im trying to think... Everything different between the boat and the dyno... Waves... Vibrations.. Angle.. Drives... Trans

Might come to doing a compression and leak down unless you already have. I realize their fresh engines but...

Sounds dumb... But thinking out loud.. Do TRS have the fin anodes above the prop? Possible it kicked sideways when drive was out back on?

I did in fall both engines all 16 within 5 psi across board ..

Tim I have the same issue on my Cafe. Both motors dead on until about 2800 RPM then the port lags between 100-200 RPM. It has been like this since I bought it. Changed the drives from 1.36 to 1.50 and propped accordingly, still the same lag. Bumped power on both motors, AFR's the same, went from 26 to 28 pitch bravo props, still the exact same issue. Did some prop testing and threw a set of labbed 27 pitch Hydromotives on it, couldn't plane for chit but both motors were dead nuts identical, I mean spot on through the entire RPM range. Went back to my 28 Bravos since they have worked the best, and stopped worrying about it.

A thought, have you swapped drives side to side, spinning in to see if the lag changes?

Sounds very reasonable. Good post. Just looked back to post # 4 & 5 though???

exactly, leading me to distributor, coil, and wiring to look at, floats good, airflow good, all the other things are good

It lags with all 3 sets of props I have tried, never swapped drives but when I first did engines last June they were equal, then all of the sudden they were not and have yet to be, that's one reason I dynode to rule out engine issues, that's why I am trying to look at things that change once in the boat.

I must figure it out because I know its gotta be something dumb, I am gonna try everything I can until I figure it out lol

they why would they dyno identical?

I don't know how your charging system is wired, but a simple check. Check all battery's and connections. Possible a alternator is causing more draw on one motor than the other. I could be way off, just a idea.

Check your Drive Alignment , Engine Bed Might have settled. Swap Drives , if it doesn't move . Swap Engines see if it moves .

no adjusting with offshore mounts, drives slide right in no issues...

check voltages running on hose all over, both engines identical, now going across waves in lake I have no way to check besides dash gauge that reads same as other, engines dynod with alternators and sea pumps.

Do you now leave fenders hanging off this side of the boat. :stooges:

I had t realized how much time had lapsed between dyno and run time. PLUS you mentioned they were reasonably close to identacle RPM's "in boat" and then now this.

omg that MUST be it!! LOLOL

I think next step for chits and giggles is to swap distributors (msd ready to run) so all ignition is in that, just in case for some reason it acts up under way in boat and did not on Dyno, if that is not it, the coil is next, then if that's not it... going to run direct wiring from ign. switch directly to distributor bypassing my engine harness, On dyno we direct wired dist. we did not use my engine harness for power to ign. that's where I am starting next...

built engines and put into boat last june, ran good for a few weekends same rpm, then a drop on port I noticed, played with it last summer a little no changes, was happy to be boating, pulled over winter to dyno and replace a bad trans, engines dyno identical, put in boat still have rpm drop, fast forward to now lol

How did mild not talk you into new programable distributors. :picard1:

Went back and read original thread. I misread the dyno'd after noticed rpm loss with run time. This is a real beiotch. Swap drives or swap engines. Or lose more hair mean while. So to date did you do the coil swap including ign box?

It's a long shot for sure but are you running choke plates?

He has, he and I talk a lot... when money is there and I have a MSD fail I will look into it, right now just wanna make these run right haha

no plates on these.

Got a plug wire arcing somewhere. Run in the dark with no lights? I know it sounds stupid but problems can show up where you otherwise might not unless you live near a graveyard.

all good, no I am swapping ignition parts tomorrow after work, test this weekend, one part at a time, I didn't mess with things on engines much because of the dyno showing same, but ignition can act up in boat and not on dyno, so I am going to start looking there now..

I swapped full wire sets between engines, I am tellin ya I don't almost everything lol

Well at least your wise by the one thing at s time scenario. Process of elimination. You'll get it. temps much hotter in bilge than dyno room also.???

Not sure, engines only run at 110 water temp so not a huge change I guess.

tim,can you feel a power loss on one engine or is it just different tach readings?

finite adjustment of the turbo-encabulator?

I can feel a loss, at first I hoped it was a tack or off reading but the boats down 2-3 mph also..

haha maybe that's the issue!!

How many hours ago, though? Might be worth another quick check just to make sure it is nothing internal cropping up. Tranny maybe?

I can't see how this would be Stecz's fault, but you never know.......

Fuel pressure the same on both engines?

Mark

my guess is valve seal issue on one engine.time for another leak down check.

20 hours ago, also remember rpm drop was there before last falls compression testing so that's not gonna be it, also if engine was down a cylinder that would have shown on dyno also.

Why would they dyno identical then? Was down most of last summer, dynoed identical and still down, not sure how that can be a cylinder issue, yes I know I have potential disaster bob cams but if down a cylinder that woukd have shown on dyno. I could be wrong but the issue was there way before dyno, not on dyno then again after dyno, so I don't think it's mechanical in engine.

Yes 6-7 psi

If it has not been mentioned earlier within this thread, then a leak down test is one of the best tests you can do as suggested here by Mike Tkach....it eliminates a lot of guess work-----and it does not matter how fresh or new the engines are.