LSI Posted June 26, 2014 Share Posted June 26, 2014 What is the sweet spot on the MP8 505 hp 2014? Is the 445hp the same? Quote Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/ Share on other sites More sharing options...
wheeler73 Posted June 26, 2014 Share Posted June 26, 2014 Depends on which model it is. There is an indicator in the dash display that are 2 $$ signs that indicate when you are running in the sweet spot. Quote Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-250566 Share on other sites More sharing options...
j_martell Posted June 26, 2014 Share Posted June 26, 2014 Mp7 405 m is 1200-1700 rpm @ 75% throttle or less...... Find the power graph and keep it in the peak torque revs..... Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-250628 Share on other sites More sharing options...
bbigrig Posted June 28, 2014 Share Posted June 28, 2014 All the MP8's are pretty much the same. The torque curve starts around 1100rpm and drops off just under 1500 rpm if i remember correctly. somewhere around 1400 is the sweet spot. Anymore then 1450 is wasted fuel. These MP's pull like hell right down to 1000rpm. I tell the guys not to bog them down that low but they handle it well.(All of the newer MP literature I have are missing the graph's for some weird reason???) 445 and 505 act very similar in torque etc. except for needing to feed more horses. Keep in mind you get into a whole different animal with the 505E+ (Econ-boost)There is a big difference in performance that I and my dealer have noticed with regards to weather or not your MP8 is an Econodyne, Maxicruise or Maxidyne.We have found and our dealer agrees that the Maxicruise is getting the best all around performance results for grunt and fuel economy. The best performer we have is the MP8445C (Maxicruise) Our 505E (Econodyne) should be the fuel miser that it isnt and in performing has fell flat on its face.That is the engine we reflashed to a 445C. It has gained in fuel mileage (almost 1/2 an MPG) and pull on long grades as reported by the dedicated driver.The stock trucks the dealer is ordering in are predominately Maxicruise.(C Engines) Our 445C with 13 Fuller and Eaton 355's on 22.5 rubber runs 1400rpm at 105km/hr Quote Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-250844 Share on other sites More sharing options...
j_martell Posted June 28, 2014 Share Posted June 28, 2014 II though I had a brochure on my tablet with the engine specifics for the MP7, but now.I can't find it. Tried Google and got a bunch of things, but not what I was looking for...I don't know how reliable this info is, but seems about right.......Says 1400rpm cruise for MP7 405-M, which is 90km/h in 8th gear (Eaton 8LL Over)......that would be why I get better milage hauling gravel out of Paris (max speed 80km/h + 10) than hauling a light load of trash out of Richmond Hill (max 100km/h on the 401, and electronically limited @ 105km/h) Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-250850 Share on other sites More sharing options...
LSI Posted June 28, 2014 Author Share Posted June 28, 2014 All the MP8's are pretty much the same. The torque curve starts around 1100rpm and drops off just under 1500 rpm if i remember correctly. somewhere around 1400 is the sweet spot. Anymore then 1450 is wasted fuel. These MP's pull like hell right down to 1000rpm. I tell the guys not to bog them down that low but they handle it well.(All of the newer MP literature I have are missing the graph's for some weird reason???) 445 and 505 act very similar in torque etc. except for needing to feed more horses. Keep in mind you get into a whole different animal with the 505E+ (Econ-boost)There is a big difference in performance that I and my dealer have noticed with regards to weather or not your MP8 is an Econodyne, Maxicruise or Maxidyne.We have found and our dealer agrees that the Maxicruise is getting the best all around performance results for grunt and fuel economy. The best performer we have is the MP8445C (Maxicruise) Our 505E (Econodyne) should be the fuel miser that it isnt and in performing has fell flat on its face.That is the engine we reflashed to a 445C. It has gained in fuel mileage (almost 1/2 an MPG) and pull on long grades as reported by the dedicated driver.The stock trucks the dealer is ordering in are predominately Maxicruise.(C Engines) Our 445C with 13 Fuller and Eaton 355's on 22.5 rubber runs 1400rpm at 100km/hrFor a 8mpg road truck I should go with 445C MP8 M-Drive direct,2:54 rears or maybe 2:66.I run 62 to 65 mph Quote Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-250876 Share on other sites More sharing options...
rsb502 Posted June 30, 2014 Share Posted June 30, 2014 Im not hearing good things about the higher gears and m drives here, a couple folks have already gone back to maula trans, one went to eaton autoshift. apparently if there is any internal issue at all you have to swap the whole m drive, there is almost no repairability at all. sounds like your going to gear it a little high to me, I would shoot for around 1400-1450 at my cruise speed, 2.66 puts you around 1300, better go up a step to get it where your not lugging it all the time. an Od trans (.74), low pro 22's and 3.36 put you at 1350 @ 65, 3.55 puts it just over 1400 @ 65. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-251109 Share on other sites More sharing options...
upsman Posted June 30, 2014 Share Posted June 30, 2014 A direct drive top gear would be more fuel efficient and use less power. Quote Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-251127 Share on other sites More sharing options...
bbigrig Posted July 2, 2014 Share Posted July 2, 2014 For a 8mpg road truck I should go with 445C MP8 M-Drive direct,2:54 rears or maybe 2:66.I run 62 to 65 mphI would avoid the really fast gears for an M-Drive. I would spec an overdrive Trans and a 3.36. I have no interest in anything faster then that as it just puts more torque load on the drive shaft and trans components. These M-drives are single countershaft and the last time I checked we spec slower rear ends to make easier work for our engines and transmissions among other reasons. I fear huge vibration and premature drivetrain wear with all of these super fast rear ends for fuel economy on flat land.Sure the truck will save fuel with the faster rears on a flat but for every incline it will have to work harder to crest the hill.With the spec you are thinking about you would need a direct drive with those rears. You would be cruising at around 1300-1350 with those numbers for 62mph. (approx)The 445C and Fuller 13 with 355's 22.5 rubber is getting over 8mpg for 62mph. I double checked and its running 1400rpm at 105km/h I think its the best of both worlds. Quote Link to comment https://www.bigmacktrucks.com/topic/36151-sweet-spot/#findComment-251335 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.