383 Enchanter I/O - What Prop

[SneakyPete]

Hey all,
I have a 1983 Enchanter I/O with an Alpha, and a 383. It is spinning a 25' Mirage to about 4900rpm or so and I am getting 71mph on GPS. The motor is built to make its best power at 5800rpm, and I would at least like to see 5500rpm. I was thinking maybe a 21' prop. What prop an pitch do you recomend?

 

[wca_tim]

Hey pete, have you been able to try something like a hydromotive quad 4? maybe in a 23 pitch? do you have any dealers that have a used prop wall you can play from?

I'm running a different gear ratio and higher pitches these days, if it was easier to do would loan you a few props in the 21-26 pitch range to play with while I'm not using them (I'm currently running props in the 27-29 pitch range, but may go to different gear in the future and so don't want to get rid of them).

You might be well advised to go with a smaller diameter / less blade area in a 24 or 25 pitch... like a turbo 2+2. a mirage is a lot more blade area than probably need... Just a thought...

 

[SneakyPete]

I have no idea where I need to go, I would like to drop in pitch to put less stress on the drive, but I have limited prop knowledge, so I don't know what style/brand to go with. I one point I was warned to never use a 4 blade prop on an alpha with hight horsepower, I assume for longevity reasons. I tried the Mercury Marine propeller site and it chose a Laser II for me, but as far as I know (or have been told) these hulls like a lot of bow lift. Do you know of any companies that let you try a prop before you buy?
Stability and handling have been great with the current Mirage. No chine walk at all.

 

[bigsbetter]

Pete, Do you know of any prop shops in your area? A small business shop will usually work with you on purchasing a prop. The shop I usually deal with will let me buy a used reconditioned prop off the shelf and try it, and then bring it back and try a different one. It seems to work better if I buy a cheaper prop then bring it back if it doesn't work right and go up 25-50 bucks to a more expensive prop, rather than buying the expensive one first and asking for a refund while I want to try the lesser price prop. That's what I've done in the past, But I've learned that ebay is a VERY good place to expierement with props. I'll buy a prop and try it and then sell it if it doesn't work. I've never been burned or lost more than a couple bucks for shipping. GEt them R's up to 5500 like you said.A Tempest prop with the vent holes plugged up would be a great try, maybe a 23 Tempest, and I prefer the regular Tempest rather than the Plus. Hydromotives are great props but for your Alpha I think it would be too much strain. They are big heavy thick bladed props that really work well on Bravo's.

 

[wca_tim]

so far a hydromotive quad iv has been the fastest on my diplomat... I'm running a mirage right now, but it has too much bow lift for the current set-up and porpoises a little too easily.

On bow lift, I heard the same thing as you about bow lift, BUT have found that with the heavier engine in the boat it actually runs much smoother and flatter (and faster) with sternlifting and neutral props. I don't know bout that no 4 bladed prop thing, I know that my set up handles a lot better with a 4-blade on it.

In terms of bow lift, a laser 2 has quite a bit of bow lift... and is typically a fast prop on a light boat. I actually just gave a 23" laser 2 away a few weeks ago and have one more just like it. Before I put the current engine in my boat I ran 21-26 inch props, but since I decided to use the 1.8 gear ratio and turn props designed to be more efficient at top end (ie pitch ca 2x diameter) I've been playing with 27-39" props right now. I tried a 1.47 ratio upper and it just didn't run as fast. I may be picking up an alpha ss drive, and so would probably go back to the 1.5 ratio once i get it set up. I really like the 4 bladed props...

many times local shops will have a stash of used props on hand that you can try out and buy for reasonable money - often you have to ask. I can think of three local dealers that will let me burrow and try props that they have on hand, and then sell for somewhere around half list for a new one if in good shape. I've also bought a number of props off ebay... like the beautiful labbed 27" spinnelli 4-blade that's sitting on the fireplace waiting to be tried this coming weekend...

the most important thing i would say when trying props, is not to necessarily take conventional wisdom as the gospel. case in point is my current boat. everyone says bow lifting prop... well, it is hard to keep on the pad, doesn't handle well and has an issue with porpoising with bow lifting props, with stern lifting and neutral rpops, it's faster, handles much better and planes nice and even with very good manners, no loose feeling in the ass end like when trimmed out with a bow lifting prop... and so far that's at 75+ gps...

btw, your carb is working fine, but I think I'm going to try it with a 750 Holley dp on it...

 

[SneakyPete]

Tim,
Are you interested in unloading the 23" Laser. If you are, I am interested in it. If I remember correctly, 1" of pitch = 200rpms or so. So if I went from 25p at 4900rpm, and to a 23p of the same model prop, I would be at 5300rpm in theory, correct? A Laser has less blade area than a Mirage, so by going from a 25p Mirage to a 23p Laser, I could possible pick up more than the standard 200rpm per inch of pitch, correct?

 

[illMATTic]

I bet you will pick up more rpms with the laserII but your slip% may go up. I think the blades are smaller on the laser props. I am at 15% with my 21P laserII. I need a bigger blade and more pitch. I was looking at a 24 or 25P myself.

