Need help rigging an etec

[82rude]

Problem with the prop that hit 5200 rpm is if you add weight ,people ,gear,extra gas ,is that the rpms will drop off sharply unless you had the boat at its heaviest when you tested.Ive never seen power grafs from any mfg but I sincerely doubt you lose your 40hp at 6000 rpm, other wise I would think they would not have it as the wot range.My reasoning for this is the guys that over rev outboards ,the 90 evinrude being an example for speed applications .There are some post floating around on here about it.I know on my boat at 5700 which is close to my hp if I gun it to 6000 she will jump ahead.That being said I normally loaf around at 45 to 5000 as that's the sweet spot for fuel economy and still decent speed.

 

[Patfromny]

What is the max HP rpm for your engine? Let's assume it is 5600, you have answered my question in saying that you get the max efficiency at that rpm. I don't need to see a graph to tell you that if it is rated for 40 or 60 at 5600, then every rpm above it is dropping off. Otherwise it would say 60 hp @ 6000. The difference in lower as apposed to higher rpm is that the engine is still pulling and making more power as apposed to 6000 where it is done and declining. Set all that aside and just do the math on this instance. If I am going 28.3 at 6000 but 30.4 at 5200, which would you prefer? Another thing to explain my train of thought is that if it is doing 30.4 at 5200 and I haven't reached max HP rpm, how fast will it go at max rpm range? I know it goes slower above that number. Drastically so. Everything being equal, the boat should get faster than 30 as I get closer to the max HP rpm since it is still climbing the hil to max rpm right? So why not shot for that? I have gone to 6000 and seen it decline so that isn't right either. I'm sure it will be a great ski prop and should sit at 5600 - 5400 with two people in the boat and a skier pulling the boat back. At that point, speed doesn't matter as long as the skier is able to stay on top of the water. And if it has the sweet spot it will also be getting great Gas mileage while doing so.

Do me a favor and see if you can get the same prop but two inches higher in pitch. I bet you get closer to 40 or even above and you'll get better gas mileage. Don't just assume that the prop you had laying around is good enough. Shoot for the max rpm hp number and the boat will be a better all around functioning piece. I don't claim to know anything about props or these etecs yet but I understand horsepower ratings. I have been playing with muscle cars and drag cars my whole adolescent/ adult life. No difference from a boat to a car as far as a dyno reading. You shoot for the sweet spot to put the most power to the ground that you can at all times. I hope you understand where I'm coming from. Let me try to find some dyno charts to show you the dramatic decline an engine takes after peak hp. A common term is that the hp just drops off the table as an explanation of power loss after peak rpm.

I agree with you on the 5200 prop being woefully under rpm once a few people and a cooler are put in the boat, that is why I am still searching for the "right prop". Thanks for your help and I truely appreciate the difference in opinions. It often times solves the problem just by hearing a different point of view. Keep them coming

 

[Patfromny]

Herected is a perfect example of the dropping off the table phrase. Not a boat but you can get why I am shooting for the 5500 range.





This isn't meant to portray an etec engine but rather a typical dyno reading. At some point the etec will fall off the table. Not having seen these charts for an etec I can't tell you when this happens but it seems to be happening around 6000 for my engine with the lower mph.

 

[82rude]

2 strokes and 4 strokes are different so yes id like to see the graf for a 2 stroke does it drop as fast as a 4 stroke or slower? .Mine makes 60 at 5750 but heres my rub .Unless we dyno the motors were exactly does it start to drop?50 more rpms 100 200?ive added more weight to my barge so going to a 17p might not work well but I've already put my 17p 4 blade solas on to try again .Idealy a 16p would be perfect I believe but nobody makes one anymore so I would have to get my bud to alter one of my props to 16p.

 

[82rude]

Just read an interesting article about the etec injectors.They are capable of 80hp per cylinder,up to 10000 rpm.So Im surmising that hp and rpm is all controlled by the mapping of the emm.So in theory the emm may give me 60 hp till the revlimiter for all I know.see where I'm coming from?Does the comp command that hp starts dropping off at 5900 or 6100?A Swedish company dyno a 150 hp h.o. etec that was tuned, to 184 hp!

 

[Patfromny]

Here is something interesting straight from evinrude. Looks like power starts to drop on mine after 5700. Yours might pull to six if max hp was at 5750. Mine is 5500.

 

[Patfromny]

I think hp drops off once the engine can no longer handle more gas/air. Things like bore and stroke, read material. since there isn't a cam shaft. At a certain point the engine just can't push anymore air through itself and power drops off. With a cam shaft you can tune in where you want the power to come on and shut off but to get max power you need to put in bigger pistons and port heads or get larger heads, larger exhaust etc. Just have to make it pump more air. That's all an engine is doing. Taking good air and pumping out bad. Boring a 40 .030 over will produce more power. Polishing intake and exhaust ports will also. Just have to make it a larger or more efficient bad air pump.

 

[Patfromny]

And the Emm does regulate the hp so I suppose it drops off on the best hp curve they could come up with to make it a forty horse engine. It seems they use the same injectors for all etec engines but the Emm is what tells the engine how much fuel to let through. The nature of an engine raising in rpm is such that the hp map will be a curve. It demands more fuel and air as it raises in rpm until the injectors stop putting out more. After that, the engine is demanding more fuel than the injector is giving and the bottom falls out. They program the computer to increase fuel as the engine demands more with things like exhaust temp sensors which add more fuel if the exhaust temp rises. Fuel actually acts as a coolant in the combustion and exhaust chambers. The more fuel the cooler they stay. This is why running lean is not good for an engine. It can over heat the rings and score the cylinders.

