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  #26   IP: 199.116.74.233
Old 08-30-2017, 02:58 PM
clark800 clark800 is offline
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I had the old-style cone-shaped regulator in there, but yes it came out.
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Old 08-30-2017, 11:32 PM
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Nice. Keep that thing handy...I suspect they are not made any longer and you might be able to sell it to another forum member!! Or, maybe send it back to Moyer for reconditioning and re-sell to someone that needs it.
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Old 10-06-2017, 03:30 PM
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Update

I pulled the engine out and sent it back to the mechanic I bought it from. He didn't find anything obvious, but replaced the oil pump and a bunch of internal parts. He ran a two hour test without load and said it ran perfectly. I reinstalled it and after all that ended up with the exact same problem.

So the new thing I noticed is that it does seem to hold oil pressure in neutral. In neutral at ~2000RPM, it starts out at 60PSI for 20 min, then falls to 40PSI over the next 20 min. After an hour it was at about 39PSI. Then I shifted to forward and within one second the oil pressure fell from 39PSI to 20PSI. From there the oil pressure gradually fell to about 15PSI over the next 20 minutes until I stopped the test. Readings were fairly consistent between the electrical and mechanical oil pressure gauges.

Also, the temperature was holding at 155F after an hour in neutral, but rose to 180F after shifting into forward. The mechanic said that the engine should never go above about 140F since the thermostat is disabled to protect the engine from salt water.

Is it possible that the engine is over-loaded? Would overload cause an immediate 50% drop in oil pressure? I can turn the shaft by hand when in neutral, both before and after running the test. The propeller I have is 17x12in whereas the manual calls for a 16x11in (this is for the 2:1 reduction gear). The mechanic didn't seem to think this was a big enough difference to cause such an issue. Is it worth buying a smaller propeller to test?
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Old 10-06-2017, 03:44 PM
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I see a few potential problems here and we will start off with the prop. You most certainly can have issues with a too-large prop. Can we find out the manifold pressure at a few RPM points, say 2000, 2500, and 3000? If you can't even get to 3,000 with the reduction gear the prop is definitely too big IMHO.
Second off is the cooling. High temps can very well result in low oil pressure. You should acid/vinegar flush the engine and then set it up with no thermostat, a bypass valve in the closed position, and see what you get.
Lastly is the oil itself. Single weight oil basically gets thinner when hotter and thicker when colder. With the notable exception of old 2-stroke Detroit Diesels, the day when single-weight oils are desirable is well in the past. I use Shell 15w40 Rotella that acts like 15 weight when cold, thus easier starting, and 40 weight when hot, thus better oil pressure when hot. I have tried a number of oils over the years and found this oil to hold pressure better over a wide range of temperatures compared to others I have tried.
If you give all this a try I am pretty sure we can figure something out.
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Old 10-06-2017, 08:13 PM
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Quote:
Originally Posted by clark800 View Post
The propeller I have is 17x12in whereas the manual calls for a 16x11in (this is for the 2:1 reduction gear). The mechanic didn't seem to think this was a big enough difference to cause such an issue. Is it worth buying a smaller propeller to test?
You are definitely over propped. I can't say whether or not it's contributing to your immediate symptoms but you are not doing this engine any favors with a prop this big.


Quote:
Originally Posted by clark800 View Post
The mechanic said that the engine should never go above about 140F since the thermostat is disabled to protect the engine from salt water.
Do you have any further detail on exactly how the thermostat was disabled? Was it removed? Did he block or restrict the bypass? If not, disabling the thermostat also disabled the cooling system and this elevated temp symptom suggests that's exactly what is going on.
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Old 10-07-2017, 11:07 AM
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Did your mechanic confirm that all the bearings, including the cam bearings, were correctly measured and replaced?
As stated previously Your issue is consistent with slightly worn cam bearings.
Also, the oil pump can't just be replaced on an A4 as it's also the main bearing cap. To replace the assembly would require line boring. So I'm curious as to what he replaced when he stated he replaced your oil pump. The pump gears are matched to the housing.

Don can have your pump tested and rebuilt. It's expensive and would do nothing if your bearings and journals are not up to specification.

I'm sorry you're having to go through this.
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Old 10-07-2017, 02:34 PM
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Thanks for the replies!