 

[Big Dave]

I wonder if the 4 blade was the cause of the upper gears exploding on mine???
I love the way the boat rides and handles with the Mach Sterndriver, I wish someone would have come up with the molds for them.

 

[Big Dave]

Yes, you will gain more rpm with the laser II just because of the smaller dia and smaller blades. With the longer hull, you may need more of a bow lifting prop than those of us running v8's in Diplomats.

 

[SneakyPete]

So many variables...What are the characteristics of the Laser, is it a bow lifter. I just pulled my drive today, found water in the bellows, and the u-joints were wet, I guess I will be doing bellows this winter. Should I replace the ujoints as well?. Also, if the drive oil looks fine, there is no way for the water to have damaged the internals of the drive correct?

 

[wca_tim]

a laser 2 has a decent amount of cup and is a bow lifting prop. My boat porpoised with it when not at wot, and your assessment of the situation is pretty spot on in my opinion - I have a feeling you'll be at the upper end of your rpm range and that you'll pick up a good bit of speed. It would probably be close to ideal on your rig if you're hunting for wot at 5500 or so. In fact, depending on how much more power you're making now, you might well be able to turn a laser in 25 - especially if you play with the vents to get your holeshot back after being a little over-propped out of the hole...

I'm fastest and more stable running a 4 bladed prop, and quite frankly am going to continue to do so. The mirage is only because it was cheap and I was waiting until I could try some others. My hull (and Daves) are a bit shorter than yours and have the weight distributed a little differently - didn't come out with a v-8 in them.

As far as the alpha drive, I'm just assuming that it's a wear item with more than a few hundred horsepower and keep a spare... So far I broke the lower drive shaft with the v6 and lost a u-joint when running the current engine... It is my understanding that it should be fine if I do my part and don't ramp wakes under heavy throttle, etc, etc, etc... Note that I've run for 10 miles plus at near full throttle so far without problems (and a four bladed prop). It's not so much the number of blades as it is blade area and the amount of torque it takes to turn (ie. how well it bites in the water). I'm thinking that I'm going to build my own this year and have some ideas to make it a little more robust in the process... including cryotreating the gears and bearings, etc... and perhaps adding a dry sump lube set-up if possible. First I'm going to run the temp gauge in there. I would consider a bravo drive, but on this boat, that's 200 pounds too much more right in the ass end.... Next one will be a little biugger and a bravo I suspect...


I'm not interested in selling the laser 2 because it's probably close to right on the nose if i go back to a 1.47 gear ratio in the future (as is in the alpha ss set-up I'm calling a guy about this afternoon ....).

If you lived closer, I'd give you several to play with for a few weeks before you buy something. I know you're straight up.

 

[SneakyPete]

Thanks for the help guys, lots of good info here. I pulled her out for the season, so I will have to wait till next year to to get numbers, but I will try and pick up a 23p Laser II over the winter.
Tim,
Are you running an external hydraulic ram? Might be something to look into, you are getting deep into the 70's. I am saving for one, but my exhaust outlets are even with the gimbal which will require a long ram and some thinking in order to get the correct set up.

 

[wca_tim]

my diplomat poroises with a laser 2... and did with the v-6 in it... it's a bow lifting prop. My slip numbers were under 10%, more like 8 I think. remember that you're running the drive fairly deep (ca. 7 1/2 inches below the pad), so it's a whole different deal than a laser 2 on an outboard.

I hear yuou on hydraulic rams, so far it handles great and no problems... The exhaust wouldn't be in the way for me, the internal factory steering is so tight in there that I wound up coming out above the rub rail... kinda loud, but definately no in the way of anything mechanical...

I need to call a guy back about an alpha ss outdrive, but haven't had the time (we're making an offer on a house tomrrow), but if I don't get the ss with the 1.5 gear ratio in it. If I'm still running the higher gear and on the 27-30" props when you put in the Spring, drop a note, maybe I'll ship you a box of props to run and send back... If I go back to playing with a 1.5 ratio drive, I'll need the 21-25" props sooner.

either way, enjoy!

ps. what heads and cam are yoiu running now? I'm goig to upgrade I think, no options on the intake really, the spark arrestor is kissing the engine hatch now, but I'm thinking a set of AFR 195's and a litle more cam would be good for another 50+ horsepower...

 

[SneakyPete]

I am running those new AFR 180 Eliminators. Stainless intake and Inconel exhaust valves. The 180E's outflow the old 195's despite having a smaller port. Bob Madera of Marine Kinetics custom spec'd the cam and recomended the heads. The cam is a billet hyrdraulic roller (Cam Motion) with Morel Lifters. I can't quite rememember the specs, but it is 234* intake and 240* exhaust duration at .050 and .534 and .571 lift. Bob is a freaking rocket scientist when it comes to this stuff and has forgotten more than I will ever know. He will custom build the cam to the current or future motor specs and desires. The cam and the lifters were $1k and money well spent. The heads are great, and piece of mind with the inconel valves is geat. The inconel valves are a touch taller above the retainer, so my intake and exhaust pushrods are different lengths (only by a little tho), like a BBC. The pushrods are by Trend (great turn around, good price, quality stuff-as recomended by Bob).