I can't seem to find any information about how the HO Cummins produces more torque and HP than the standard 6.7L. All I can find is the compression of the HO is lower (16:1 vs 19:1) which sounds counterintuitive to producing more power. It appears to have the same turbo, fuel system, bore, stroke, etc. Can anyone shed any light on this for me?
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HO Differences
- Thread starter wiseguy
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D
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Boost + Fuel
Lower compression through (speculative) different head. more boost, more fuel, PCM tune.
ETA: Different pistons, more boost and fuel through tuning.
(HO is 16.2:1 for the record)
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MikeXM
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Of course this is just more than add fuel to the mix. There are a lot of parameters involved, both software and mechanical.
I was being sarcastic and oversimplified it to vent cuz the HO is a fuel guzzler IMHO.
D
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I would agree. For the difference in power versus the SO, I think they missed the target on the HO. My 6.4 gasser got 7.5-8.5 mpg pulling my toy hauler, even fully loaded. This truck does it in a more relaxed fashion, and even with the trailer dry and empty barely touches 10 mpg.
MikeXM
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Average 13. Best tank 15. Worse tank 10.
You have the SO?
MikeXM
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If Ford can have higher HP, Torque and yet better MPG I don't see why I can't have my cake and eat it too.
There was a time where the SO was the king of MPG. Let's be honest, the HO is a let down on this aspect.
Still love the truck.
D
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It ALWAYS makes sense to be concerned with overall efficiency. If fleets running Class 8 trucks are very concerned about it why shouldn't I???
The Cummins has never been the fastest, but always had a torque advantage, and at lower RPM, and got better mpg, especially when working. Now, none of those advantages exist.
I am a Cummins guy all the way, but Cummins and Ram had better wake up. Loyalty to the "Big C" will only go so far.
AKDoug
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When my truck (3500 CC HO LB SRW) started out I averaged 16mpg on a 2500 highway mile run with little idling. The trip back with an empty gooseneck I ran about 12mpg.
I had the VB6 recall done shortly after I got back from that trip. Unlike many others, I didn't see a drastic drop in MPG. Over time (the next 20K miles) I have slowly crawled up to being able to run an honest 19mpg on long runs at 70mph. Just dropping to the speed limit of 65mph will bring me to 20mpg. I bet that dropping to 60mpg would gain me even more, but who wants to do that? Towing wise, the only fair loads I can compare are when running my empty 6500# gooseneck. When I first started pulling it I was running at 12mpg. Yesterday I went 200 miles one way empty and got 14mpg and I ran at 70mph a bunch of those miles.
I also have a two ISX's. A very early 600hp signature series, a 2005 EGR motor at 565hp, and a new 500hp X-15 on the way. It'll be interesting to see the mileage. However, it really wont' be a fair comparison because the engines will be in three different body style tractors. I make my money of a short haul contract that has fuel surcharges and standby time figured in, so fuel isn't as big of an issue for me as it would be if I was an OTR type operation.
I had the VB6 recall done shortly after I got back from that trip. Unlike many others, I didn't see a drastic drop in MPG. Over time (the next 20K miles) I have slowly crawled up to being able to run an honest 19mpg on long runs at 70mph. Just dropping to the speed limit of 65mph will bring me to 20mpg. I bet that dropping to 60mpg would gain me even more, but who wants to do that? Towing wise, the only fair loads I can compare are when running my empty 6500# gooseneck. When I first started pulling it I was running at 12mpg. Yesterday I went 200 miles one way empty and got 14mpg and I ran at 70mph a bunch of those miles.
I also have a two ISX's. A very early 600hp signature series, a 2005 EGR motor at 565hp, and a new 500hp X-15 on the way. It'll be interesting to see the mileage. However, it really wont' be a fair comparison because the engines will be in three different body style tractors. I make my money of a short haul contract that has fuel surcharges and standby time figured in, so fuel isn't as big of an issue for me as it would be if I was an OTR type operation.
I'm getting 23 mpg HWY running empty, and I'm not deleted but I also didn't do the VB6 recall and don't want to.
I recently returned from aproximately 2400 miles long trip through the Rockies, pulling 5,000# camping trailer. I averaged 12.7mpg for a whole trip.
I disagree with your assertion that HO is a fuel guzzler, it's getting better mileage running empty than my 5.7L Tundra that I sold to get RAM, and when pulling this same trailer, it's a much much better MPG than the Tundra.
I recently returned from aproximately 2400 miles long trip through the Rockies, pulling 5,000# camping trailer. I averaged 12.7mpg for a whole trip.
I disagree with your assertion that HO is a fuel guzzler, it's getting better mileage running empty than my 5.7L Tundra that I sold to get RAM, and when pulling this same trailer, it's a much much better MPG than the Tundra.