Twin engine duramax truck...

[Chevy1925]

Im with Dave and Anthony. Big reason i feel this way is due to the RPM Geiser trophy truck. it is not an apples to apples comparison but its the closest thing we have to compare.

The RPM truck is a dual engine, dual transmission truck but the difference is, it uses one engine/trans to drive the rear end and the other to drive the front end. both transmissions are TH400 with lock up that are shifted via 1 cable at the driver seat. The engines are fly by wire throttle controlled and setup similar to how monster max is. This truck has compeated for the last 4-5 years now and shifting has not been an issue. if it was, they would be seeing a higher breakage rate of driveline parts than a typical 4wd truck but they dont.

Again, they are not tied to the same t-case but the ideas behind it are extremely similar and can be used to reason why it wouldnt be an issue.

TBH, for all we know, thats what they did in monster max - 2 TCM's

 

[shakenfake]

@Chevy1925 He stated in an early video that they do have 2 TCMs. Almost positive of this.

I couldn't understand why he didn't do exactly what you are saying though, have one control the front and another control the rear. That seems more logical but then again the whole truck isn't logical lol

 

[Chevy1925]

@Chevy1925 He stated in an early video that they do have 2 TCMs. Almost positive of this.

I couldn't understand why he didn't do exactly what you are saying though, have one control the front and another control the rear. That seems more logical but then again the whole truck isn't logical lol

his earlier ones say that but that changed later on saying it needed to drive off 1 tcm but then never clarified, just said "its running" and drove it.

running 2 cases presents its own issues as far as space. drivelines need to be offset, t-cases off set, enough room for a large enough case and so on. the trophy truck is VERY tight in the chassis with all the driveline parts lol.

 

[shakenfake]

Ah you might be right. Sort of seem to remember that, will have to watch them back at some point

I think space isn't too much of an issue on that truck lol
He did have to lower the weight of it since it was so heavy though, that was kind of funny.

 

[gmduramax]

his earlier ones say that but that changed later on saying it needed to drive off 1 tcm but then never clarified, just said "its running" and drove it.

running 2 cases presents its own issues as far as space. drivelines need to be offset, t-cases off set, enough room for a large enough case and so on. the trophy truck is VERY tight in the chassis with all the driveline parts lol.

You almost wouldn’t need a drop t case just angle both motors down and run a long drive shaft, rear engine runs front axle

 

[Chevy1925]

You almost wouldn’t need a drop t case just angle both motors down and run a long drive shaft, rear engine runs front axle

dry sump the engine, custom trans pan and filter for the angle, point pinion angle up and cut/turn knuckles and that bitch would be good to go.

 

[Leadfoot]

How are the cranks tied together? Using that logic then I should not be able to put my truck into park with the engine running or I shouldn't be able to stop the truck in drive/reverse with the engine running.

You're forgetting the absolute biggest key here in an automatic transmission, the torque converter.


As for the drop box/combiner, you're mostly correct. They do actually have a video about it on his YouTube channel ages ago if you go dig for it. Being that the engines are facing opposite ways the rearward engine has to actually make a direction change to spin the output shaft of the dropbox/transfercase the proper direction.

It's the reason in one of my responses I said: "in "theory" they are crank to crank" with quotes around the theory. As I know they aren't welded together or forced to be synced 100% of the time. Also stated in a previous response I did not forget about the torque converter or the fact that automatic transmissions in general are hydraulic couplers between the engine and driveline: "What's nice is when the TCM commands Park or Neutral, the engines can be started/stopped independently without worrying about one engine trying to affect the other (beats having to start both at the same time), as the transmission becomes a disconnected hydraulic coupling." which addresses what you said about putting truck in park or shifting forward/reverse with engine running.

Not trying to be an ass, or a jerk just genuinely trying to figure out the logistics given what I know about multi-engine tractors (which don't use multiple transmissions).

Edit: Given the issues they had with 2 TCM's and going to 1 (which I'm sure was much more complicated), makes sense for the reasons I stated. If what others keep bringing up about there not being major issues with transmissions being in different gears for short periods of time, they would have stuck with the 2 TCM's.....

 

[Leadfoot]

Im with Dave and Anthony. Big reason i feel this way is due to the RPM Geiser trophy truck. it is not an apples to apples comparison but its the closest thing we have to compare.

The RPM truck is a dual engine, dual transmission truck but the difference is, it uses one engine/trans to drive the rear end and the other to drive the front end. both transmissions are TH400 with lock up that are shifted via 1 cable at the driver seat. The engines are fly by wire throttle controlled and setup similar to how monster max is. This truck has compeated for the last 4-5 years now and shifting has not been an issue. if it was, they would be seeing a higher breakage rate of driveline parts than a typical 4wd truck but they dont.

Again, they are not tied to the same t-case but the ideas behind it are extremely similar and can be used to reason why it wouldnt be an issue.

TBH, for all we know, thats what they did in monster max - 2 TCM's

Two engines and two transmission running axles independently would be similar to running different R&P ratios front and rear. There's bind but between gear slop and tire slip at the ground a certain amount of mismatch (ring and pinions that differ slightly numerically) can be overcome (some truck pullers do it but they are also not running on asphalt), and neither engine has a direct connection to the other in the scenario of the Geiser truck. Once you force both through the same t-case (or drop box in this case) without some sort of slipping coupler it becomes a MAJOR issue.

Monster Max did try 2 TCM's initially but was proven an issue when the transmissions were in different gears at the same time (truck would literally stall when converters locked). Cody said a lot of time was spent trying to make 2 work, and they had to run the truck on one engine/tranny combo OR the other at first, but the only way to run both transmissions simultaneously was with a single TCM so both transmissions were in the same gear at the same time or bad things happened. To me it makes a TON of sense (and is backed by their failed attempts and final solution), but others are saying no and I'm just trying to understand if my logic and their real world experience is flawed or if there's something I'm missing because there are SMART people in this thread who say otherwise.

