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| Building a T750 OMC motor and TESTING http://ww.w.hpbc.ca/viewtopic.php?f=24&t=3268 |
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| Author: | Hounddog [ March 3rd, 2016, 10:36 am ] |
| Post subject: | Building a T750 OMC motor and TESTING |
The most popular motor currently running in T750 is the 2 cylinder 60 hp OMC. We use the same base powerhead as the SST45 tunnel. The major factor with all of the T750 motors is power to weight. The minimum weight boat, motor and driver is 594 lb. Almost impossible to get there unless you weigh 130 lbs. The four stroke motor weighs 250 lbs by itself, they will be over weight. There is a good advantage weight wise and power wise running the OMC. How does a used non rebuilt 60 hp OMC run on a T750? We have had several examples. Eric ran one on his heavy VooDoo and ran low 50's. On lighter boats they are seeing 52 to 55 mph. The speed is similar to a long shaft 70 hp OMC and they handle much better. What to look for when re-building. Crank and rod issues...poor cranks and the rods can rub on the block. Easy fix. There are lots of low cost used parts available. Re-building Use NEW parts for pistons, bearings and seals. Get the SST45 engine spec sheet off the web. Compare your motor specs to it. The motor is normally very close and you can blue print your motor to those specs. OR buy a used SST45 complete powerhead. Many racers have done that. You can run a stock tuner, modified stock tuner, SST45 tuner or any tuner. Remember the boat is not a tunnel and the RPM range will not be as high as the tunnel. SST45's run 7200 to 7500 rpm. The same motor on a T750 will turn 6700 to 7200 and the power really drops off at higher RPM. A 6700 rpm motor with the right prop can perform better than a 7200 rpm motor. What do you gain by doing all this extra work? You will see a increase in top speed of 1 to 2 mph. The DIFFERENCE is how much faster you get to top speed. ACCELERATION!! TESTING Here is a video of Jakes T750. Jake rebuilt the motor, he only cleaned up the ports, so there is more power to be made in that motor. The top speed is 57 mph. The corner exit speed is 40 mph. The key to racing is how fast you can get thru the corner and how long it takes to get to your maximum top speed. If your exit speed from the corner is 35 mph, it will take you a longer distance and more time to reach 57 mph. The QUICKER accelerating boat will beat you every time. HANDLING! T is a drivers class. Talented drivers do better and it takes practice in RACES to get to Jake's level. T750's generally run more setback than T850. Some run 6 inches. Reason: Racers use the weight of the motor to carry the nose. The setback shifts the weight back. You do not want to use up motor horsepower just to lift the nose. Here is the video; https://www.youtube.com/watch?v=vdsi1bARVZc |
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| Author: | phillnjack [ March 5th, 2016, 3:01 pm ] |
| Post subject: | Re: Building a T750 OMC motor and TESTING |
that is not hanging about at all. by keeping the motor at those specs it will last a long time. good video |
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