The 2H/12H-T/1HZ/1HD-T/1HD-FT Gturbo Alternative Tech Thread

[mudgudgeon]

Yeah, so turbines work by first choking and then expanding the gas through the blades.

Is this effectively accelerating the gas flow as it passes through the turbine? For lack of a better analogy, similar to a venturi effect?

the oversized exducer can explain the poor low end response. This is basically a turbo suited to a high rpm 2.0L petrol engine.

That was my thoughts too.

looking at their facebook page (can't find a web page), looks like drift cars is their main focus.
Sounds like they've missed the mark.

 

[Dougal]

@Dougal i agree with the high trim for sure .
Garret turbines arent my favourite for diesel use either, if that's what it is.

Waste gate setting can impact drive pressure depending how it is tuned .

It's possible to preload the wastegate actuator so much that it limits the gate movement . I see it when guys are trying to lower egts they pull fuel out, boost drops off because there's not enough energy to maintain turbine drive even though it's still revs to redline . So they crank up preload on the wastegate. Boost comes back up, Top end Afr's are lean, but top end Emp and egt are still high , it's a balance and it depends on many factors total cc/1000 how the timing is mapped, turbo makup, Inlet restriction ect

Normally the above scenario has decent spool though

But if the turbine side is incorrect for your vehicle your doomed from the start .
Re. Turbine design, Garret turbines are less forgiving than Borg Warner and mhi with diesels .

Yeah Garrett's main aftermarket is boosting high rpm petrol engines. Their catalogues often can't provide a good match for high boost and low rpm diesels.

 

[Dougal]

Is this effectively accelerating the gas flow as it passes through the turbine? For lack of a better analogy, similar to a venturi effect?

Yes, accelerates and chokes the flow in the housing then expands it through the turbine wheel.

 

[Mcreight911]

Food for thought emp management . My personal car runs a 10psi actuator and a boost controller . With the 10psi actuator and no boost controller I can get 15psi, with boost controller I get 26psi and drive pressure is never over 1.2:1

With a 22psi actuator and no boost controler I get 25-26psi and drive pressure spikes to 1.5:1 just before the gate cracks . One the dyno torque is down with the 24psi actuator from the point drive pressure goes above 1.2:1 untill it comes back down, which when the gate finally opens .

With the 10psi spring, as emp builds it cracks the gate just enough to stabilise drive pressure but not lower boost (your tune and pump play a big part here and not just cc of fuel) . It does slow the rate at which boost builds slightly

With no fuelling changes and the 10psi wastegate spring The rate at which boost builds is reduced a minute amount compared to the 24psi spring, but torque is still up.

What actuator combo will work for you is something your turbo builder should be able to work out . Or Hours of testing .

 

[Dougal]

Drive pressure isn't a thing to be scared of. It's necessary for the turbine to work and with the inlet pressure and flow provides the drive energy. The hotter you run the lower drive pressure can be for the same turbine power.

With a fixed geometry turbine you have to gain drive pressure with rpm and with wastegating. Because that's how the turbine is fed more power.
Technically as soon as you wastegate then your turbine is undersize. A wastegate is a valve that lets you compromise and run a smaller turbine for better low end boost and torque while not completely choking off the top-end.

I prefer to run a firmer spring gate and let the boost open it. Gates intended to open with lower boost can struggle to hold themselves shut under high emp conditions (i.e cold acceleration).

 

[diby 2000]

Thanks @Mcreight911 that's good info.
Couple of questions.
When you say boost controller, you use an electronic boost controller yeah?
If so, what controller do you run?
When you ran the 22psi (or 24psi I'm not sure) actuator spring, at what boost pressure and rpm was the drive ratio at 1.5?
Was the drive ratio constantly increasing from idle up to this point?
What ratio did it come back down to and how far after the crack rpm did it take to come back down?
I agree that torque delivered is more important than the boost level. How minute was the difference in reaching peak boost (in rpm)?

Luke did tell me he has found the 14psi spring to work the best and that's what I have right now, but he did say that he recommended a good EBC over the bleed valve that I am currently using.

