vinny p.
Active member
Well it took me long enough. I have been searching for a used -2 Imco for a while. Finally, I found one for sale about 1/2 hour drive from my house. I still dont believe I found one locally. The lower was virtually new. Test time only on it. The only bad thing was that it has Imcos old style tapered vertical shaft. Not a good thing, I have broken one before. A new one is about $550. I tore the drive apart ( because I am anal, and dont trust anyone ) , the internals were like new. The gears didnt even have a wear pattern on them. I took those gears out and set up my spare set of cryoed gears I had sitting on the shelf. I will send these new gears out to get treated and keep them for a rainy day. I decided to roll the dice and not go for the new style vertical shaft yet. I figured, if the boat didnt like this lower, why bother spending the money on the shaft? If it worked out, then I would swap shafts. Last year I very briefly got to test a -1 Imco lower with good results. Being that the results were positive, I wanted to see what a -2 would do.
Heres what my first test day resulted in. First the conditions. 85*, humid and dead flat water. Not good for speed runs. In my experiences with this boat and the standard lower, I would expect to run 80 mph in those conditions. In good conditions, I can run 83 with the standard lower. My first concern was getting up on plane. I eased the stick forward, next thing I knew, I was up on plane.
I thought to myself, that was easy, lets see what happens when I turn at cruise spped. I trim up and settle in at a nice easy 60 mph cruise, come to the first turn, drop the drive as I uually do and turn. No blow out . OK, that went well, push the stick forward , hit the trim and lets see what happens. No stability problems, speed comes up. Tops out at 82.6 mph. My best ever under those conditions. Although the testing is far from over, it seems that I will be able to gain at least 3 mph. I am hoping this weekend brings some chop in the bay and some rollers in the ocean. I am still wondering what will happen when I attempt to take some jumps. My guess is I will be fine. Being that getting up on plane was no problem at all, I can only assume, the prop shaft height is still ok. I did find 1 problem. My tach seems to have had enough. It is the factory 6000 rpm tach from Checkmate. It was reading 5700 rpm at top speed. Spinning a 25" Hydromotive P5-X at 5700 rpm, with a speed of 82.6 mph, equates to only 7% slip. I dont think so.. I plan on bringing a clamp on digital tach this weekend to check it out. My guess is I was spinning about 5900 rpm, with 11% slip.
More testing results to come..
Heres what my first test day resulted in. First the conditions. 85*, humid and dead flat water. Not good for speed runs. In my experiences with this boat and the standard lower, I would expect to run 80 mph in those conditions. In good conditions, I can run 83 with the standard lower. My first concern was getting up on plane. I eased the stick forward, next thing I knew, I was up on plane.
I thought to myself, that was easy, lets see what happens when I turn at cruise spped. I trim up and settle in at a nice easy 60 mph cruise, come to the first turn, drop the drive as I uually do and turn. No blow out . OK, that went well, push the stick forward , hit the trim and lets see what happens. No stability problems, speed comes up. Tops out at 82.6 mph. My best ever under those conditions. Although the testing is far from over, it seems that I will be able to gain at least 3 mph. I am hoping this weekend brings some chop in the bay and some rollers in the ocean. I am still wondering what will happen when I attempt to take some jumps. My guess is I will be fine. Being that getting up on plane was no problem at all, I can only assume, the prop shaft height is still ok. I did find 1 problem. My tach seems to have had enough. It is the factory 6000 rpm tach from Checkmate. It was reading 5700 rpm at top speed. Spinning a 25" Hydromotive P5-X at 5700 rpm, with a speed of 82.6 mph, equates to only 7% slip. I dont think so.. I plan on bringing a clamp on digital tach this weekend to check it out. My guess is I was spinning about 5900 rpm, with 11% slip. More testing results to come..
