Mitsubishi 4D34-2AT3B diesel swap into 96 FZJ80

[rain76king]

Jealous!

 

[SuperHatch]

Just got 21.6MPG with the new 37s and stock gears still.

Also just installed my turbo upgrade. It is a MHI 20G with a TD06 compressor cover hybridized with a TD05 Turbine Wheel, allowing me to retain my stock turbine housing. The turbo cost me $400 shipped freshly rebuilt. Some differences to note. The new CHRA is both water cooled and oil cooled, I did not plumb in the water cooling, although I might someday. Also, the oil food is a M12x1.25 banjo fitting as opposed to the stock M10x1.25 banjo fitting. Drains are identical.

I also decided to further modify the turbine housing to facilitate the installation of a TiAL 38mm external wastegate.

First pic is getting read to pull the old turbo.

Second pic is the 20G CHRA in the housing (verifying fitment before pulling it)

Third pic is the two CHRAs side by side.

 

[SuperHatch]

First pic is the two turbos side by side with the compressor housings installed. Yes, I painted it red to match my intake manifold.

Second pic is my turbine housing modded to fit the wastegate. Sorry I don't have more pics of this, but my wife came in and snagged the good camera while I was working and I was stuck with my phone camera. I ported the exhaust manifold a bit and the turbine housing a bit, also ported the wastegate portion of the housing a lot. easily doubled the wastegate flow if not more. The stock wastegate is small, like 18-20mm, the flapper can only open 1/3 of the way before it hits part of the turbine housing, and the flapper door opens in a direction that blocks the flow of the exhaust gas. I was concerned that I might have too restrictove of a turbine housing for this size compressor, so the large wastegate should help prevent excessive exhaust manifold pressures and allow for more precise boost control. We'll see if it works well or if I wasted my money.

The third pic is the new turbo installed on the motor.

 

[SuperHatch]

Finished product, not bad. And the last pic is my hidden external gate.

First drive impressions? Barely any noticeable lag compared to the stock turbo. Hits a hundred or two RPM later, but hits harder. Only getting 15PSI of boost now, which is strange. Going to check for boost leaks at some point.

Do I need to add fuel to light off a bigger turbo?

 

[Dougal]

What are the wheel size differences between your old turbo compressor and new? Generally if you keep the same turbine and increase the diameter of the compressor wheel then you get more boost earlier in the rpm range (because the comp wheel has a higher tip speed).
But if you just go for a larger trim wheel, you get slower spoolup and the risk of surge.
If you need to add fuel to retain spoolup, then you have increased your EGT's throughout the range, this can be a big problem towing at at altitude.

There's no benefit to porting wastegates, on a diesel they are shut 99% of the time and when they open they only need to open a little to bypass a lot of gas. Why are you going for an external gate?

 

[SuperHatch]

Stock compressor is an MHI 14B Wheel with a 1.695" inducer and a 2.285 exducer.
Upgrade is a MHI 20G Wheel with a 2.070" inducer and a 2.680 exducer in a larger compressor housing.

Both turbos utilize the same TD05H turbine wheel with a 1.930" exducer and a 2.200" inducer.

I have not touched the fuel... my question was if I need to increase fuel to see more boost?

The larger compressor wheel is heavier than the stock wheel with a greater moment of inertia. It will take more work to accelerate it with the same input pressures and temperatures on the turbine side.

It is a fairly close minded statement to make that there is no benefit to porting a wastegate on a diesel. While the same rules of thumb don't apply as do gassers, there are tremendous benefits to a higher flowing more efficient wastegate. Reduced manifold backpressures when using small turbine wheels at high flow, reduced EGTs as a result, and better overall efficiency.

 

[Dougal]

Yes you can always expect more lag with the bigger wheel, but under steady state you should get boost at least as early as you did earlier.

It is an informed statement that there is absolutely no benefit to porting a wastegate. None.
The wastegates job is to control boost by controlling the pressure in the turbine housing. It only opens as much as it needs to and is never fully open on a low revving diesel.
Porting it has no impact on manifold pressures, EGT or overall efficiency. It's a bypass valve which is regulated by boost. Any attempt to lower manifold pressure via the wastegate will reduce boost.

There is a simple test to see if your wastegate hole is too small. Disconnect the wastegate arm and go for a drive.

 

[SuperHatch]

How many years did it take you to become as arrogant as you are?

Even a low reving diesel can create enough exhaust volume that a sufficiently small turbine housing can become an exhaust restriction.

