Modded 3.0 Johnson with MAD EFI

I guess what I relly want to know is how much can you pull off the pylon? And, if you pull off the stern eyes, how do you rig it?

jim

 

This will be a "fun" boat for ripping around when it is calm out. The gear reduction in my experience makes it much easier to hold speed. I rigged several boats with the 130 V4 from 1996-2001 and that had the high altitude gear ratio. Pulled stronger than the Eagle 60 degree V6 and held speed very very well. It should provide a broad rpm range to make speed holding easy and have tons of low end power. Strictly a personal boat, but the times you can go wide open in an 18 are so few and far between that I would rather emphasize the low end and make it easy for anyone to provide a good pull.

 

OK, how about comparing the pulling power of a 2.5 liter 200 Merc to a big block.

jim

 

And, the eagle 60 degree V-6 has issues with both the throttle linkage and in particular the spark advance mechanism which consists of a plastic on plastic bearing and race. This set up will stick and since it depends on a spring to return it to retard, it can stick and make speed control very difficult. Both my motor and my daughter's motor had this problem.

Once that is fixed and the slack taken out of the throttle/cable system (with springs on the motor and the binnacle) the speed control can be excellent with a 17 pitch uncupped prop. The high altitude gears would no doubt help also, but it is quite good now. It turns about 26 to 2700 at 16 now.

jim

 

The 2.5 200 Merc is a great motor and is fine for personal ski boats and has been used over the years by many ski teams. Very fast motor and feels strong when you run one on a boat. But, hook 24 skiers to a pair of them and compare it to a pair of 3.0 or 3.3L motors and there is a huge difference. You can pull 24-28 with a pair of 200 2.5's, but a pair of 175 2.5's will do the same thing.
Put a pair of big blocks on the back of a twin and I've seen as many as 36 pulled. I've pulled 30 with a pair of 225's. The drivers with big blocks pulling 24 will not have to roll out as fast, whereas a driver with a pair of small blocks is going to have to roll much faster and get the rpms up to make sure you don't sink the pyramid off the dock.

As I said, great motor for individual use, but the big blocks do have alot more torque which I believe helps to make speed holding that much easier.

I believe the new small block E-tecs have gone to a more traditional throttle linkage setup as opposed to the carb/Ficht 150/175:

 

I have heard the e-tecs have a better set up. I can understand the comparison of the twin rig 20's and I appreciate you posting that.

I do not have any experience with pulling big loads with an 18 and I am interested in the difference in pulling power between the small block and the big block on the 18. I just wonder if the hull can handle the difference without pitching up too much.

I understand how to rig a low pull set up on a twin rig, but I have never seen one on a single rig. Maybe they are not necessary.

You and I agree on the gear ratios. The newer Merc big blocks come with a 1.75 ratio with an optional 1.62. This is fine for top end, but it disadvantages them for low end pulling power unless they have so much torque that it does not matter.

jim

 

I have wondered about the total weight vs the hp pushing it as well. The 18's being a smaller boat and lighter, I wonder if the bigger motors would be too much for pulling swivel. For other stuff where there is more load on the engine I don't think it would be a problem - higher gear ratio helps though as you have a larger rpm spread with less effect on speed.

Almost every Evinrude V6 ever produced runs a 1.86:1, the new magnum gearcases on the big blocks are 1.85:1, I think this is a great ratio for the big blocks. The Yamaha 150 Vmax motors always came with a 2:1 which made it a great ski engine, lots of low end and excellent speed holding. Yamaha also has the best throttle linkage on the motor end, though that advantage is less on their newer HPDI motors.

Back when Merc got heavily back into show skiing alot of teams were putting the 2:1 cases from the 2.0L V6's on the 2.5's and that had a decent result.

Motors/gear ratios:
Merc 2.0l carb V6 and 135 2.5L Opti 2:1
Merc small block EFI/Opti 150-200 2.5L 1.87:1
Merc 3.0L EFI (200, 225, 250) 1.75:1
Merc 3.0L Optimax(200, 225) 1.75:1

Yamaha 150 Vmax 2:1 (any fuel induction, EFI, Carb, HPDI) 2.6L
Yamaha 175 200 2.6L 1.86:1
Yamaha 200-225 VMax OX66 EFI 1.81:1
Yamaha 225 - 300 Vmax HPDI 1.75:1

Evinrude/Johnson V6 is always 1.86:1 except for 2002 and up 3.3L which are 1.85:1 in the magnum case, still 1.86:1 in the high speed case on the HO models.

Rated hp is not always the main factor for me in powering a boat. For a small V6 the 135 Opti is a great value as it has the 2.5L powerhead, and a 2:1 ratio which is nice for water skiing. It is also cheaper than the 150 and performs very close to it.
Yamaha 150 Vmax carb is a great ski motor because of its torque and the 2:1 gear ratio.
In our experience every time we've run a pair of 175's it has been almost as good or as good on the low end as the same block 200 if they offer it. Our 175 Vmax hpdi's we ran in 2001 were very strong and we pulled 28 with them. I suspect they were ported for low end power.

 

As many of you know, we run a small twin rig for our team. We had twin 90's on it last year when we could not get 115 E-Tecs.

We do this mainly because it is easier for our dealer to re sell those motors as opposed to a single 200 or 225, but the result is a great towboat. It has a smoother, stronger pull off the dock for pyramids/doubles but also is very very easy to hold speed with. It lacks on top end compared to a single 225, but makes for a very easy towboat to drive for a new or more inexperienced driver.

 

I found out that the smaller motors are less sensitive on the throttle (for swivel) when we converted my daughter's boat from the 150 to the 75. Her boat is running a stock merc throttle and their cable set up with a 17 aluminum prop.

It is running at a higher percentage of it's total power and pretty good rpm with the stock 2.25 gear. It takes some movement on the throttle to change the speed much which makes it easier. The light weight is an advantage when running slow. My boat comes on plane at about 10 mph set up the way it is. It has good speed control from about 14 up.

As you know, my boat is a converted I/O. It lost 600 pounds in the conversion. The V-8 that came out was 198 hp. It has better performance and much better handling with the 150 outboard. I would not consider a big block for my use for that reason. I am curious what the boat will do with the big block that it can't do with a properly set up small block with a 2 to 1 and say a torque shift prop which starts out a 11 pitch or even that 16 pitch that you like.

I believe that everyone should run what they want and I am just trying to pick your brain because you have experience that I do not have. I would hope that riverat would contribute to this also.

jim

 

The 18' Dyne that our team used to have had both a carbed johnson 150 (2001? first year with BRP) and a 175 evinrude injected (one year newer than the johnson). They both had the same 17 pitch prop, and both performed quite well. Slow speed control was ok. I believe it had a teleflex throttle on it, and was a bit sticky. The 175 did seem to pull a bit more (off the dock or top end with barefooters). I think the biggest pull we had was 6 couples off the dock, using the pylon. The bow did rise, but nowhere near high enough to need to back down. I would say the guys were averaging around 200 lbs, and the girls were averaging about 130. We are not known for small people.

I am going with a 2006 Evinrude HO on the one I am working on getting now. The HO makes it a big block, so I am looking forward to some serious torque. I am hoping for 8 couples off the dock, and 6-7 barefooters at 40+. If the new BRP throttle is as smooth as it sounds, I should have much better control of low end speed than with the other boat, even with the larger motor.

I think I already have a perma-grin