Alpha 1 Nose Cone installation

[remlinger]

I installed on my Enchanter a nose cone on the Alpha 1, by doing this I droped 600rpm's off of top end (4400 down to 3800) Still pushing 64mph, 5mph less than my best run. I would guess that the increase of water to the prop by installing the nose cone has cut down on slippage between prop and water.

Running a 25p mirage SS prop on the 350ci 260hp mercruiser.

Any suggestions, if I were to decrease pitch of prop would I increase torgue, speed as well as rpm's.

Also any recommendation on prop type / style. 4 blade vs. 3, cleaver.....and so on.

Thanks

 

[aaronmt]

I would remove the nose cone, they really actualy will hurt performance unless your jacking the motor up which you are nt able to do. They look cool but arent needed or recommended in your situation. Even in unless your loosing water pressure they can slow you down. Aaron

 

[remlinger]

Easier said then done. More than likely I would replace a whole lower unit housing. The Nose cone is fully epoxied to the housing.

The factory cavitation plate sits about 3-4" above the bottom of the boat. With the nose cone installed it has reduce cavitation problems which I had out of the hole and in turns. Also I have not experianced lose of power at full up position on the out drive at full throttle, nice rooster tail.

Without removing it any suggestions regarding props come to mind.

 

[JW]

The unfortunate answer is, you'll never get your best top speed with a nose cone on that boat. Nose cones really only work if you can run with the motor trimmed level rather than at high trim angles like you need to get that boat to fly. When you trim up to fly the bow, you're now draggin a lot longer bullet through the water, and at an angle the nose cone is not designed to work.

I wouldn't even mess with props at this point. You really have to go back to stock with that lower unit, then play with props. Sorry...

 

[remlinger]

Thats what I was afraid of.

 

[Blizz]

You should be able to get if your persistent enough. Use a mallet on the cone to break it free.

 

[aaronmt]

Im kinda courious how you were able to buy a nose cone for that application, I would think somebody would have said something honestly. Good luck just make sure ya try to get the same gear raito if ya get a new one. Nothing I hate worse the being the berrer of bad news, I would realy atleast give it a try to remove it , at this point whats the worst that can happen ya end up getting one anyways. Post some pis maybe we can help. A fresh set of eyes always helps. Aaron

 

[Blizz]

Just goes to show that to many people int the industry are just out there for your buck and don't care. Or they have no clue what they're telling you and that's just as bad.

 

[remlinger]

I purchased it through Eddies Marine Supply.

i can't complain, since I installed it i have experianced better accelleration, turing and less cavitation and however a loss of rpm's and 4 mph.

For S's and G's i'll do a little R-n-D and experiment with props first prior to prying off the nose cone. i'll post the results which ever they mey be.

 

[CheckmateFever]

I installed on my Enchanter a nose cone on the Alpha 1, by doing this I droped 600rpm's off of top end (4400 down to 3800) Still pushing 64mph, 5mph less than my best run. I would guess that the increase of water to the prop by installing the nose cone has cut down on slippage between prop and water.

Running a 25p mirage SS prop on the 350ci 260hp mercruiser.

Any suggestions, if I were to decrease pitch of prop would I increase torgue, speed as well as rpm's.

Also any recommendation on prop type / style. 4 blade vs. 3, cleaver.....and so on.

Thanks

Your running a 25p SS on your Enchanter and was getting 4400 rpms?? Wow, i'm haveing trouble even getting 4000 rpms out of my 23p, which is 60mph on GPS. Do you have any mods done to your engine?? I actually lost RPM's this season as well, i had my Enchanter converted from stock thru-prop over to straight thru-hull exhaust and high-perfomance aftermarket aluminum manifolds, i went down from 4200-4300 rpms to barely 4000. I did change props but i kept the same pitch of 23. It's amost the end of the season, i'll probably worry about it next season, for now i just have to stay outta the throttle.

 

[daren34]

prop calc says 61 mph at 12 percent slip

what is the diameter of your prop?

have you run a gps yet?

daren

 

[Blizz]

CheckmateFever your new prop could've killed your 2-300 RPM by itself.

 

[remlinger]

if my memory serves me correctly pitch is only one factor in prop sellection. Blade shape regarding actual configuration and cupping comes into play as well.

Checkmate Fever in '86 was the 350 also rated at 260hp?

 

[CheckmateFever]

if my memory serves me correctly pitch is only one factor in prop sellection. Blade shape regarding actual configuration and cupping comes into play as well.

Checkmate Fever in '86 was the 350 also rated at 260hp?

Yup, my 350 is rated at 260hp, they didn't change how they rated them from 86-87 did they?? Net Hp vs. Hp @ prop rating i mean.

Daren, does that sound right for my set-up too, 60 (gps) at 4000? I don't know how to calc. slip and actual speed. The dia. on my prop is 14 1/4", it's a Turning Point Express. My old prop was 23p but less dia. I added some horsepower (at least should have) with the performance exhaust manifolds and goin from thu-prop hub to thru-hull exhuast.

 

[daren34]

you should be turning 4400 to 4800

you 350 will be happier if you are turning 4800 wide open trimmed out

so either you need nore power or a little less pitch

if the boat handles good with that prop see if you can spap it out

did you ever get a new carb after the exaust work?

with an edelbrock performer (not rpm) and a marine 650 holley (or 800 edelbrock)
i think you would bring you rpm's up

daren

maybe add a set of 1.65 roller rockers (supposed to be 15 to 20 horsepower)

 

[remlinger]

Heres a thaught. I just had the transom plate rebuilt. Would there be any reason for them to replace the gears during that proceedure. It was not until after that work that I noticed the reduced RPMS. Granted I added the nose cone as well, but I had it on prior to the repairs and only was out twice on the boat prior to the repair. I did not notice as great of a drop in RPM's at that time. But you are always more perceptive after work was done and thats when I noticed the increased drop.

In regards to RPM's I was turning 5200 with the facotry installed 19p alum prop, 4800 with an up grade to a 23p alum and around 4200 to 4400 with the 25p SS Mirage.

Now with nose cone and repairs I'm at 3800. Seems like an awful large drop.

I'm goint to call the marina who did the work to see what was installed to see if the gears were changed out and were correctly sized.

 

[CheckmateFever]

you should be turning 4400 to 4800

you 350 will be happier if you are turning 4800 wide open trimmed out

so either you need nore power or a little less pitch

if the boat handles good with that prop see if you can spap it out

did you ever get a new carb after the exaust work?

with an edelbrock performer (not rpm) and a marine 650 holley (or 800 edelbrock)
i think you would bring you rpm's up

Is there a difference in carbs for prop exhuast boats and thru-hull exhuast boats?? I believe my stock carb is, which is a 4 barrel, is only 500 or 550 cfm. I can't imagine the carbs would be different, seems like that would affect the hp rating. Yes the boat handles and cruises great with this prop, just won't spin up like it should. Very frustrating, the motor purs like a kitten and runs great, but every one else seems to be faster and gettin alot more out of their 350's than i am.

 

[Blizz]

No the carbs are the same but if you open the exhaust to much with a stock motor it kinda kills the power and torque #'s It's kind like putting 31/2" exhaust on a stock powered car sounds great but loses some umphh. But there are probably a few slight changes in the setup of the motor and carb

 

[remlinger]

what was the correct gear ratio for my 350/260hp alpha. the shop told me they install a 1.50 gear.

 

[daren34]

1.5 ratio is standard with a v-8

do you know gps speed before the work was done

you will need more carb with the open exhaust

daren