4100 rpm with a potentiometer on the ICP

[Blown262]

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.

As of yet, I haven't had any contact and I've hit 4K+ quite a bit. I have only hit it with clutch dumps and free spins, never actually sustained RPM while under load. I'm pushing the limits, I know, but I am curious as to how far you can push these motors before you run into problems. I know someone out there has found out first hand exactly how far you can go before it physically can't take it anymore. I want to know how close to the edge I'm walking here.

 

[Luke@MillerPerformance]

One of two things is going to shut your truck down at those rpms:
1. the cam gear will decide it wants off the cam (they are press fit) and take out the cam sensor. Also the valves will hit the pistons.
2. It's a 7.3, it's not well balanced from the factory, and it has PMRs. You're going to punch some holes through the sides of the block.

Those guys with Cummins spinning 5K are not stock. Most likely the are 6.4 motors. 6.7 crank with custom rods in a 5.9 blocks. This corrects the rod angle to allow the high rpms.

You need to remember, a 7.3 is a big motor to be spinning that fast. That extra 1.4 liters of displacement makes a big difference. Those clutch dumps have caused piston contact. Just because it still runs doesn't mean the haven't hit. I've got a set here to prove it.

 

[Blown262]

One of two things is going to shut your truck down at those rpms:
1. the cam gear will decide it wants off the cam (they are press fit) and take out the cam sensor. Also the valves will hit the pistons.
2. It's a 7.3, it's not well balanced from the factory, and it has PMRs. You're going to punch some holes through the sides of the block.

Those guys with Cummins spinning 5K are not stock. Most likely the are 6.4 motors. 6.7 crank with custom rods in a 5.9 blocks. This corrects the rod angle to allow the high rpms.

You need to remember, a 7.3 is a big motor to be spinning that fast. That extra 1.4 liters of displacement makes a big difference. Those clutch dumps have caused piston contact. Just because it still runs doesn't mean the haven't hit. I've got a set here to prove it.

Great insight. To the cummins, guys I cruise with have hit 5k on stock block 5nines, but a boat load of other work and regularly hit 50psi+ and put down 1k+ torque. I can't comment on the specifics, as I'm not a cummins guy (even though I have a fleet of over 10 of them) As for the valve contact, I have scoped the motor through the injector sockets and have no evidence of valve contact. When I pull the injectors for replacement, I will scope it again and see if I have hit since then. If it happens that I have over stressed this motor, it happens. I have a set of replacement forged rods with pistons and I know I'm getting to the point in the lifespan where a valve job will be beneficial. At least it's held together this far lol. And it's good to know about the cam gear. I didn't know they were pressed on these motors, and that changes my outlook on things. Reminds me of what happens with the old 3.4L V8s in the SHO Taurus. I will be pulling the resistors out tonight as I don't want the cam gear breaking loose on me. That always scares me.

 

[lincolnlocker]

you need to dig back 15 or so years.. lots of people have been there done that.. prolly as early as 1995... all this stuff you are asking about can be quickly found in a google search.. lots of guys have done it and failed and thats why you dont hear of it now.. i bent 8 pushrods in my dually with stock springs and push rods. every piston had markings on it from playing wack-a-mole with the valves.. there have been many bone stock trucks just driving down the road that has bent pr's when the cps hiccuped.. my dually did that once with the cruise set at 65.. you get near 3800rpm and chit starts moving to fast for stock components.. pmr rods in a 7.3 are going to let go at some point unless the tunes are spot on and everything stays tight....

live life full throttle

 

[Blown262]

I have done many Google searches on the subject. There isn't a lot of info on stock block 7threes going 4k+. As for the tunes, beans tunes have been great thus far. EGTS dont get crazy, there's almost no smoke down low and nothing up high. The motor internally seems almost perfect still. Blackstone tests every other oil change and everything is on the low side and if I scope the pan, the crank, rods, and piston bases all look pristine with no heat marks and all the squirter are still in place. I have no blow by and the cylinder walls still have some cross hatch on them. The truck has runn Rotella T6 5w40 for the last 70k+ with Motorcraft filters and it's doing damn well considering the abuse it's taken.

 

[lincolnlocker]

you go girl! like i said. theres reasons why its not a common thing to do. but carry on in your awesomeness and dont bitch when it installs windows 7.3..

live life full throttle

 

[Blown262]

My previous post was me saying I just removed the potentiometer. I'm well aware of the risks I'm taking putting the truck through this kind of abuse. If it breaks, I can only blame myself. I'm not one to bitch about broken parts. It's part of the game, is it not?

 

[lincolnlocker]

right on man!

live life full throttle

 

[TyCorr]

Your pistons have valve marks on them. Guaranteed.

Guys have made it to 4500 in built motors. Your stock pmr motor is so far from that discussing doing it with the two as if they have any connection is pointless.

Get some bigger injectors and decent tunes and you'll blow that pmr quicker and much more funly so.

