Alumacraft tunnel hull PROBLEMS

I have a new 2013 1860 alumacraft flat bottom tunnel hull with a 115 e tec and no matter what prop we put on it we cant get more than 4500 rpm and 35 to 38 mph. Do I need to vent the tunnel? Running a 3 blade aluminum prop right now tried a 21 19 and 17 pitch all the same readings. no jack plate yet that’s on its way. the motor is mounted in the second hole. Any help would be greatly appreciated

sounds like a motor problem to me. when I got my new rig I was having the same problems with trying to prop it, after a few different props, moving the motor up and down on the transom I took it in and they found that one of the plug wires was not pushed on all the way. check and make sure that they are making contact at each end.

The Etec might have some sort of auto break in period where it doesn’t go above a certain RPM.

I’d ask someone who knows Etecs or call the dealer you bought it from.

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The Etec might have some sort of auto break in period where it doesn’t go above a certain RPM.

I’d ask someone who knows Etecs or call the dealer you bought it from.

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I would investigate this option first. Re-proping definitly should have shown some variation in RPMs in my experimentation.

My dealer told me there is no break in on an Etec. It does however have a double oiling process for the first 5 or 10 hours running over 2000RPM. Hope that helps

Something is wierd. You should gain close to 200 RPMs with each inch drop in pitch. I vote for something limiting the motor.

Dont know about 2013 but the 115 has an exaust valve that should open at 4500 rpm. They have been known to stick. Wot should be 5500 to 6000 rpm.

I vote something wrong with the motor you should not have to put a jack plate on the motor it should be on the 3rd hole and thats all you need those boats ride like a bullet very fast have them put the motor on a computor before you keep messing around and really get confused with where your at with proping and height

Called the dealer hopefully get it there soon to get it hooked to the comp and checked out. Anybody vent their tunnels iv read some stuff on it and I get mixed reviews does it help or not worth the hassel. I want this boat to be a screamer on the river any extra mph the better.