alpha drives and big props??
 

currently im turning 21 pitch mirages on my boat and i have had 23 cleavers on it which seemed to work ok but both get a fair amount of prop wash out of the hole. im wondering if i switch to a 23 pitch mirage or a 24 4 blade if id blow my drives.

I have alpha outdrives and twin 454s which are built up for speed. ive been told by a few people that i will blow up my drives if i switch to a 24 4 blade or even the 23 pitch marige. Im not going to be doing hole shots or putting a lot of stress on my outdrives because i know they are the weak link here. so if i take it easy could i spin 24's.??

also what size do you think is best for my application?

28'baja
8500 lbs dry
twin 454's (alpha drives)
with the current 21 pitch mirages it runs about 5500-5600rpms wot.

thanks for the help

Also, is anyone aware of any kits available to beef up alpha drives? (i have drive showers installed on both outdrives but i was wondering if anything else could be done)

Wow! I'm surprised you have not already fried those drives with that much RPM. You must be very conservative out of the hole to have them still working.

Try a 23" pitch Mirage Plus and see if you can get the same or better speed at a lower RPM.

thanks for the advice.. ill try that and yes i dont go over 3000 rpms coming out of the hole. i only use the minimum rpms to get the boat on plane..

what about anything bigger than the 23 mirage.. would 4 blades be too much? or a bigger 3 blade?

The reason they are still whole is the high rpms. If you turned bigger props to pull the revs down that would work them harder.

that makes sense.. 1000 12 once arm curles are much easier than trying to put a keg to your lips once. :drink:

i was thinking that i could possibly get a balanced medium if i had 24 pitch 4 blades and was just very conservative out of the hole... would that work ok or am i just in for a recipe for disaster.. I need to make a choice on props soon because i dont have a set and im sick of borrowing those 21 mirages every weekend..

Man 5600 rpm is brutal, what kind of work has been performed to the motors to allow that kind of ceiling?

dart high rise intakes, 850 holley, roller rockers, bigger roller cam, forged crank and rods. id like to lower the rpms down to around 5000 and still make the same amount of speed if not faster..

Oyyy.... I'd be VERY careful. I would do a little searching for Alpha performance threads. If you are married to the Alpha's, there are some upgrades for them. They make heavier duty gears-sets for the upper units. They make a stronger drive shaft that omits the o-ring groove for between the upper and lower unit. There are prob. more, but those are the first few off the top of my head.

When the Bravo 1 propellers were introduced many guys tried them on their TRS drives and promptly wiped them out. (Especially if they were high hour units.) I think the Alpha drives would suffer the same fate. The 4 blade props are a little too efficient and put a lot of strain on the gears, etc. I still think the 23' Mirage Plus will put you where you need to be.

Where's that darling Julie from Throttle Up when you need her?

A friend has a 24 outlaw with the 454 330hp alpha. Went through two drives in about 3 hours when he tried a 4 blade. Prior to this the original drive had 300 trouble free hours, and the replacement has another 40 hours using the original three blade prop.

Thanks Banzer. You confirmed exactly what I'm saying. If I owned a set of 23" Mirage Plus I would have already lent them to you to try.

I am currently running a 30 Bravo on my alpha, with 1.82 gear, no probs yet. This is threw a pretty stout SBC. I did how ever break the drive last year.

John

The small block tends to be kinder to the little Alpha. The torque curve has much to do with it. That seems like a pretty tall gear for a stout SBC. What RPM range are you in?

Baja I've got a pair of 23 mirage plus in excellent shape, just got MRI'd and tuned. PM me if you're interested..

I am still hitting the stutter box@ 52-300. So if this one holds up on the top end, no hole shots btw. Also this is a supper light boat. I am going to try and find a labbed 32B prop... Then will be the blower and bravo drive next spring :drink:



John jr