@joe_db
I don't have parts for testing the manifold pressure yet, but I didn't have any trouble getting to 3000RPM and the experts at the local propeller shop said the propeller probably wasn't a major issue if I can get to that RPM. I am thinking of testing with the propeller off to see what happens.

The engine is already running with no thermostat - the mechanic disabled it somehow to prevent salt water damage with higher temperatures.

Shell Rotella 15W40 was suggested above and I tried it and it had no effect.

@ndutton

The thermostat dome is still on the engine. I'm not sure exactly how he disabled it. I can ask next time I contact him. If the cooling system was disabled, would the engine hold at a temperature of 155F for an hour at 2000RPM in neutral?

@Mark

I haven't asked about the details yet. I'll contact the mechanic after testing without a propeller.
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Old 10-07-2017, 07:51 PM
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Quote:
Originally Posted by clark800 View Post
The engine is already running with no thermostat - the mechanic disabled it somehow to prevent salt water damage with higher temperatures.

The thermostat dome is still on the engine. I'm not sure exactly how he disabled it. I can ask next time I contact him. If the cooling system was disabled, would the engine hold at a temperature of 155F for an hour at 2000RPM in neutral?
Entirely possible. There's very little load on the engine out of gear so it doesn't produce much heat.

In the first sentence quoted above we have conflicting information, the reason I asked for more accurate detail before. Ask the mechanic if the thermostat was physically removed or disabled (it can't be both). If the former, did he block the bypass? If the latter, exactly how was it disabled? If the thermostat was removed and the bypass was not blocked at the same time you do not have a functional cooling system.

The thermostat in our A4 does not function the same as grandpa's Chevy, it's way different. It can't be simply removed without modifying the cooling system too.
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Old 10-12-2017, 12:46 AM
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@ndutton: I think you might be on the right track with suspecting the cooling system, or at least something related to the temperature. Here's why I'm suspicious about the temperature:

1. The engine seems to run a lot hotter than it should given that the thermostat is disabled. I still don't know exactly how it is disabled, but if I clamp off the bypass hose it seems to have no effect on the water flow out the transom or the water temperature, so I believe the bypass is internally blocked to force all water through the block at all times.

2. The mechanic said he could never get the engine over 140F, even running it in gear (without load) at 2000RPM+, whereas I'm seeing 155F in neutral and 180F in gear at 2000RPM with load. Of course, the propeller is slightly larger than the specification, but I took it to 4000RPM in gear, so I have to doubt that the extra inch of pitch and diameter is causing a big problem. Plus the propeller can't explain the higher temperature in neutral.

3. The water temperature reaches ~170F prior to oil pressure issues arising, so the elevated temperature may be causing the oil pressure issue. For example, if there is some kind of cooling failure, some parts of the engine may be significantly hotter than the temperature sender. It seems less likely that the causality is reversed because the oil pressure decline does not seem to be associated with a further temperature increase.


But I'm having trouble figuring out what might be causing the elevated temperature.

I checked the flow rate and about 6 gallons/minute of water is flowing through the cooling system, so that looks good.

I clamped off the bypass hose and it had no noticeable effect on the water flow rate or water temperature, even when clamped from a cold start. Also, the temperature pattern is the same when clamped. So I think the water is flowing through the block.

I checked the exhaust backpressure and it fluctuated wildly between about 1PSI and 3PSI, with brief spikes down to 0PSI and up to 4.5PSI, with an average of what I would guess as 2.5PSI, though it was too erratic to read clearly. This is higher than the specification, so I tried disconnecting the exhaust system and initially the temperature dropped from 160F to 140F in about a minute in neutral, but then it climbed back up to 160F just as quickly when I shifted into gear, and then I had to abort due to carbon monoxide alarms.