 

[Dougal]

How many years did it take you to become as arrogant as you are?

Some people can read and learn.
Some people can be told and learn.
Some have to pee on the electric fence for themselves.

Even a low reving diesel can create enough exhaust volume that a sufficiently small turbine housing can become an exhaust restriction.

Yes, but a wastegates can only bypass that to cap boost, it cannot change the operating pressures. If you want to run at lower manifold pressures you need a larger A/R housing.
This is why variable geometry turbines were invented. Because wastegated housings cannot in any way mimick changing the A/R ratio of a turbine housing.

Porting wastegates is a waste of time. You can listen to me or you can measure your manifold pressures before and after (pee on the electric fence for yourself). It's your free time. Try it and get back to us.

 

[SuperHatch]

Some people can read and learn.
Some people can be told and learn.
Some have to pee on the electric fence for themselves.

And some people get to the point where they think they know so much that they:

Can't possibly learn any more
Assume everyone else knows nothing
Approach every situation with no intention of conversing, but rather to flex their mental muscles

Yes, but a wastegates can only bypass that to cap boost, it cannot change the operating pressures. If you want to run at lower manifold pressures you need a larger A/R housing.

I never stated anything contrary. My point, if you actually cared to know, was when you exceed the flow capacity of the wastegate. Exh Manifold pressure increases, boost exceeds the target, and you can overspin the turbine past it's design characteristics. This is when a larger wastegate is needed, not before.

This is why variable geometry turbines were invented. Because wastegated housings cannot in any way mimick changing the A/R ratio of a turbine housing.

Again, I never said they could, you can feel free to go back and reread my posts if you'd like.

Porting wastegates is a waste of time. You can listen to me or you can measure your manifold pressures before and after (pee on the electric fence for yourself). It's your free time. Try it and get back to us.

Again, not a waste of time.

Unless you actually care to carry on a conversation, I would appreciate you excusing yourself from this thread.

 

[Dougal]

I never stated anything contrary. My point, if you actually cared to know, was when you exceed the flow capacity of the wastegate. Exh Manifold pressure increases, boost exceeds the target, and you can overspin the turbine past it's design characteristics. This is when a larger wastegate is needed, not before.

You claimed lower manifold pressures, lower egt's and better overall efficiency. All of which are impossible to acheive by playing with wastegates.
The only way is to change the A/R of the housing. Here is exactly what you wrote:

It is a fairly close minded statement to make that there is no benefit to porting a wastegate on a diesel. While the same rules of thumb don't apply as do gassers, there are tremendous benefits to a higher flowing more efficient wastegate. Reduced manifold backpressures when using small turbine wheels at high flow, reduced EGTs as a result, and better overall efficiency.

Boost creep from exceeding the flow capacity of the fully open wastegate is something I have never seen on a diesel. This is why I suggested unhooking the actuator and going for a drive.

With 15psi max your wastegate isn't a problem and neither is turbo overspeed.

If you want to use labels like "arrogant", "close minded" and the like, it's best to understand the topic first.

 

[SuperHatch]

You claimed lower manifold pressures, lower egt's and better overall efficiency. All of which are impossible to acheive by playing with wastegates.
The only way is to change the A/R of the housing. Here is exactly what you wrote:

Boost creep from exceeding the flow capacity of the fully open wastegate is something I have never seen on a diesel. This is why I suggested unhooking the actuator and going for a drive.

With 15psi max your wastegate isn't a problem and neither is turbo overspeed.

If you want to use labels like "arrogant", "close minded" and the like, it's best to understand the topic first.

I have used the same stock turbo and the same upgraded turbo on gassers. On a 2.0L 4 cylinder engine. Ironically it uses the same turbo, stock. That engine revs to 7200 RPM and makes 10psi stock. That stock turbo was good for 15-18 psi, but at 18psi it was just a hair dryer.

On the 3.9L diesel, which revs to 3800RPM, that turbo made 10-11psi stock and made 15psi no matter what I did with the wastegate... Double the displacement, half the revs, same behavior, peaked my interest.

On the same 2.0L cars, the same upgrade turbo will make much more power, but will experience wastegate creep when trying to run lower boost at high RPMs.

This happens for the same reason I mentioned. A very small internal gate with an obstructed flapper.

Judging by the similar behaviors with the stock turbos, I made a preemptive strike with the external gate.

Now I know that EGTs differ between gassers and diesels, and I know that 4 high volume pulses at half the velocity will behave differently than small volume pulses at double the velocity, but not that much differently.

