Max rpm our 7.3's can effectively turn

[Powerstroke Cowboy]

You took it wrong.. I said shift in the HP band for pulling and racing.. Will get you moving quicker.. AND all that was said for a stock pickup... not a moded one.. With tuning you can peak power and torque right above 2000 RPM and take it all the way to 3200.
Now there is no need to shift @ 2800 rpms to stay in the power band..

 

[Powerstroked162]

I'm out......

I'm not even in but I'm out too!


.

 

[Powerstroke Cowboy]

LOL

 

[Petro]

But it is the HP that get you moving faster... If you keep it in the max torque you will not take off as fast as keeping it in the max HP... Shift where your max HP is... IF you are racing or pulling.. If you shift where the torque is you will never be in the power band.

Torque is the lugging ability of the engine and HP is the acceleration of the engine..


There are no benefits with running high RPMs on a 7.3.. That is unless you have it built for sled pulling.. then RPMs are your friend

This is the way I see it also.

 

[Wes Lewis]

I thought it was the torque cure, but shifting at leak power does make more sense now that you say that

 

[85_305]

Let me break this down real simple. RPM does not equal HP. Torque time RPM\5252 = HP

On our motors after a certain number of RPM's, (relatively low unless you do a lot of work. All of it very costly) torque goes down as RPM's go up. Therefore as the RPM number gets larger, the Torque number gets smaller, usually smaller enough that the HP number also gets smaller.

It is not as simple as saying RPM's = HP.

Thanks for the break down and correction

Put ur wheels on a dyno and log 1500 to 4000 rpm. Alot of this info will make more since.

Very true

There is a reason that the 7.3l come from the factory limited to 3400 RPMs.

Right, but most vehicles come w/ governors or rev limiters... but as I posted earlier, lots of vehicles can make a lot more power over stock at much higher rpm's with no ill effects. I'm wondering why the 7.3 isn't one of those engines that can do this.

stock valve train. bent the first push rod in the winter driving down the road in a snow storm 1500rpm's... bent 7 more between 2500rpm's and 4000rpm's in the last couple years. .. all 8 pistons are cracked, and most have valve marks/indents in them... didn't even have a clue the pistons where cracked. took it in to the shop for comp 910 springs and had them take the heads off to go through the valves and make sure the valves weren't bent...

Wtf? How did a push rod bend just driving in the winter? Is that just the nature of these trucks?

rpm's for pulling, as in wheel speed? the way i learned the concept of tq and hp is tq gets it there hp keeps it there...

for those that need an image of the two together.... solid line is hp and dotted line is tq

live life full throttle

Thats a beautiful curve.... super flat...

I constanlty ask myself this question as I can change my WOT shift RPM.

Ive talked to Nate on what cc's my injectors flow at ____RPM/PW and realized there is no solid answer one tuner/mechanic can give me to the ideal RPM to shift at.

The best option in my opinion is to strap it to a dyno and see where she falls on her face and tune the shift to that rpm(slightly before)

If there is no power at 3800RPM why run it out that high ? Your truck us stock (mostly) so why the need to turn such a high RPM ? Ford slapped a sticker on the valve cover stating peak HP@____RPM. I believe its 2800.

OP, you are asking a question that has a combo of no right answer or 1,038,482 right answers.

Good thinking. Thats probably why everybody says to live tune these trucks because a shipped tune may shift too high/low for the truck.

thanks for the input so far everybody.

 

[Short Bus]

I see a fair number of upgraded motors get disassembled after failure have valve imprints on the pistons..... so take that for what its worth.... you'll never change the piston to valve or piston to head clearances inside a motor and if they are tight from the factory... yep you have contact..... if they are loose from the factory and you upgrade springs and keep the RPMs moderate... then you don't have contact....

My favorite picture to show in times like this is:

How close did that piston need to be that head so you could read the engraved marking on the top of the piston? It sounded smooth while running at idle.... it was disassembled because it popped a head gasket. This was a "built" motor assembled by a "racing" shop...... I'd have to go see if I still have the notes on this, but IIRC this clearance was right at the tight edge of factory, perhaps just a TOUCH tighter.....

Piston out of the same motor:

This motor had beehives in it with a well known camshaft.

ehh that engine looks familar, is it mine?

 

[Hotrodtractor]

ehh that engine looks familar, is it mine?

Yup. LOL

 

[Short Bus]

well then to clarify, i had NOTHING to do with the first assembly lol. That was all my machine shops doing!

 

[woodduck97]

85 305 How old are you? people have explained the same shat over and over maybe you need to go to PSN or something.

 

[85_305]

what does my age have to do with a good question that I cant seem to find much information on?

 

[woodduck97]

Well everyone has explained how many rpms it will run and why ok. It is just like this
http://www.youtube.com/watch?v=1E6IfdUJn6s

It just does.

 

[85_305]

And my question is not how many can they run, but rather why cant we spin 5-6k rpms like cummins, tdi's, and duramaxes can. Whats physically stopping these motors from producing those kinds of rpms.

 

[Hotrodtractor]

And my question is not how many can they run, but rather why cant we spin 5-6k rpms like cummins, tdi's, and duramaxes can. Whats physically stopping these motors from producing those kinds of rpms.

You don't see stock engines such as your examples spinning those RPMs unless its a moron blipping the throttle in neutral and you sure don't see the power range being usable there on any of those engines stock - some of those you don't see any usable power range there with electronics installed at all.....

 

[ChattyCathy]

And my question is not how many can they run, but rather why cant we spin 5-6k rpms like cummins, tdi's, and duramaxes can. Whats physically stopping these motors from producing those kinds of rpms.

Because it is old ****ty technology that sucks.

 

[85_305]

Because it is old ****ty technology that sucks.

lmao!!!

 

[woodduck97]

Because it is old ****ty technology that sucks.

And that is the exact reason!!! Old ****ty injection components that were not made to work at high RPMS!!!!

 

[Tim @ P.I.S.]

And my question is not how many can they run, but rather why cant we spin 5-6k rpms like cummins, tdi's, and duramaxes can. Whats physically stopping these motors from producing those kinds of rpms.

Fuel. With a twist.

Hardware can do it, Software cannot.

 

[golfer]

Hardware can do it, Software cannot.

hmm.

we're running the factory PCM with normal tuning software to run the CR 7.3L, FWIW

 

[Meniacal_Mark]

It's already been explained quite simply. If you want those kinda rpms you're gonna have to dump some $$$$$$ into it.