QSM11s installing EGT

Steve, thanks for chiming in. My manifolds where sent out (by me) to be milled and where perfect prior to the new (and improved) gasket installs. I am inclined to agree with you on the mechanic re-using some old parts i.e.:bolts etc. I felt like the "Cummins mechanic" was trying to get as much out of me(or the P.O. ) as possible but that's another story. As stated a lot of my cruising is done at 800-1000 rpm's and I was under the impression to not "push" them as to not blow the gaskets but now I'm not sure what rpm is better for the motors? I will agree that in 2 seasons of approximately 300 hours they have run flawless. The maint after 1000 hours is minimal, I swapped out the air cleaners for tony's and 1 set of impellers. Annual oil samples come back excellent and both motors are like twin brothers. I wouldn't go abusing them however so I will remain in my cruise parameter and hope I'm doing the right thing.
 
Joe, if your goal is to enjoy the cruise and save a ton of fuel, then that's fine but I wouldn't be afraid to run them because of the gaskets. That's what these things were built for. 300 hours is way to soon for a gasket failure. We all have different thoughts but I tend to think it's good for the turbo to spool up and let the engines run at the 1900-2050 range? I vary my cruise speed between that range on different trips. I find that below 1900, it seems that the speed is reduced more than the fuel burn and it gets worse as the rpm's goes down until your at displacement speed of around 950 rpms....so it's not an efficient cruise speed. Naturally, if in rough seas, I have no choice but to reduce my speed to whatever is the most comfortable cruise. Are you going to live with the port engine or have it done again? I'm curious if it's the same cylinder gasket.....
I too replaced my air cleaners but went with the Walker Air-seps. Pricey but I remember getting a great deal on them at the time. The girl mis-quoted me and then realized it...and told me she would honor the price.... That was a good day!
 
IMG_581.jpgI installed a Spa dual EGT last year and very happy with it. Dual digital readout with ability to label, change colors, alarm, etc.

Motors are Cat 3208s and had temp readings in 850-880 range which is borderline high. Found had leaking exhaust elbows and worn turbos. Replaced both and brought temps down to mid 600s. CAT tech says would hav fried the motors if ran another season.

So was EGT worth it, you bet!

will post pic
 
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You have the same EGT SPA gauge I have to be I stay the 18th & 19th of July. My understanding of Tony's comments lead me to believe along with the GPH being held <20GPH and 950 degrees with the dry exhaust is about as good/safe margin. That being said is still no guarantee that you want have some Exhaust leak as others have found. It's only a matter of time before most all of us have enough of a leak that we will pull the manifolds and have them checked, milled and hopefully a better gasket set installed. The EGT is just another part of the equation to try and decrease excess heat by monitoring the system.

With regard to my my comment about more maintenance issues with the QSM11m's than my 3126 Kitty Cats relates to the QSM after-cooler manufacture's servicing. Salt water use applications if I understand correctly recommends pulling them every two years for proper servicing. With fresh water flushing you can typically extend this to 3-4 years. The boat I purchased as less than 800hrs and are 11 years old. One aftercooler replaced this winter by the PO and one passed the pressure testing after cleaning and servicing. The L&M was around 8k from memory as I don't have it in front of me plus the 4.5K for one new one. Short sighted imho not to have replaced both of them at the same time as L&M paid would have covered changing both plus an additional 4.5K.

That basically says shortly im going to spend another 9K + to change the one left while it could have been done for around 4K as I would not have sent either of them out for cleaning and testing knowing what I know.

All of my Kitty Cats exchangers were pulled (7) once in 2014 before we went in 2015 to run the AGLCA and the total bill was less than 12K including the valves being lashed. I'm lead to believe from what I've read the Cummins Aftercoolers are not as robust as the Csts. I don't have written factual comparison just personal experience with what I had and now have along with my readings which could be wrong. I've seen the cost of a friends QSM11 aftercooler and manifold issues and with some failer on the part of a mechsnic's the Cummins repair bill ran around 30K.

Its my job to study the info I can find and make the best semi-educated decisions I can to protect my investment and minimize unplanned down time.

Certainly hope I'm not affending or creating any scare tactics for anyone as that is not any intention of mine.

All we want is safe boating, great times and "Gimme Time" to enjoy ! Nn
 
I'd love to see some more talk about QSM propping. I know mine is close to stock and runs 20 GPH at 1750ish. I don't run at 2000 rpm so not sure what gph is there, but probably 25. I've spoken to Sea Ray and others and they say fine. Boatdiesel and SBM say that's killing the motor. I do have a heavy lift/dinghy that aren't helping.

So how many motors with stock config are blowing up? How many are out there with a couple thousand hours and no issues? Would be great to have real info - less stories of friends of friends.

if I decide to repitch the props, any advice (have never done this before). I've read that divers can remove and replace props (in lieu of hauling?). What should I expect for cost and complications? Looks like I'd have to request a 150-200 rpm change to even get in the ballpark of recommended propping.
 
Matt & Keli,

First off I don't have all the answer but here is some info on my boat as it stands today, (2) people, full fuel & water, 1/8 waste, no dingy but otherwise fully gear with loaded
Port GPH Starboard GPH. Km+-
1810, 20.1, 1800, 19.7. 18-19
1900, 23.0, 1900, 21.6. 20-21
2000, 24.7, 2000, 23.6. 22-24

Props has some work by previous owner to reduce fuel burn trying to get a happy medium of speed, fuel burn, excess heat on manifolds and turbos. Don't have the prop info with me but next week going to reduce pitch to cut 150 off and see where I go from there. The boat runs great imho but know the heat is excessive imho.

Im not aware of any engines bowing up. What I am aware of is the first question any boat test asked about a new boat is, how fast will she run and that's generally how they leave the show room floor.

