FINALLY ready

[Frank Acampora]

Well, finally sold the engine that was on this test-bed boat and mounted the experimental 85. Water test tomorrow. If I don't get over 55 MPH, I will deem the porting and added exhaust chamber volume a failure--too much work for too little return

 

[foodfisher]

Re: FINALLY ready

Was 66 Monday. You do it too!

 

[tater76]

Re: FINALLY ready

Well...??? I hope the delay in response is due to being busy and not upside down in that test boat! LOL! Really though, how was it?

 

[Frank Acampora]

Re: FINALLY ready

Nothing to report yet.

As with any experimental engine it has expected problems. I started it and ran it in the driveway. BUT: First time out it started but stalled and then the starter motor failed. Replaced the motor--three times. One had a bad bendix, one had no power, and one had a bad upper bearing. That's what I get for using used parts.

Second time out, it started and ran but it was not getting fuel and I never reached full throttle, in fact most of the time I was at less than 1/4 throttle. Power trim locked up. Frustrating: it was the second trim unit on the engine and worked fine in the driveway. Replaced fuel pump and lines, fuel bulb, and changed filter. removed carbs and reset them. Found nothing wrong. Replaced complete power trim unit and motor (see my post about which lines are up and which are down) --hope the third time is the charm.

I am now waiting for time and good weather to test the engine again. AND---I STILL need to get a good 12 pole tachometer. I really don't want to take one from a working boat.

 

[tater76]

Re: FINALLY ready

It seems that anytime you start to "Improve" on the factory design, the reliability goes out the door. This is my experience, but it's also a hell of a lot of fun when they work I have been waiting impatiently since you started the milling process, just to see if my 85's should receive the same treatment LOL. I hope the gremlins get worked out, and you can open it up!
As for a tach, what about a tiny tach? the little digital box one? They are pretty cheap.

 

[Frank Acampora]

Re: FINALLY ready

Well: Finally fixed trim, fuel pump, tach, and other issues. The engine is a big disappointment. On the 14 foot test hull with a 13X19 prop it only turned 4000 rpm and 35 MPH. This is slower than my 2 cylinder 60 pushed this boat. Compression is 145 on all cylinders so it is NOT a sick engine.

I think I may have gotten too aggressive with the porting and now have a high RPM engine that is being loaded down by too much prop--Wish I could find an 11X 21 prop to see if she would pull better at high RPM. OH Well-- Next test will be with a 17 pitch prop to see if she revs up better--then a 15.

Anyway, it WAS an experimental engine which I built just to see.

 

[foodfisher]

Re: FINALLY ready

:blue:

 

[wickware]

Re: FINALLY ready

Hello Frank! I hope you know your safe limits with MPH experiments and Etc. I feel your enjoyment as I do the same with Lawn equipment modifications. Remember. Our Old Chryslers need you and Nordin (20 + more years) or we would be Dead In The Water. Take Care And Be Safe!!!!

PS. BTW, How do you grease frozen trailer rollers (grease or oil and where)?

 

[smax]

Re: FINALLY ready

I have a pretty nice Rampage 13 1/4"x16P stainless prop that ran great on my 85hp but is too small for the new 125hp. Might sell it or trade it for a bigger prop.

 

[tater76]

Re: FINALLY ready

When you say high RPM, how much higher are you thinking? Like the race boats of that era? Also, was there any torque to the motor? any gain that is?

 

[Frank Acampora]

Re: FINALLY ready

Well, I am not giving up on the engine yet.

The next test will tell. I will take an older 19 pitch prop and cut down the diameter to unload the engine. If she spins up to speed and gives good RPM then I will know it is porting. While modifying ports does increase horsepower, this horsepower is developed at a higher RPM than an un-modified engine. It also decreases mid and low range torque.

So, I would be trying to get up around 6000-6500with a small diameter high pitched prop. You can not go fast with a low pitch prop so diameter needs to be reduced.

Stay tuned for further results--However, At this time I would need to state unequivocally that this port modification is NOT suitable for a recreational engine.

 

[smax]

Re: FINALLY ready

Porting done correctly should increase horsepower and torque throughout the entire power curve. The thing that makes people think it decreases bottom end and midrange is that it changes the power curve from a gradual arch to a sharp peak with the max output being at a higher RPM. You shouldn't lose low or mid range power it is just moved to a higher less usable RPM.

The problem you may run into with decreasing diameter on your prop is that if you go too far the prop won't have surface area on the blades to lift the hull out of the water which of course means decreased speed.

I love seeing stuff like this so I really hope you find the set up that is going to work. What is your current prop to pad measurement? Since your compression is still good do you think maybe you went to high with porting and decreased your quench area to the point that the engine isn't able to make enough power?

 

[Frank Acampora]

Re: FINALLY ready



I did not raise the ports, simply eliminated two inter port webs. The real problem is that I made three changes at one time: I ported the exhaust and bypass, I ported the piston skirt, and I increased exhaust chest volume. Thus: I can not attribute the power loss to any specific one. The only change that I can reverse is the exhaust chamber volume.

Piston skirts and lower cylinder walls were ported on the bypass side to hopefully get more gas flow and more oil to the small end of the rod. Since it is on the bypass side, It should not have affected crankcase compression. It is really not any different than a loop charged piston with ports in the skirt.

So, if a smaller diameter prop does not help, the next step will be to remove the extra exhaust chest volume. Then, if that does not help, I will add it to another ported 3 cylinder engine I have that does give expected performance and see what it does. That way I may be able to eliminate one of the variables.