Rosie,

The plugs looked great. Some minor carbon deposits around the base, just above the threads, but none on the insulator it electrodes. There was also no erosion to the electrode. They looked essentially new, which they are; they were replaced about this time last year. I have not had a chance to do a plug chop, to get a proper plug reading, though

It’s looking like we’re going to be going out on Saturday. I’ll report initial findings. Don’t know if I’ll get a chance to do the plug chop, though. The water stays pretty rough at Caesar’s Creek.

Thanks. Brad.
(937)545-8991

Rosie,

We went to Brookville Lake exactly once. We didn’t care for it. Too rough. Too much of a free-for-all. The “party cove” was OK, but standing on bottom right behind the boat was a bit unnerving. I guess I’m just spoiled on Cumberland.

Thanks. Brad.
(947)545-8991

I know what spot you’re talking about at Brookville. We avoid that spot because it’s so shallow and nothing but rocks.
it is a ROUGH lake on the weekends but we like it because you’re allowed alcohol in the boat in Indiana and my wife likes her beer when she’s in the boat. lol.

The compression numbers are very good. Go run it with new belt. I’m 90% sure it will be back to normal

Griff,

I'm certainly hoping so. I'm optimistic. The pessimist in me is still thinking about the injectors, though. We'll see.

Thanks. Brad.
(937)545-8991

Rosie,

FWIW.... I don't believe alcohol is allowed on Caesar's or East Fork Lake (the two overgrown ponds in Ohio that we frequent when we can make it to Cumberland), but we do it anyway. And I KNOW alcohol isn't allowed on Cumberland (at least, it USED to be prohibited), and the lake patrol would only harass you if you were being a problem.

Thanks. Brad.
(937)545-8991

Boost is down? Belt will be the culprit if you don't see any obvious perforation on the plumbing between the procharger and intake (I suppose you could have a rotted out intercooler, which wouldn't be visibly obvious).

Fuel pressure is down? No, it looks like fuel pressure is where it should be for the amount of boost you report.

Check the idler/tensioner bearings, and take a straight edge and verify that the tensioner is aligned properly and not at some angle.

Plugs? Sure, if they have been running pig-rich then swap em. I see you did a compression test. But male a note to open the throttle next tine you do it so your results are correct.

Speed? If you got 68 out of the boat with hea y fuel load, cooler, gear, people, then if you run it with 1/4 tank of fuel, one person, no gear, no water in the freshwater tank (if you have one) and it's a cool 60 degree day then you'll see that 71 on the clock (assuming you run a prop that doesn't bump the Rev limiter).

Weight matters if you're looking for that bug number.

Throttle chops aren't spooky in a vee hull at the speeds you're running. But reading plugs is a lost art. If you aren't sure what you're looking at, then it wont tell you much
Insulator color, heat line on the electrode, evidence of bright specks, these are all part of the insight of what your plug is seeing at soeed, but the differences are very slight.

Before you look ANYWHERE else, get your lost boost back.

Has anyone actually ever compared compression test results with throttle closed vs open?

Closed throttle blades still permit air passage, along with IAC passages. How else could an engine idle? It might take an extra revolution or two, but since a compression tester "stores" the pressure until released, the end result should be the same assuming you crank the engine long enough to get a stable reading.

McCollinsTN,

Belt is changed. Testing on Saturday. I'll review fuel pressure then. Tensioner and pulley are good. Pretty much identical to the new one I didn't replace it with. Maybe a bit more free spin on the pulley, but that's to be expected with some run time on the bearings. Plugs are changed. I cannot, for the life of me, find anything that might be a leak in the intake tract between the blower and the throttle body. I've looked every time I've been under the sun deck since the power has dropped off. The intercooler is sound. Again... I've looked. The boat only has 190-something total hours on it and was absolutely babied for the first 143 of that (not that we are abusing the boat in any way). I think, as I gather, what is most telling about any compression test is the consistency across the cylinders, and I'm told mine are within an acceptable range. I was very happy there wasn't that ONE cylinder at, like, 50, or whatever.

I'll take pics of the plugs after a throttle chop, because... NOPE... I don't REALLY know what I'm looking at. I'll post those pics here for more knowing eyes to review. Rev limiter is set at 5250, just to ensure we don't hit it under normal conditions, and we don't air the boat out, literally AT ALL, so....

I'd like to build a monster engine, replace the drive, and reach for 85, but I don't know as I'll ever convince the wife that's "necessary" (SIGH). For now, I'm happy with 65MPH or so, given our current set-up.

Thanks for the input. It's all being absorbed as best I can.

Thanks. Brad.
(937)545-8991

Guys,

Took the boat out yesterday with the new blower belt and new plugs. Nothing has changed. Still hitting a rev wall at ~2500RPM at takeoff until it starts to plane off. Still takes what seems like forever to plane off. Still hits a rev wall of ~4100RPM at something just short of 2/3 throttle on the stick. Still topping out a good 10MPH short of what I’ve had the boat at. Still only showing ~1.5 lbs or boost. Still only showing ~50lbs of fuel pressure above zero manifold pressure. Still crossing zero into positive manifold pressure at ~3600RPM.

Unfortunately, due to our being significantly out of routine getting to the lake, I did not have the tools to read the plugs, so I still have not done a proper throttle chop. I know this is still a necessary step, and I fully intend to do so. In the meantime….

Where else might I might look? I’m still convinced there is not a compromise in the ducting between the blower and the throttle body. I cannot speak for the internals of the intercooler, but I can vouch for water flowing through, and I see no evidence that water is going through the engine. Not sure if these two facts indicate a lack of compromise to the intercooler, but I can’t imagine one or both wouldn’t change if there was an internal compromise to the intercooler. Surely, if there were a breach. In the water passages in the intercooler, water would be going through the engine, right? Any way to check without pulling and inspecting? Not that I’m opposed to doing so…

Anybody want a free weekend on Cumberland? Just bring your intuition, experience and diagnostic tools. 😃

Thanks. Brad.
(937)545-8991