Why 2650rpm max?

[JasonS]

I found these interesting statement on a tractor website:

One other differenc is that the connecting rods are lighter in the truck motors.

As J said, some of these ld engines had better crankshafts but not all of them. I have five of these motors and only one has the better crankshaft. I think that only the turboed truck motors had the better crankshaft.

With that being said the military engines run smoother and have a better crankshaft than the civilian engines.

You can read all of the posts here:

Yesterday's Tractors :: View topic - hercules

 

[patracy]

Thanks for the bump to the thread, that reminds me, I need to ping ARP to see if they've came up with anything...

 

[JasonS]

Thanks for the bump to the thread, that reminds me, I need to ping ARP to see if they've came up with anything...

Any update?

 

[patracy]

Any update?

I gave them all the measurements (all specs), but apparently that's not enough. They want a detailed drawing as well. If someone has a spare bolt laying around, that'd probably be easier.

 

[cranetruck]

I gave them all the measurements (all specs), but apparently that's not enough. They want a detailed drawing as well. If someone has a spare bolt laying around, that'd probably be easier.

His answer...

 

[Lar45]

I have a couple of questions.
1. Could the piston and rod assembly be taken out the bottom of the block? Preferebly with the crank still in place.

2. Does current diesel feul atomize easier than when the motors were first made?
I'm wondering if there might be any kind of predetonation going on with the advanced injection timing?

3. Does anyone run this motor without a turbo, and do they have the same rod problems?
I think I read somewhere that the initial engines were non turbo with high compression, and later had turbos put on them without lowering the compression.

If this was a problem could we find a pile of new pistons on the auction site and have the cup made larger.

4. Would it be possible to make a jig of some kind to press the rod bolts out and press new ones in from the bottom of the engine?

5. Is there any extra clearance between the rod and the block? Would larger rod bolts help? Or just stay with the stock size and use ARP ones...

6. Has anyone thrown a rod useing less volatile feuls, motor oil, veggie...?

I do not own one yet, I am not a mechanic...

Does anyone have pics of the bottom end showing the crank and rods clearance with both sides of the block?

 

[Westech]

#1 no
#2 its the same
#3 yes there are N/A engines and all multi's are 22-1
#4 no
#5 ARP does not make the correct bolt
#6 unless your running nytro it does not matter
#7 Google.

 

[stumps]

MF engines don't atomize the fuel. They squirt a stream of fuel into the combustion chamber formed in the piston top. The fuel boils and splashes up into the hot air, and burns slowly. That is why the MF engine is called a Whisper Diesel engine.

Keep your engine speed down, and you will never witness a thrown rod. 2700 RPM is rather a lot for such a heavy piston, and such a long stroke.

MF turbos aren't there to increase performance, but rather to assure sufficient air to keep the engine from smoking. They have minimal boost. The EPA requirements for pollution reduction forced the turbo.

-Chuck

 

[m-35tom]

chuck, have you ever seen a MF injector on a test pump? i have a tester and they seem to put out the same mist that other injectors do. just wondering, injectors in cat and cummins spray almost sideways across the piston top while the MF sprays down into the cup. i wonder if that fact alone is enough to burn the fuel more slowly.

tom

 

[OPCOM]

A bit of topic but since many here are into hot rods so I'd like to share something. The 73-74 Pontiac TransAm's had an optional engine, the Superduty 455. In '74 it was the most powerful of all Detroit auto engines. Pontiac actually had planned to use it for the 71 GTO but it was delayed 2 years while they developed a stronger connecting rod. During these 2 years the HO455 with sold. It used with cast rods. Since any Pontiac V8 engine an use any rod (except the 301/303/366 racing engines) it is a great way to hot rod the weakest link. It can extend the operating range of any engine by over 1000rpm, with no loss in safety factor. A 326 with it is safe to 9500rpm.

Features include-

Forged SAE8640 (Chrome nickle molybdenum alloy- a bigger deal in 74)
Heat treated to 35 Rockwell C
Shot peened
7/16 boron steel rod bolts
Bolt ends counter sunk for micrometer stretch tightening(.006")
Windows near bearing ends as bolts are .001" away from shell (so area is not super thin)
Lightened small end (the area that reciprocates)
Massive big end ring (to prevent distortion)
Max material near bolt head (where a big hole is)

Pontiac rules the road! I used to have a 1970 GTO with tempest front clip, a 400 with an 850 spread bore double pumper with manual secondaries, and edelbrock torquer, 4-speed, and the rear end from a station wagon (2.73?) which was the secret weapon. Made a great show of smoke dumping the clutch off the line (but didn't hook due to the rear ratio) and would run 160+ on the highway. The car looked like h-e-double-toothpicks and had lots of rust holes but Z rated tires and proper brakes and suspension etc. all hidden away and I used to bet suckers into highway racing and take their money when they'd top out haha! The motto was "I'm fast because I'm running from the junkyard" IROC Z had nothing. A Mustang 5.0 outran me to 140 because it had nitrous but he couldn't keep that up, or didn't have the nerve to. It also got about 20MPG at 80MPH. The good ole days.

 

[m-35tom]

patrick, i didn't realize you had been so wild, back when.

tom

 

[stumps]

chuck, have you ever seen a MF injector on a test pump? i have a tester and they seem to put out the same mist that other injectors do. just wondering, injectors in cat and cummins spray almost sideways across the piston top while the MF sprays down into the cup. i wonder if that fact alone is enough to burn the fuel more slowly.

tom

Hi Tom,

No, I have never put an MF injector on a tester. I have been looking for a manual test pump with my name on it, but have not found it yet. Got a spare?