 

[Blown262]

When it does let go, I will be sure to have it on video

 

[Isobaric]

As of yet, I haven't had any contact and I've hit 4K+ quite a bit. I have only hit it with clutch dumps and free spins, never actually sustained RPM while under load. I'm pushing the limits, I know, but I am curious as to how far you can push these motors before you run into problems. I know someone out there has found out first hand exactly how far you can go before it physically can't take it anymore. I want to know how close to the edge I'm walking here.

I really don't mean to steal your thunder, I can dig the enthusiasm, but like others have said you aren't doing anything groundbreaking.
The last bone stock 7.3 I had apart had kisses on all 8 pistons from the valves. Short gears (4.56 IIRC), ZF-6, Superchip gold pulling a 24" goose-neck at 75mph for 260xxx was enough to float the valves into the pistons.
If the possibility of a mechanical isn't enough to deter you, then let the precipitous decrease in HP above 3100 rpm do it. Stock 7.3 heads don't flow enough air and stock 7.3 injectors don't empty quick enough to do anything useful at that number of revs/min.

 

[ja_cain]

Dude, I like your attitude. Breath of fresh air around here even if you don't know everything. What hardware are you using to scope the motor?

 

[Blown262]

No thunder stealing it's all good. I'm just curious as the last diesel was a Mercedes that would 7k no problem and I like listening to things wind out to the edge of detonation. I'll be pulling the injectors soon enough and I'll scope it and see how bad the valves bit the pistons. I appreciate the insight from all and I know I'm a little behind the times. There's a reason these 7threes are still all over the road though, so I wanted to see how far I could push the limits of a stock motor.

 

[Blown262]

Dude, I like your attitude. Breath of fresh air around here even if you don't know everything. What hardware are you using to scope the motor?

Thanks. I never expect to know everything. Always remain teachable. As for a scope I just have an off the shelf Milwaukee I use for work. It's not the best and brightest, but I can see what need to see.

 

[ja_cain]

As far as I know, the #1 limitation with the Heui system with regards to rpm is how fast the injectors can refill on the oil side once the nozzle size is increased enough to give the correct PW and fuel delivery vs. RPM. Hybrids decrease the ratio so that you don't need as much oil to displace the same amount of fuel but that only works up to a certain point. There are some individuals around here with some secret squirrel chit that may eventually trickle down to us at some point (modified internals/fast fill). Do some searching on the subject and you will find some good recent cerebral threads.

 

[Luke@MillerPerformance]

No thunder stealing it's all good. I'm just curious as the last diesel was a Mercedes that would 7k no problem and I like listening to things wind out to the edge of detonation. I'll be pulling the injectors soon enough and I'll scope it and see how bad the valves bit the pistons. I appreciate the insight from all and I know I'm a little behind the times. There's a reason these 7threes are still all over the road though, so I wanted to see how far I could push the limits of a stock motor.

It's because they don't make **** for power in stock form lol.

 

[Blown262]

275hp braaaaaapopopop

 

[TyCorr]

As far as I know, the #1 limitation with the Heui system with regards to rpm is how fast the injectors can refill on the oil side once the nozzle size is increased enough to give the correct PW and fuel delivery vs. RPM. Hybrids decrease the ratio so that you don't need as much oil to displace the same amount of fuel but that only works up to a certain point. There are some individuals around here with some secret squirrel chit that may eventually trickle down to us at some point (modified internals/fast fill). Do some searching on the subject and you will find some good recent cerebral threads.

You can overcome icp. Modded oilsides and dual pumps/gen3 will produce more oil than ANY injector can use. The actual injection system and electronic delays leave virtually no time to inject fuel at higher rpms. Then if you make headway there, pisspoor cylinder head flow shuts a door in your face.

 

[psduser1]

You can overcome icp. Modded oilsides and dual pumps/gen3 will produce more oil than ANY injector can use. The actual injection system and electronic delays leave virtually no time to inject fuel at higher rpms. Then if you make headway there, pisspoor cylinder head flow shuts a door in your face.

Pretty sure this is the answer to the question, lol.
Ever had this truck/engine on a dyno? Before you get your pride hurt, I'd call swamps i.e. golfer on here, and talk to them. They have a pretty deep background. May learn a few things the easy way, lol.

 

[ja_cain]

You can overcome icp. Modded oilsides and dual pumps/gen3 will produce more oil than ANY injector can use. The actual injection system and electronic delays leave virtually no time to inject fuel at higher rpms. Then if you make headway there, pisspoor cylinder head flow shuts a door in your face.

Good point about the electrical side. I bet someone has a solution to that one also. I seem to remember some comments from other threads eluding to that. I could be wrong though, as my brain has gone to chit lately. Maybe stiffer spring and stronger electromagnetics. IDM would need to be beefed up too. Ported heads and aftermarket cam are a no brainer for high rpm operation. If the p-pump conversions can reach higher rpm's then the heui system should be able to get close once it's other short comings are addressed. Though I have not followed the p-pump thread well enough to be able to extrapolate.