Twin turbo CRD

diesel_guy86 · **Posted:** Thu Sep 26, 2019 8:46 am

Thought I'd start a post to show a project im working on. This isn't my crd, I'm only doing the turbo portion of it. We're "starting" at 300hp, but figuring some overhead to go higher. The turbo system is capable of 300-400hp without leaving its 77% efficiency island.

Turbos will be my standard crd upgrade turbo but equipped with a titanium compressor wheel to more reliably cope with the >250°F air that it will be sucking in. Over that will be a Garrett GTX2871R that i have custom tailored with tighter clearances for higher efficiency, as well as full complement ceramic hybrid bearings that are far superior to the steel bearings it came with.

Working on designing a new exhaust manifold for higher flow. This will place the factory turbo higher, and out more to make pipe routing easier and more efficient. Manifold is figured out, but still in design stage at this point. It will be a stainless billet piece, machined from 2 halves and then welded together. The turbo flange part will be "modular" lets say. Meaning the manifold will come blank, and a custom made flange will bolt on that will let you adapt whatever turbo you want to run.

Injectors will be atleast 45% over, may go 50-60% depending on what's available.

I believe the engine will be getting all proper machine work done, head decked and studded etc. A rod has been sent to Carillo for them to make us some bulletproof rods. The balance shaft assembly will be deleted and the rotating assembly balanced. Pistons may or may not be ceramic coated, that is up to him. There will be enough air available to keep egts down, so technically they shouldn't need the added protection, but we all know we should always double wrap our pistons.

Last on the list is intake. The factory job sucks. Ive been studying it here and there, and it looks like i should be able to machine off the entire intake portion. From there a better designed intake manifold/ runner assembly will be welded on.

I have pics of the project already underway. I just need to find an image hosting site that works. Photobucket is dead, and imageshack won't let me upload pics.
If you are on Facebook, search Blackbird Innovations, give it a like and you should be able to see the current progress so far. I realize not everyone has Facebook, so if there is a good image hosting site, please let me know.

TKB4 · **Posted:** Thu Sep 26, 2019 9:11 am

Imgur is a good hosting site.

Keep up the great work !!!

diesel_guy86 · **Posted:** Thu Sep 26, 2019 10:40 am

The turbo outlet vband flange is extra thick, meaning there isn't an aftermarket option available. so i had to make my own. This is just a prototype, the next ones will be shorter, and done on cnc.

Next i needed a new flange so i could mock up the turbos new location. I ended up cutting it out of 1/2"

Here's a shot of how the turbo will sit. Actually, I've changed it, and it's now parallel with the head, instead of angled down like this.

Mock up tube only! This is just for checking clearances in the engine bay. The final product will probably end up being tighter, i want it to be as "loose" as possible to keep flow as smooth as possible.

WWDiesel · **Posted:** Thu Sep 26, 2019 11:55 am

Looking good and looks to be well thought out!
Just not sure how long this little engine can handle two turbos? One seems to tax it if boost is turned up.
How you going to get the ECM to handle/read the much higher boost levels, different MAP sensor?
If I turn the boost up on mine much above 28, it will throw it into a limp mode. I presume the MAP is running out of the upper end of the scale? :banghead:

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

I do seem to recall it's a 3 bar MAP sensor, which is pretty typical for production cars.

I'm always excited to see compound turbo setups but IME they are pretty rare on small displacement engines.. It'll be very interesting to see how this turns out!

diesel_guy86 · **Posted:** Thu Sep 26, 2019 1:11 pm

My engine survived for 50k miles at boost levels over 30, but to honestly answer your question, i don't know. I don't know if anyone knows, but we'll find out. I meant to add, the new exhaust manifold will have a wastegate to bleed off any excess exhaust pressure and bypass it around the factory turbo, which should help keep drive pressure ratio close to what it is normally. It might even be better with the better flowing manifold.

We've already installed and scaled a 4 bar map sensor. This will read to 44psi of boost, but will still need a boost gauge since the obd won't show boost past 21-22psi.

Lots and lots of math, followed by some experience, was used to size this system. So im pretty confident in how this compound system will behave. It will be 100% streetable and work great for towing, although the jeep this system is going in isn't being built to be daily'd

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Was that "survived 50k" because it then exploded, or because you sold it or took it apart? If explosion, what was it that failed? Were you doing this on a stock fuel pump? I'm just curious... My CRD is the first turbodiesel I've owned!

WWDiesel · **Posted:** Thu Sep 26, 2019 3:15 pm

diesel_guy86 wrote:

My engine survived for 50k miles at boost levels over 30, but to honestly answer your question, i don't know. I don't know if anyone knows, but we'll find out. I meant to add, the new exhaust manifold will have a wastegate to bleed off any excess exhaust pressure and bypass it around the factory turbo, which should help keep drive pressure ratio close to what it is normally. It might even be better with the better flowing manifold.
We've already installed and scaled a 4 bar map sensor. This will read to 44psi of boost, but will still need a boost gauge since the obd won't show boost past 21-22psi.
Lots and lots of math, followed by some experience, was used to size this system. So im pretty confident in how this compound system will behave. It will be 100% streetable and work great for towing, although the jeep this system is going in isn't being built to be daily'd

Two questions; how did you get to over 30 boost levels with stock MAP? :shock:

You stated: "It is an absolute pressure sensor, not gauge pressure. It reads from absolute 0, or -14.7psi at sea level. So maximum boost it can read is 29.4 gauge pressure."
Please tell me more about the 4 bar MAP sensor. Is it sill scaled the same on the low end and how does the temperature bulb readings compare along with all the other parameters?
Very interested and I do have a mechanical boost gauge.
Is it a simple change of the MAP sensor and if so what is the PN?

flash7210 · **Posted:** Thu Sep 26, 2019 3:34 pm

Quote:

how did you get to over 30 boost levels

I’ve gotten to 28-29 psi boost by wiring in a circuit that allows me to “fool” the MAP sensor.
But it usually causes a underboost code when at light throttle.