You can get big turbos on small gas engines to spool faster by retarding timing in the pre spool region to put more heat in the turbine.

This applies to diesels as well, but the problem is that I can only adjust timing by physically moving the pump due to the mechanical setup. I don't want to do this because of the impact to fuel efficiency and part throttle driveability.

That is why I spoke about adding fuel to light it off sooner.

 

[Pacer]

I was going to say something like: "Looks great SuperHatch, you have been doing you research, and diving right in.
I'd love to see a pic of the rig sporting thirty sevens "

Please put this to drama to rest gentlemen, you are both tremendous sources of tech and inspiration to the rest of us. Thank you for sharing your experiences and knowledge.

Let us know how she drives once you check for leaks.

Cheers,

 

[Dougal]

The biggest single difference between petrol and diesel turbocharging is the exhaust temperature. Diesels have to run smaller turbine housings for the same compressor size and the wastegate on a diesel is only open at near full rpm and full load. Even then it doesn't need to open much to regulate boost. The rest of the time it's clamped shut so there's nothing to be gained by playing with it.
I'm running my 4BD1T with no wastegate actuator.

The wastegate porting myth is unfortunately quite well entrenched on the internet. Despite the complete lack of supporting evidence.

 

[astr]

SuperHatch:

Don't let Dougal discourage you. I think you should go ahead and piss on the electric fence. Be sure to post up the results. Video would be good

Dougal:

Which method did you use to come to your conclusions - Read, listen, or the electric fence?

 

[Dougal]

Dougal:

Which method did you use to come to your conclusions - Read, listen, or the electric fence?

I have a highly instrumented electric fence, I use that to prove my ideas.

 

[SuperHatch]

I was going to say something like: "Looks great SuperHatch, you have been doing you research, and diving right in.
I'd love to see a pic of the rig sporting thirty sevens "

Please put this to drama to rest gentlemen, you are both tremendous sources of tech and inspiration to the rest of us. Thank you for sharing your experiences and knowledge.

Let us know how she drives once you check for leaks.

Cheers,

Thanks, plan on checking for leaks when I get home from work today.

The way it is now, it seems to come onto boost at the same RPM as before the upgrade, the difference is that off boost, EGTs are higher and it feels slower, on boost EGTs are lower and feels stronger.

The biggest single difference between petrol and diesel turbocharging is the exhaust temperature. Diesels have to run smaller turbine housings for the same compressor size and the wastegate on a diesel is only open at near full rpm and full load. Even then it doesn't need to open much to regulate boost. The rest of the time it's clamped shut so there's nothing to be gained by playing with it.
I'm running my 4BD1T with no wastegate actuator.

The wastegate porting myth is unfortunately quite well entrenched on the internet. Despite the complete lack of supporting evidence.

Understood...

Why is there are difference between gassers and diesels as to what a "safe" EGT is? Both engines typically have AL pistons and both have piston cooling jets. The diesels have larger sturdier pistons with a greater thermal mass, so why does it seem that 1200-1300* is the upper safe limit on a diesel and some gassers will say that 1600* is ok?

My assumption is because the diesels are usually at load for much longer periods of time than a car...

SuperHatch:

Don't let Dougal discourage you. I think you should go ahead and **** on the electric fence. Be sure to post up the results. Video would be good

Dougal:

Which method did you use to come to your conclusions - Read, listen, or the electric fence?

It doesn't discourage me, his comments continually challenge my thought process and force me to re-evaluate the decisions I've made.

The issue I have is simply with the delivery. I know, I know, grow a set...

 

[Dougal]

Understood...

Why is there are difference between gassers and diesels as to what a "safe" EGT is? Both engines typically have AL pistons and both have piston cooling jets. The diesels have larger sturdier pistons with a greater thermal mass, so why does it seem that 1200-1300* is the upper safe limit on a diesel and some gassers will say that 1600* is ok?

My assumption is because the diesels are usually at load for much longer periods of time than a car...

I think even though the petrols have a higher exhaust temp, the average cylinder temperature is about the same limit as a diesel. Petrols start with a cooler charge (cooled by evaporating fuel) and have lower compression so the difference between peak combustion temperature and exhaust temperature is smaller on a petrol.

Essentially, with lower compression you can run hotter exhaust temps without melting pistons. Modern TDi car engines are running over 800C and running compression ratios around 14-16:1.

 

[SuperHatch]

That makes perfect sense, thank you.

 

[Dougal]

Happy to help.