- Thread starter
- #21
opps that didn't work, try this?
http://www.youtube.com/watch?v=e3QHa0Dp2FQ
http://www.youtube.com/watch?v=e3QHa0Dp2FQ
4BT vs OM617
- Thread starter xunogil
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Wow...
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- #23
x2...
I'm surprised no one has brought up the issues of highway rpms on the two motors.
The 4bt will require an over drive. 4:11 gears, and 27% over drive with 33" tires will net you maybe 60-65 mph at max comfortable RPMS. @1800
The OM617 would bogg down at the same rpm as she likes to rev @ 2800 at peak torque (my numbers could be wrong) So if you ran the OM617 and a 700r4 or nv4500 you would constantly have to drop it down to 4th gear to pull anything more than a steep grade. a stock H42 would be fine with a OM617 with stock 4:11 gears and 33" tires. A 1-2" body lift and 4" suspension lift should be plenty to clear pan with no mods to pan. This would leave you at about 2800-3000 rpms at 60-65 mph with a few rpms to spare. Since thats about as fast as you want to go in a 40 (and i daily drive my 40) you'll be happier with her highway manners being that she's not "reved out" SM465 would be sweet on an om617 since you won't need overdrive unless you're in the midwest, florida or drive way too fast to be in a 40.
i'm currently working on another diesel build. Last one I had i went with the isuzu 4bd1t to ranger OD to h42. Great MPG's but with 31" tires and 3.7 gears she didn't like 70mph much and thats a much smoother engine than the 4bt IMO.
I tow sailboats with my 40 and i'm worried that the om617 will be under powered for that compared to my current SBC. But i'm after MPGs and a sweet diesel sound.
if you do go 4bt the ford RTS 4 speed overdrive transmission is a great choice. I'd go with one with the .781? final drive compared to the .701 final drive and 35" tires to be comfortable at 65mph.
you can get an RTS tranny adapter for the LC transmission but you can't get a SBC to RTS adapter so the 4bt with ford adapter is about your only choice to use a short 10" overdrive tranny.
The nv4500 is nice as well as a 700r4 but too long for what i want on a highway driving stock wheel base 4" lift SUV.
The 4bt will require an over drive. 4:11 gears, and 27% over drive with 33" tires will net you maybe 60-65 mph at max comfortable RPMS. @1800
The OM617 would bogg down at the same rpm as she likes to rev @ 2800 at peak torque (my numbers could be wrong) So if you ran the OM617 and a 700r4 or nv4500 you would constantly have to drop it down to 4th gear to pull anything more than a steep grade. a stock H42 would be fine with a OM617 with stock 4:11 gears and 33" tires. A 1-2" body lift and 4" suspension lift should be plenty to clear pan with no mods to pan. This would leave you at about 2800-3000 rpms at 60-65 mph with a few rpms to spare. Since thats about as fast as you want to go in a 40 (and i daily drive my 40) you'll be happier with her highway manners being that she's not "reved out" SM465 would be sweet on an om617 since you won't need overdrive unless you're in the midwest, florida or drive way too fast to be in a 40.
i'm currently working on another diesel build. Last one I had i went with the isuzu 4bd1t to ranger OD to h42. Great MPG's but with 31" tires and 3.7 gears she didn't like 70mph much and thats a much smoother engine than the 4bt IMO.
I tow sailboats with my 40 and i'm worried that the om617 will be under powered for that compared to my current SBC. But i'm after MPGs and a sweet diesel sound.
if you do go 4bt the ford RTS 4 speed overdrive transmission is a great choice. I'd go with one with the .781? final drive compared to the .701 final drive and 35" tires to be comfortable at 65mph.
you can get an RTS tranny adapter for the LC transmission but you can't get a SBC to RTS adapter so the 4bt with ford adapter is about your only choice to use a short 10" overdrive tranny.
The nv4500 is nice as well as a 700r4 but too long for what i want on a highway driving stock wheel base 4" lift SUV.
I am curious how the heavyish Mercedes 300TDs can cruise at highway speeds with the OM617 so well without reaching the end of their power? I see posts about cruising at 70mph easily in them. Are they running massive overdrives? because their tires certainly aren't very tall. I think I get you are saying it is when they reach a slope they start to struggle.
Can't wait to learn about this first hand when I can get back into the project. The guy that had the motor had it on 37s and broke a rear axle with the motor, but otherwise he was really happy with it. (he went to 40s and a v8). I wouldn't compare a 617 to an SBC. It is more along the lines of a 3RZ.
