Let's Discuss Ways to Increase Power Output

[Watwood]

So these motors are ~7.8 liters and produce 140hp and a little over 300ft/lbs. I would like to discuss ways to improve this (in addition to turning up the injection pump) as a stock 5.9 liter Cummins produces 200hp, but more importantly, 400+ ft/lbs within the same RPM range; not to mention a "turned up" Cummins can easily produce 450+ hp and 800+ ft/lbs.

1. Intercooling: I believe this would be a quick and easy way to gain a decent percentage increase in power, it would allow a cooler/denser charge of air which would in turn allow more fuel to be dumped into the combustion chamber.

2. Coolant flowing through the head: (Note! I do not own a M35A2 yet, just started doing research, so I have not looked at one of these engines in a while but...) Is there not a way to bypass the coolant flowing through the head. On modern vehicles this is just a way to help warm up the motor to operating temps. on cold starts, so if there's an in and out hose, just unhook them from the head and run a hose between the two.

3. Turbo: Update the turbo to one that spools quicker while maintaining boost throughout RPM range, look past C and D turbos. This could mean fabricating a new manifold. I would have to do my research on turbos as this would not necessarily mean slapping a huge diameter turbo on as it needs to spool quickly.

4. Compression ratio: These 1600lb beasts are sitting at 22:1. Guh Lawd. I know they were originally designed to be N/A so this is excusable. So, anyone every tried dished pistons or would this completely kill the multi-fuel capability?

LOL, by the time all this was done one prob. should have just slapped a 12 valve Cummins in it. Throw some feedback at me.

 

[doghead]

Yup, install the motor of your choice, not alot to be gained with a multi-fuel. If you modify it, it will no longer be an "Authentic Military Vehicle". Consider the "history" before deciding to mod one, please.

 

[Chinookpilot77]

this has been discussed many times my friend, once at least by me. The bottom line is this, the head gaskets and head itself can't really handle much more...as you noted 22:1 is awfully steep.

Also, as you mentioned by the time you did all of this, it WOULD be cheaper to drop in a cummins. I plan on doing that if and when my multi ever completely fails, but hopefully I'll get quite a few years out of her...

Although multis are much cheaper than a cummins swap!

 

[frodobaggins]

If you modify it, it will no longer be an "Authentic Military Vehicle". Consider the "history" before deciding to mod one, please.

Cough, Cough, Doghead, you may want to run, you are in the Modification and Hot-Rodding section !

 

[scooter01922]

Yup, cheaper and easier to drop in a cummins if you really need the power. But ya know, as you don't actually own one yet i suggest leaving it be a while once you do get one. The multi does surprisingly well in its intended role.

 

[scrapman]

Head gasket problems could be reduced by o-ringing the TD block. Balancing the rotating assembly. Pistons are a limiting factor, no aftermarket stuff available that I know of. Reduce the weight of the crank by turning down the counterweights & have it indexed ground. Lunati is a good source for this. Heat relieve, polish the beams & shot peen the rods. Exhaust ports in particular, clean & gasket match removing all casting roughness polishing with a cartridge roll. ARP can provide rod bolts. De-burr, gasket match & polish exhaust manifold. Back cut the valves & polish. Upgrade intake valve springs, more boost is trying to push the valve off the seat. Just in general all the principals that apply to any hot rod application can be used here. Alot of die grinder use & precision machine work can overcome many of the inherent flaws of a mass produced machine.

 

[dittle]

Then the next thing to consider is once you increase the power that is available you will need to monitor everything behind it. Not saying that the deuce drivetrain is weak, but it was designed for such and such power for a certain job. Take the Cummins you keep referencing and jack it way up....how long until that Dodge tranny/drive train starts to fail when you give it the full power available from that engine?????

 

[Chinookpilot77]

Generally the first thing done in any cummins build is a few thousand dollars in the auto tranny...a grand maybe for the manual.

 

[yeager1]

The LDS/LDT come in at least 3 versions. The top being 210hp, stock! I would guess this is probably the top end of what the motor could reliably make by turning the fuel up, assuming your radiator will keep your engine temps down. Not huge numbers, but very respectable and certainly enough to second guess a motor swap.

