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Thread: Performance Improvements possible with newer 4 stroke outboards

  1. #41
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    Quote Originally Posted by Hounddog View Post
    The T750 boats are 55 to 67 hp. The T850 altered 56 OMC ‘s are 100 hp plus. Speed wise the T750 record is over 65 mph. Our best T850 recorded speed is 80 mph while the UIM T850 record is 68 mph. Overall all the feedback I get about the 60 is positive. Interesting that you have a 12 x 22 Mercury prop. The original model of that prop is liked by many T guys. With your boat you may find it is too much prop. I would not be surprised if an 11.5 x 18 works better. One last comment....I had a fellow running a 1998 59 cubic inch 2 stroke Mercury switch to the 4 stroke. The 2 stroke acceleration was better, but the 4 stroke was only 1 mile an hour slower. So for a non race application...equal!!
    Cool, yea i may need to drop some pitch and or diamiter but i know i could sell the 12x22 easily as they are very good on the f4s boats, i may try one of Mr Hills props if it dosent work or trade mine for another merc cleaver.

  2. #42
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    Quote Originally Posted by Hounddog View Post
    We currently have a prop shaft UIM rule.....basically it must be below the bottom of the boat and we allow nose cones but not low water pick up nose cones or remote transom water pick-ups. We put the nose cone rule in because many T boat owners up here ran SST 60 lower units. At first in 2006 we thought the SST 60 lower units would be an advantage over the nitro case. This was race proven to be false, the nitro case is the faster case on a T boat. The Yamaha small case is even better and the Mercury case even better provided the carrier did not come out. APBA VP75 run the large case with the prop shaft 5 inches?? below the boat plus a much heavier minimum weight. That class has really grown and has many good looking expensive boats racing....and it is much slower compared to our T classes. A few years a go we ran a short shaft big foot 49 with the 725 lb T850 minimum weight in T750. The actual boat and driver used was well over 850 lbs. The boat was a top 3 runner back then. We dropped the idea after one season because it was obvious that had the boat been close to the 725 lb weight, it would dominate.
    Maybe??? When T850 is reviewed for 2020 we could revisit this idea with a minimum weight at 850 lbs.
    Wow, large gearcase with propshaft just under and very low ratio was fast??
    What caused that do you think, more diameter with low ratio would get you out of the corners I guess?
    How many seconds in a lap for your typical course?
    Would make a cheap class i thought, big case on a 15" with stock 49er

  3. #43
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    Quote Originally Posted by Powerabout View Post
    Wow, large gearcase with propshaft just under and very low ratio was fast??
    What caused that do you think, more diameter with low ratio would get you out of the corners I guess?
    How many seconds in a lap for your typical course?
    Would make a cheap class i thought, big case on a 15" with stock 49er
    We tried the 49-big foot-15 inch for several reasons. One was to compare the performance to the VP75 class which only allows long shaft motors. We had tried the long shaft version with a Checkmate a few years prior. T racers did not like the way the long shafts handle. The FE Class prior to 1975 ran big foot short shafts, so we were following that model. The test boat ran 57 to 58 mph with a 12.5 x 24 omc prop. Our course is approximately 1 mile at most sites....top T750 boats about 67 seconds....top T850 boats under 60 seconds. There is a big difference in lap times after lap 3....when we had 9 boats in a heat the water is rough! More prop diameter helps out of the turns in rough water. Another option we have tried on a lake runner is running the higher ratio 2 cylinder nitro on a 49. Works well and is less than half the cost a 3 cylinder nitro. I personally like this option better than the big foot.....same lower cost, but boat handles better and is 3 to 4 mph faster...low 60’s.
    Last edited by hydrospeed77; 1 Week Ago at 05:58 AM. Reason: fix quote closing tag