Can't wait to learn about this first hand when I can get back into the project. The guy that had the motor had it on 37s and broke a rear axle with the motor, but otherwise he was really happy with it. (he went to 40s and a v8). I wouldn't compare a 617 to an SBC. It is more along the lines of a 3RZ.
the om617 doesn't need the massive overdrive, it makes peak torque/horse power at higher rpms. IIRC the max hp is around 4,000 rpms. The OM617 is a shorter stroke motor than the 4bt. Think of an OM617 as a diesel that performs like a gas engine. Only more economically.
I you wanted to run 37" tires you would want a 1:1 final drive with gear ratios somewhere in the 5-6 range. You'd really want low gears!!!!
I you wanted to run 37" tires you would want a 1:1 final drive with gear ratios somewhere in the 5-6 range. You'd really want low gears!!!!
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- #28
Thanks a lot, this is the kind of info I like, the last thing I want is to have it all together and then realize my gearing is all wrong. After all this I think I am going to go with the OM617 for what I am looking for I don't think the 4BT is what I need, if I was making a crawler or something more of an expedition type setup then maybe but right now it is seaming like a no brainer when i really consider what the 40 will be used for.
I was thinking of using an H55F, but you bring a good point about these vehicles not being meant to drive at 70+ mph, and since the OM617 does have its sweet spot at around 2500 rpm I guess the H42 would be just fine. Considering cost and all, do you think it worth trying to mate it to a H55F or (for both options, 3.73 and 4.11 gears I am not sure what the ring size is on the 40?) should the H42 do just fine with lets say 31" tires. Or would I find myself at times hoping I had that 5th gear?
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- #29
I own an 85 300cd that has the OM617 stock in it, I can drive 70+mph and its only revving at around 2100rpms I do have slightly taller tires but nothing to much bigger than stock. I guess i can drive it around to verify but I think if i were to be driving with the tack around 3k in the highest gear I would be cruising over 80mph. but I still think that at 80 im only at 2500rpms
keep in mind that the 40 is about as aerodynamic as a dumpster. You'll want to stay as close to the peak torque rpms as possible to maintain cruising speed. With my 4wheel drums properly adjusted and all new TRE's and an alignment every few months. I consider 65 to be my max comfortable speed on 32s. I've got a 2.5" front springs and 4" rear with stock shackles. Some with larger kahones than i may prefer white knuckle driving and push it to 70-75 which i'm sure would benefit from OD
As far as MPG's go don't be shocked if you only hit a max of around 20 with the om617 as it is a little under powered, the bigger the tires the more you'll push it. You could play around with gears and a 5 speed OD tranny to get the off the line numbers and top cruising rpms to jive a little more evenly but i belive it would be a bit of trial and error to find the happy medium....or some time studying a dyno graph and gear ratio calculator. However the numbers to push our dumpster like aerodynimcs won't be factored in a graphic calculation.
After having a 2f, 1f, 4bd1t and SBC the SBC is by far the most friendly in any given gear with power to spare. And i have a tired 305. I can only imagine what a fresh TPI 350 lightly moded with 300-400 hp would feel like.
I've come to the conclusion that unless you spend a lot of time off road, run WVO or just love diesel that a SBC is the way to go
A ricer that used to tune all my hondas says that with the new SBC injection systems (about 2010 & up) he could tune me to get 25-35 mpg highway on the highway, based on what he's done with full size chevys.
I however have the diesel bug...i like my cruiser to sound like an old kubota tractor.
I will be sturborn and go with another diesel swap, my nighbors will hate me when i warm her up in the mornings and my girlfriend will think it sound's like a noisy tin can that rides like a shopping cart. But i'll be grinning ear to ear every time i take her down the road...bruised kidneys and all.
As far as MPG's go don't be shocked if you only hit a max of around 20 with the om617 as it is a little under powered, the bigger the tires the more you'll push it. You could play around with gears and a 5 speed OD tranny to get the off the line numbers and top cruising rpms to jive a little more evenly but i belive it would be a bit of trial and error to find the happy medium....or some time studying a dyno graph and gear ratio calculator. However the numbers to push our dumpster like aerodynimcs won't be factored in a graphic calculation.
After having a 2f, 1f, 4bd1t and SBC the SBC is by far the most friendly in any given gear with power to spare. And i have a tired 305. I can only imagine what a fresh TPI 350 lightly moded with 300-400 hp would feel like.
I've come to the conclusion that unless you spend a lot of time off road, run WVO or just love diesel that a SBC is the way to go
A ricer that used to tune all my hondas says that with the new SBC injection systems (about 2010 & up) he could tune me to get 25-35 mpg highway on the highway, based on what he's done with full size chevys.
I however have the diesel bug...i like my cruiser to sound like an old kubota tractor.
