4100 rpm with a potentiometer on the ICP

[Blown262]

So, being a chronic tinkerer, I'm never satisfied with things the way they are. I like to experiment with little tweaks and whatnot, and I decided a while ago that I was going to piggyback my ICP with a 20kw potentiometer and a switch to kill the modified signal. I have an on-off-on switch with one pole going to the potentiometer and the other going to a momentary switch on the pedal at WOT which in turn activates a 1.8k ohm circuit on the ICP. One thing I have noticed is, whenever the potentiometer is cranked pretty high <5kohm, or when the WOT switch is activated, my fuel cutoff goes from 3400 all the way to 4100+. I've never actually pushed the truck past 3700 under load, but it feels like it wants to keep going. My EGTs start creeping into the mid 13 right at the top, which is why I've never gone past 3700. Everything else seems to be acting pretty normal under the circumstances. Now I know my ICP readings are incorrect, but I read about 4200+ above 3krpm and my injector pulse is all over the place (probably my scanner not keeping up). Am I doing sever damage this way because of the improper injector timing in relation to the increased icp? Sorry for the essay but I was just curious if anyone else has been ballsy/stupid enough to push a 7.3 (PMR motor no less) this far. It's held together for 15k with this setup, but I rarely run with the potentiometer or resistor active. It smokes a lot.

 

[Blown262]

That should read 20k ohm potentiometer.

 

[Powerstroke Man 6.4]

My drag tune on my old 7.3 full fueled to 4500 at WOT ,all stock 350,000 mile 99.5. Yes it is not recommended to do this but I had no problems at all.

Swamps 160/100 swamps IDM T500 38R

I ran that tune all day everyday.

 

[Powerstroke Man 6.4]

Also once you hit a certain RPM (don't remember the #) the FDS will cut in and out which will make the truck cut in and out and exhaust will start to have a "popping" sound.

 

[Blown262]

That's what it does for me if I decide to dump the clutch. Everyone asks if I have 2 step and I tell them I have severe spark cut. Now with the timing being changed by the fooled ICP signal, does this add more fuel earlier and bump my cylinder pressures, or does it go the other way and add fuel to end of the cycle? Or does it not add fuel at all?

 

[Blown262]

Another question about PMRs; can these handle higher RPMs than forged being as they should theoretically be better balanced? I know they have higher tensile strength than forged rods, but less give and tend to shatter when stressed. I have a set of forged rods with pistons for when these can no longer handle what I have planned.

 

[lincolnlocker]

all it does is bump the oil pressure in your injectors. its a really bad mod... can ruin good components..

live life full throttle

 

[Strokersace]

Isn't this basically the 10k mod from around 15 years ago?

 

[Blown262]

Isn't this basically the 10k mod from around 15 years ago?

That's exactly what it is. This just has adjustability and can be turned off. It is solely for when I want to mess around on the road. But my question still remains: can the PMR motors handle more RPMs than forged because of the characteristics of the rods?

 

[lincolnlocker]

That's exactly what it is. This just has adjustability and can be turned off. It is solely for when I want to mess around on the road. But my question still remains: can the PMR motors handle more RPMs than forged because of the characteristics of the rods?

exact opposite.. pmr's are weaker rods.

live life full throttle

 

[Blown262]

I was told by an engine builder that PMRs are superior in almost every aspect, except for flexibilty. Because of the lack of a grain in the metal, you get more consistent strength throughout the rod, giving it a slightly higher tensile strength. The problem is when you start stressing the rods, they don't have any give in them, resulting in rods that will exploded when your cylinder pressures get too high. I have a set of forged rods that will be going in this (or another) motor once these rods have exhausted there useful lifespan. I have heard many conflicting stories about PMRs. Most say they are useless past 400hp while others say they have 600+ on them. I need first hand experience to see what these are truly capable of, and so far they have handle a pretty intense amount of abuse without anything in the motor showing any signs of letting up just yet. Time will tell and I will be sure to have a video of it when the motor let's go

 

[Blown262]

Fwiw, I was talking to my builder when I was building a 4.6 twin cam motor that had a forged crank and PMRs so I don't know if this carries over to the diesel world.

 

[Bluke]

The 10k mod does ok on stock trucks. Seeing you have a chip. I wouldn't use it. The tunes already change the tuning to produce more icp. With good tuning pmr motors are good to around 450. What usually takes them out is high cylinder pressure at low rpms

Also why are you going to such a high rpm. Red line is 3200. I don't foresee your motor holding together too long.

 

[Blown262]

It's strictly a mod for fun and stupidity. Nothing more. As for the RPM, that's what this post is for. I know these motors can spin to 3800 all day long. Most diesels I've dealt with are under stressed for longevity. I've seen cummins motors near 5k stock blocks. I'm curious to see what the max rotation speed is on these. Piston speeds at 3k rpm arent very fast so I can see these being able to turn a good amount of rpm safely, I just want to know what the threshold is where it starts to come apart or slap valves

 

[Arisley]

At high RPM's, there is not enough time to empty an injector into the cylinder. That is the downfall of HEUI injection systems.

I predict a new engine modification soon. It will be a crankcase ventilation mod.

 

[Blown262]

That makes sense and would explain why CR motors have an easier time spinning those RPMs. My CCV dumps under the truck

 

[Blown262]

At high RPM's, there is not enough time to empty an injector into the cylinder. That is the downfall of HEUI injection systems

Theoretically speaking, a set of 160/80s could help get more fuel in a shorter PW and help with high RPM fuel delivery? Or is it something else like oil delivery or the injectors themselves that controls that?

 

[Bluke]

That makes sense and would explain why CR motors have an easier time spinning those RPMs. My CCV dumps under the truck

There will be a few more windows in the block for the vents.

 

[Blown262]

There will be a few more windows in the block for the vents.

Time will tell. I don't 4K is too terrible of an RPM for these motors to handle. That's a piston speed of ~1400ft/min which isn't a terrible amount of speed. My old Mercedes diesel with cast rods would spin 7K+ (obviously a completely different animal, but I like revs) which is 1750ft/min on horrendously balanced rods and pistons (50-100grams difference per setup)

 

[Isobaric]

Piston speed is only part of the equation. Reciprocating mass also has to be considered.
At 4100 you are going to have piston to valve contact with the stock cam profile and valve springs.

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