This exhaust test is the most promising finding because it's the only time I've seen the temperature fall to 140F and also the exhaust is one of the few variables that differ between my setup and the mechanic's. Is it possible that elevated exhaust backpressure could cause overheating without affecting water flow rate?
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  #35   IP: 24.152.132.65
Old 10-12-2017, 07:49 AM
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Clark, my comments address only operating temperature and do not attempt to connect it to oil pressure. The temperature may be completely unrelated but it still needs to be dealt with. A few observations from your last post:
  • I'd still like to know if you have a thermostat installed or if it was removed, same question I've been asking for nearly a week. It's easy to find out, remove 2 hex nuts and have a replacement gasket on hand.
  • Clamping the bypass should not have any effect on water flow under any circumstances so flow rate is not an indicator of the coolant path.
  • With a waterlift exhaust system, exhaust backpressure is expected to fluctuate, higher when pushing out a water batch.
  • 4000 RPM in gear??
  • Please remind me, raw water cooled, right?
  • When was the last acid flush performed? Has the water jacket side plate been removed for inspection?
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Old 10-12-2017, 09:02 AM
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Redline for an A4 is 3600 RPM, so 4000 is pushing it
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Old 10-12-2017, 12:40 PM
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Quote:
Originally Posted by clark800 View Post
I pulled the engine out and sent it back to the mechanic I bought it from.
So, if the engine was removed (from the boat?? ) and ran great for the mechanic, what is different from his bench test and the boat test? Fuel supply, water intake and exhaust systems.

I also agree with Neil's questions..a few things need to be clarified to actually understand where we are at and where we are to go.
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Last edited by sastanley; 10-12-2017 at 12:42 PM.
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Old 10-12-2017, 01:08 PM
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Can we confirm the engine can swing a 17x12 prop at 4,000 engine RPM
Also can we confirm the engine oil pressure drops right away in forward? Does the reduction gear use engine lube oil? Is it doing something to the oil? Did we ever get oil temps?
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Old 10-12-2017, 01:17 PM
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Mark, after reading this thread I think most of your trouble may just be heat. Get a cheap IR temp gun and check the temp of the oil via the oil pan.

If the oil temp is rising more than the water temp as the pressure drops you may just have the oil pressure adjusted to high. Starting cold and at 1500 rpm's what is the pressure? 60 is way to much!!!

Oil being pumped at higher pressures will make a LOT more heat. That with the fact that you are running way to hot on the water side will really add to temps.

Was the block, manifold and head "boiled out" when the mechanic worked on it?

Did you ever turn the key back to on after the engine was stopped at 180* if not do so. Shut it down and wait about 5 minutes and then check the temp, this temp is a far more accurate indication of the "RUNNING TEMP" of the engine in a raw water cooled engine. My ole RWC A-4 ran at about 130 and the 5 minute shut down would yield around 160. Remember a RWC engine is bringing in cold water where a HX is running very warm water into the engine. My guess is you will see over 200* and bingo low oil pressure too.

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Old 10-12-2017, 02:43 PM
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Last night, I happened to browse the Indigo web site and noticed their discussion of oil pressure vs temperature. Note that this is pursuant to a sales pitch for their engine oil cooler. I wasn't previously aware that this was such a problem as to require another accessory!

I was thinking, "Gee, I'd like to see some data on that." The graphs above seem like a good start. But I think we'd really need to see oil temperature, not water temperature.

Quote:
"As designed and built the Atomic 4 has no provision for cooling or warming the oil. As a result, it takes about an hour of operation for the oil to get up to a reasonable operating temperature and continued operation beyond about an hour causes the oil temperature to continue to rise until it gets quite hot and thin. Depending on the condition of the bearings and oil pump in the engine, this is quite often seen as a significant drop in oil pressure."
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Old 10-12-2017, 03:06 PM
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Quote:
Originally Posted by toddster View Post
Last night, I happened to browse the Indigo web site and noticed their discussion of oil pressure vs temperature. Note that this is pursuant to a sales pitch for their engine oil cooler. I wasn't previously aware that this was such a problem as to require another accessory!

I was thinking, "Gee, I'd like to see some data on that." The graphs above seem like a good start. But I think we'd really need to see oil temperature, not water temperature.

Quote:
"As designed and built the Atomic 4 has no provision for cooling or warming the oil. As a result, it takes about an hour of operation for the oil to get up to a reasonable operating temperature and continued operation beyond about an hour causes the oil temperature to continue to rise until it gets quite hot and thin. Depending on the condition of the bearings and oil pump in the engine, this is quite often seen as a significant drop in oil pressure."
If you have the Indigo filter, it is easy enough to shoot the filter with an IR gun and get your oil temperature. I don't think we know the OPs oil temps yet.
Just FYI, too much under 180 will not be good at boiling off moisture and hydrocarbons.
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Old 10-12-2017, 05:26 PM
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Lots of great questions, I'll try to answer them all.

The engine is raw water cooled.

