Intake/exhaust port CFM flow? Porting the heads? Tech babble.

[w3azel]

Yes, high compression + high boost = blown heads. Here is where I need things explained to me. Is the thermal efficiency advantage worth keeping or is it better to drop the compression and up the boost. How do these two paths differ in EGT, engine temp, power, and fuel efficiency. Two paths, lower the compression and upping the boost to keep the heads on. Keep the compression, max the boost at 20 or 25 but do it early and waste gated. Fire ring the heads to keep them on.

What I am especially interested in is if the high compression is what leads to the rear cylinder over heating. Also which path will help keep our already high EGT from going up anymore then needed. More boost keeps temps down, but high compression is supposed to keep temps down as well.

 

[Hottrodd789]

Has any one thought about having the crank lightened witch allows to rev faster and higher!

 

[welldigger]

Has any one thought about having the crank lightened witch allows to rev faster and higher!

Considering cranks also break on these engines I don't think removing material from it and turning it faster will be a good idea. Diesel engines don't like high revs. Balancing the crank and other rotating assembly would save some wear and tear.

 

[Hottrodd789]

Everything breaks!!, any thing in this thread runs the risk of breaking an engine wether blowing heads of or melting a piston from over fueling. a lighter crank is def a option that many performance diesel engines use u don't take it,off where it is needed it would come of the balance side u have to think even 1 lb lighter at 3000 rpm is a lot of force that is reduced besides what do u think u do when balance it u take weight off....!!!!

 

[rustystud]

Interesting, the difference in "valve events" between those two models. How can that be if the camshafts and timing gears were identical for all of these engines?

BTW, I see you have the -35 TM. Not in digital form, or....??


G.

I have the manual "TM 9-2815-210-35" in paper. I thought of putting it on the site but it's 500 pages and I would have to scan each page twice.

 

[welldigger]

I realize this. But the multi fuel does not like to be revved. It has a weak bottom end. It's prone to throwing rods along with broken cranks. Gaining rpms isn't the way to gain reliable horsepower from these engines.

 

[w3azel]

The engine will do 3000 rpms as it is. Adjust your rev limiter and you can see yourself. The issue is with the rods and the heavy pistons. Rod bolts are known to break or shear maybe? Look up the design to see what I mean or search rod bolts.

 

[w3azel]

I have the manual "TM 9-2815-210-35" in paper. I thought of putting it on the site but it's 500 pages and I would have to scan each page twice.

Kinkos can scan and make a pdf for you.

 

[rustystud]

I'm not in the "lets see how much power we can make" camp. I'm in the lets make some decent power and good reliability camp. I think balancing the crank and rods would be a good step, but first I would have the rod ends checked and machined with new 12 point bolts installed. Then I would attack the oil system, making sure there is good flow to all parts of the engine. Most people do not realize that most manufacturers used step drilling on there blocks. I don't know if the multifuel is one of them , but I would check and if it has I would drill out the passages to the proper size. "IHC" was notorious for this. There small block 345, 392 engine would have a 5/8" drilled hole at the main galley by the oil pump, but at the front of the engine it would only be a 1/4" hole. The problem was this feed the crank and number 1 and 2 rods . This engine was famous for oil starvation of the rod ends at number 1 . By drilling out the passage to the full size of 5/8", you would eliminate this problem. Next I would upgrade to the LDS engine Injectors and Injection Pump. Then I would go after the heads and valves. Then see if I could get a cam ground to use roller lifters . You probably could use the stock cam as it is a forged billet cam, just have it reground and hardened. This would be a good start on fixing this engine and still keeping it a multifuel.

 

[rustystud]

Kinkos can scan and make a pdf for you.

Kinkos wanted $300.00 to do it . I already asked.

 

[Docluvstrucks]

Diesel engines don't like high revs.

Tell that to my 81 Rabbit Diesel. That thing will wind up.

 

[JasonS]

Yes, high compression + high boost = blown heads. Here is where I need things explained to me. Is the thermal efficiency advantage worth keeping or is it better to drop the compression and up the boost. How do these two paths differ in EGT, engine temp, power, and fuel efficiency. Two paths, lower the compression and upping the boost to keep the heads on. Keep the compression, max the boost at 20 or 25 but do it early and waste gated. Fire ring the heads to keep them on.

What I am especially interested in is if the high compression is what leads to the rear cylinder over heating. Also which path will help keep our already high EGT from going up anymore then needed. More boost keeps temps down, but high compression is supposed to keep temps down as well.

The high compression hurts overall efficiency because it results in more frictional losses and more blow-by. It also causes higher peak cylinder pressures which stresses the engine. If you look at modern engines, they have lowered the compression ratio and increased the boost. The engine texts say to use the lowest compression ratio that meets the cold start requirements.

 

[Docluvstrucks]

The high compression hurts overall efficiency because it results in more frictional losses and more blow-by. It also causes higher peak cylinder pressures which stresses the engine. If you look at modern engines, they have lowered the compression ratio and increased the boost. The engine texts say to use the lowest compression ratio that meets the cold start requirements.

But how would lowering compression affect the multifuels ability to burn waste oil and other readily available combustibles? If I lost the multifuel ability then tweaking the LD/LDT is an exercise in futility. Just buy a Cummins and be done with it but not desireable. It has to be a balance of the best of both worlds.

 

[rustystud]

But how would lowering compression affect the multifuels ability to burn waste oil and other readily available combustibles? If I lost the multifuel ability then tweaking the LD/LDT is an exercise in futility. Just buy a Cummins and be done with it but not desireable. It has to be a balance of the best of both worlds.

I totally agree ! That's why I'm going with making the engine as strong as possible (within reason) and tweaking the injection system.

 

[Docluvstrucks]

Maybe I'll just buy a used LDS for $2500. I mean where else can you free up 80hp from a LDT and still keep it multifuel. Just buy an LDS and throw it in. Done

 

[JasonS]

Maybe I'll just buy a used LDS for $2500. I mean where else can you free up 80hp from a LDT and still keep it multifuel. Just buy an LDS and throw it in. Done

Turn up the fuel on an LDT; same thing and you can save $2500. It is only 40 or so HP difference.

 

[Docluvstrucks]

Turn up the fuel on an LDT; same thing and you can save $2500. It is only 40 or so HP difference.

Hmmm? I thought I have read on here the LDT is 138hp and the LDS was 210.

 

[JasonS]

Hmmm? I thought I have read on here the LDT is 138hp and the LDS was 210.

Based on the TMs, the LDS465-1/A has 175 HP. Hardly seems worth $2500 for the difference which can easily be made up with a tweak to the LDT's injection pump.

 

[w3azel]

The high compression hurts overall efficiency because it results in more frictional losses and more blow-by. It also causes higher peak cylinder pressures which stresses the engine. If you look at modern engines, they have lowered the compression ratio and increased the boost. The engine texts say to use the lowest compression ratio that meets the cold start requirements.

Ok so if we wanted to lower the compression would the easiest way be to swap the pistons with the tractor version or de-stroke the engine a little.

 

[JasonS]

Not having any idea of the resulting outcome, it would be an expensive test. If you have the money to play around, probably better to try something newer like a DT360 or 5.9 cummins. Better oem and aftermarket support.