6lya-ute

28bhm

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Max. RPM is 3300 my props pitched to give me just that. So should I be running 80 percent of 3300 or 3-400 lower then wot (3300)? I've been running it at 2800-2900 and she purrs but if I run it at 2650 which is 80 per. it sounds like it wants a lil more!
Any responses would be appreciated.
 

captainlarry84

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Load

80% load is not 80% of max RPMs. The only way to see if you are running at 80% load is with a pyrometer. The 6LY puts outs 1280 degrees on the pyrometer @ 3300 RPMs.
Yanmar recommends a max continuous pyrometer temperature of 1080 degrees, which 84 % of 1280 degrees. Your Yanmar will put out exactly 1080 degrees of pyrometer temperature @ 3100 RPMs if you are wheeled correctly.
If you are running between 2800-2900 RPMs your load is most likely 70% which is well under the max they recommend.
The pyrometer is an excellent investment for motor longevity.
The photo shows the pyrometer wire which is directly through the turbo blanket. Easy install.

Picture 031.jpg

pyro.jpg

Picture 024.jpg
 

osprey47

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Who makes your pyrometer? Can't make out the logo on the dial face?
 

captainlarry84

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Isspro makes the finest units. Easy install cost about $300.00. The gauge measures the exhaust heat. It you are putting out too much heat you are over wheeled or overloaded. If you are not putting out enough heat you are lacking performance.
The gauge can pick things such as a bad injector which could be over fueling a cylinder which can go undetected by the operator.
I have used pyrometers on all of my boats and recommend them on all repowers for all mechanical diesels.

http://www.isspro.com/page.php?page=Performance_Diesel_By_Product_Series

http://www.isspro.com/index.php

pryo 2.jpg
 

Beamie

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Another accurate measure of load is charge air pressure "boost air". See what the manual says for max air boost or see that it is at wot and take a percentage of that.
 

djmarchand

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Don't forget that this is a 6LY-UTE which is a 315 hp engine, not the 370 hp of the 6LY-STP. I run my 370 hp Yanmar which is propped to reach 3.400 rpm at 2,800.

I think the OPs engine propped to reach 3,300 would be fine at 2,800. It probably will be producing about 200 hp at that rpm.

David
 

captainlarry84

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Agreed another qood guage to have. The better Yanmar panels "C"come with the boost guage. Most builders and owners get the "B" panel without this added feature. The B Panel is much smaller. The photo shows the expanded C panel. This C Panel also has a Transmission Presure guage.
21.4 knots boost @ 1.75 15.5 GPH @ 3300 RPMs...Perfect!

Last photo show and empty boat fresh splash the Yanmar overturns the 23 X 21 wheel by 200 RPMs. Buy mid season The WOT of 3500 RPMs will be down to 3300 RPMs. Turbo boost is maxed out at 2. Pyro (not shown @1280 degrees) Flo scan @ 18 GPH @ 23 knots.

boost.jpg

kristen 042.jpg

kristen 045.jpg
 
Last edited:

greg

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One thing to keep in mind is that the yanmar tach's are notoriously bad at accuracy.

You really want to photo tach the engine to determine true rpm's.

Mine for example reads 150 rpm's hi. If I measured my wot performance, I'd be way off if I relied on the tach alone.
 

capt38

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Capt Larry, thanks for the explanation of how 80% load is calculated. I was always under the (wrong) impression it was 80% of RPM. Also good info on the boost gauge. You can learn so much from the experienced people on this site.
 

captainlarry84

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One thing to keep in mind is that the yanmar tach's are notoriously bad at accuracy.

You really want to photo tach the engine to determine true rpm's.

Mine for example reads 150 rpm's hi. If I measured my wot performance, I'd be way off if I relied on the tach alone.

All boat tachs should be compared with a photo tach. Agreed on Yanmar Tachs they are notorious for reading high. In fact at the start of every year you should always photo tach your motor.
 

captainlarry84

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Max. RPM is 3300 my props pitched to give me just that. So should I be running 80 percent of 3300 or 3-400 lower then wot (3300)? I've been running it at 2800-2900 and she purrs but if I run it at 2650 which is 80 per. it sounds like it wants a lil more!
Any responses would be appreciated.

Just for my little data base of knowledge. What size propeller & reduction gear. At 3000 RPMs what is you speed?
 

28bhm

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Just for my little data base of knowledge. What size propeller & reduction gear. At 3000 RPMs what is you speed?

I'l have to get back to you on the gear and the speed at 3000 but the prop is 22/20p. At 2800 I get a strong 18.5 knot cruise. My mechanic uses a digital photo tach at 3000 under a load to adjust my tach. Soooo I'm having a stainless exhaust elbow made and I'll have him put a port in for a pyrometer.
Thanks for the replies
 

jerseysportfisher

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Isspro makes the finest units. Easy install cost about $300.00. The gauge measures the exhaust heat. It you are putting out too much heat you are over wheeled or overloaded. If you are not putting out enough heat you are lacking performance.
The gauge can pick things such as a bad injector which could be over fueling a cylinder which can go undetected by the operator.
I have used pyrometers on all of my boats and recommend them on all repowers for all mechanical diesels.

http://www.isspro.com/page.php?page=Performance_Diesel_By_Product_Series

http://www.isspro.com/index.php


ISSPRO makes a nice 2 in 1 boost egr gauge
 
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