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-   -   Information on the new DD8 (Detroit Diesel) (https://www.forestriverforums.com/forums/f240/information-on-the-new-dd8-detroit-diesel-219473.html)

tanagnos 10-26-2020 11:38 AM

Information on the new DD8 (Detroit Diesel)
 
2 Attachment(s)
Here is some information on the DD8 that I thought would be helpful.

Attachment 241941

Attachment 241942

V6TOY4X 10-27-2020 09:28 PM

Thanks, a man can never have enough techie specs.


Nice to see another high level exec providing information direct to the inmates!


On the surface there is no replacement for displacement so when I see the DD8 at 7.7 litres vs. the ISL's 8.9 I pause for a bit but the numbers look close. I am going to look for a dyno curve for both to compare.


With the XL staying with the 450 ISL for the time being, do you think there is any chance the DD13 makes its way into the line up?


I have an uncle who has a Sport chassis with the 505/1850 DD13 to pull his toys and it PULLS so nice!


Any idea of what increase in price would be?


Answer what you can, just day dreamin'

Invisibleman 10-27-2020 09:48 PM

The Detroit generated sheet is a sales pitch, just like Cummins matching one for the L9. The spec sheet is another story. Although personally I for one don't have the knowledge to compare the two specs. I go by in the field experience. So far, I have nothing particularly negative on the Detroit DD8. It seems to me they are getting similar specs out of smaller displacement with new technology. But that is my uneducated opinion and I really would not have any preference of one over the other, at this point in my research. But I really doubt Freightliner would put an inferior product in their chassis. BC did a very interesting history on Freightliner/Detroit somewhere recently in the Dynamax forum.

bclemens 10-28-2020 01:31 AM

Main "takeaways" for RV use in discussions with the head guys at Freightliner...

Variable cam phasing keeps your aftertreatment system at the right temperatures during low-speed operation. That means fewer (or no) parked regens

Better fuel economy

quieter

Simple, fixed-geometry, turbocharger for performance, efficiency and reliability (two stage)

A variable-speed fan and advanced cooling system providing shorter fan-on times for increased fuel efficiency (There seem to be mixed responses on the ISL variable speed fan...but I know I have heard complaints about how loud the fan can be and seems to default to high. Hoping the DD8 is not the same)

DETROIT CONNECT™ VIRTUAL TECHNICIAN (3 years is included at no charge)

sconnors11 10-28-2020 11:06 AM

I probably missed something in translation. There are really very few instances where a fixed turbo would be more efficient that a properly tuned Variable Geometry Turbo (VGT). With the VGT you can set a target RPM map to keep the turbo at Best Efficiency Point (BEP) throughout the operation range.

Interesting stuff, though. I built a 5.9 Cummins, Pre DEF, that had 30-40% more usable power that the "higher power" 6.7 Cummins that came in my 2014 Ram 2500. The manufacturers play games with when the max power is allowed and max power duty cycles, especially with automatic transmissions.

bclemens 10-28-2020 11:20 AM

Quote:

Originally Posted by sconnors11 (Post 2441460)
I probably missed something in translation. There are really very few instances where a fixed turbo would be more efficient that a properly tuned Variable Geometry Turbo (VGT). With the VGT you can set a target RPM map to keep the turbo at Best Efficiency Point (BEP) throughout the operation range.

Interesting stuff, though. I built a 5.9 Cummins, Pre DEF, that had 30-40% more usable power that the "higher power" 6.7 Cummins that came in my 2014 Ram 2500. The manufacturers play games with when the max power is allowed and max power duty cycles, especially with automatic transmissions.

It is likely a stretch on the efficiency...though two stage helps, I think focusing on the reliability would be the key point. Certainly less things to go wrong...but not sure how often VGT's are failing either...certainly not for RV's

sconnors11 10-28-2020 11:34 AM

VGT's Achilles heel is buildup of carbon deposits. That said, it seems like RVs are generally loaded enough to burn the deposits off, unlike an unloaded pickup commuting short trips in the cold.

There's a reason why most diesel engine OEMs use VGTs when meeting emissions. That said, I'll look into DD's dual stage turbos. Maybe it's just marketing with similar operation.

sconnors11 10-28-2020 11:48 AM

After googling around it looks like they're referring to a compound turbo setup.

Here's a setup by MAN, not sure if that's what they're actually using.

https://www.youtube.com/watch?v=P9dOwDKH978

Very interesting. Done right, there are few drawbacks to a compound turbo approach, other than initial cost and engine compartment space. I was considering doing compound turbos to my 5.9L engine but balked at the $3000 parts cost.

Exciting stuff to see an OEM use this approach... At least for a nerdy Engineer like myself.

LSLBlues 10-29-2020 12:06 PM

Brian - I see on the Dynamax website for both Force and DX3
Detroit DD8 7.7L Turbo Diesel Engine (375 hp/1,050 lb-ft. of Torque)

Does that mean you're switching over to only the DD8 on both Force HD and DX3 or people will get an option between ISL and DD8?

tanagnos 10-29-2020 12:11 PM

yes , we will only be offering the DD8 in the Force HD and DX3.

LSLBlues 10-29-2020 02:41 PM

The website still lists
Dual-Stage C-Brake by JacobsŪ with High/Off/Low Braking Dash Switch

Is that accurate? The DD8 uses the same engine brake as Cummins? Will have High/Low?

tanagnos 10-29-2020 03:35 PM

The DD8 will have the High/Low dash switch.
The function is the same built as part of the Detroit engine so its all Detroit.

Invisibleman 11-01-2020 10:45 AM

Sconners. That Utube was very, very cool. I'm not a mechanical engineer, but even I get it with those really well done graphics. Thanks


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