  4. #44
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    Quote Originally Posted by Hounddog View Post
    We tried the 49-big foot-15 inch for several reasons. One was to compare the performance to the VP75 class which only allows long shaft motors. We had tried the long shaft version with a Checkmate a few years prior. T racers did not like the way the long shafts handle. The FE Class prior to 1975 ran big foot short shafts, so we were following that model. The test boat ran 57 to 58 mph with a 12.5 x 24 omc prop. Our course is approximately 1 mile at most sites....top T750 boats about 67 seconds....top T850 boats under 60 seconds. There is a big difference in lap times after lap 3....when we had 9 boats in a heat the water is rough! More prop diameter helps out of the turns in rough water. Another option we have tried on a lake runner is running the higher ratio 2 cylinder nitro on a 49. Works well and is less than half the cost a 3 cylinder nitro. I personally like this option better than the big foot.....same lower cost, but boat handles better and is 3 to 4 mph faster...low 60’s.
    thanks Hounddog
    sounds like there are lots of options and sustainable/easy to find parts
    I thought about a new mid for the 56 so it bolts up, 15" and solid mounts, go racing ( cut drive shaft)

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    Quote Originally Posted by Powerabout View Post
    thanks Hounddog
    sounds like there are lots of options and sustainable/easy to find parts
    I thought about a new mid for the 56 so it bolts up, 15" and solid mounts, go racing ( cut drive shaft)
    Here in Ontario, Canada we have a shorter boating season and all fresh water so motors last longer and are in better condition compared to most areas. The 75 cent Canadian Dollar hurts when buying from the USA. With the above in mind I think a Hobby T Class would grow once we got a few boats racing. We need to take advantage of the good low cost motors available here and keep the spec rules simple and easy to understand.
    HOBBY T CLASS
    - V hull
    - 850 lb minimum weight
    - bone stock 3 cylinder 60 cubic inch maximum ..no custom parts!..Stock head and stock compression!
    - no blueprinting
    - MOTORS..choice of long or short shaft model
    - OMC 49 small carb...choice of big or small lower unit
    - Yamaha 52 no CES parts...choice of big or small lower unit
    - Mercury 49, 52 or 59 bone stock
    Should be a 55 to 62 mph class.
    Current Other T rules would apply.

  6. #46
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    Quote Originally Posted by Hounddog View Post
    Here in Ontario, Canada we have a shorter boating season and all fresh water so motors last longer and are in better condition compared to most areas. The 75 cent Canadian Dollar hurts when buying from the USA. With the above in mind I think a Hobby T Class would grow once we got a few boats racing. We need to take advantage of the good low cost motors available here and keep the spec rules simple and easy to understand.
    HOBBY T CLASS
    - V hull
    - 850 lb minimum weight
    - bone stock 3 cylinder 60 cubic inch maximum ..no custom parts!..Stock head and stock compression!
    - no blueprinting
    - MOTORS..choice of long or short shaft model
    - OMC 49 small carb...choice of big or small lower unit
    - Yamaha 52 no CES parts...choice of big or small lower unit
    - Mercury 49, 52 or 59 bone stock
    Should be a 55 to 62 mph class.
    Current Other T rules would apply.
    solid mounts?
    I have watched a few videos of that long shaft stock class and its a bit dodgy

  7. #47
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    Quote Originally Posted by Powerabout View Post
    solid mounts?
    I have watched a few videos of that long shaft stock class and its a bit dodgy
    Solid motor are part of the current T rules so Hobby Class could use them. The idea in Hobby Class is for the person who just wants to try T racing. They are not going to rebuild the motor, they will just buy a used cheap one and run it. T750 and T850 are very competitive classes where racers need to spend more. Hobby racers will use loaner props and safety gear. They will likely have less than $1500.00 invested. You will see experienced T racers and former champions run in this class. They want to grow the sport and are there to teach. We could see loaner complete outfits where newbie racers just sign up for an event. The low cost and availability of equipment make it possible!
    Likes Powerabout liked this post

  8. #48
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    That Hobby, 750 and 850 sounds like a good time.

  9. #49
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    Quote Originally Posted by slowJEEP View Post
    That Hobby, 750 and 850 sounds like a good time.
    Racing any class with those engines always make a great class

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