Prop question again, sorry

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GilesB

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Hi. I have just spent hours tralling through forum searches on here and SeaRay owners club. However its taking me so long to get an answer I'd rather try this.

I have a 1997 Sea Ray 240 Sundancer (sportscruiser) with a 5.7L merc V8 putting out 210 Hp. My current prop is a 14.25 inch x 19 pitch. I'd like to get the best speed and hole shot speed possible so

Should i replace the 8 year old ali prop with a stainless & what size ?

I have been offerred a 14.5 x 19 which is just 1/2 inch bigger for a cheap price, but will this make any difference & what difference will it make ?

Should i instead go for a SS prop of the same dimensions as the current one ?

Thanks for any help

Giles
 
Hello a little more information would be helpful.....
Do you have an Alpha sterndrive or a Bravo 1
If its an Alpha you will find the four blade ally prop will give you your requirements ask you local dealer for an ALPHA 4 20" PITCH
If it is a Bravo 1 i would suggest a REVOLUTION 4 @ 19" pitch this is also a 4 blade prop.
If you can provide more info i can work out a more definate prop for you.

Gear ratio ???
age??
type of drive???
 
Hi Mercman & thanks for your reply.
Its an alpha 1 drive from 1997. I dont know the gear ratio unfortunately, any idea how or where i could identify this ?

Does increasing the pitch lower the WOT rpm ?
Also, I heard that 4 and 5 blade props were better at the hole shot but worse at top end, any truth in this ?

How much am i likely to pay for a 4 blade 20" ally prop ?

FYI - current performance, fully fuelled & watered with 2 up and a weekends gear on board (+dinghy & outboard), is lucky to get 28 knots wot 4300 rpm. Needs 3400 to stay on the plane. Put 5 or 6 peeps on board and she struggles.

Thanks again
 
gear ratio should be on the port side of the gearbox next to the serial number.
if you have a serial number for the sterndrive i can get the ratio for you.
unfortunatly because of the type of cruiser you have and the type of drive you have getting the right prop can be tricky.
normally you find the 240 sundancer with a bravo 2 or 3
we have fitted the alpha 4 on a couple of searay cruisers and the owners have been happy with performance/economy.
dropping the pitch will increase the WOT. so if your doing 4400rpm on a 21 going to a 19" will take it to 4600rpm in theory.
the 5.7L is 250 horse power 5.0L is 210-220
so if you have a 19" at the moment it would be worth going for a 17" you may gain a couple of knots.
 
Hi

I thought the 5.7 came in different outputs dependant on whether it was an L or an LX etc. I beleive from research that the 5.7L is just 210 output (carb fed). It also feels like 210 by the preformance.

Anyway, i live 200+ miles from the boat so i will dig out the serial number from the survey documents tomorrow (in my garage) and hope you can assist in pinning down the drive ratio. I would rather have a bravo drive, obviously, but i think in 1997 the basic option was a alpha.

Cheers
 
Are you sure about your engine size, as 210 hp from a 5.7 sounds way too few hp, the 5.0LX put out 230hp. Forget the alumimium prop, if you want the best holeshot and top speed its got to a stainless prop as any experienced user will tell you, once you have tried a stainless prop you won't buy ally again. Have fitted SS 4 and 5 bladers to many american boats with V8 Alpha drives and all the owners were impressed with the performance gains, especially in turns. Slight loss of thrust in reverse due to the rake of the blades, just needs a bit more throttle, but is outweighed by gains in ALL other areas.
I had a High 5 on the back of a Bayliner 2655 for 8 years continually in the sea and it was as good as new when I sold it, you won't find an ally prop that will last that long.The top speed was no worse than with the bog standard ally prop, (5.0LX motor Alpha 1 36kts on the GPS 2 onboard)but the hole shot and turning was much improved, we even water skied behind it!
 
Thanks for the input. The engine is a 1997 model and carb fed (not injected) so i am open to discussion regarding the output. But it is definately a 5.7L

My broker estimated 250, my surveyor thought 240, but i did some research into historic Searay owners manuals and think it may only be the 210Hp version. 2 Barrel carb 5.7L - not an LX or other derivative...

My engine S/N is 0K039436

Any help gratefully received on both issues !!!!
 
2bbl sounds like 5.0ltr to me. Have you got the casting No: on the rear of the block near the distributor?
 
Hi Col. I may be misleading you on that point. there is a chance that the carb is 4bbl. I havnt serviced this engine myself much so cant recall.

Virtually all the boats i viewed from Bayliner, Maxum, SeaRay etc from the 1995-1998 were using the same 5.7L Merc. It was the starting point for them. Only when the EFI / MPI units came in did they use the 5.0

My Searay manual talks about the following:
5.7L Alpha (my set up)
5.7 EFI Alpha
5.7LX Alpha
5.7LX EFI

It suggests my ratio as either 1:62:1 or 1:81:1

This is all they offered in 1997 - according to the SeaRay parts manual.......unfortunately no ratings on any of them !!
 
Unfortunately the serial No doesn't identify the gear ratio, that is written on the Mercruiser sticker around the top section of the drive, if its worn away as usual then the ratio is engraved along with the ser No on the side of the upper gear housing under where the sticker would have been, I imagine you will have 1.81:1 on that size/weight boat but double check to be sure.
I ran a 19" High 5 on my 26ft boat (5.0LX 230hp 1.81:1) and it gave exactly 4500rpm, so you if you are in the 4400-4600 rpm window already with an ally prop you should be able to go for the same pitch with the SS. Don't be tempted to go up a pitch as it won't buy you more top speed, it will give poorer results and load the engine up which can burn out the pistons. If you really are unsure go to a dealer as they WILL have find the correct pitch by trial and error, if you buy the prop yourself a lot of dealers won't exchange it once its been fitted and in the sea. Whereas they will change it if they do the job.
 
if you have access like my self to the registration site the serial number does give you access to the registration form xwhich was filled out when new.this has all the model/serial numbers and ratios.
I have done this and pm the information to giles b.
I even have all the new purchasers details when it was signed of. The pdi engineers details and the sales person........big brother is watching.
 
I do have acess to Mercruiser, Volvo and Yanmars registration sites, but as you can see from my bio I have moved onward and upward from the workshop side of things and can't be arsed to trawl through ser no's, so its good we have people like you to do it for us.
 
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