Perkins 6.354 Diesel Engine Fuel Economy

[konazihua]

I AM CONSIDERING THE PURCHARE OF A 34'LRC CALIFORNIAN WITH TWO
PERKINS 6.354 185 HP DIESEL ENGINES. THE OWNER STATES HE CRUISES
AT 12 KNOTS RUNNING AT 2200 RPM. ANY IDEA HOW MANY GALLONS PER
HOUR WILL BE BURNED AT THIS SPEED?

[NotQuiteLost]

I've got a Perkins T6.354M on my sailboat, and when I reverse-calculated my fuel consumption over the course of about three and a half day's operation, it came out to just a shade over 2gph. I only ran 1800-2000RPM, but whatever it's worth, that's about what I burned.

[Stillraining]

Wow!...Thats a good fuel burn rate..I want to know your secret!

Im not sure that's possible though...not disbelieving you but my experience with several 150+ horse diesels puts it at 2 to 2.5 times that amount.

My 4-154's ( 62 hp ) will burn 1.5 gph at 1800

FWIW my 6-354 in my Massey Ferguson tractor used 4+ per hour @ 2000 rpm as well.

[Sailmonkey]

The only real way to determine how much fuel burn is to measure what percent of throttle is needed to achieve 2000 rpm. Then you can calculate the fuel volume burned based on injector pump volume at %of full rack. It can vary widely since 2000 rpm at no load takes less fuel than 2000 rpm at full load.

[Marinheiro]

In my power boat days I ran a 32' Vindex (NZ) with a 185hp HT6-354.4M Perkins (bit of a mouthful), clean bottom and all running well cruised at 15 kts 2200rpm burning 30 lph - which equates to producing around 150hp.
That Californian will be alot heavier with the 2 Perkins and all the other paraphenalia so if correctly propped each engine is probably burning around this amount. 12kts is a very inefficient speed for a power boat of this size.

[Stillraining]

Originally Posted by Sailmonkey

The only real way to determine how much fuel burn is to measure what percent of throttle is needed to achieve 2000 rpm. Then you can calculate the fuel volume burned based on injector pump volume at %of full rack. It can vary widely since 2000 rpm at no load takes less fuel than 2000 rpm at full load.

Or install one of these...

[NotQuiteLost]

Originally Posted by Stillraining

Wow!...Thats a good fuel burn rate..I want to know your secret!

Im not sure that's possible though...not disbelieving you but my experience with several 150+ horse diesels puts it at 2 to 2.5 times that amount.

My 4-154's ( 62 hp ) will burn 1.5 gph at 1800

FWIW my 6-354 in my Massey Ferguson tractor used 4+ per hour @ 2000 rpm as well.

Yeah, I've found the same thing browsing other forums when trying to figure out what it *should* burn. I mean I could be off by half a gallon, but that's it. I have 500 gallons of fuel, and during my Pacific crossing I ran it to the bones going non-stop from Seattle to Cebu. I know exactly how much my generator consumes via tests confirming the specs, so unless I've got an extra couple hundred gallons of diesel somewhere of which I'm unaware...

So not that I blame you for not believing me, frankly I wouldn't believe me, either. But I've checked and re-checked my numbers plenty of times...I had to be pretty much exactly right for my final approach here, as I only figured to have maybe 20 gallons left by the time I dropped the anchor. I ended up pretty much exactly where I thought, using my numbers to project forward.

Could be my tachometer wasn't working properly, but I was getting hullspeed of 7-7.5 out of it...I'd have to think that to drive a 45ton boat like this that fast, it would have had to be 1800+, but I'm certainly no diesel expert.

[Sailmonkey]

Originally Posted by Stillraining

Or install one of these...

Cheater

[Stillraining]

Originally Posted by NotQuiteLost

Yeah, I've found the same thing browsing other forums when trying to figure out what it *should* burn. I mean I could be off by half a gallon, but that's it. I have 500 gallons of fuel, and during my Pacific crossing I ran it to the bones going non-stop from Seattle to Cebu. I know exactly how much my generator consumes via tests confirming the specs, so unless I've got an extra couple hundred gallons of diesel somewhere of which I'm unaware...

So not that I blame you for not believing me, frankly I wouldn't believe me, either. But I've checked and re-checked my numbers plenty of times...I had to be pretty much exactly right for my final approach here, as I only figured to have maybe 20 gallons left by the time I dropped the anchor. I ended up pretty much exactly where I thought, using my numbers to project forward.

Could be my tachometer wasn't working properly, but I was getting hullspeed of 7-7.5 out of it...I'd have to think that to drive a 45ton boat like this that fast, it would have had to be 1800+, but I'm certainly no diesel expert.

You have a excellent engine set up then...don't let any Laural and Hardy boys work on it, or kiss that fuel consumption good by...

Its also amazing that its pumping out 185 horse doing that...mine is only rated at 104

I think this would be about the only benefit of a day tank is being able to totally verify any engines fuel performance...I know we changed buttons in my IP to get better fuel economy in one of my Dump trucks but we sure didn't double it...maybe 20% improvement with a noticeable 20% loss of power...I lost one gear climbing hills for the sake of fuel economy.

[NotQuiteLost]

I think one thing to definitely take away from this thread is that my experience is not to be counted in the general fuel economy question. Either I'm really, really wrong (and had an extra ~150-200 gallons of diesel onboard!) or I've got a magnificently tuned and well-performing setup.

So, disregard my entries here when trying to answer the question

[Stillraining]

I never said i didn't believe you...just that it didn't seem possible...Iv been proved wrong on many things in my life.

I know for a fact you know how much fuel you hold...your the one paying the bill..

Carry on

[goin2slow]

A friend of mine had a non turbo 354 in a 38x11 great lakes cruising boat and we calculated his fuel usage different times at 1.75 gph at around 8 knots

[defever]

my 20 ton trawler has this perkins and at 1850 rpm/7.5 kts i burn 2 gph.. w/ 450 gal. on board i have a pretty huge range...yipeee

[newlazydays]

I have a 6.354 naturally aspirated Perkins in my ketch which is now 30 years old. As far as I know it has never had a major overhaul. When I bought the boat 8 years ago the hour clock was broken and I put a new one in. I have since done 3500 hours (I charter the boat) and it is still running strong. At about 1800 rpm I estimate that it burns a little under 2 gallons an hour and pushes the boat along at something just under 7 knots. I change the oil every 200 hours (Rotella 40) and generally don't push the engine too hard. The only major work I have had done is a rebuild on the starter motor and a replacement for the wet exhaust elbow.

[Stillraining]

Well according to you all ...my 4-154...should be burning .75 ghp or less....I'm going to install a flow scan to see for sure....I'll be tickled pink if this is the case...

The tiny Yanmar in my Mini Excavator uses more fuel then that...and the specks on my little 1800 rpm 3 cylinder Cummings powered 8kw gen-set says fuel burn at 50% load is double that amount...but you cant all be wrong so somethings up.

Maybe its a boat installation that is the key to the miserly fuel economy...but I doubt it....every single gas engine boat installation I know of uses 3 times the fuel as the same auto installation.