Trojan Boat Forum

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

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

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?

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.

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.

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 ?

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 ...

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.

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.

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

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

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.

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.

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 ?

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