Power Output:
LDT: 134 hp-330 lbs/ft
LDS: 180 hp-440 lbs/ft
210 version: 210 hp- 515 lbs/ft* Estimated*

 

[scrapman]

Ahh...Screw It!! I'm going to let Wiley Coyote guide me and just order me some ROCKET roller skates. See Ya Suckers***

 

[Westech]

I don't know about you guys but when I rebuilt the top end and installed a injection pump off a 5 ton I had all the power I needed. Really I could keep up with the over the road trucks no problem on the interstate. The only problem was the 9% grades + on the up side. It would slow down to 45 but I was right there next to the over the road trucks. On the flats I could reach just about 65 MPH with the 11:00 tires. With a cummins swap I'm sure you could get up the hills faster but the RPM seams to be the limmiting factor. I dont know if I would be wanting to spin the drive train much faster then the 28-2900 RPM that I was cranking out. I think a over heat or low luberacating condistion could accure.
Just some spamers 2 cents.

 

[OD_Coyote]

Make sure you buy "Acme" rocket roller skates.

 

[mudguppy]

Head gasket problems could be reduced by o-ringing the TD block. Balancing the rotating assembly. Pistons are a limiting factor, no aftermarket stuff available that I know of. Reduce the weight of the crank by turning down the counterweights & have it indexed ground. Lunati is a good source for this. Heat relieve, polish the beams & shot peen the rods. Exhaust ports in particular, clean & gasket match removing all casting roughness polishing with a cartridge roll. ARP can provide rod bolts. De-burr, gasket match & polish exhaust manifold. Back cut the valves & polish. Upgrade intake valve springs, more boost is trying to push the valve off the seat. Just in general all the principals that apply to any hot rod application can be used here. Alot of die grinder use & precision machine work can overcome many of the inherent flaws of a mass produced machine.

i think scrapman is right on the money, here.

i would think that custom pistons and rods would be the way to go - lower the compression down to 16-17:1 w/ some custom H-beam rods that will allow some rpm.

turbos are easy. injector tips could be EDM'd if you start lacking fuel. 5T injector pumps could probably bring more fuel than required.

Generally the first thing done in any cummins build is a few thousand dollars in the auto tranny...a grand maybe for the manual.

a full-tilt auto tranny will cost between 5 and 7 grand. for the nv4500, you need $1k for a clutch and a few hundred bucks for a bigger input shaft and 5th fix. the input is only needed after about 550hp and up - the rest of the tranny is fine.

 

[mudguppy]

... With a cummins swap I'm sure you could get up the hills faster but the RPM seams to be the limmiting factor. ...

why? my cummins will run up to 4k rpm. i generally won't need much more than 3300, but it's there if i need. the only real problem starts at about 4200 rpm - harmonic vibration. you need a fluid damper and balanced bottom to run past it. then you're good to go on up to 5k....... if you got the fuel!!

either way, i agree that you probably wouldn't run up a long 9% in 3rd screaming at 4k rpm. but what that allows you to do is run out 3rd completely so that you can get into 4th at a better spot in your power band; say 2k or so. then you can maintain your speed.

no?

... I dont know if I would be wanting to spin the drive train much faster then the 28-2900 RPM that I was cranking out. I think a over heat or low luberacating condistion could accure. ...

are you talking transmissions? if so, then i disagree only because the transmissions used behind the cummins are also used behind bigger gas motors that have a much higher rpm band.

or, if you're talking about using the cummins w/ the spicer 3053 series, i guess i'd also disagree for the same reasons - the gasser in front of the 3052 was rated to run at, what, 3300+ ??

 

[Watwood]

I dont know if I would be wanting to spin the drive train much faster then the 28-2900 RPM that I was cranking out. I think a over heat or low luberacating condistion could accure.
Just some spamers 2 cents.

What do you mean? When you say drivetrain ,do you mean engine only, as in the oil pump might not be able to keep up? I don't know each individual transmission gear ratio (1st through 5th) but it's essentially negligible as I'm quite sure 1st - 3rd are less than 1:1 , 4th is probably 1:1, and 5th might be a slight over drive, aka, all this truck is, is gear, especially when you factor in the 6.72:1 final drive ratio which is huge. Plus I thought these rockwell axles were the best thing since sliced bread? Are the trannys (not human ones) weak, how bout the transfer cases? Just from being around the trucks I'd guess not.