Technically as soon as you wastegate then your turbine is undersize. A wastegate is a valve that lets you compromise and run a smaller turbine for better low end boost and torque while not completely choking off the top-end.

This was my thoughts also. I can see what @Mcreight911 is saying about the drive pressure and delivered torque though.

I prefer to run a firmer spring gate and let the boost open it. Gates intended to open with lower boost can struggle to hold themselves shut under high emp conditions (i.e cold acceleration).

This is my thoughts also. This is the path I'm currently heading down.
I would love to have a good EBC but I don't have the funds available for it. And if I did I'm not sure I could justify it when that money could be put to use elsewhere.

 

[Dougal]

I can see a dyno giving slightly more transient torque with a dip in boost from a wastegate cracking open early. But I'd rather have the boost TBH. Once the exhaust temp comes up the drive pressure drops and you've got that torque.

 

[diby 2000]

I do see what you are saying. And I'm no expert, I'm just trying to learn from others who know more and have more experience than I do. Such as yourself.
I can see how it might work though as its all an efficiency game. Less drive pressure essentially means the engine is breathing easier. I can see how this could result in better delivered torque. The difference is in the detail though I think.
For example does 5% more torque under 1800 rpm result in 50rpm later boost? 100rpm later? 200rpm?

To be honest, it would be nice to say I can make 40psi before 1800rpm. But I would rather say (an feel) that I can make 1000Nm under 1800rpm.
I don't think I will be saying either of those but you understand what I'm saying.

 

[Dougal]

I do see what you are saying. And I'm no expert, I'm just trying to learn from others who know more and have more experience than I do. Such as yourself.
I can see how it might work though as its all an efficiency game. Less drive pressure essentially means the engine is breathing easier. I can see how this could result in better delivered torque. The difference is in the detail though I think.
For example does 5% more torque under 1800 rpm result in 50rpm later boost? 100rpm later? 200rpm?

To be honest, it would be nice to say I can make 40psi before 1800rpm. But I would rather say (an feel) that I can make 1000Nm under 1800rpm.
I don't think I will be saying either of those but you understand what I'm saying.

There are transients and steady state. On a dyno you're measuring transients over a few second pull (in the majority of cases). I care more about steady state which is reached once the exhaust and turbo housing heat-soak. In this situation you've got max heat to the turbine and minimum drive pressure.

In the transients I'd rather have more boost sooner to keep smoke away. This is why I don't like spring only wastegates or drive pressure actuated waste-gates. Because they drop boost in those times when you're accelerating cold. Giving higher measured power through the transients but also richer A/F and some smoke.

 

[diby 2000]

Ok, I see what your saying. Yes I agree. Most of the driving, that I do at least, I am looking for the quick acceleration when the the housing is relatively cool (<300c pre) such as following someone waiting for an opportunity to overtake or accelerating from a standstill turning onto a street etc. I would prefer to do this without the producing a cloud of soot.

 

[vwluv10338]

Ok gents, I'm back from my off road trip. I ran the stock turbo with the fuel settings the same from where I had them set with the MMP turbo but I also built a 3" downpipe. With this set up the boost was building a few hundred RPMs earlier than before and there is more drivability over stock. I'm a bit over fueled off boost with just a touch more smoke than I want if I stomp it. A more gradual acceleration will show no smoke. I also installed a bleed valve and was running 15 psi. While driving through the mountains there was a huge difference in power. As soon as I hit an incline the truck would start to slow and I would have to add pedal to keep up my speed. When I went through the same mountains with the MMP turbo I would just keep my foot steady, the boost would begin to rise along with the EGts and my speed would be steady. I had plenty of power left for passing where I had none with the stock one. Also at ~68mph on the flats I was pushing 10-13psi vs 7psi with MMP.
I will be super curious how it acts when my new turbo gets here. Hopefully the specs will not be flawed from the start and I can get something close to what was advertised. If not, just from what I can see driving the turbos back to back is it was still a good increase in performance and drivability. If I could go back I would have saved more and bought a GTurbo but since they are so much more money I may have never pulled the trigger on one so who knows.

 

[diby 2000]

That's a good comparison @vwluv10338. It will be interesting to see what the difference is once the replacement gets to you.
Where you traveling lighter this trip?

