Mastercraft Posted August 26, 2018 Report Share Posted August 26, 2018 The sticker on the door frame says my engine doesn' t make rated HP until 2000 rpm.....does anyone really run that high? I don't think I've had it over 1650. 2009 Volvo 780 D16 535hp 1850 ft-lbs I shift 3.36 Thermo King Tripac APU DIY Bed and Frame Extension ET Hitch, Stellar EC2000, EcoGen 6K 2002 F350 CC Dually w/ Lance 1181 2012 Mini Cooper S 2007 Teton Royal Freedom " The only place you will find success before work is the dictionary " Link to comment Share on other sites More sharing options...
Av8r3400 Posted August 26, 2018 Report Share Posted August 26, 2018 HP means almost nothing. Torque is the number and that will peak at 1200-1400 in most HDT engines, and where you operate most of the time. Av8r3400 Thunderstruck - 2012 Volvo VNL 730 D13 iShift Slick - 2021 Grand Design Momentum 397TH I'd rather die trying to live - Than live trying not to die. -Leonard Perry Link to comment Share on other sites More sharing options...
Exile Posted August 26, 2018 Report Share Posted August 26, 2018 Only need to rev that high if youre loaded and trying to build up speed for a hill. not much need pulling an rv. 98 379 with 12.7 DD LG Dodge w/5.9 CTD Chrome habit I’m trying to kick. Link to comment Share on other sites More sharing options...
noteven Posted August 26, 2018 Report Share Posted August 26, 2018 Published “Rated HP” is commercial “industry standard “ agreed to be reported at governed rpm on stickers and spec sheets. Modern engines develop their max power at 1400-1600 rpm and their max torque at 900-1200 rpm. Cruising in between the two peak numbers with the lowest manifold pressure possible for the speed you want is where best fuel economy is found. Truck engines are governed at rpm higher than their peak power - to increase driving flexibility under certain conditions such as making up shifts in soft conditions or up hill. - to allow more engine retarder brake power to be available. Retarder brake “holding power” is a function of rpm - much more is available at 2000 than 1200. "Are we there yet?" asked no motorcycle rider, ever. Link to comment Share on other sites More sharing options...
Stepchild Posted August 26, 2018 Report Share Posted August 26, 2018 Torque and HP are affected/related by RPM. For a flat torque (TQ) range the HP has to increase to make the same TQ at higher RPM. To make the truck go you need axle TQ to make force where the rubber meets the road. Transmissions can multiply TQ a great deal so not a factor at low speed. Once up to speed you must overcome drag and/or gravity (uphill). Once the TQ (think of it as force) and axle RPM (axle HP) exceeds the engine output you will slow. HP should remain the same from engine output to rear axle except for some loss. Probably preaching to the choir. Good discussion on Wikipedia on Stroke Ratio for various engines, motorcycle to large marine diesel. Diesels are under square. Link to comment Share on other sites More sharing options...
rickeieio Posted August 26, 2018 Report Share Posted August 26, 2018 HP = Torque, expressed in pounds-feet, X RPM / 5252. Peak numbers aren't nearly important as the area under the curve. HP sells, torque gets the job done. KW T-680, POPEMOBILE Newmar X-Aire, VATICAN Lots of old motorcycles, Moto Guzzi Griso and Spyder F3 currently in the front row Young enough to play in the dirt as a retired farmer. contact me at rickeieio@yahoo.com Link to comment Share on other sites More sharing options...
noteven Posted August 26, 2018 Report Share Posted August 26, 2018 Before we head off on the hp vs torque tangent .... I forgot to answer the OP question. No you don’t need to run a 16 litre HD truck engine to 2000rpm to “make” enough propulsion to tow a rv. Select D for go and enjoy the scenery. Im not checked out left seat in iDrive for how you acess full retarder power when you want. "Are we there yet?" asked no motorcycle rider, ever. Link to comment Share on other sites More sharing options...
sclord2002 Posted August 26, 2018 Report Share Posted August 26, 2018 High idle is 1650 rpm on my 2006 Volvo D12D. I'm not sure if it is rpm limited when in neutral below what it will rev in gear, or not. I do know I have never seen 2000 rpm under any circumstance. Charlie Don't ever tell a soldier that he doesn't understand the cost of war. Link to comment Share on other sites More sharing options...
jcussen Posted August 26, 2018 Report Share Posted August 26, 2018 My series 60 made rated hp at 2100 rpm. Foretravel 40ft tag 500hp Cummins ISM 1455 watts on the roof, 600 a/h's lithium in the basement. Link to comment Share on other sites More sharing options...
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