Then the next thing to consider is once you increase the power that is available you will need to monitor everything behind it. Not saying that the deuce drivetrain is weak, but it was designed for such and such power for a certain job. Take the Cummins you keep referencing and jack it way up....how long until that Dodge tranny/drive train starts to fail when you give it the full power available from that engine?????

Dodge has never been known for their automatic transmissions. The manual trans in the Cummins trucks could hold their own, they just need a clutch that can hold the power.

I'm not talking making 500hp with this truck, just in the 300ish range so it can get out of it's own way and turn the 395s I'd be looking to put on it

 

[OPCOM]

Regarding the stock M35 transmissions, there was a post about the ridiculous speed at which 2nd gear spins on its shaft when the multifuel model is in 5th, and that the transmission was designed first for use as the non-overdrive behind the gasser. Then with the later multifuel, overdrive was added by swapping positions of 4th into 5th and changing the gear thus lost between 3 and 4 to the overdrive gear. That is why 3-4 is such a reach of RPM and why the 4-5 gears seem to be in reversed positions. On the overdrive model the shifing is 1_/2\3_4/5 and on the non-overdrive, the shifing is 1_/2\3_/4\5. It was also said that 5th is weak in the overdrive transmission. Part of that discussion was about a special overdrive gear (0.69?) and also about drilling more oil holes in 2nd gear because it would be screaming on the shaft. There was supposed to be some result of long term testing. I do not know if that is complete or not. Along the same line, some parts kits were proposed, but I did not opt for this since I do not have the skill and special tools to take transmissions apart.

One thread about this may be this one:
http://old.steelsoldiers.com/index....13559&postdays=0&postorder=asc&highlight=0.69 - Note the posts by M35-Tom. This user nad previously built a M35 with the name Millenium Deuce due to its speed.

and
http://old.steelsoldiers.com/index....20350&postdays=0&postorder=asc&highlight=0.71



Can anyone comment or make corrections on this?

 

[1stDeuce]

Opcom, what "special tools" are you referring to??? Admittedly, my helper was "special", but he's no tool!!

Really, I pulled the trans apart in truck with zero special tools... Well, I did have to pull the rear output bearing off with a puller, but I got it in a set of three at China Freight a long time ago... Is a three jaw puller "special"??


As for speeds, don't forget about those poor top loader axles... with the engine at 2600RPM, the driveshafts are running over 3000 RPM... That's really trucking for that heavy a driveline it would seem. Ever feel a diff after a few road miles? HOT!! And of course, second gear is going to be just screaming on the mainshaft, but M35Tom has identified an improvement for that...

Just turn it up a little, watch the EGT's, and don't think it's every going to be a rocketship... IF they're all like mine, you can't shift 'em that fast anyway...
C

 

[Broke Down]

if you wanted some more power you would need more fuel, then more air. you put fueld to it you need a better source of air via larger turbo. but i understand that these engines have head gasket problems. if a head stud was offered that could solve some issues. does anyone have an accurate number on the boosted pressure? if there was someone that could offer a oring gasket kit that would help even more. now you have more power what about the bottom end? can it handle the new found torque? figured i'd throw that out there. i got a hopped up cummins my self.

 

[mudguppy]

if you wanted some more power you would need more fuel, then more air. you put fueld to it you need a better source of air via larger turbo. but i understand that these engines have head gasket problems. if a head stud was offered that could solve some issues. does anyone have an accurate number on the boosted pressure? if there was someone that could offer a oring gasket kit that would help even more. now you have more power what about the bottom end? can it handle the new found torque? figured i'd throw that out there. i got a hopped up cummins my self.

the motor already uses studs. and with 22:1 compression ratio, the mains, rods, heads, and even block itself can't take much more strain than it's already under.

the multi is a far cry from "under-rated" as the cummins is.

 

[tm america]

you could build a multi up but it wont be cheap. id go with kemetic head gaskets find a way to get another oil squirter on the bottom of the pistons. put and inner cooler on the some five ton injectors maybe some slight port work on the head and maifolds i think the rods are one of the biggest weak points that isnt fixed with getting egts down .ive been looking into building one up i think i could do it cheaper than putting a cummins in there