Prop question

summer storm · Post by **summer storm** » Tue Oct 26, 2010 5:14 pm

Does anyone have an idea about what size the prop should be on a F26 flybridge with a 5.7 LT and 1 to 1.5 tranny. It has been reported to me that this engine will produce 275 hp.

This has been a long refit (rebuild) and I would really like to put the boat in the water once and not have to pull it out again to change props.

IF needed I could start with the factory prop size but I also don't have that info.

Looking for a nice range of power and speed, a balance of both.

thanks

Stripermann2 · Post by **Stripermann2** » Tue Oct 26, 2010 5:36 pm

Don't have first hand info but you can try Michigan prop for specific specs for your set-up and they will reply with a size.

http://miwheel.com/PropItRightSizing.aspx

MattSC · Post by **MattSC** » Tue Oct 26, 2010 6:09 pm

Doug,
The F-26 came with a 14 x 10" super cupped prop. Though that is with a Borg Warner velvet drive 1:1 with a 1" shaft. What type of transmission do you have?

k9th · Post by **k9th** » Tue Oct 26, 2010 6:30 pm

Doug -

Most 5.7L engines I know of are about 250-255HP. My Mercruiser 255s are the 5.7L and are rated at 255HP. My last boat had the OMC 5.7L and it was rated at 250HP.

rbcool · Post by **rbcool** » Tue Oct 26, 2010 7:33 pm

Mine are 5.7 Crusaders spitting out 270HP.
Some years ago I came across a formula for prop sizes on the internet, wish I could remember where.

prowlersfish · Post by **prowlersfish** » Tue Oct 26, 2010 8:08 pm

Most F26 s I belive are 1 to1 so if you have a 1.5 to 1 it will take a larger prop . How much room do you have for a larger wheel ?

rossjo · Post by **rossjo** » Tue Oct 26, 2010 9:54 pm

summer storm wrote:... with a 5.7 LT and 1 to 1.5 tranny... 275 hp ...

275hp 5.7 w/ 1.5:1 ...

Doug - is that the original engine? If so ... 275hp sounds a bit strong.

Ok - heres my plug - http://BoatDiesel.com has the best prop calculator I've seen ... $25/year ...

I should get a freebie for all the plugs I put in for them ...

aweimer · Post by **aweimer** » Wed Oct 27, 2010 2:18 am

From the Trojan spec sheet i have.

F-26 w/225 Chry Direct, 14x10 S. Cup (12-145)
F-25 w/225 Merc. Direct, 13x10 s Cup (12-083)

That is the from the 1975 manual. Hope that helps.

Its direct drive, or Vdrive? I have a 255 merc which is the 5.7L, that is on an F-30 though, manual says up to 255hp in the F26 but doesn't list the prop size for it. The 255hp merc in the F-30 has 14x10 s. Cup, (12-385).

Thats all i have. Good luck.

aweimer · Post by **aweimer** » Wed Oct 27, 2010 2:20 am

summer storm wrote:Does anyone have an idea about what size the prop should be on a F26 flybridge with a 5.7 LT and 1 to 1.5 tranny. It has been reported to me that this engine will produce 275 hp.

Sorry missed the 1.5:1, that on a 5.7 according to the 1975 specs would be a 16x15 S. Cup.

rossjo · Post by **rossjo** » Wed Oct 27, 2010 8:38 am

"According to the specs" ... where do you finds these specs? A link - or scanned image would be great!

aweimer · Post by **aweimer** » Wed Oct 27, 2010 9:29 am

All part of the manual i purchased from Bob. I will get this page scanned and post it.

summer storm · Post by **summer storm** » Wed Oct 27, 2010 9:14 pm

I asked 3 times about the horse power, 275 sounded like a lot to me. But I was told that this engine (a volvo penta) has a vario cam? and the stated output is 275 Hp. If you haven't guessed this is not the factory engine or tranny. I am starting to doubt that the tranny is 1 to 1.5, the tag is gone I don't know how the mech is finding out the gearing.

It looks to me that the 14X10 S cup will do the job.

Thanks for all the input, the boat came with the wrong prop and now I have a good starting place.

aweimer · Post by **aweimer** » Wed Oct 27, 2010 10:46 pm

everything i posted were around stock options. If its a repower you should use a calculator to determine the prop.

You will need weigh, waterline length and a few other mechanical things. As stated in prior posts here there are some nice ones out there.

Michigan Wheel has a nice one too. Check them out.

prowlersfish · Post by **prowlersfish** » Thu Oct 28, 2010 6:28 am

You can find out what the gear is by using a photo tach on the engine and the prop shaft . Uless you have the 1 to 1 the 14x10 is the wrong prop . You can't tell what ratio it is by just looking at it But you can tell if its a 1 to 1 can you post or email me a photo ?

what prop did it come with ?

summer storm · Post by **summer storm** » Thu Oct 28, 2010 10:01 pm

prowlersfish wrote:You can find out what the gear is by using a photo tach on the engine and the prop shaft . Uless you have the 1 to 1 the 14x10 is the wrong prop . You can't tell what ratio it is by just looking at it But you can tell if its a 1 to 1 can you post or email me a photo ?

what prop did it come with ?

The prop it came with is completely trashed and the boat is up out of the water (for the photo tach) but here are some photos of the tranny

http://picasaweb.google.com/yachtMissyB/TrojanRefit#

thanks

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