As I understand it, the MF injector has multiple personalities: Thick fuels will atomize because you are pushing large molecules through the orifice at very high pressure, thin fuels will just stream because the pressure is so much less.

The engineering texts I have read on IC engine design said that this feature was used to great advantage in the MF.

Gasoline if allowed to atomize would burn instantly as it was leaving the orifice; using up the air around the injector, and quickly coking its tip. Because of that fact, the orifice size was chosen so that gasoline squirts unburnt onto the walls and bottom of the relatively cool combustion chamber, and as the hot pressurized air in the chamber makes the gasoline boil, the vapors then ignite. This process takes a fairly long time, and happens far away from the injector nozzle.

Medium grade fuels, like diesel oil, pass through the injector nozzle somewhere between atomizing, and streaming. As a result, partly boil off of the bottom of the chamber, and partly burn in the hot air... they still burn more slowly, and over a much longer time than they would in a conventional diesel... hence the name: Whisper Diesel.

Heavier fuel oils pass through the injector at a much higher pressure, and atomizes more completely, but the resulting fractured globs are big and heavy, and burn quite slowly when exposed to the hot air in the combustion chamber.

I have heard SS members describe the sound of their MF engine burning straight gasoline as sounding like it was crackling, or spattering.... we all know that an MF engine burning diesel oil sounds smoother and quieter than a usual diesel engine..., but straight motor oil sounds even more muffled and silky smooth in comparison.

I believe that if you want to get a true picture of the character of the MF injector, you will have to try it with gasoline, diesel oil, and motor oil as test fluids.

-Chuck

 

[m-35tom]

chuck, well i have an old bosch tester and will have to try gasoline etc. where are you in maryland?

tom

 

[stumps]

Hi Tom,

I'm near Frederick.

I am certain that a manual tester could easily overcome the pressure valve in the injectors, but I wonder if it could achieve the operating pressure of the MF injector when using the thicker oils?... or the operating volume necessary when using the thinner gasoline? Most of the testers are, I would think, rated for diesel fuel.

Probably a stupid question, but I have never had a tester, so I don't know what they are capable of.

-Chuck

 

[cranetruck]

Here is the tester as shown in the TM. Should be good for the fuels listed for the MF engine.

BTW, if you want an even quieter engine run it on veggie oil/Bio diesel. Some power is lost, however.

 

[stumps]

Hi Bjorn,

I was looking on ebay, and noticed a guy selling pop testers built from little hydraulic jacks. Then I did a google search on fuel injector pop testers, and found this link:

How to build a diesel injector pop tester - PeachParts Mercedes ShopForum

This guy shows how he made a pop tester from a jack, and from what he describes, it sounds ideal... plus I have all of the necessary gauges, and parts!

Fun times will commence!

-Chuck

 

[66kaiserld1d]

wow after i read this whole thread come to realize all the good suggestions and ideas... i mainly mess with gas engines but i went to school for gas and diesel im only 22 but dont be fooled this fleet i worked for a couple years back all the cummins isx engines and cat 15's they had in their fleet trucks they had us flip the rod bearings at 250k and replace at 500 k this one guy in the stall next to me had the great idea its not tight unless its 10ftlbs over and indeed wasted 4 engines doing so they only intended the bolts to be tightned so much .. metal fatigue has got to be the biggest part in this, rod bearings dont do much other than touch the metal on the crank on startup if you have oil pressure and the bolts are tightned properly there shouldnt be an issue if you have an engine vibration theres a chunk missing somewheres .... a rod shouldnt fail if the engine is within safe operating range..... pushing the redline on a very unique engine is ****... i havnt had the chance to have one apart yet but from yalls comments the piston is different in shape and injection is different.. higher compression equals more thrust on the crankshaft thus more wear ... check your bearings and bolts use a magnifying glass replace them its a miniscule thing to do unless youd like to waste an engine i dunno just some thoughts guys

 

[cranetruck]

Hi Bjorn,

I was looking on ebay, and noticed a guy selling pop testers built from little hydraulic jacks. Then I did a google search on fuel injector pop testers, and found this link:

How to build a diesel injector pop tester - PeachParts Mercedes ShopForum

This guy shows how he made a pop tester from a jack, and from what he describes, it sounds ideal... plus I have all of the necessary gauges, and parts!

Fun times will commence!

-Chuck

Let us know how it goes. I have a bunch of injectors that will need to be tested one day, perhaps I'll follow your lead here.

 

[brianp454]

Hey guys,

We have some good info on the injector stuff in another thread: http://www.steelsoldiers.com/showthread.php?107021-Fuel-Injector-Issue-LDT-465

Also, my YouTube video of bench testing is: http://youtu.be/uUFJ2s6XPlw

Enjoy!

 

[rustystud]

I don't know if anyone is still reading this post, but since I'm a Newbee and have only gotten so far in my reading I'm really behind the eight ball here.
As a ASE certified Master Mechanic for over 30 yrs I've seen a lot of engines blown apart. The main reason I've seen pistons ventilate blocks is due to
lack of oil. Most all diesels and heavy gas engines ( IHC etc.) have large surface areas on the rod bearings and when these engines start spinning high
they really need the lube to keep the clearances up. Remember, the bearing really rides on a film of oil not the bearing itself. When you spin high with a low volume
oil pump and low pressure like the multifuels (30 psi ) the system cannot keep up with the oil lose, this creates heat, which creates friction , which creates added stress to the rod bolts,
which ends up with rods flying through block ! That is why all racers use high pressure, high volume oil systems costing lots of money !
I've built up International engines that can really rev , but you need high tensile strength bolts, balanced rotating mass, and really good lube systems. Not to mention
high pressure valve springs and lifters and cams !