Starboard Engine didn't come up to RPM

[jrmccoy]

Gentlemen,

I took Maggie Mae out for about a 15 mile cruise in perfect weather here in Charleston last weekend, and when I got out in CHS Harbor I had plenty of room so I decided to run her up to WOT as I do periodically to spin up the turbos and get her breathing well.

These are DD's 8V71T's (435HP) on my Hatt 53...and for the first time in 5 years my STB engine couldn't break 1600 rpm....port side was winding up well over 2100 but STB just more or less topped out at 1600....running clean filters and fuel on raycor 1000's ...bottom not bad (but not suspect because port engine did just fine), good oil pressure.....ran fine right up to 1600, and back down, but not beyond. She normally doesn't smoke at all after a short warm up period, but when I run her up to WOT often she will smoke a bit more for a moment...but she was throwing out a lot of smoke when I went to WOT...more than usual. Wondering if it could be a bad turbo? or both? There are 2 turbos per engine.


I'm a bit mystified...

 

[SKYCHENEY]

What color was the smoke. Black is from lack of air aka bad turbo.

I would first look at lack of fuel. Did you change secondaries?

 

[Briankinley2004]

I doubt it would account for that much difference but were you running the synchronizer? The slave engine will not turn up as many RPM's on the Glendenning. I think mine was about 200

 

[racclarkson@gmail.com]

Likely turbo/charge air failure/restriction. See if you can spin it/them freely. Check your charge air piping. Shutdown flap partially closing? Intercooler dirty/clogged?

Re: synchronizer. My motors will both top out on sync right on the button.

 

[jrmccoy]

I doubt it would account for that much difference but were you running the synchronizer? The slave engine will not turn up as many RPM's on the Glendenning. I think mine was about 200

I don’t actually have a synchronizer so that wasn’t in play.

 

[brian4190]

This might help

https://www.sbmar.com/featured-article/understanding-low-power-troubleshooting/

 

[pdog]

Could be a bad injector. Had this exact problem a few years ago on my 8v71 TI's. Bad injector was my issue.

 

[rustybucket]

what rpm WOT are you getting at the dock in neutral?

I'd start at the air filters and work my way in looking for suspects. If the air filter is good and clean, check the turbo for wobble/play and free spinnage. Intercooler, air flaps, piping...etc all could be suspect. A loose air pipe or air hose would loose boost pressure and demonstrate bad turbo symptoms, so look for places for air to escape, busted hose, loose clamp...etc

Were you feeling any new vibrations? A line or obstruction wrapped on the prop can lug one engine as well, may be worth going for a swim if the air intake system all appears up to par.

Black smoke, under powered should be restricted air problem.