 

[Patfromny]

I just compared the 40, 50, and 60 hp on the evinrude site and they have the same displacement. So I would imagine that your peak hp rpm has to be higher. Your emm is just letting more fuel in at the upper end of the rpm range making your hp curve longer. When my fuel max limit is reached, yours still has some left so as mine dies yours still is getting more fuel. This alone can explain why your boat pulls at 6000 and mine dies.

 

[Patfromny]

Your boat also has something called an exhaust cooler? But that and the Emm seem to be the only glaring differences. The 60 hp HO has a larger engine at 79.1 cubic inches as opposed to the 52.7 ours share but if you look, the peak rpm range drops to 5000-5500. So it is probably a detuned 90 or somethinget and the injectors are being restricted like mine.

 

[Patfromny]

Pretty cool aside from the evil prop topic huh? Lol

 

[82rude]

Actually yes.I always equate props as not a science as most believe but witchcraft!You can have 2 rigs similar but both will run differently.Im sure you will figure it out,dont give up that motor deserves better and I firmly believe you would regret getting rid of it.Is there any chace you could get access to 4 bladed props and try them out?

 

[82rude]

the 60 has a different cyl/crankcase assembly also.

 

[jakedaawg]

Pm sent

 

[82rude]

Fyi evinrude has a forum for etec owners .Also for bigger motors but interesting is scream and fly,and continuous wave.Be aware some of those sites can get pretty nasty at times,unlike here which is very civil.

 

[Patfromny]

Actually yes.I always equate props as not a science as most believe but witchcraft!You can have 2 rigs similar but both will run differently.Im sure you will figure it out,dont give up that motor deserves better and I firmly believe you would regret getting rid of it.Is there any chace you could get access to 4 bladed props and try them out?

I think I'm going to exhaust my options in the 3 blade world first. I don't know how to multiple post so I'll answer some of your other comments hear too. I guess the part numbers might be different on the crankcase but the 40 to 60 share the same cubic inch of 52.7 I think. Don't know why they'd change the crankcase and keep the cubic inch. I would suspect they are the same but what do I know. The etec board is something I want to browse but not into the flame type chat rooms. I am easily excitable and am too old to deal with pompous Jerks who wouldn't speak that way to you over the phone or in person. If you have to hide behind a key board to yell at people you can keep your opinion. Not saying that's what the board is because I haven't been there but if it is, no thanks.

 

[Patfromny]

Well, the newest prop wasn't the answer. It went slower than the other two and only achieved 5150rpm. The mechanic was here with the laptop for the test and was going to the marina with the prop shop after me. I gave him my cupped 13.5 x 15 prop and asked him to have the shop straighten out the cup. As suggested by Jakedawg. I held off on cutting the diameter down. Two reasons there, i believe in changing one thing at a time and learning the result before moving on. Secondly, I'm super cheap and am hoping just the one step will work. This will probably not be done this weekend so the final result will be known sometime in September. the lake is 4 hrs away and with a teenage daughter as well as commitments of our own it is tough to dedicate a weekend to here.

Now that I have actually gotten some seat time for myself, I have noticed that the boat proposes badly before I can fully trim the engine. The mechanic suggested that I can raise the engine a hole and it might get better. He set the new engine to the same height as the old 35. Does this sound like a viable option or am I looking at trim tabs in my future"

 

[jakedaawg]

You wont need tabs. You jave a metal boat. If propping and engine height dont solve it a small deflector type thingy coould be placed on the bottom at the stern. Not ideal but inexpensive. That is a trick we used on Old Woody's. Ones that had a bowed hull

 

[Crosbyman]

about EMM time logs .... two measures are taken KEY ON and RUN time ...if the key was left ON without running the time values gradually spread apart.

 

[Patfromny]

Cool, thanks Jake. The fixed plate things are what I was thinking. Thought they were called smart tabs or trim tabs but have never looked at them. If I get more then a couple of days up there I will play with the engine height. I also want to get that uncupped prop on her before doing anything. There are a few things I'll need to address with the new engine. It pulls hard right when coming off wot but hard left when launching. One hand on the wheel stops it from happening but I guess I was a hands free guy with the old engine. We had two couples up with us and where too busy entertaining for me to start playing. I will say one thing about the new engine, IT IS AWSOME. It went about 27 with me in it and didn't want to go below 25 no matter what I did to it. I had my wife and I in it, 25. I had my wife and I and were pulling one of our guests behind on a tube. 25. Three guys with fishing gear. 25. Crazy that it didn't change much from just me and then no matter the load it just wanted to go 25. That was with the 13 pitch prop that spins the motor high. That will def. Be my go-to prop with multiple people or for tubing. It is plenty fast and just jumps up on plane no matter the load. Love it. At this point would be happy with 28 if I can get her into that 5600 range.

Thanks for the info Crosbyman. I figured something had to be up with those numbers. My Brothers 2011 etec that he bought new has the same difference in hours thing so I stopped worrying.