The thermostat was removed and there is a plastic cone (a dispenser for silicone tubes) wedged into the bypass hose to block flow. I took the plug out to confirm it is intact. I don't think it forms a perfect seal, but it looks like it would restrict the flow a lot.

The mechanic said he did not do an acid flush when rebuilding the engine, but cleaned all the parts manually while rebuilding. At this point there is only about 5 hours on the engine since the rebuild and the symptoms have been the same since the beginning.

The mechanic said that he did check the bearings and journals. He said that his tests would have caught something if there was an issue there.

The reduction gear does use the engine oil. I don't think it does anything to the oil aside from use it on the gears.

I can confirm that the engine reaches 4000RPM with a 17x12in propeller and the 2:1 reduction gear. I could see the turbulence in the water from the propeller. Of course this assumes the tachometer is working. I believe it is because it sounds like it is idling at 1000RPM, running normally at 2000RPM, and getting a bit scary at 3000-4000RPM.

I don't have any oil temperature reading yet, but after stopping the engine after reaching 180F and leaving the temperature sensor on, the temperature rises to 210F or above.

The oil pressure drops rapidly after shifting into forward only if the temperature is already high. If I shift into forward while the engine is still warming up the oil pressure is maintained.

I do have the Indigo oil filter and previously tried it without any noticeable effect. Adjusting the pressure regulator on the oil filter did not raise the oil pressure after the problem started.

The mechanic was pretty confused by the problem too; he said he's sold many engines and asked the buyers about them and everyone else's run at 130F and go up to 150F after shutoff (versus 180F and 210F for mine). He seemed to agree that the exhaust system is the prime suspect, although without any ideas of what might be wrong with it.

I'll describe my exhaust system in case that raises any issues. Starting from the exhaust flange, there is a 1.25in bronze nipple, then a 1.25in to 1.5in bronze adapter, then a 1.5in bronze nipple, then a bronze elbow pointing upwards, then a Yanmar mixing elbow where the water enters, then an 8in long 2in diameter hose directly downwards to an LSS50 Vetus waterlock muffler, then a 2in hose to a Vetus 2in to 1.5in adapter, then 12ft of 1.5in hose that crosses into the lazarette and initially rises about 4ft then gradually descends down to an elbow connected to the thru-hull on the transom. All the components in the exhaust are new except the thru-hull and elbow. I verified that there is no blockage there.

I tried removing the rise in my exhaust hose to see if it would lower the backpressure. The pressure wasn't noticeably different (perhaps a bit lower, though again really hard to get a single number out of it), and it was still running at 155F in neutral.

@Dave: Yes, the oil pressure starts out at 60PSI from a cold start. This was set so that the warmed up oil pressure would be 40PSI. It does hold at 40PSI after warmup if I stay in neutral. I didn't know that the higher oil pressure would produce a lot more heat, that is interesting. The mechanic didn't seem to think 60PSI starting pressure was an issue. Also, I'm not sure how high initial oil pressure could account for how his tests ran at much lower temperatures. I haven't made any adjustments or modifications to the engine since his tests.
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Old 10-12-2017, 06:17 PM
Dave Neptune Dave Neptune is offline
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I don't know what you think but an engine rebuild absolutely should include block, head and manifold cleaning (boiling out).

If you have been running for a while at those temps the block could be salted up good.

Perhaps check the Tee fitting on the side of the cover and confirm it is clear and clear into the block.

Can you guess how much water is coming out of the exhaust? Can run at idle and stick a bucket under the exhaust to see how much water is being pumped. I don't remember how much is supposed to be pumped but someone whose memory is better will probably chime in with the info.

Try completely blocking the bypass too, may glean some info there too.

With the Indigo set up which has it's own pressure regulator be sure the opening where the stock one was is clear. May have something stuck in there causing a good deal of work (heat) for the oil pump.

With good water flow and a clean block your trouble should be getting heat not to much of it. The salts will begin to deposit around 160* or so. The running core temp of the engine is at 210* according to your 5 minute finding~good info.

