Suggestions on new props for 336
 

On my 27 fountain going from a 23 mirage(non-plus) to a lab finished 23 mirage(non-plus) gained 300 rpm and a couple mph top end. Then changing to a 23 4 blade spinelli dropped a mile or two top end but added more out of the hole punch and mid range cruise efficiency and also reduced top rpm by a few hundred rpm.

On my new 336 Formula with 454 mag's the top rpm with 23 mirage plus props is 4700-4800 rpm.

Wanted to know who has lab finished their existing mirage props and who has switched to 4 blade props and their results. I would like to get my peak rpm to 5000 at WOT. Also interested on out of hole and mid range benefits seen from those who have switched to 4 blade.

As always many thanks for your knowledge.

On my 89' 311 SR-1, with your basic 454 Mags, I swapped from 23 inch Mirage to 24 inch Hydromotive Quad IV's and gained 7mph at cruise and 3mph at wot according to my gps. My boat is ass heavy. The Hydromotives lifted the stern out of the water a bit more, ergo less drag, and overall the boat rode more level. Exhaust noise went up to because the box was further out of the water, noticably louder, not obnoxious, just louder. The guys at Hydromotive were very patient with my questions and told me exactly what I could expect. The 7mph cruise increase was just great. Went from 47 to 53. Much quicker up on plane, effortless, and stronger midrange punch. Couldn't be happier......

Formula Outlaw- What were your cruise and WOT rpm with the 23 mirage (non plus?) and 24 hydromotives? With that change you went up quite a bit in pitch. I would have thought that you would have gone to a 22 or maybe a 23 hydromotive but would have never guessed a 24 pitch. My understanding is that a 24 hydromotive would be theoretically similar to a 26 mirage prop, not close to a 23.

As a comparison our power is the same but the weight of a 336 is much higher than a 311 which might affect my prop choice.

I'm running 23" labbed mirage (non-plus) props on my 336 with hp500's and 1.36 drives. We just got the boat last year and haven't tried any other props. One engine is in getting a refresh now, so I'll be able to do some better testing later in the spring. The Hydromotives sound like a pretty good choice.

Powerguy, you are completely correct in the theory that when you go to a four blade as opposed to a three blade, the "ratio" changes. The rule of thumb is that if your running "X" pitch three blade, then switch to a 4 blade, then you should downsize an inch or two to be equal. HOWEVER, here is what happened. Like I said, the Hydromotives are designed to add stern lift, and my boat is real ass heavy. Once up on plane, the Quad IV's lifted the stern of my boat, I'm guessing here, probably at least two inches maybe three. It was basically the same as reducing the "X" demension on drive position. Kind of like installing a set of 2 inch shorter IMCO lower cases. There is where I got such less drag, and was able to gain rpm. On boats that are not as ass heavy as mine, you would not see the same increase, it some instances it might actually cause too much lift and you could lose speed by the increase prop slippage. The guys at Hydromotive explained this VERY thoroughly to me before I decided to give the props a try. They told me if they were not real real close with their estimates,
they would fully refund me the money for their props. I noticed the difference as soon as the boat started to accelerate to pop up on plane, much quicker, much easier, not as much throttle required. Once up on plane, I could feel the boat was "freed up". Every aspect of running on plane was so much easier. Stayed on plane at lower rpms than with the Mirages. Overall, those props did exactly what Hydromotive said they would. Hope this explains what and how I gained the rpms.

With the Mirage's I was running around 4850 wot, with the Hydromotives I'm right at 5000. I use 3400/3500 as my cruise speeds, sometimes a little higher. From 3300 up to 3650 or so the speed difference stayed right at 6/7 mph. Once I got above 3700, the speed difference started to diminsh, down to about 3mph at wot.

Hope this helps. Any other questions please ask. Russ

p.s. If you call Hydromotive, ask about the new five blades........

I would guess that my 336 is as ass heavy or maybe a little more so than Formula Outlaw. It does make sense that the more boat out of the water the more speed. It sounds like a swich to a 4 blade prop is the logical step forward.

Has anyone tried Bravo 1 4 blade props on their older Formula as it is my understanding that new boats come with Bravo 1 4 blade props. I have read that the Bravo 1 prop is better out of the hole and midrange than the hydromotive for similar applications but they are cut differently so the prop sizes will be different.

I talked to Hydromotive about this, and they said that the plain Quad IV provides stern lift for rear heavy boats (similiar to a Mirage), while the Quad IV-X is very similiar to the Bravo 1 props, which provide bow lift. Bow lift is typically needed on newer stepped hull designs. According to Hydromotive, Mercury does not have an answer for boater who want stern lift in a 4 blade. I also talked to Mercury Racing labs about this, and they in a round about way said that the Bravo probably wouldn't be the best choice, but who knows, give it try they said.

Powerguy, how much does your 336 weigh? A 311 weighs 7400 dry, with most of that in the rear with engines, trannies, and drives.

I am going to try a set of Bravo's on my 311, but probably won't get a chance until late May or June sometime. I am thinking that at higher speeds, the bow may start to plow, but I'll have to wait and see myself.

Jaybird, I don't know what you are running for power, but I can assure you I don't have ANY trouble with the bow "plowing".

Just out of curosity, if your 311 is already stern heavy, (like they all are) why do you want to add more bow lift with the Bravo 1's????????

When I was running the Mirage, at WOT "Outlaw" always seems a little high in the nose. With the Quad IV's the boat rides more level, just higher out of the water. This was visually confirmed by a buddy who was running along side me. For whatever it's worth, that's my experience.

Outlaw,

I am only trying the B1's because a friend has a set to lend me, so why not? I was saying that I don't think the B1's are the right prop, but because I have access to set I am going to experiment.

