How to Determine Drive Pressure?

[EliSweet2202]

So I have a 01 cummins its pretty much stock other than I have a 62/68/12 with a quadzilla on level 4. I currently have the defueling setting set to 35 pounds because I am on stock bolts but I just learned that drive pressure also affects the head gasket and the ratio needs to be 1:1 correct me if I'm wrong but that's what I've read. How do I figure out what that pressure is at and how do I fix it? In the future I do plan on doing 7x0.12 SAC injectors, DAP valve springs, Hamilton Extreme Duty pushrods, and ARP head studs. Whenever I go to do all this I also want to pull the head and get it surfaced and ringed if ringing is needed. 

[Dieselfuture]

Need a hole in exhaust manifold next to the egt probe if you have one, before the turbo. Some go 1/8 some go 1/4 supposedly 1/4 doesn't plug as fast, some put filters in too. Then pick copper, ss, break line etc for tubing to cool the line before you connect to plastic that goes in the cab. May need something to dampen exhaust pulses, like snubber or needle valve.

Look at Manton pushrods site for valve train stuff.

[EliSweet2202]

So Is this a gauge that I have to keep permanently? I already have a second port in my manifold that I can pull my EGT probe.

[Silverwolf2691]

At your boost level, I wouldn't sweat it, unless you get the crazy idea to start trying for 60+ psi.

 

Drive to boost should be 1.2:1 or lower for best efficiency I believe. I think that because I remember reading that the HE351CW or VE causes up 2:1 drive to boost because of the small exhaust housing. like @Dieselfuturesaid, you would need another hole to attach some line or a sensor to. Although the attached photo is a creative way of doing the setup. The coil is needed to cool the gasses down so you don't melt anything. So yes you would need a permanent gauge. 

 

Fixing drive pressure is either a wastegate or larger turbine housing. Again I don't think you should have anything to worry about.

 

As for your head, get it entirely rebuilt while you are getting it machined. If I had to say any upgrades while its out, top hat valve seals and don't forget the valve guides. Made that mistake, now the head has to come off again.

 

Go with o-rings not fire rings if you are going down this path, unless you are going to like 80+ psi.. 

 

Just gonna ask, why do you want to take the head off? Is the gasket bad? Reason being, the head is very heavy (150lbs), and just taking it off to take it off is not advised..          

 

[Mopar1973Man]

I'll be the first to admit reaching 50 PSI of boost on a 12 cm2 housing is bad and blew my head gasket. On top running 29 degrees @ 3k.

 

Even with studs I'm limited to 35 PSI now till I can get a bigger turbo and a in line exhaust brake. But the side effect of my setup is 28.04 Highmark MPG. 425 miles on a half tank.

Edited September 24, 2021 by Mopar1973Man

[Threadzy]

@Mopar1973Man wouldn’t having a bigger turbine wheel help? Your turbo is 60/60/12? 

[Mopar1973Man]

Yeah but need to replace the exhaust brake because I have to keep the stock turbine housing. So it close to 2500 dollar upgrade needed.

Edited September 24, 2021 by Mopar1973Man

[Threadzy]

Couldn’t you mill yours out and buy a 67mm turbine wheel? Or do like I did and buy one milled already with the bigger wheel. Much cheaper. Or am I misunderstanding you? 

[Mopar1973Man]

I would better to change the full turbo and exhaust brake reducing more restriction. Get away from the exhaust brake limitations of the turbos that only fit my set up. 

[EliSweet2202]

@Silverwolf2691 So the head gasket is good as far as I know I went a little high on the boost when I got this tuner without realizing lol. Anyway I just wanted to put a new gasket on it for preventative maintenance along with getting the head ready to handle the power I'm throwing at it.

[Dieselfuture]

On 9/24/2021 at 9:52 AM, Mopar1973Man said:

I would better to change the full turbo and exhaust brake reducing more restriction. Get away from the exhaust brake limitations of the turbos that only fit my set up. 

It's too bad this place closed down or at least it says that on line 

https://www.google.com/search?q=North+American+turbo&oq=North+American+turbo&aqs=chrome..69i57j46i175i199i512j0i512j0i22i30l2.1528j0j7&client=ms-android-google&sourceid=chrome-mobile&ie=UTF-8

I'm happy with the turbo I got from them for $800 62/67/12 still able to use exhaust break with 5 bolt flange. I'm keeping it at low 40 psi on max setting to stay safe, and most of the time I don't really get over 30. 

Maybe someone else can build something similar for you, unless you going to put in a bigger turbo and then get an in line EB which would probably cost more then just building a turbo for 800 and using what you already have.

[Threadzy]

I’m extremely happy with mine as well. I got all my parts to build mine from flea bay. Most parts are Turbo lab. I also drilled  out the wastegate to 7/8” both sides are gated now. My Pacbrake down pipe is a true 4”.  If it was a toy and not my DD and workhorse and had the extra coin I would have gone with a GXE style turbo. I’ve also read the in-line exhaust breaks aren’t as efficient as the turbo mounted.  

[Mopar1973Man]

1 hour ago, Threadzy said:

I’ve also read the in-line exhaust breaks aren’t as efficient as the turbo mounted.  

 

Yeah but limits selection of replacement turbos being there is very few than can accept a turbo mount exhaust brake. 

[Silverwolf2691]

On 9/24/2021 at 8:25 PM, EliSweet2202 said:

Silverwolf2691 So the head gasket is good as far as I know I went a little high on the boost when I got this tuner without realizing lol. Anyway I just wanted to put a new gasket on it for preventative maintenance along with getting the head ready to handle the power I'm throwing at it.

