Reply With Quotethread jacker...Mr. mandella, please ignore my gay friend Don....Carry on with your questions...
I will drag this thread straight to bench racers, if you dont STOP now!
oh, so now you are trying to recruit him to your gay swinger lifestyle? :jawdrop:
thread jacker...Mr. mandella, please ignore my gay friend Don....Carry on with your questions...
thread jacker...Mr. mandella, please ignore my gay friend Don....Carry on with your questions...
I will drag this thread straight to bench racers, if you dont STOP now!
I thank everyone for their comments. I have also read the other thread regarding Mandellas with interest. If I have read things right, the Mandella hull is certainly not the best for high speeds but 85 is certainly possible with the right set up. 30% slip is not abnormal for this boat. To answer a couple of questions, I chose 6000rpm purely on spec, not anticipating such high prop slip. Motor is strong enough to take 6500rpm when power falls off quickly. The crank might be the weak link as it is an offset ground stock crank. Motor was built before all the new stuff for 460's. Everything else is top notch.
It has been suggested that only way to go faster is to spin prop faster or increase the pitch. This will require more power. Not sure what replacing the 25 gears with 18 would do as you would have to rev motor to 6400 to achieve same level of performance as at present. Unless I have missed something or do not understand.
At this point I am assessing what I should be doing. Leave the boat as is and enjoy, add some more power or move on to a different hull that will be more amenable to higher performance. I just hate to abandon a boat I have spent a lot of $$$ and time on.
Thanks again.
I had a blast running my boat in the 80-85 MPH range. The reason SuperDave reccomended lower gears is that bigger gears is a trap many v-drivers fall into attempting to get higher top end numbers while simultaneously loosing the snappy acceleration. For example, you will lose about 4 MPH on the top end by going from 25 gears to 18 gears (with the same redline) but....the acceleration difference is huge. Most of the fun in these boats is not just running at top speed, but how quickly you get there is a big part. Since they are recreational boats and we want them to last a long time, if you are going to flat foot the thing for anything over 10 seconds, you should probably have one had on the bible (as Jim Wilkes likes to say).
I don't know anything about Fords, so I have comment on that.
I spent a LOT of money trying to make my Mandella go fast. I think your 85 MPH goal is pretty reasonable but you will want spin more RPM to get there so you don't give up your acceleration by using bigger gears.
I also got to a point where I was done trying to make old boats go faster than they should. As SuperDave said 73 was very very fast for these boats back in the day. I was told these Mandellas were made when what they needed to win a marathon race was go 70 MPH without breaking.
Hey Donald and Ricky...
I started a new thread for Q-ball in the proper forum: I am gonna be so fast.... (http://www.***boat.com/forums/showth...42#post2640142)
I have never really liked the phrase "slip" or "slippage". I prefer the term "Efficient" or "Efficiency", like the prop and gear choice were %80 efficient. I don't think the prop is "slipping", or it would be cavitating. It is producing a certain amount of thrust in the water and the total sum of drag from the boat is working against it. Mandella69's boat is only %70 efficient by the numbers. I would not look so much on gear and prop changes, but what kind of changes can make this boat more free in the water? First thing I would is ask where is the cavitation plate at top speed. If it is not level or up a little, then make changes to the setup so that it is. Are the springs strong enough to hold the plate up at speeds. 75 mph on a Mandella is about where the plate gets sucked back down and will limit the speed to that. I know, because I owned a Mandella for several years and had a lot of fun with it. Ideally, you should shoot for %80 which would be 84 mph at 5900. That is probably a good rpm for stock heads. You need a set of TFS heads or other after market ones to turn them 7K. And even with that, most 460s are cast iron crankshafts. My $.02
I have never really liked the phrase "slip" or "slippage". I prefer the term "Efficient" or "Efficiency", like the prop and gear choice were %80 efficient. I don't think the prop is "slipping", or it would be cavitating. It is producing a certain amount of thrust in the water and the total sum of drag from the boat is working against it. Mandella69's boat is only %70 efficient by the numbers. I would not look so much on gear and prop changes, but what kind of changes can make this boat more free in the water? First thing I would is ask where is the cavitation plate at top speed. If it is not level or up a little, then make changes to the setup so that it is. Are the springs strong enough to hold the plate up at speeds. 75 mph on a Mandella is about where the plate gets sucked back down and will limit the speed to that. I know, because I owned a Mandella for several years and had a lot of fun with it. Ideally, you should shoot for %80 which would be 84 mph at 5900. That is probably a good rpm for stock heads. You need a set of TFS heads or other after market ones to turn them 7K. And even with that, most 460s are cast iron crankshafts. My $.02
Good point.
I thank everyone for their comments. I have also read the other thread regarding Mandellas with interest. If I have read things right, the Mandella hull is certainly not the best for high speeds but 85 is certainly possible with the right set up. 30% slip is not abnormal for this boat. To answer a couple of questions, I chose 6000rpm purely on spec, not anticipating such high prop slip. Motor is strong enough to take 6500rpm when power falls off quickly. The crank might be the weak link as it is an offset ground stock crank. Motor was built before all the new stuff for 460's. Everything else is top notch.
It has been suggested that only way to go faster is to spin prop faster or increase the pitch. This will require more power. Not sure what replacing the 25 gears with 18 would do as you would have to rev motor to 6400 to achieve same level of performance as at present. Unless I have missed something or do not understand.
At this point I am assessing what I should be doing. Leave the boat as is and enjoy, add some more power or move on to a different hull that will be more amenable to higher performance. I just hate to abandon a boat I have spent a lot of $$$ and time on.
Thanks again.
The 460 cranks are not the weak link, the stock rods are. Use a light piston and a decent aftermarket rod and the short block is good to 7500+ providing the clearances are set up for that. Make sure it has a good supply of oil [10 qts or more] and a good pump. The 460 2 bolt block is ok to use up to 750- 800 HP, some have pressed it more but tune ups are very criticle. Check out what some of the truck pullers are doing with 460 Fords, studded 2 bolt blocks, cast cranks and turning 8500-9K for 25-30 seconds at a time. You say you have an offset ground crank, what is the stroke and what rods/pistons do you have?
I tend to agree with les, where is the cav plate set at WOT and how is the boat riding? i.e. where is the water breaking on the hull. Mandellas run pretty loose at higher speeds sorta dancing on the tail which is not always the most comfortable feeling but that is where they get efficient. Check the cav plate set-up as described by Les and run the boat up as loose ( plate up ) as possible and let us know how things change. One other question, how much gas and other crap are you hauling around? Finally 25s are pretty big but if your motor will carry the nose you will get in the 80s.
The 460 cranks are not the weak link, the stock rods are. Use a light piston and a decent aftermarket rod and the short block is good to 7500+ providing the clearances are set up for that. Make sure it has a good supply of oil [10 qts or more] and a good pump. The 460 2 bolt block is ok to use up to 750- 800 HP, some have pressed it more but tune ups are very criticle. Check out what some of the truck pullers are doing with 460 Fords, studded 2 bolt blocks, cast cranks and turning 8500-9K for 25-30 seconds at a time. You say you have an offset ground crank, what is the stroke and what rods/pistons do you have?
I stand corrected. You are right. Back when we built a 460, I think Pro Stock cars were using cast cranks and doing well. We would buzz it 7K with a 22 gear. Later I had heard it kicked a rod out, (stock ones), but I had lost touch with the owner. As I remember, the exhaust ports on the stock heads were the limiting factor. We had some TFS heads with Ross pistons to match. Sounded great.
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