One thing I did not consider is that neither transmission could be in park if trying to drive the truck (even on one engine/tranny) unless it was physically disconnected from the drop box as the park pawl would lock that input. So when they tested with just one engine/tranny, the other had to be physically disconnected from the drop box or non driving trans in Neutral.

 

[gmduramax]

Two engines and two transmission running axles independently would be similar to running different R&P ratios front and rear. There's bind but between gear slop and tire slip at the ground a certain amount of mismatch (ring and pinions that differ slightly numerically) can be overcome (some truck pullers do it but they are also not running on asphalt), and neither engine has a direct connection to the other in the scenario of the Geiser truck. Once you force both through the same t-case (or drop box in this case) without some sort of slipping coupler it becomes a MAJOR issue.

Monster Max did try 2 TCM's initially but was proven an issue when the transmissions were in different gears at the same time (truck would literally stall when converters locked). Cody said a lot of time was spent trying to make 2 work, and they had to run the truck on one engine/tranny combo OR the other at first, but the only way to run both transmissions simultaneously was with a single TCM so both transmissions were in the same gear at the same time or bad things happened. To me it makes a TON of sense (and is backed by their failed attempts and final solution), but others are saying no and I'm just trying to understand if my logic and their real world experience is flawed or if there's something I'm missing because there are SMART people in this thread who say otherwise.

One thing I did not consider is that neither transmission could be in park if trying to drive the truck (even on one engine/tranny) unless it was physically disconnected from the drop box as the park pawl would lock that input. So when they tested with just one engine/tranny, the other had to be physically disconnected from the drop box or non driving trans in Neutral.

Would it completely kill the motor or make one engine fall under the turbo and not make power? There’s too many questions we don’t have the answer to. I’ve seen sled pullers run multiple engines and they do just fine.

 

[1FastBrick]

Do any of you remember the Jeep Hurricane Prototype/ concept Circa 2005?

It had 2 Hemi Functioning engines and transmissions that were tied together Via a Custom made one off transferase. This is an illustration of it and how the steering works.

But it's not a true representation of the actual case used. I worked on this project but we weren't allowed to bring our phones in or to photograph any of it but it was a really cool project. The case was all 1 piece and the internals came from 3 different transfer cases. They actually applied for a bunch of patents. They commissioned Rod Millen Motorsports to build a RAW basic tube chassis to make everything Functional and to work out the bugs. Once it was proofed out, we transferred everything over to the carbon fiber tub.

 

[Leadfoot]

Would it completely kill the motor or make one engine fall under the turbo and not make power? There’s too many questions we don’t have the answer to. I’ve seen sled pullers run multiple engines and they do just fine.

Yes they do, but utilizing a single transmission/gearbox with multiple inputs. Most have some sort of clutch on each engine that allows each engine to couple/uncouple. Some start one engine with a traditional starter, and the others can me turned over by the power of the first engine by engaging a clutch (often operated by air). Only time it's an issue is if one engine blows during a run even killing that engine's ignition does nothing as the others keep spinning it (often with major consequences and flying parts). An operator could theoretically disengage that engine using the correct lever or air switch, but they usually have their hands and feet fully occupied in the middle of a pass.

 

[Leadfoot]

https://urldefense.com/v3/__https://fb.watch/iArFqmzaTS/__;!!P_vj-BUkwjF5!eTalFA4-RT_cc2QNV539hM_LptaUs5Wd7zRrRVLYXVRGbLJteC8y6FODBI9Mozx8MSpo3Pw7BtVj8eOTzZFuXu0OWU8vyg$

This is what I'm familiar with. Each engine clutched and instead of a transmission they use a "reverser". It doesn't have progressive gearing, it just forward, neutral, and reverse (and can handle a boatload of torque).

When the clutches are engaged each and every crank is tied to every other crank. If they grenade a motor early on and the run is good, they'll stay in the throttle and the dead engine goes along for the ride at high RPM usually tossing rods and piston parts the entire track. Usually a good light show too (especially at night) as fuel is still flowing (one of the reasons they are required to wear full SFI gear head to toe).

 

[Chevy1925]

you very much could be on to something Lead. there is clearly parts ive forgotten about that Cody stated.

it could be a fact that during a shift, one shifts faster which trys to accelerate the other trans and throws the second trans which may have just started into its initial shift proceedure, for a loop. since these things complete a shift in 7/10 of a second (or there abouts), thats a long shift to happen and could play a part?

 

[Dozerboy]

We have had always had issues with Allison and the way they "think". Most of us have had nasty shift for some reason or another. I could only imagine how bad it would freak out if the 2 where totally independent systems and they did there own thing. Maybe if it was just a show piece it would be fine, but we all know that truck is going to take a thrashing.

I like and respect Cody he has done a interview an it sheds some more light on him. He's an entertainer. No different then people in movies. I and I'm willing to bet he has more in common with us then most of the people in Hollywood. He also stands up for himself. He is going to court over some BS tickets he got from some "good old boys" in law enforcement. And a prosecutor that wants to take advantage of celebrity status.

I'm not trying to change anybody's mind about him. If you don't like him don't waste your time watching the interview. It probably wouldn't change your mind but it does show a better side of him.

Source: https://youtu.be/21qBO_uFQGM

 

[shakenfake]

Definitely second Dozer on this one.

Still hate the change he made when he moved out of Indiana. Totally understand it but it changed him.

 

[Trimox]

Is it just me or does the use of the word "like" in that video not disturb anyone else? Could not watch more than 2 mins.