New Concept Race Saw

[Dennis]

Ok boys..got the new saw I found at a military garage sale...

I have a prototype HFE (Heavy Fuel Engine or Diesel). The military calls diesel fuel and JP-4 fuel "heavy". The carbs were used on the prototype to prove concept several years ago.... Fuel injection was a necessary apparently due to negative G's induced by maneuvers so the current design runs injected. Otherwise it is just a stroked and supercharged 2 stroke diesel. Makes around 48HP on diesel. There are no pipes and since they used it for recon, no noise was preferred.... I don't know what we can do on Gas or Alky etc, but I know for sure it would be alot more.... The supercharger and interface gear drive were designed to run off the center of the crank by a gear. Initially, it was found that an injection pressure of 5 to 7 atm was sufficient to effectively atomize the heavy fuel (diesel) and air mixture for combustion in a stratified-charge spark ignition engine. Only a few modifications will be needed for Gas or Alky....

Those are twin 088s under the hood boys....What is a Rotax??

Darn...ok..I will have to modify the new pic as it is in the wrong format..i will work on that...

 

[JimL]

And what exactly are you thinking not posting a picture!!!!!!

 

[Dennis]

Jim...i cant figure out why it wont go into format...i will add it..but my comp wont let me open it...in this particular format...except that bitmap is too large...grr...I apparently shouldnt play with computers...jpeg says it wont open..but i am adding it in jpeg..whatever the heck that is...

okok....got it..but now the pic sucks...but its still pretty

 

[sedanman]

Hmmm, Looks a little like a snowmobile!

 

[Dennis]

Sedan...some of the things we cdns say is true...lol...

This particular engine, is in fact a pair of 088s...cylinders, pistons..wrist pin and rings....then the crank was manufactured as well as the rod to create a different stroke....Cylinder heads were built to incorporate an intake port, the glow plug..and an electronic spark assist. The manufactured head also has to be able to withstand a cylinder pressure of over 900psi to gain the hp although the static compression ratio is low....the fuel injection for the deisel is about 300psi....

This engine ran for over 400hours on the dyno at full load, before the military would pass it for recon...so the reliability is there...at 8-9000 rpms...the dyno is reading 47+ hp

It looks like it isnt the candidate for my saw....but...there is a prospect of a twin opposed (180 degree) 088 Hotsaw....supercharged....gasoline...100hp? LOL

 

[homelite360]

boy thast sounds like it would be either a nasty hot saw or a heck of a go kart engine. i would like to find one of thse. it would be intresting to play with.

 

[sedanman]

Dennis, If you say it's a flux capacaitor then that's what it is! My only problem is "carbureted diesel" that doesn't sit well with me. I thought all diesels had to be injected because there is no ignition system and the injector pump controlled the timing. Also, all the diesels I've ever seen had no butterfly to regulate incoming air, they got all they wanted and the throttle cable went to the injector pump. I'd be interested in reading some more about this engine, it sounds like an engineering marvel. I must add that I have only ever seen 4 stroke diesels. I never did spend much time looking at the Jonsereds diesels as I was so blown away by the collection that they were part of.

 

[Dennis]

Sedan....the diesel is injected..those carbs were strictly for prototype..to prove the concept feasible before it went to deisel..this particular "two stroke" deisel is pretty much a marvel..in the fact that the engine creates so much hp for so little disp. the germans build alike engines as well....but the two stroke deisel "jimmy" engine that is supercharged and has been around for many years...the 71 series v8 318 creates 292hp...

 

[Harley]

Hey Sedan,

The early GM Diesels were two strokes. I guess they weren't really early but you know. The 3-71, 4-71, 6-71, the ones that had the rootes blowers on them.

 

[dbabcock]

I may be mistaken, but don't two stroke diesels have valves or at least one valve?

 

[Dennis]

Doug..from what I understand its an intake valve on the Jimmys...i think to keep up the combustion chamber pressure..not sure though...still learning this deisel thing...

 

[sedanman]

Harley, I am aware of two stroke diesels , just haven't seen any up close. There was an air cooled two stroke diesel too (for trucks), I think the manufacturer was Deutz.

 

[treefarmer]

2-stroke diesels

As I recollect, the GM/Detroit diesel two-strokes utilize circumferential ports within each cylinder for intake. The ports are exposed on the piston's downstoke. Four overhead exhaust valves remove the spent fuel. The supercharger provides scavenging. Large displacement, two-stroke diesels are still used in some applications, such as generators and locomotives.

-Clark

 

[Mack]

2 stroke Jimmies can have either 2 or 4 exhaust valves per cylinder, they also have an intake port through the cylinder wall. A 2 stroke diesel must have a blower of some sort to run, as there is no intake stroke as in a 4 stroke and crankcase vacuum/pressure can not be used for air induction, as it is in a chain saw. The Detroit's, (EMD's etc.) are rated by displacement / series. A 6-53 would be six cylinders of 53 cu. inches each, or 318 cu. inch, an 8V-71 would be 568 cu. inches, an EMD 16V-645 is 10320 cu. inches, etc.
Horse power ratings vary greatly due to injectors, rpm, boost, fuel, porting, etc. You will see stock 6-71s rated from 145hp up through 400hp.