it a while ago so I built the flatbottom to redeem myself! We run on a lake 25 miles from Lake Tahoe, Lake Topaz, NV. Most hot boats have been kicked off due to excess noise, speeding in wake zones etc., but we try to stay in line, at least most of the time, so 90 mph is more then adequate. I will experiment with boost, rpm and gears this season and keep you posted. Our daycruiser puts out 16 lbs boost at 6800 and has 1.22 gears in it. We have had 5 skiers behind it at once and use it primarily for skiing and cruising. Will be selling off more v drive stuff later on ebay, will let you know.

Kurtis500
04-16-2002, 11:00 PM
I agree on the 37's. That is a tall gear in the boat.It's probably a non-runner flat and a little heavy. A low boost motor also. I ran a similar combination in a flat with 29 gears, killed it on the start and took a while to start carrying the boat. I actually ran the exact same et's with 12% gears. Either topped out the motor early and gained little (2-3 mph) from half to finish, or with the 29's at the finish it was still pulling. 22's were best for my set-up. Anyways, try them out, if not buy light weight hydro, they'll work in there.

Infomaniac
04-17-2002, 07:33 AM
I would run the 2 blade. If it does not leave good you can have the dia reduced to about 10 3/4. It should burn the prop then when it leaves. That should help.

V-Drive Tom
04-17-2002, 07:58 AM
Sorry Infomaniac, but cutting the prop down to wing-nut size isn't a great idea. (It will make it so your grandma can drive the boat.) But any time you go under 11 inch dia. your maken the wrong move. (only on super lite race boat and still I would not recomend it.) The dia. and blade area is whats most effective until the prop becomes efficient. You always want to run the most dia. your comination can handle!

V-Drive Tom
04-17-2002, 08:09 AM
I see guys have them cut down like that and it renders them useless. Not trying to be a peckerhead about it. Just feel I have to say it so guys don't go trying to fix a different problem by cutting their prop. (tried to spell maken with a little slang!.. didn't work!) Im a crappy writer! O-WELL!

PGF545
04-20-2002, 10:30 AM
I think thats kinda a trick question, because we have 2 Menkins props that are the same pitch and dia and they both do something different. I do agree with everybody else that a 37 gear is going to be too much, I would think that a 22 or 25 might work better but it will probably add some RPM. Tom is diffently the man to talk to though, we have bought several things from him, good guy to work with.