Considering Shorties for my Bravo's
03-25-2016, 11:29 AM
#1
Registered
Thread Starter
Considering Shorties for my Bravo's
I'm running twin late '90's model Bravo I's on my '79 255 Formula. What is a reasonable amount to expect to pay for a pair of shorter lower units ?
03-25-2016, 10:27 PM
#2
Imco -2 shortie lower half only routinely sell for $2500 here. I sold one for that. If they have the bigger shaft they can go for more. BUT unless you plan on adding a lot of HP the standard shaft will be just fine for your boat. ( I ran 2 IMCO -2 shorties on my 34 SCARAB behind 650 HP for wuite a few years without a single failure. ( I lost one vertical shaft on a lower but that was caused by a defect in the shaft)
03-26-2016, 07:34 AM
#3
Registered
Thread Starter
Imco -2 shortie lower half only routinely sell for $2500 here. I sold one for that. If they have the bigger shaft they can go for more. BUT unless you plan on adding a lot of HP the standard shaft will be just fine for your boat. ( I ran 2 IMCO -2 shorties on my 34 SCARAB behind 650 HP for wuite a few years without a single failure. ( I lost one vertical shaft on a lower but that was caused by a defect in the shaft)
Tommy Hofstetter and I were looking at this one day and he explained to me that with the drives running that deep it doesn't matter how much power I put in the water...the boat won't run much faster.
Last edited by sprink58; 03-26-2016 at 07:46 AM.
03-26-2016, 11:41 AM
#5
How fast are you running now and how much H{??? From experience I would suggest that you put the $ and time into something that is more designed for speed not comfort. On my SCARAB I gained 1 to 2 MPH but handling improved drastically. I used to have to trim a lot for top speed. After the -2 shorties I didn't have to trim so much. If I got into rough water going fast and hit a rogue wave the boat no longer shot for the moon and ran flatter.
04-03-2016, 05:23 AM
#6
Registered
Join Date: Apr 2013
Location: Bay City, MI
Posts: 274
Likes: 0
Received 0 Likes
on
0 Posts
If i remember correctly, the speeds sprink posted after the motor upgrade were very impressive.
Edit, found it
Edit, found it
OK..the difference is dramatic...however.... this boat with 800 plus horsepower is a bit over powered...HELL it's a LOT over powered!!! As a result I have absolutely got to add drive and tab indicators. the boat is so sensitive to trim at speed that it's very easy to over compensate or over correct for tilt and trim. Once proper trim is achieved through trial and error this thing is a bullet. The acceleration from 25-30 to 65-70 is scary...I mean like really scary!! Add lack of ability to make minor trim adjustments to compensate for any "twitchiness" and you have your hands full.
So I'm cruising around outside in the ocean this afternoon about 35 MPH at less than 2000 RPM (I know...unreal)...find a several mile long stretch of clean water about a mile off the beach and let her fly....65 comes as soon as the secondaries open with 70-75 coming seconds later with NO HESITATION. The bow rides perfectly and the hull is planted as it should be with no wobble or chine walk. I hit a roller and caught a bit of air...as I instinctively pulled the throttles...soon as I come down I nail the sticks and the bow finds the sky as the Vortecs say hello to the water with out a bit of fade. I glanced at the GPS and see 78 as I crap my pants...left hand with a death grip on the wheel...right hand getting fuel out of the reach of this monster.
It's at this point I realize two things...This can hurt you bad...and it want's to go!!!
So the plan is as follows:
1. Mechanical/Cable real time drive trim indicators
2. K-Planes (280's) instead of Bennett s...for real....with trim indicators.
3. Trim switches in the throttles.
4. Kill Lanyards.
5. Life line jacket.
6. Hydraulic External Steering.
As I was running around outside I thought...I need 10 more feet of boat...this is nuts!!!
I have successfully developed a propulsion package for this boat that exceeds the original design limits of the hull...plain and simple. Additional torque and power is un necessary..period.
