10m mid cabin - Crusader 8.1's initial impression

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zedtwentyate
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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by zedtwentyate »

BobCT wrote:
Tue May 04, 2021 10:02 am
Kegan, thanks. I'll keep updating this thread. Correction on props. New ones are 18x20 (not 21). Michigan Wheel, nibral DQX.
When you buy a spare set, let me know so I can buy your old 4 blades!
Kegan

1986 Trojan F-27 (SOLD!!!)
1989 Trojan 10 Meter Mid Cabin

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BobCT
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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

Well, I kept them as a spare set. The prop shop cupped them as much as possible. They’ll get me home but probably not a pair I could run for long.
1988 10m mid cabin

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

So the plot thickens and not in a good way. Here is the rabbit hole sequence of events:

I had a bunch of codes which seemed to be voltage related. To address that:


1) I reseated the ECU connections and disconnected the slave/master connector so I could keep any issues isolated. I load tested the battery (good) and double checked all of the ground connections, then cleared the codes. Went out for about a 90 minute run and had the Diacom plugged in the whole time. No codes appeared. I think these were actually stored codes from running it on the hard and the battery was low. I’m calling this issue good for now. I was also feeling the Stb engine bucking a little at higher RPM’s and checked the fuel pressure underway. The Crusader spec is 37-43 @ idle and 44-48 @ WOT. I had 37 at idle but only 39-40 at my highest RPM’s which were around 4,400 with a huge caveat:

I’ve never had a scanner (Rinda Techmate Pro) connected while underway. I happened to glance at the engine RPM’s and noticed they were about 450 RPM’s HIGHER compared to my tachs. (This is “engine speed”). I have been judging my speed, fuel burn (all much better than the 454’s) compared to my tach readings since the first run. These are the same tachs I had with the old engines as well. These 8.1’s are supposed to hit 5,000/5,200. If this is based upon “engine speed” and not what I’m seeing on the tachs then I’m not looking nearly as good as I thought numbers wise.

Putting that aside for a minute, it did feel like the engine I tested today was either starving for fuel at my highest RPM’s and maybe the fuel pressure number bears that out. Crusader calls for 1/2” fuel line. I have 1/2” coming OUT of my Racor to the engine but my original 3/8” from the tank to Racor. I can upgrade this section on both engines. My original theory was that the 8.1’s would need less fuel at WOT but the RPM’s are higher so maybe not the case. I’m not worried about figuring this part out.

My biggest concern right now, is the engine speed THE source of truth or do I have a tach issue x2? (and props that are nowhere near correct)? The delta is at lower RPM’s as well:

tach 2,700 = 3,150 scanner
tach 3,000 = 3,440 scanner
tach 3,400 = 3,850 scanner

Obviously the idle isn’t 450 RPM’s too high so this difference kicks in somewhere up the range. Both are Faria tachs replaced by me when I re-did my helm about 5 years ago. It’s weird to me that both are off in synch (literally). And, I’ve owned the boat for a long time and surprised I would hear/feel such a big RPM difference especially at the lower 3k 454 cruise range. On the flo-scans, I recall (and prob have video) of the fuel burn jumping up as the secondaries were opening and that was around 3,100ish.
At around the same tach RPM’s on the new engines, it “feels” the same not 450 RPM’s higher but it looks like that’s the case.

I can’t imagine any scenario where the scanner data would be wrong and my tachs correct right? If I only had digital gauges on my Garmin, those are the RPM’s I would dealing with. What does this really mean? You can’t fudge the speed and fuel burn, that’s still better than I had but I’m now thinking it’s a much higher RPM range than I first thought.


Bob
1988 10m mid cabin

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by prowlersfish »

I would get a photo tach and check. Make sure your looking at rpm on the scanner not desired speed.
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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

I will double check with my IR tach. Here’s a quick video showing the difference underway:


https://youtube.com/shorts/VqMMWj7bhb0?feature=share
1988 10m mid cabin

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by prowlersfish »

FWiW tachs were likely off on the old engines too. If the photo tach shows them off, are the tachs adjustable? I assume they run off the ignition.
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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by captainmaniac »

Some tachs have a selector on the back for 4, 6, or 8 cyl engines and scale the incoming signal accordingly. If that applies to yours, any chance the selector is not fully seated in the right position?

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by RWS »

prowlersfish wrote:
Sun May 09, 2021 12:43 pm
I would get a photo tach and check. Make sure your looking at rpm on the scanner not desired speed.
+1

Bob,

Don't stress over this

A phototach running off a 9 volt battery is surprisingly inexpensive

This will tell the truth as to where you are.

