Hitting hydrodynamic limit of Alpha One? Maybe Wrong Prop?
 

Hey guys! Like a lot of you, on the quest for more mph!

Here's my situation. I have a 22'+ Stingray Maxim powered by a built 383 SBC (AFR 190's, 224/230 HR, 9.4:1) and it seems like I'm hitting a wall at about 67mph+.

I have ran the boat to 70mph GPS @ 5200 rpm and took a while for those last few mph. I'll get to 67mph fairly quick with the current 14.5" x 23p Stiletto 3 blade that I bought off craigslist haha! I feel like I'm not getting enough bow lift with this prop. Blow's out with a hair more trim above input shaft centerline. I've also been told by Tom @ Hydromotive that I'm at the limits of the stock nose cone of the Alpha. Any truth to this?

I have also tried a borrowed 21p Rev4 prop which is 14 5/8". Picked up a few hundred rpm, still same top speed, didn't blow out as early, was able to take some more trim.

Looking for any input from anyone with experience in this type of setup. I Build racecars and this is just a fun hobby but still looking to maximize this setup.

I feel like I need more bow lift, and a little more rpm. Any ideas?

Here is a flyby video of my boat.

https://youtu.be/MxztEWLQf-U


Thanks!

Total truth. I'm a live witness.

I had one blow out at 65mph. Every single time. Same exact speed. At first I thought the coupler broke. Would go right into free rev. 21" and 23" Cleaver, 22" Turbo, and yes, even a 23" Stilleto. Installed a Hydromotive nose cone and it took care of it. totally. Unfortunately, that cone was one of the last Hydromotive made for those drives.

Now, many have gone into the 70's with no cone...so...I don't know why some blow out earlier..propshaft height ? or ? .but they do...and get ready for some people to say a cone is not needed until over 80mph, but these people will be regurgitating Bravo info. So, don't listen to that. LOL.

I've read a lot of info regarding when the nose cone is needed. Most of what I have read is an Alpha setup needs a nose cone @ 65mph+.

Mine blow's out regardless at 68mph +/- 1mph, and in some chop I'll go 70mph before it blows out.

I was referred to Bob's Machine shop in Florida. I talked to them, emailed them my info, just waiting on a response as to which cone is needed.

Tom @ Hydromotive told me to get nose cone before purchasing a prop from him.

Just seeing what others have experienced with similar setups.

Just watched the vid..yes, the bow should be a little higher. On that water, the front running surface should not have been touching.

With the limited props I've tried I don't think I've used a known "bow lifting" prop.

I was thinking about a Mirage 3 blade.
Or maybe just bite the bullet and order the Quad IV Hydromotive but I've heard it's more of a stern lifting prop which is opposite of what I need.

Hey there Timmy. Not sure if you remember me, but I bought that forged 370 LS off of you a couple years ago for my turbo'd 72 K/5 blazer. Small world, lol. Welcome to OSO.

Sorry I can't be of any assistance with your Alpha questions.

Thanks man! Hope all is well with your K5!

I sent my alpha lower to Bobs Machine shop and they installed the nose cone and repainted the lower, looked perfect when it came back. This was more than 10 years ago so don't remember the price but well worth it. Ran high 60's with a mirage 3 blade, believe it was a 23P