Further development of this piece of equipment will be rigging and engineering to harness this power to weight ratio into a safe usable form. The Vortec Small Blocks coupled to Bravo drives have exceeded my expectations...NO $HIT...Really? LOL
Stay tuned...
Oh...forgot to mention...coming back in to the ramp that I chose way far inland...I hit a BFR 2500 and put a ding in my starboard prop so back to Frank and Jimmy's
So I'm cruising around outside in the ocean this afternoon about 35 MPH at less than 2000 RPM (I know...unreal)...find a several mile long stretch of clean water about a mile off the beach and let her fly....65 comes as soon as the secondaries open with 70-75 coming seconds later with NO HESITATION. The bow rides perfectly and the hull is planted as it should be with no wobble or chine walk. I hit a roller and caught a bit of air...as I instinctively pulled the throttles...soon as I come down I nail the sticks and the bow finds the sky as the Vortecs say hello to the water with out a bit of fade. I glanced at the GPS and see 78 as I crap my pants...left hand with a death grip on the wheel...right hand getting fuel out of the reach of this monster.
It's at this point I realize two things...This can hurt you bad...and it want's to go!!!
So the plan is as follows:
1. Mechanical/Cable real time drive trim indicators
2. K-Planes (280's) instead of Bennett s...for real....with trim indicators.
3. Trim switches in the throttles.
4. Kill Lanyards.
5. Life line jacket.
6. Hydraulic External Steering.
As I was running around outside I thought...I need 10 more feet of boat...this is nuts!!!
I have successfully developed a propulsion package for this boat that exceeds the original design limits of the hull...plain and simple. Additional torque and power is un necessary..period.
Further development of this piece of equipment will be rigging and engineering to harness this power to weight ratio into a safe usable form. The Vortec Small Blocks coupled to Bravo drives have exceeded my expectations...NO $HIT...Really? LOL
Stay tuned...
Oh...forgot to mention...coming back in to the ramp that I chose way far inland...I hit a BFR 2500 and put a ding in my starboard prop so back to Frank and Jimmy's
Last edited by Fischan; 04-03-2016 at 05:30 AM.
04-03-2016, 07:45 AM
#7
Registered
Thread Starter
It will get up and get out of the way for sure !! Tommy being my go to Guru....told me with as good as it is, I am always going to be limited by how far below the hull the props were running. I will see an honest 75 with 1~2 foot seas...just a bit less on smooth flat water.
I asked Tommy about tweaking the Vortecs on his Dyno for a bit more power. Thats when he looked at the configuration and explained the concept of getting the props running closer to the surface and in his opinion I am about at the max with the way the drives are set. He added that no matter what we pick up with power it won't translate to a top speed increase.
I've forgotten the exact dimensions as to how far down below the chines the props are running...but I think they were about 2~3 inches lower than a twin 272 SR-1 are.
I asked Tommy about tweaking the Vortecs on his Dyno for a bit more power. Thats when he looked at the configuration and explained the concept of getting the props running closer to the surface and in his opinion I am about at the max with the way the drives are set. He added that no matter what we pick up with power it won't translate to a top speed increase.
I've forgotten the exact dimensions as to how far down below the chines the props are running...but I think they were about 2~3 inches lower than a twin 272 SR-1 are.
04-03-2016, 08:37 AM
#8
Registered
iTrader: (5)
X dimension won't change, that's the crank centerline, but the propshaft height will go up, 1-2" depending on which lowers you buy. By the looks of the pics, and knowing a little about the older formulas, your drives are probably 7" below the running surface.
04-03-2016, 09:48 PM
#9
Registered
Thread Starter
It's a science I have never explored with stern drives other than having Alpha SS drives behind twin 320 EFI's in a '86 272. With twin cleaver 23" props it was a 70 MPH rig. I'm guessing but it wouldn't surprise me to know that the 255 is at least 3" deeper than a 272.
It sure handles heavy water like a champ for 25'-5" hull..."Wave Crusher" LOL
It sure handles heavy water like a champ for 25'-5" hull..."Wave Crusher" LOL