It's possible BOTH the instruments are incorrect.

I bought this one in 2014

https://www.amazon.com/gp/product/B001N ... UTF8&psc=1

it's only $19

Get it and put the question to rest

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

Good idea, I own an IR tach already and even had the foresight to apply the tape “just in case” so here I am!

I can’t imagine how the data feed from the ECM could be inaccurate but I’ll let the handheld tach settle the bet.

On the tachs, they’re both set for 8 Cyl and untouched since I first set them a few years back. I agree, this might have been an issue on the old engines. I’m pretty sure they do have a calibration adjustment.
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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

I called Faria and they said the scanner/ECM RPM's are "the" source so adjust the tachs to those numbers and call it a day. The guy I spoke with wasn't surprised that both were off the same amount. Thinking back, I'm pretty sure I was coming up short on the old engines but didn't really dig too hard.

This is a bummer for sure but there's nothing I can do but correct the difference. I'll be cruising in the 21k/22k range which I was never able to do with the 454's but a 24k cruise is off the table. I believe my RPM's at that speed are really around 4,100 vs the 3,600 I'm seeing now. Scary to think that I literally tripped over this issue or I would have just run them. If I get to 5,000, which now I think I came close to unknowingly, 75% of that number puts me at 3,750 RPMs.

Time to adjust the tachs and hopefully my punch list will start trending down.
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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by RWS »

and then there were those pesky props........................

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

Posting here as well:

I adjusted the tachs to the “real” numbers and went for a cruise last night. Verified by the ECM output:

3,400 19.1k 28gph
3,600 21k, 30gph
2,800 14k, 20gph

I have a couple of more hours of break in run time, oil change then I’ll see what my WOT looks like. Depending on how you look at it, I have a feeling that I’m propped correctly. Doing the math with tach issue, I think I hit 4,800 already although that wasn’t the plan. I think when it’s all said and done, I’ll be cruising in the 21k range. Maybe the props can be tweaked and I can pick up another knot but would do that in the off season.

Bob
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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by RWS »

It is interesting that the fuel burn is nearly flat throughout the 2,800-3,600 RPM range.

I suspect a tweak in the props will yield more improvement than you speculate.

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

quick update, I finished up my break in period of 10 hours and changed the oil. I cut open the filters and didn't see anything of concern. I also sent the oil samples out to Blackstone, maybe I'll get those results this week.

After the oil changes, I hit 5,000 RPM's and backed off because of the issue on my Stb engine. The idle surges at around 1,300 RPM's up/down by 100RPM's or so. It's fine until I get to around 4,500 and then it feels like it's running out of fuel. I did run it with a fuel pressure gauge and it's under spec (new pump) so I have to troubleshoot that. The port engine is fine. I don't know how much OVER 5,000 it would go but I hit 29k before I backed off. I'm hoping that the low RPM surging and the high RPM issue are one problem and not two. First thing I'm going to do is check the vent line. I was going to swap my 3/8" fuel lines like I mentioned above but the port engine is fine so I really don't think that's the issue. Definitely not at such low RPM's.

I actually came back to port so I could connect my oil pressure gauge was reading way too high, near 80 at idle. I connected a gauge and it's fine. I installed a new sending unit and same issue. I wonder if the "T" that I'm threading into is partially clogged? It was fine for the first 8 hours. At this point, I've replaced almost all the sending units. That has been really annoying because it's been one "oh crap" moment at a time.


Bob
1988 10m mid cabin

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Re: 10m mid cabin - Crusader 8.1's initial impression

Post by BobCT »

While I'm on here, I figured I would update this thread for maybe the final time. I don't see a whole lot changing now that I have about 60 hours on the 8.1's. Good news, I think the compression has increased a little as they have broken in, I would say that my average cruise speed has crept up now, maybe 1/2k or so. Reviewing video of my longest trip a few weeks ago (about 160 miles) my average was 3,600/3,700 RPM's @ 32GPH with a speed of 21.7k or 25 MPH.

On the oil front, I think I'm in better shape break in wise. Consumption is trending downwards now. No oil used over 11 hours port, 1/2 QT on Stb. Stb does have the rear main cap leak which I mentioned before. I'll probably just live with it, maybe consider fixing it end of next season. Of the oil used, I don't how much is leaking vs. burning so maybe I'll decide at that point.

Still chasing the low RPM surge and oil pressure on Stb is still reading too high at cruise. Gauge, sender and signal wire right back to the helm changed. I'll get this figured out.


Bob
1988 10m mid cabin

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