coromandeljohn
New Member
Can anyone advise of expected consumption at normal revs? Thanks
Thanks. Its 3.9L and is supposed to cruise at 1800 -2000rpm
Google is your friend ........Can anyone advise of expected consumption at normal revs? Thanks
If I could have found it on Google, I wouldn't be asking.....Google is your friend ........
My apologies, it is a 4-270 of 4.42L swept volume, 53-62bhp, 1800-2000rpmIf its only 3.9 lit its not the 4 270 its a 4 236 the same as the on I an currently rebuilding
You've got the right engine, but it's an open sea boat, to be run above 1800rpm. Thanks for your info.Looks like it's a 4.4L inline 4cyl used in farm machinery of the day, de-tuned to develop max. torque at around 1000RPM. Depending on what boat it's in and loading it probably won't burn much more than 2-3 gallons an hour, much less if used on inland waterways.
We have the Perkins M92B, direct injection, 4.4L maximum revs 2400. Max torque at 1200rpm. Pushing a 19t boat at 6 kts in flat water @1200rpm is 3.3 l/hr. It goes up a lot if we increase revs to as much as 8l/hr at full revsWithout knowing what it's pushing 2-3 gallons is as close as you'll get.
thanksWithout knowing what it's pushing 2-3 gallons is as close as you'll get.
Thankyou. Mine's about 6tonnes, so you've given me a figure to work from.We have the Perkins M92B, direct injection, 4.4L maximum revs 2400. Max torque at 1200rpm. Pushing a 19t boat at 6 kts in flat water @1200rpm is 3.3 l/hr. It goes up a lot if we increase revs to as much as 8l/hr at full revs
Post#13 is about right. It is irrelevant what the engine is capable of producing. As post#10 suggests there are different ratings for this engine depending on the governed maximum revs. 2000 will produce the 62hp, 2400, 85hp. you will cruise at 1800, or drawing around 50hp. Rule of thumb is 1l/h per 10hp, so 5l/h or just over 1 gallon. My guess is that you will not need to go over 1500rpm for 6 knots+ with lower fuel consumption. You have far more power available than you can use so important to get the propeller right so that you load the engine properly.Thankyou. Mine's about 6tonnes, so you've given me a figure to work from.
ThanksPerkins 4236 driving a 10t displacement boats (+ a bit for stores), deep forefoot, encapsulated keel, skeg, therefore a a lot of volume underwater. I get a consistent 0.75 gallons per hour, about 1500 rpm, 6 kts. The figure is accurate from fill up volumes.
Thanks. My post #7 finally defines the engine. You can try for more than 2000rpm, but probably in vainPost#13 is about right. It is irrelevant what the engine is capable of producing. As post#10 suggests there are different ratings for this engine depending on the governed maximum revs. 2000 will produce the 62hp, 2400, 85hp. you will cruise at 1800, or drawing around 50hp. Rule of thumb is 1l/h per 10hp, so 5l/h or just over 1 gallon. My guess is that you will not need to go over 1500rpm for 6 knots+ with lower fuel consumption. You have far more power available than you can use so important to get the propeller right so that you load the engine properly.
I assume your rule of thumb is for indirect injection?Post#13 is about right. It is irrelevant what the engine is capable of producing. As post#10 suggests there are different ratings for this engine depending on the governed maximum revs. 2000 will produce the 62hp, 2400, 85hp. you will cruise at 1800, or drawing around 50hp. Rule of thumb is 1l/h per 10hp, so 5l/h or just over 1 gallon. My guess is that you will not need to go over 1500rpm for 6 knots+ with lower fuel consumption. You have far more power available than you can use so important to get the propeller right so that you load the engine properly.
No, its a rule of thumb to provide a guide and usually overestimates actual. My last 3 30hp nominal engines cruised at about 20hp and consistently burned just under 2l/h. The point that I was making was that the previous estimates of 2-3 gallons an hour were way out. Very few people actually run their engines in auxiliary yachts at constant speeds for any length of time so the constant consumption shown on the graph is not really particularly useful. An average for mixed use is more useful.I assume your rule of thumb is for indirect injection?
From the Perkins graph for my engine, 1200rpm is spot on at 3.3l/hr, about 50hp
8m waterline, and has been running for years...A 6 tonne boat only needs around 35hp to achieve hull speed so your engine is way OTT. No point in taking it over 1500rpm. Check what revs you get without load in neutral then check the reduction ratio and get a propeller which will restrict revs to about 200rpm below maximum no load rpm.