I will be sturborn and go with another diesel swap, my nighbors will hate me when i warm her up in the mornings and my girlfriend will think it sound's like a noisy tin can that rides like a shopping cart. But i'll be grinning ear to ear every time i take her down the road...bruised kidneys and all.
the h55 is only a 16% overdrive compared to the 27% that you'll find on the 700r4, ranger OD and nv4500.
You'll probably only use it on the highway but with a 1:1 4th and low first gear it would make a great all around tranny. H55 would not have near enough OD for the 4bt. an H55 with ranger OD would give good highway rpms for the 4bt.
I'd stick with the 4:11 gears. even if you stuck with the H42.
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- #32
Hmm well I to love the sound and just merely the idea of having a diesel, one of my goals is to have nothing but diesel vehicles, I have some motorbikes, that might prove harder but I believe where there is a will there is a way but I might just keep those gasoline maybe just have them be 2 stroke. Anyways, yes I know the SBC option is out there but I just don't feel to comfortable with their reliability, I know there are good options out there but I have seen to many with only about 100K on them, needing new bearings and such.
I feel there are still diesel options that can get you the performance and MPG options you can get from a well built SBC, one might need to consider an OM606 or maybe a later VW TDI motor but I think there are options out there. i was thinking the OM617 would be the best option for a 40 but it really comes down to what the 40 will be used for.
Tranny options: I guess my initial concerns with the 700r4 is how much fab work will have to be done to get that one to work. about the nv4500, I've heard their people complain that they don't like how they shift and that the gears steps are not vary freindly?
I feel there are still diesel options that can get you the performance and MPG options you can get from a well built SBC, one might need to consider an OM606 or maybe a later VW TDI motor but I think there are options out there. i was thinking the OM617 would be the best option for a 40 but it really comes down to what the 40 will be used for.
Tranny options: I guess my initial concerns with the 700r4 is how much fab work will have to be done to get that one to work. about the nv4500, I've heard their people complain that they don't like how they shift and that the gears steps are not vary freindly?
Big fan of the om617, an excellent and overbuilt motor. Get some ideas from the guys over at superturbodiesel. A suped up injection pump (like a mÿna from Finland) and a larger turbo will give you all the power you need and more. Rebuilding mine (300cdt) into one of those beasts is yet another of my back burner projects, I'd love to stick it in a 40 that was missing its original motor someday.
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- #34
Hey now I have an 85 300cd as well and thats also my plan for it eventually, once I feel it's time to pull the motor, so far she is doing just fine.
I've been.following those guys a while now. Do you have any idea of the current cost of their high performance pump? Last I looked it was some 2000+ usd. A 175-200 HP om617 swap would be perfect for a 40.
You cannot use your IP off your motor. The IP they mod with longer plungers and different springs (I think) are the "M" pumps that came on Euro models. But I believe you can find that pump in the states on the NA 5cylinder OM617. Don't know the cost of the Myna pump mod or speak dutch but it seems like it would be a pain in the ass finding a pump and sending it to Finland. But they sure do run!
I think your intentions were high performance or non-stock performance you might consider another engine. My .02
I think your intentions were high performance or non-stock performance you might consider another engine. My .02
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- #37
I'm not looking for crazy HP out of this 40 but I do want an over all well performing rig.
but yes the OM617 are very good reliable motors but not the best for performance mods, I guess if you are looking to build a high performance mercedes diesel the OM606 would be a good motor to work with?
I did read you could take a turbo off of a cummins (hy35?) and put it on the om617, max out fuel screw on the stock OM617 pump and get 150-160 hp so long as your valves, throttle cable, and alda are all adjusted properly (as well as timing chain tension and all your timing)
I would put the 4BD1T/2T Isuzus and 3.3 Cummins on your list to consider.
I don't have a tach on my OM617 in the FJ55, but at 65MPH with a H42 and 3:73s I'm sitting at a comfortable 850* EGT and pushing 7.5psi of boost. This motor can handle a sustained 1200* with a MB specs saying 1400* max, so there is plenty left if you want to cruise at 75 with a 4 speed 
I don't do this often, these old beasts just weren't built for that kind of highway speed IMO. Here are the factory specs on the OM617a (turbo) engine:
It really doesn't matter what RPMs you are turning on a diesel, you just want to make sure your temp and EGTs are within the range of the engine/turbo ... obviously the RPMs play directly into that.
Tucker
I don't do this often, these old beasts just weren't built for that kind of highway speed IMO. Here are the factory specs on the OM617a (turbo) engine:It really doesn't matter what RPMs you are turning on a diesel, you just want to make sure your temp and EGTs are within the range of the engine/turbo ... obviously the RPMs play directly into that.
Tucker