 

[vwluv10338]

That's a good comparison @vwluv10338. It will be interesting to see what the difference is once the replacement gets to you.
Where you traveling lighter this trip?

I may have been slightly lighter on this trip but not by much.

 

[serenity]

@Dougal, could a wastegate that has too much preload and doesn't open enough at high rpm cause high egt's? Not mmp related, I'm just curious.

 

[Dougal]

@Dougal, could a wastegate that has too much preload and doesn't open enough at high rpm cause high egt's? Not mmp related, I'm just curious.

Nope. If it won't open far enough then you'll get boost creep (boost increases with rpm) and the extra boost will depress EGT. The relationship of EMP to EGT is low and overshadowed by basically everything else.

 

[Mcreight911]

Nope. If it won't open far enough then you'll get boost creep (boost increases with rpm) and the extra boost will depress EGT. The relationship of EMP to EGT is low and overshadowed by basically everything else.

Have you measured shaft speed before ?

 

[Mcreight911]

Thanks @Mcreight911 that's good info.
Couple of questions.
When you say boost controller, you use an electronic boost controller yeah?
If so, what controller do you run?
When you ran the 22psi (or 24psi I'm not sure) actuator spring, at what boost pressure and rpm was the drive ratio at 1.5?
Was the drive ratio constantly increasing from idle up to this point?
What ratio did it come back down to and how far after the crack rpm did it take to come back down?
I agree that torque delivered is more important than the boost level. How minute was the difference in reaching peak boost (in rpm)?

Luke did tell me he has found the 14psi spring to work the best and that's what I have right now, but he did say that he recommended a good EBC over the bleed valve that I am currently using.


This was my thoughts also. I can see what @Mcreight911 is saying about the drive pressure and delivered torque though.


This is my thoughts also. This is the path I'm currently heading down.
I would love to have a good EBC but I don't have the funds available for it. And if I did I'm not sure I could justify it when that money could be put to use elsewhere.

Turbo smart eboost is the controller i use

With the heavy spring I was seeing 1.5:1 at 18-1900 rpm it dropped as the gate cracked then slowly increased again toward redline .

I check just to make sure and I was using a 14psi spring not a 10psi like I stated above .

 

[Mcreight911]

There are transients and steady state. On a dyno you're measuring transients over a few second pull (in the majority of cases). I care more about steady state which is reached once the exhaust and turbo housing heat-soak. In this situation you've got max heat to the turbine and minimum drive pressure.

In the transients I'd rather have more boost sooner to keep smoke away. This is why I don't like spring only wastegates or drive pressure actuated waste-gates. Because they drop boost in those times when you're accelerating cold. Giving higher measured power through the transients but also richer A/F and some smoke.

Why so focused on "more boost" wouldn't you rather more volume ?

 

[Mcreight911]

I test both transient response and steady state And aim to maximise power and torque in both situations whilst maintaining safe egt's

 

[Mcreight911]

Electronic boost control makes life easier, you can preset your desired max boost and when you want the gate to start opening . This allows you to get max spool possible from a turbo and maintain desired emp.


EMP Effects actuator operation points.
Actuator ratings can be a max travel rating or a start of movement rating
Winding on excessive prelode can limit total actuator movement

With a manual boost controller. Set the controller to achieve your max boost and a spring preload setting that opens when you need it to

@serenity The goal is to have a spring or preload setting that holds against emp without loosing spool but still allows enough gate opening to bypass enough gas away from the turbine to maintain desired emp and still hold peak pressure right throughout your rpm range. It's a balance, to much travel you loose boost not enough travel emp becomes excessive and you loose volume not psi, which brings egt's up.

Psi is just a measure of restriction. Volume of air pumped (lb/min) is what we need so we can add more fuel to make more power. The earlier the turbo can supply the volume the better.
The psi to lb/min relationship will depend on you specific turbo .

I may be wrong but I mention the lighter actuator spring and emp managent because I have a feeling mmp has set his turbos up that way for a specific reason .

Given the turbo specs I'd expect better results than some have mentioned . I've used bigger/less suited combos and achieved faster spool rates. And without being a soot monster on spool up .