I have been following a number of threads here about building power in a 7.3 and don't seem to see a clear answer about the following.

In the world I live in nothing comes for free. Some folks here have invested fairly large sums of money in their engines to build power either to tow or just for fun. If larger turbos, injectors, and tunes, among other things enter the picture, other components have to carry the load that increased horsepower and torque places on them.

Everything has a limit and I know in theory, it is about 500 horse from the reading I have done, but surely there is some negative before that point. Inquiring minds want to know.

Steve

 

Actually - somewhere above 400 HP is the line in the sand. After that, you need mods to the block - studs, valve springs, upgraded head gaskets, etc.... I have read many horror stories when chasing 500 HP. Many give up on the truck... but not before melting the Buck$Zooka from overuse.

I'm no expert on metallurgy, nor do I have years of experience with racing motors - but I can share what I've learned to-date. 400 HP seems to be a nice target that offers plenty of permagrin, without the headache of bending stuff. Even the PMRs are rumored to handle this power level without issue - if tuned appropriately.

 

All the researched I have done for my 02 shows the main weak point for our 7.3 (99-03) are the powdered connecting rods vs the forged connecting rods on the OBS trucks. I believe once you get past 425hp its not if but when you'll through a rod. Then there's your tranny but that's another chat.

My plan is to make a stronger tow rig that'll still get me to 3/4 million miles (at least). My hp I'm aiming for is the 380 - 400 range. I plan on going in stages and dynoing after each stage to get her all dialed in.

 

I hope you will post the dyno results. I would really like to see the difference specific changes make. I suspect you will reach diminishing returns quickly after the first couple of steps. I question aftermarket component manufacturers claims as well as the potential placebo effect that comes along with purchasing a mod.

Steve

 

Not so much with the diminishing returns. There is a lot of preliminary work that needs to be done before adding the 400 HP fuel. During the prep, you see moderate, small, or no gains (think transmission upgrade). Once every thing is in place, then you unleash the beast to execute a huge lunge. This could be the bigger tune for your already-acquired big sticks, or simultaneous big sticks and tune.

It's like getting the drunk after the hangover.

 

Thinking more along the lines of once you get to 300 horse, how much does it cost to get to 350 and then 400?

 

I already have my new transmission picked out which I'll replace when mine kicks the bucket. My next step well be a tune , 4" turbo back and rebuild my turbo (seals, brass 360 degree thrust bearing, ect) with a billet wheel, 1.00 A/R turbine housing and a adjustable wastegate probably all from BD Diesel. I'm not expecting a big jump in hp I'm more looking for better response and keep her burning clean. Next stage and will probibly be my last will include stage 2 injectors (160/80) single shot..?.. split shot.. still unsure, a beefed up HPOP,Thruster II Turbo GTP38 Performance Edition with this bad boy by BD Diesel, new high performance intercooler and a tune to maximize everything with minimum smoke.

Other upgrades that'll get done
-regulated fuel return
-oil cross over or just removing the check springs
-Aluminum radiator (when the stocker wears out)

I'm curios to see the dyno results too bad I just can't do it all right now! haha


2002 7.3 F350 CC/SB 6.0 tranny cooler, 6637 filter mod

 

Steve, my goal is to be just south of 400 HP at around 380-390 as my sweet spot for towing heavy and daily driving in the future.

I knew this is where I wanted to be and specifically looked out for the truck we ultimately bought. Which is a 2000 with forged rods and a ZF6 manual transmission. Right off the bat, the transmission and the rods can handle what I throw at it in regards to power.

I am building a strong and reliable truck the right way. I made sure the truck was 100%, then built on from there ensuring that whatever I just completed to add power or add longevity, its counterpart mod was completed as well.

Just with the modifications/improvements I have already done it is a completely different truck. I look forward to it being even better and my happy place will be with 160/80 injectors and a KC38R turbo. After that, it will be monitoring and maintenance from there on out.

 

I have followed your build. The point at which I am stuck and there is no good answer is how much to throw at a 15 year old truck. I was hoping to see how much changes step-wise actually bring to the table. I am thinking the most conservative way is to start with an exhaust system. I am going to look around and see if there is a local dyno and how much it costs to use it.

I expect even a bump to 300 horse would be easy to feel, but I am not convinces that just tunes will do that. As I am sure you figured out by now, I am data bound.

 

Yes, just tunes will get you up and over 300 HP on a stock truck...and it is really easy to feel it and smile really big.

But it comes at a price on a stock truck. The turbo and the transmission will be the first casualties.

Making 400+ HP is not for the irresponsible, impulsive owner. All that power, misused, has cost a lot of owners a lot of money.

I built my X one step at a time. A little one year, a little more the next year, etc. Took me almost 5 years to get to the signature I have now. It doesn't get driven hard (my wife drives it 90% of the time), but when we need to merge on the highway we can merge! If we need to pass something quick, we can. We can pull trailers like there is no tomorrow with no EGT concerns. It is a lot of fun to have the power. Takes discipline not to abuse it and cost yourself more money.

 

The way I see it is this. I have built my truck up to a point where it is a very capable machine. Although, I strive for easier and cleaner power with the upgraded injectors and turbo the cost is minimal compared to what a new-ish diesel truck costs. I have about $16K total into my truck as it sits today, and that is a far cry from even a 2011 first gen 6.7 diesel.

That is not to say that the truck around the engine and transmission is not falling apart, or will require maintenance. Although, I bet a hub for a 2000 F-250 is much cheaper and easier to install myself than a hub for a 2016 F-250.

I love my truck. When I go out to start it up, I smile and even at idle it sounds like a diesel truck should sound. To each their own, but I plan to drive my truck either until the government takes is from my cold, dead hands.

An exhaust is a good start, what do you have for an intake? AIS or S&B are good choices if you have not upgraded that. A billet turbo wheel can make a big difference in performance and a fresh turbo rebuild is only ~$60 for peace of mind.

A Hydra tune of your flavor is a great way to unlock all sorts of potential, even in a stock truck. Not to mention additional features like high idle and no start.

In my opinion Steve, a dyno is wasted money that could be put toward other areas. I really don't know what a dyno cost, but you could probably get the turbo rebuild kit for the same price. To me, my own personal opinion is that I don't give a damn what HP rating I can pull on the dyno. What I care about is drivability of the truck when not towing and towing performance or ease of moving the trailer from one place to another no matter the distance.

An example of this is the OUO traction bars. A lot of people buy them because they want to lay down rubber, roll coal or whatever. I had axle wrap even when the truck was unloaded. The OUO bars for me were not a performance upgrade, but were a force multiplier because I can now apply throttle as a natural movement instead of trying to coax the load forward.

To each their own Steve, only you know what is right for you, your truck and your family. We are only here to help you make informed decisions, just like you have helped me with our trailers so many times in the past.

 

The AIS can handle anything stock injectors/turbo throw at it, but it needs the fender mod to handle the tuner and 4" exhaust. Once you change the sticks and/or turbo, that AIS is outta there.

4" exhaust, better intake, and red line mod allowed me to get up to 22 PSI boost on stock tuning - and it let that gratifying whistle out of the pipe. That is a fantastic place to start (assuming the rest of the truck is 100% and the money isn't needed elsewhere) - because these mods are coming anyway.

I hear the part about being responsible with 400 HP in 8000 pounds of crabbing steel, glass and rubber. Once you have this power level, it is strictly an outside toy - no nearby traffic allowed (except when passing):