Gotta say, I’m not a fan of compound turbos. Usually means twice the lag.
But I guess they do have their place. (tractor pulls come to mind)

Now, dual sequential turbos are cool but the modern VNT kinda made that obsolete.

However I am interested in a improved high flow exhaust manifold.
Tubular header pipes maybe?
It’s ok if the turbo has to stick up through the hood.
I kinda like that look

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

Shouldn't a compound turbo reduce lag for a given cfm? Isn't that the point?

flash7210 · **Posted:** Thu Sep 26, 2019 5:26 pm

thesameguy wrote:

Shouldn't a compound turbo reduce lag for a given cfm? Isn't that the point?

It’s more like a 2 stage air compressor.
First turbo compresses the air. Second turbo compresses it even more.
One turbo feeds another turbo.

Twin sequential turbos were meant to reduce turbo lag by having a small turbo that functioned at a low rpm and a large turbo that functioned at a high rpm.

diesel_guy86 · **Posted:** Thu Sep 26, 2019 5:27 pm

"Survived 50k" and then smoked a deer and was totaled lol.

WWDiesel, i deleted the factory vnt turbo and installed a Garrett GT2860R. So all the vnt tables were ignored, any sort of under/overboost cel was ignored, and it was back to just a normal diesel engine. Except it was a large turbo for this size engine so the low end torque that make these engines so nice was sacrificed. However i was able to get to 270hp. I will look for the 4 bar map sensor. Masshole is there one who did it, he would be able to answer the tuning questions.

Flash, a properly designed compound setup should have a 0 difference in lag compared to stock. But alot of people think "bigger turbos are better" and then suffer lag. This system is still using the factory turbo, so lag will be the same. In fact this is beneficial in getting the low pressure turbo to light. The sooner the engine can make power and develop excess exhaust energy, the sooner the lp turbo will spool.

Thesameguy, the purpose of a compound setup is to be able to supply the amount of air needed (lbs/min) at the pressure needed, while retaining more ideal spool characteristics. When you start needing to make big power, the amount of boost needed goes up, and can exceed what a single turbo can efficiently produce. With a compound setup, the pressure is split between both turbos, making their life much easier, essentially they are both doing half the work.

WWDiesel · **Posted:** Fri Sep 27, 2019 2:55 am

For you techies, this is a very good video on VV turbo performance by Gale Banks. It's not on our turbo, but the basics are the same.
It gets a little deep, but very good food for thought and worth the time to watch.

https://www.youtube.com/watch?v=FZahZTZFN7I

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

diesel_guy86 wrote:

Thesameguy, the purpose of a compound setup is to be able to supply the amount of air needed (lbs/min) at the pressure needed, while retaining more ideal spool characteristics. When you start needing to make big power, the amount of boost needed goes up, and can exceed what a single turbo can efficiently produce. With a compound setup, the pressure is split between both turbos, making their life much easier, essentially they are both doing half the work.

Yep, exactly. "More lag" should not be a characteristic of a compound turbo... less lag while still winning big boost is exactly what compound turbos fight!

diesel_guy86 · **Posted:** Fri Sep 27, 2019 11:52 am

Banks puts out awesome stuff. He doesn't just show you what's better, but he explains why. My favorite ones are the ones dealing with density, 99% don't understand it and think that boost is what makes power.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

flash7210 wrote:

Twin sequential turbos were meant to reduce turbo lag by having a small turbo that functioned at a low rpm and a large turbo that functioned at a high rpm.

Yes, but we all know that didn't work out. *cough* FD RX7 *cough cough* MkIV Supra.

Variable geometry, variable nozzle, twin scroll, ball bearing et al technology made sequential turbos obsolete decades ago. The result is definitely not worth the complexity.

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

diesel_guy86 wrote:

Banks puts out awesome stuff. He doesn't just show you what's better, but he explains why. My favorite ones are the ones dealing with density, 99% don't understand it and think that boost is what makes power.

Boost makes mad power, yo. :BANANA:

flash7210 · **Posted:** Fri Sep 27, 2019 12:43 pm

thesameguy wrote:

flash7210 wrote:

Twin sequential turbos were meant to reduce turbo lag by having a small turbo that functioned at a low rpm and a large turbo that functioned at a high rpm.

Yes, but we all know that didn't work out. *cough* FD RX7 *cough cough* MkIV Supra.

Variable geometry, variable nozzle, twin scroll, ball bearing et al technology made sequential turbos obsolete decades ago. The result is definitely not worth the complexity.

Yes.seemed like a good idea at the time.
VNT works better.

I guess I’ve never driven a truck with a properly set up compound turbo.
One of the work trucks is a Powerstroke with a compound turbo.
The lag is significantly bad.

diesel_guy86 · **Posted:** Fri Sep 27, 2019 3:36 pm

Your probably experiencing dead pedal. Seems all newer diesels have that now. In fact its so bad "pedal commanders" have come out that increase the throttle sensitivity. They help, but a new tune works the best.

diesel_guy86 · **Posted:** Mon Nov 04, 2019 12:44 pm

Credit goes to masshole for doing the CAD work, he is awesome.
This is one-half of the new exhaust manifold we're designing. Much better flowing and will have a T3 outlet flange, it can be adapted from there for whatever turbo someone wants to put on. Will be machined from stainless, and then welded together.

Twin turbo CRD

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