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Old 10-12-2017, 06:47 PM
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Taking a look at this, something is very far wrong with the prop and engine RPM.
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Old 10-12-2017, 08:51 PM
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Yanmar mixing elbow? This bring's Dave's water volume inquiry to the forefront. They are known to have problems as they age., for example . . .
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Old 10-12-2017, 09:48 PM
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Bad Oil Pump

While 60 psi at a cold start up is higher than we would like to see, my experience with the Indigo filters tells me that it can be significantly higher on A4s with great oil pumps. The filter regulating valve is not capable of dumping very much oil so high cold pressures are not unusual. That suggests that this engine has a bad oil pump as it "only" develops the 60psi reported despite the Indigo regulating valve being set to the very high side. Mark is absolutely correct in saying you cannot simply swap out an oil pump. The only thing you could swap out would be the two gear elements and they are not necessarily the "smoking gun" with gear pumps. Gear pumps are very sensitive to the amount of "end clearance" between the ends of the gears and the casing/cover. Just a few thousands can be the difference between a good pump and a bad pump. Typically, the casing and cover do most of the wearing and then there is the whole question of the thickness of the cover gasket. I think at this stage of the game, sending the pump to Moyer Marine for testing and overhaul would be a smart bet.

I am not convinced that the engine is running hot. When it was stated that the mechanic never saw it get over 140F, how was he obtaining that reading? Did he have the cockpit gauge from the boat, did he have some other perhaps non compatible gauge, or did he shoot various spots with an IR gun? I would definitely recommend that you shoot the fitting at the end of the manifold where the cooling water is exiting with an IR gun. Since you have no thermostat and no bypass, that reading will tell you what the engine coolant temperature is.

My two cents.

Tom Stevens
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Old 10-12-2017, 09:56 PM
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@Dave: I just removed the bypass hose, stopped off both barbs and ran another test where it is physically impossible for any water to bypass the block. Same results, after 10 min in neutral and 14 minutes in gear at 2000RPM, water temperature had risen to 175F and oil pressure had fallen to 20PSI.

The flow out the back appeared to be the same as before, which I previously estimated at 6 gallons per minute since the intake pulled almost half a five gallon bucket in 20 seconds. It definitely looks like a lot of water is coming out the back and is comparable to videos I've seen online of other Atomic 4s.

If I understand correctly, since ~6 gallons per minute is the expected flow rate, this should rule out blockages in the water path correct?

@joe_db: I don't see what is very far wrong there; it recommends a 15x10in 2 blade propeller for the reduction drive and says "Propellers listed are suggested for average boats and not necessarily recommended for all hulls. If in doubt, write factory for specific recommendations." I have the original manual that came with my boat and it calls for a 16x11in propeller. The 17x12in propeller I have is just a bit larger than that. As for RPMs, I would interpret that as indicating that 3500RPM is the maximum "safe" RPM, but it seems feasible that it's possible to go above the safe limit for a couple seconds. You would think though that I would max out at a lower RPM since my propeller is slightly oversized, but perhaps that paradox could be due to the fact that all my tests are at the dock and the boat is never in motion.

@ndutton: The mixing elbow (as well as the entire exhaust system) is new (~5 hours of use during my testing), so although I'm concerned about the exhaust, it's hopefully not age related
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Old 10-13-2017, 09:26 AM
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If you can exceed redline with that big prop, you have to be getting around 35-40 HP or so. Did your mechanic mill the head and give you 150 PSI compression or something????
* either that or your transmission slips
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Old 10-13-2017, 10:15 AM
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Quote:
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@ndutton: The mixing elbow (as well as the entire exhaust system) is new (~5 hours of use during my testing), so although I'm concerned about the exhaust, it's hopefully not age related
New or not, at 170° ~ 180° operating temp for a raw water cooled engine the water passage inside of the mixing elbow can [salt] crystal up like a geode. I'm not saying I have some mystical power to know for certain this is your case, just mentioning the possibility.

I continue to struggle with the max RPM vs. propeller size data. Regarding the "minor" difference between the recommended 15x10 and your 17x12, my experience is that the difference is HUGE and is likely reducing the max RPM by somewhere between 700 and 1000 RPM (pitch alone accounts for a roughly 400 RPM reduction) which makes the 4000 RPM in gear data problematic. If all the reported data is accurate, you have a very special engine and I'd like to chat with your rebuilder over a steak and lobster dinner at my expense.
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Old 10-13-2017, 10:17 AM
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I continue to struggle with the max RPM vs. propeller size data. Regarding the "minor" difference between the recommended 15x10 and your 17x12, my experience is that the difference is HUGE...
+1.

Bill
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