 

If its not leaking, I wouldn't touch the head beyond putting head studs in. You can replace them in one at a time.

 

To be honest, I'm (personally) on the fence with your situation. I've seen people with just threading studs in one at a time go and push 60+ with a much bigger turbo. But with my Edge EZ and 50s (7x008) I was doing 30-35 psi when I romped on it, with an HX35. Smaller to yours in every way except exhaust housing size (and even then.. but that's a turbo theory discussion for another time). I never put studs in until my head gasket started weeping out the side in the semi usual spot and had to swap it..

 

7x012s (250s ± 50hp) and a 62/68/12 are a solid but very hot 500-550hp combo, possibly higher. What are you doing with the truck? If towing heavy all the time id suggest a slightly smaller set of injectors. If hot rodding around, by all means run them. Just to put this out there too, you could also run a much larger turbo with 250s.. 64.5/73.4/12, smaller 66 turbo, 64/68/14, and similar. The 62/68/12 is geared more towards 100-200hp injectors. I also know that the 62/65/12 is a well liked turbo and pairs really well with 150s. @Mopar1973Man is running them with a 60/60/12 HX35/40 hybrid, and can blister the tires in multiple gears...

 

Not trying to dissuade you from doing what you want to do, just wanting to make sure you don't have a hot, smoky, worse mpg mess than when you started. 

[EliSweet2202]

2 hours ago, Silverwolf2691 said:

 

If its not leaking, I wouldn't touch the head beyond putting head studs in. You can replace them in one at a time.

 

To be honest, I'm (personally) on the fence with your situation. I've seen people with just threading studs in one at a time go and push 60+ with a much bigger turbo. But with my Edge EZ and 50s (7x008) I was doing 30-35 psi when I romped on it, with an HX35. Smaller to yours in every way except exhaust housing size (and even then.. but that's a turbo theory discussion for another time). I never put studs in until my head gasket started weeping out the side in the semi usual spot and had to swap it..

 

7x012s (250s ± 50hp) and a 62/68/12 are a solid but very hot 500-550hp combo, possibly higher. What are you doing with the truck? If towing heavy all the time id suggest a slightly smaller set of injectors. If hot rodding around, by all means run them. Just to put this out there too, you could also run a much larger turbo with 250s.. 64.5/73.4/12, smaller 66 turbo, 64/68/14, and similar. The 62/68/12 is geared more towards 100-200hp injectors. I also know that the 62/65/12 is a well liked turbo and pairs really well with 150s. @Mopar1973Man is running them with a 60/60/12 HX35/40 hybrid, and can blister the tires in multiple gears...

 

Not trying to dissuade you from doing what you want to do, just wanting to make sure you don't have a hot, smoky, worse mpg mess than when you started. 

So it doesn’t tow very often maybe a couple times a month nothing heavy 6,000 to 7,000 pounds. I’m wanting it to be at if I ever needed it to tow heavy across town or state it wouldn’t struggle doing it and it to be fairly quick around town. A couple of guys I talked to recommended the 7x012 Sacs to conserve the vp44 with using less wire tap. I’ve always thrown the Idea around of running compounds around using my old hy35 or maybe a milled hx35. I wouldn’t really need them other than to say i have two turbos and my hy35 is just sitting collecting dust needing a rebuild. 

 

I may go ahead and do the studs one by one I wasn’t sure if the head was another weak point for the 24v. I think if I do lift the head in some way I’ll just go ahead and ring it and have work done to it. That being said if I were to lift the head while being studded can I reuse the studs or do I have to buy new ones?

 

I do appreciate all the information and ideas I know with some of these other forums not very many people go into detail and explain everything. I’ve had this truck for a couple years and it being my first vehicle I’d hate for it to blow up doing something preventable. I really want to get it pulled it and cleaned up from its oil bath but I don’t have the room and I think I’d end up rebuilding it since it is out which isn’t ideal right now.

[Silverwolf2691]

The only "weak" part of the head is right around the thermostat housing. Large majority of us on here and other forums have had the head gasket fail there.

 

If you can lift the head with head studs you are way outside of working pressures.. 

 

7x012s while they would do what you are implying, would probably not clean up and run very warm with that turbo, unless you pull them way way way back in canbus but you might run into a pulling way to much power to keep smoke down that you loose the benefit of the bigger injectors.. 

 

The smaller injectors would also help keep egts down while towing. Compunds are an option if you are dead set on the 7x012s.. they will help if you want to use the full amount of fuel 7x012s have

[Dieselfuture]

3 hours ago, EliSweet2202 said:

That being said if I were to lift the head while being studded can I reuse the studs or do I have to buy new ones?

Yes.

Just put in studs for now and deal with the hg and the head later, because it all adds up depending on how much work your head needs. Maybe spend some money on springs and push rods for now. At some point in future you won't have to buy all these parts and can spend money on the head and whatever else. 

Like stainless diesel exhaust manifold  already has holes for egt and drive pressure  and they claim you can gain up to 20hp  and turbo responds better, plus it'll last forever. I've been looking for a used one for a while now, may have to just buy it one of these days. That's the great thing about not having payments like rest of the people I know, they make fun of me because I'm always spending little bit here and there but overall they don't seem to see the big picture on how they spend 500-800 a month and I might spend 1000 a year and most of the time it's for something I want not need, like new dash or air bag controls, stupid stuff that I can get by without. Just figured if I spend a little at a time it'll still be worth keeping and be somewhat reliable, which I can't say for many newer vehicles.