I like what I've read by Tony Anthens about the QSM11m at 600+ HP with dry exhaust. Based on about 8 boats with these engines in the 52DB what I've seen is excessive heat issues, manifold & turbo leaking exhaust gas and black soot in the engine rooms.

i have a good friend whom has had two excessive exhaust leaks as the first repair was done poorly and was not finished only to be found out a couple weeks later. The next repair was done by a Commins Certified dealer shop and was quite expensive. The first repair was lacking good & complete workmanship so that really puts a bad taste in ones mouth and he lost a lot of valuable cruising time.

This being my first QSM boat with 660HP engines and dry exhaust I'd prefer to be proactive within reason. Lots of info out there on the engines so I've tried to soak it in and make the best decisions I can.

One of your questions was about divers and prop changing. First thing I'd suggest you pick one of those props up and I am a certified diver but have no desire to try and change one of these in the water! Can it be done, I'm sure by someone and I'd do what I'd have to do but in the water, not if I had any other choice.

Hope this helps a little and I'll post more info once my prop changes are made as we are headed out for 30 days +- on the 18th. Will be traveling with two other SR, one has QSB or C's the has Mann's so should be and interesting trip North as far as Block Island, RI is the plan!

John
 
Thanks John. I feel like our props are closely matched today. Very interested to see what your results are...
 
Quality Time, you suggest taking an 1" out and don't want to question your recommendation but do you have any reference material You can point me to so I can read up quickly as I'm having the adjustment done next Wednesday?

Greatly appreciate anything I can read that can help point me in the right direction as nothing beats good ole readable documentation imho.

John
 
First hand knowledge John. I gained 100-125 RPM at cruise while still burning the same GPH.

My props were 28x32 and are now 28x31 with a #5 cup.


Sent from my iPad using Tapatalk HD
 
Just want to add my experience so far with QSM11s and prop changes that I made. Had boat hauled last year for bottom job. Had been consulting with Tony A. and wanted to work on getting closer to his recommendation. I was burning 24.7 each side at 2000 rpms and was hitting rated rpm at WOT. Had props pulled and sent to shop to take pitch out. Although props were marked 28x32 they scanned 28x32.39 so talked with prop guy to take 1 1/2" out of prop. For some reason he did his best to talk me out of taking that much out and for some reason I listened to him. I told him what I was trying to accomplish which was get to below 20gph at 2000 rpm. He worked props and they scanned at 28x31.75. Now my fuel burn is 22gph at 2000rpm and 73% load. I wish I have pushed to take the full 1 1/2" out(weak moment on my part) but plan to have this done on my next haul out which i plan to do early 2018. I did not see any real decrease/change in performance but for some reason with the reduced pitch my perception is that the boat gets on plane quicker than before. I believe I have made improvements and will continue to tweak. BTW...bought boat in 2015 with 1725 hours and no problems with engines since. I am now at 2000 hours. My first boat with diesels. So far so good!!
 
I have an excel spread sheet I've been working with on what's been done by previous owner and my first modification. I don't have my info with me as it's on my laptop at home so I'll share more info later in the week. Off the top of my head mine are 28x30 with no cup, 18+@1800, 20+1900, 22+@2000. Doesn't sound great but much better than before.
 
I have my props pulled now. Here's a table that summarizes/averages a bunch of data points.

RPM Fuel Flow Speed % Load

1940 25.2

1800 21.0 20.5 77

1750 20.0 19.3 75

1710 19.0 18.8

1650 17.8 18.9*

Here's the info from the prop shop:

YOUR PROPS SCAN TO ISO CLASS I SPECIFICATION AT 32.1 PITCH (PORT) AND CLASS II AT 32.2 PITCH (STBR).

TO GAIN 300 RPM AT WOT WE WILL NEED TO REDUCE PITCH TO 28.4
TO GAIN 250 RPM THE PITCH DROPS TO 28.9
TO GAIN 200 RPM THE PITCH DROPS TO 29.5
TO GAIN 100 RPM THE PITCH DROPS TO 30.7


Any thoughts on how you would proceed?
 
Matt,

I think you're going to be pretty close with that. If you haven't already gone and read Tony's tips about propping the QSM11s at SBmar.com I'd suggest you do.

I didn't see any WOT numbers to see if you're getting to +2300 where the electronics will kick in to limit you to about 2340-2360?

From what I've read most of the excess heat issues which creates the problems are in the 1800-2000 RPM range which is where most people cruise.

I couldn't get out last week but plan to take some more running readings this weekend so I can make my next tuning and hopefully final prop tuning adjustments. We hit 2340 at WOT and the electronics kick in to limited from there. Obviously I don't have a problem hitting the WOT marks just trying to get the fuel burn excess heat down. Currently I'm running with 30.6 on the Port & 30.3 on the Starboard and I think I'm headed down to 28.5 to 29.0 or pretty close to that.

Please let us know when ya can.
 
Took the boat out yesterday for a shakedown run and thought of your post, so I ran through the smart craft display and found "manifold temp" is that what you are looking for? By the way your model is a DB not SB sorry it's my OCD kicking in.

my boat was propped totally wrong when we sea trailed her. She wouldn't hit WOT the props where supposed to gain better fuel economy (mid range) whatever that means?all it did was load up the engines and blew both exhaust gaskets (owner paid$10,000) for repairs. He also ran the boat harder than I do as I went for the demo ride he slammed her to full throttle as I ease into it.
all I can do is keep up on all maint as there's not much to keeping them running I'm not the guy who will mess with the stock set up to gain .8 GPH so far 2 seasons and they're just fine.
Hi Steve from Aussie I’ve just brought a 2003 48DB with QSM11s what speed do you cruise at
 

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