I actually like what I've heard from you and the tech at Hydromotive that the Q-IV would probably work nicely. I am running about 550 hp motors in my 311.

Well that certainly makes sense. dduuuhhhhh.......
What kind of speed you get with those 550's? I'm looking to repower Outlaw in the not real real distant future. Looking for around 600 a side, naturally aspirated. Would love any suggestions. Russ

Outlaw - I am only guessing, but I am most likely somewhere in the low 80's. I will GPS it this spring when I am done with the motor refreshing projects. I think it could use more prop, as I am hitting 5600 rpms.

My boat had 174 blowers on it when I got it, which I probably would never have done, but now I am kind of glad they are there. Incredible acceleration. Plus the blower whine sounds really cool when you get on them! I definitely had a learning curve getting used to the maintenance /setup (had a few probs to work through), but don't be afraid of them like a lot of people are. My blocks are original 1987's, and the blowers have been on for 10 years. I have the motors torn apart currently and am refreshing the heads. The blocks look mint after all this time which surprised me. I only run about 5-6 lbs of boost, so it doesn't beat on the motors too badly.

Since I have these motors torn down, I could have gone back to normally aspirated, and ported the heads, cam change, etc, to get the power back up there, but I didn't. Instead I rebuilt the blowers and heads, and basically keeping everything else the same performance-wise. I just think it's a cool boat the way it is, as there aren't many supercharged boats near me. As I said the acceleration on this is sick... I can be going mid 50's and hit the throttles, and throw people back into their seats!

There is nothing wrong with big power normally aspirated motors, but those aren't impervious to troubles either. My friends with wild cams and aftermarket ignitions sometimes break valve springs, burn pistons, etc, so don't think that they are flawless. Big HP = big $$, and more problems always. My old smallblock boat - I think the most it needed ever was a water pump impeller and a shift cable! Those days are long gone...

I'm just saying another decent (and fun!) route to go is to build or buy a solid motor, and put a smaller supercharger on it with around 5 lbs of boost. This way you don't need to typically change compression ratios, ignitions, etc. Carbs, and fuel system will need to be changed, but just buy a long block then.

Sorry to hijack the thread temporarily!!! If you or anyone has ?'s just PM me!:)

"Jay", well now you've gone and done it. Just when I thought I'd made my mind up, you've given me more ideas. If I could "freshen" my 454's, add a procharger, it would be much less expensive in the long run. You give a very strong testimony for going that route. What kind of superchargers are you running? Thank you for all the information. It's really got me thinking now. I'm shooting for mid 80's. Russ

Jaybird-

Formula states that 336 weighs 8400 lbs which is 1000 lbs. more than a 311 ( Can that be right?). It is a non-stepped hull so stern lift would be needed. I was thinking bravo 1 props because they seem plentiful used and if I found one that was close I could have it lab finished and be into them for the price of non-labed props new.

If my 336 is really 1000 lbs heavier than I would probably need a 23 hydro or a 24 bravo 1 4 blade.

Powerguy,

As I understand it, Bravo 1 props are NOT stern lifting, they are bow lifting, which most likely wouldn't work out for you with the non-stepped hull, and heavy stern. If you try decide to try a set of Bravo's, make sure you can return them as there is a decent chance they aren't the right ones for the boat. If you want a 4 blade for stern lifting, the only one I know of is the hydromotive Quad-IV. If you buy new from them, they will allow you to try different models for only a $20 restocking fee per prop. This way guarantees that you end up with the right prop, and they get a sale. I'm considering going that route probably around June timeframe.

You could also lab finish your Mirage 23's, and probably be where you want to be RPM-wise too. However, sometimes people don't always get the results they are looking for w/ labbing, and then your stuck with the props too. I'd say get a different set of props that work out of the box, keep the 23's stock, and either sell them or keep them as spares.

I am surprised that the 336 weighs in at 1000 lbs more than the 311! Essentially they are the same boat, except the 336's had the newer platform design on the rear. I wonder why?

The Hydromotives are definitely the way to go for stern lift. Give the guys there a call and they will guide you very well. They nailed it right on the head for me. I think that for your 336 non step, I would try that route.

Are there any other Formula owners who have 4 blade props on their boats? results compared to stock 3 blade mirage or mirage plus?

Yes, I have an 89' 311 SR-1 with your stock 454 mags. The boat came with Mirage 23 inch props. After spending much phone time with Hydromotive, I went with the Quad IV's and got 7 mph more at cruise and 3 mph more at WOT. The props did EXACTLY what the guys at Hydromotive said they would. I could not be more pleased with the results.

See another post of mine on this thread up near the top.

Thanks again formula outlaw. There has to be others out there who have made the switch to 4 blades. Any 303 or 336 owners?

Re: Suggestions on new props for 336
 

Boating season starts here in a couple of weeks and I will be trying two new sets of props.The first set is 22 hydromotive Q-IV stock props and the second is a set of lab finished 23 Mirage + props. Hopefully with both changes I should be where I want to be. This should be a good comparison to others looking to change props. My 336 has stock 454 mag's.

Re: Suggestions on new props for 336
 

Dave, Get it dialed in right you don`t want to lose any ground to those cigs on the lake :D

See you in June hope to see a few more Formulas

Re: Suggestions on new props for 336
 

Powerguy, I currently run 23" Mirages but can literally run it straight to the rev limiter in an instant (around 500hp each). I am going to be trying a pair of Bravos also but like you only because a buddy of mine has a pair on his Donzi that he's willing to let me bolt on. I think Outlaw has it nailed on the head with the Q-IV's. I would even settle fo a 1-2 mph DECREASE at WOT if I could gain 7 in the middle. To make a gain at both ends is just lagniappe (pronounced: lan-yap). That's Cajun French for "a little something extra". :D :drink: