Max rpm our 7.3's can effectively turn

85_305

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So I realize that rpm=hp, and hp= a good thing... so with that being said whats the max safe rpm we can turn our 7.3's?

With my beans tunes, 1st gear will wind out to the redline (maybe 3800rpms? Dont exactly remember), which I'm told is being done because 1st gear is a reductor gear, but the following gears they shiftpoint is a little lower. I'm sure once I get trans mods and more fuel, the shift point can be higher.. but I feel that is another topic.

So what kinda rpm's can we turn in our 7.3's without an obnoxious amount of work done to the heads/internals? Does 4,000 seem reasonable? 4400rpms?
 

sniper_101

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Do you have any valve-train upgrades done?

edit - That is certainly one of the first issues to address. High rpm and boost will expose valve float and lighter valve spring's weakness' quickly.
 
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85_305

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Nope, I'm asking as a generalized question. I dont mean to say that I myself will be looking to spin more rpm's (at least, past the point of diminishing returns anyhow)... I'm just asking in general what do tuners like to spin, or what can they spin, to promote highest hp in the highest rpm possible.

If I can slap in some springs and spin 5k rpms while achieving higher hp, then I'd be a fool not to... but if the gains are minute or nonexistent in higher rpms, then this is merely a thought that I'm hoping somebody has answers to.
 

lincolnlocker

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you asking in general how many rpms a 7.3 can make regardless of mods? or how many rpms has been done safely with a stock motor.

live life full throttle
 

7.3psd97444

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I spin 4k on a daily basis. 5 speed, tyrant tuning, and, uh, thats it. Just whats in my sig.

Would I advise that to someone that doesnt want to hurt anything? No. Im either lucky or have a factory freak cuz my truck loves 4k plus RPM.

HEUI is slow. Which is why its easier said then done to get ALOT of rpms out of a 7.3 compared to a common rail equipped engine. You can safely spin 4k rpm wirth head work(springs, pushrods, ect.) And forged rods. I wouldnt want to on a PMR motor. But with an Automatic trans it depends on what you hve done there as well as tuning. 5 speed guys with the right tunes can spin whatever rpms they want/are able to do. Hence how ive hit 4500 before. If you want 5k rpm and you want it safely? Build the bottom end, and do a 5 speed swap.
 

under pressure

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Your not goin to achieve hp from rpms unless you build and tune everything to operate obove 3000 rpms.

Most lay down peak power before 3000 rpms, there are fewer making sustained power above 3000 and fewer even beyond that. Dedicated competition trucks are usually where this info is talked about from what ive read. 4000 to 5000 rpms

You could probably discuss this with 400 nozzles and 3800 icp at 3500+ rpm. (im guessing)
 
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golfer

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just because you can spin x000 rpm, doesn't mean you're going to make any appreciable hp...air flow (head flow) is the big restriction based on your constraints (..." without an obnoxious amount of work done to the heads/internals...")

just watched one of our dyno videos...datalogged 6050rpm.

but, you won't be 'computer/chip' limited at 6000rpm...if that's what you're asking...
 

7.3psd97444

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just because you can spin x000 rpm, doesn't mean you're going to make any appreciable hp...air flow (head flow) is the big restriction based on your constraints (..." without an obnoxious amount of work done to the heads/internals...")

just watched one of our dyno videos...datalogged 6050rpm.

but, you won't be 'computer/chip' limited at 6000rpm...if that's what you're asking...

:joy::):joy: I can only imagine what that sounds like
 

85_305

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you asking in general how many rpms a 7.3 can make regardless of mods? or how many rpms has been done safely with a stock motor.

live life full throttle

I'd be interested in both.. using HEUI, of course. I know w/ mechanical/CR injection anything is far game.

I spin 4k on a daily basis. 5 speed, tyrant tuning, and, uh, thats it. Just whats in my sig.

Would I advise that to someone that doesnt want to hurt anything? No. Im either lucky or have a factory freak cuz my truck loves 4k plus RPM.

HEUI is slow. Which is why its easier said then done to get ALOT of rpms out of a 7.3 compared to a common rail equipped engine. You can safely spin 4k rpm wirth head work(springs, pushrods, ect.) And forged rods. I wouldnt want to on a PMR motor. But with an Automatic trans it depends on what you hve done there as well as tuning. 5 speed guys with the right tunes can spin whatever rpms they want/are able to do. Hence how ive hit 4500 before. If you want 5k rpm and you want it safely? Build the bottom end, and do a 5 speed swap.

Yes thats true heui is a very slow injection method... do you hit 4000-4500pretty easily? Or does it seem to be wheezing at that point

Your not goin to achieve hp from rpms unless you build and tune everything to operate obove 3000 rpms.

Most lay down peak power before 3000 rpms, there are fewer making sustained power above 3000 and fewer even beyond that. Dedicated competition trucks are usually where this info is talked about from what ive read. 4000 to 5000 rpms

You could probably discuss this with 400 nozzles and 3800 icp at 3500+ rpm. (im guessing)

Why 400 nozzles? Smaller window at 4000rpm+?

just because you can spin x000 rpm, doesn't mean you're going to make any appreciable hp...air flow (head flow) is the big restriction based on your constraints (..." without an obnoxious amount of work done to the heads/internals...")

just watched one of our dyno videos...datalogged 6050rpm.

but, you won't be 'computer/chip' limited at 6000rpm...if that's what you're asking...

True, I've heard the heads on the 7.3 are abysmal . Combined with the slow injection even due to heui...
 

7.3psd97444

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I'd be interested in both.. using HEUI, of course. I know w/ mechanical/CR injection anything is far game.



Yes thats true heui is a very slow injection method... do you hit 4000-4500pretty easily? Or does it seem to be wheezing at that point

It jumps up to it like its not even a problem. Most of the time its when the tires break loose. Banging through gears under load accelerating ive only been able to hit about 3600.

Why 400 nozzles? Smaller window at 4000rpm+?

I think he was jsut giving an example.

True, I've heard the heads on the 7.3 are abysmal . Combined with the slow injection even due to heui...

...
 

under pressure

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Why 400 nozzles? Smaller window at 4000rpm+?

Big nozzle is the only way to get the fuel out in that window. Especially 3500+ rpm

Big, 200/300/400 and beyond, the more nozzle you have, the more fuel you can push into the ever shrinking injection window above 3500 rpm and continue to to make power.
 
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85_305

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Sure makes sense to me.

So is 4,000rpms a relatively safe rpm for these motors, assuming you have the proper fueling and timing for those kindsa rpm's?
 

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