gbentink Turbo Upgrade Users Thread

[mudgudgeon]

So if understand correctly the position of the fuel rod as dictated by boost pushing on the diaphram will not affect the fuel delivery to any significant amount.

If the fuel rod is depressed 5mm, fuel delivery will be constant regardless of whether it took 5psi at the diaphragm to depress the rod 5mm, or 20psi.

I thought if you are cruising and boost is 10 psi the fuel pin will be depressed (guessing) 2/3 of full travel or 2/3 up the ramp on the pin. I believed that the farther down the pin travels the more fuel ( richer mixture) the engine would get.

Fuel pin travel may not be linear. 5 psi is not necessarily 1/3, nor is 10 psi necessarily 2/3.
You are correct in regard to fuel pin travelling further down equals richer fuel mixture

one benefit of the boost compensator is having capacity to tune when the fuel rod shifts.
You can adjust preload on the diaphragm spring. more preload on the spring means you need more boost to get the fuel rod to move, which delays the addition of more fuel.
If fore example, you need 7psi at the diaphragm to overcome the spring rate and preload, 5 psi will mean the fuel rod is at its leanest position.
At 7psi, it will start to shift.
The deeper it moves the more psi is needed to overcome increasing spring rate as the spring is compressed.

 

[Dougal]

The AFC and fuel pins also only change the maximum fuel limit. They have no effect at part load.

 

[rebuilt80]

so this talk of fuel economy got me thinking. and hopefully someone can help me out. Running xxi pump/inj on a on a GrunX 25psi, 1HDFT/auto/33"/FMIC and a AFR full time at about 18-19afr maxed. I tow a heavy bastard trailer for work daily, so it gets a bit of a hard life. But what I'm trying to understand is some rough numbers of AFR with what other people are seeing. I would love to compare side by side in real life but I don't know anyone with a truck like this, so this is my tuning method... My thought is that its too fat in the mid range. Lets say cruising flat road, 100kph, I'm seeing 10psi/350pre/2200rpm/no part time kit and the AFR is (now, after a bit more spring tension) about 40. I was seeing about 35afr as a rough figure, so by adding some tension to the pin, I (and this is where I start guessing) can bring the fuel in later so that its seeing less BC controlled fuel being delivered at the listed speed etc.

Am I on the right track? Whats the gotcha, as in what happens if you go too far with adding tension? The pin won't be able to deliver full fuel at max boost? Fuel is something I have plenty of, so my concern isn't with limiting fuel at wide open, I'm trying to optimize the map at which fuel is delivered (without a dyno..) So does anyone else have a truck with a reasonably similar configuration, and what sort of numbers would you like to be seeing on the AFR? I'd love to see something like 50 cruising along the highway, but with the auto and AWD etc, I think thats a bit optimistic. Is it possible??

 

[Dougal]

so this talk of fuel economy got me thinking. and hopefully someone can help me out. Running xxi pump/inj on a on a GrunX 25psi, 1HDFT/auto/33"/FMIC and a AFR full time at about 18-19afr maxed. I tow a heavy bastard trailer for work daily, so it gets a bit of a hard life. But what I'm trying to understand is some rough numbers of AFR with what other people are seeing. I would love to compare side by side in real life but I don't know anyone with a truck like this, so this is my tuning method... My thought is that its too fat in the mid range. Lets say cruising flat road, 100kph, I'm seeing 10psi/350pre/2200rpm/no part time kit and the AFR is (now, after a bit more spring tension) about 40. I was seeing about 35afr as a rough figure, so by adding some tension to the pin, I (and this is where I start guessing) can bring the fuel in later so that its seeing less BC controlled fuel being delivered at the listed speed etc.

Am I on the right track? Whats the gotcha, as in what happens if you go too far with adding tension? The pin won't be able to deliver full fuel at max boost? Fuel is something I have plenty of, so my concern isn't with limiting fuel at wide open, I'm trying to optimize the map at which fuel is delivered (without a dyno..) So does anyone else have a truck with a reasonably similar configuration, and what sort of numbers would you like to be seeing on the AFR? I'd love to see something like 50 cruising along the highway, but with the auto and AWD etc, I think thats a bit optimistic. Is it possible??

Changing fuel pin tension does nothing at part load. Part load A/F is controlled by the load on the engine, the turbo match and injection timing.

To lean out your engine on the highway you could retard injection timing (which puts more energy into the exhaust which generates more boost) or get a tighter turbine housing.

But it's all pointless. There is no reason to go leaner than 40:1 at cruise. Trying to go leaner will cost you fuel economy as you decrease engine efficiency and increase drive pressure to get more boost.

 

[mudgudgeon]

Reduce fuel delivery at any given rpm/speed etc will just have you feeding in more right foot.

Reduce fuel, reduce power.

Gotcha is, if the boost compensator isn't feeding in the fuel to achieve the required power, you will with you right foot.

Boost compensator adjustment is a bit like programming a power chip on an electronic injected engine. It let's you adjust how much fuel is added and when.
You can change power output, and also change the drive-ability of the vehicle by having fuel available when you need it.

 

[rebuilt80]

So dougal, I guess what I'm trying to get at is some sort of figure to chase. So basically the only figures I know is 16:1 is basically raw wet fuel and 40:1 is too lean to be pushing a 3t truck economically. I've managed to make a difference with the pin tension in the area I'm talking about, so what would be a (extremely rough and subject to variation of course) figure to chase? What sort of numbers do other people in a similar situation see, as AFR is basically all I have to tune it off. Whilst I don't know where the star wheel was set when the pump was delievered, I'm at about 70 clicks tighter on the star wheel to get me to the figures I'm seeing, and to me that seems excessive (I've done it in about 10click sessions). That was progressively done to reduce the amount of fuel at full load, as it was getting a LOT of fuel... But recently I've been trying to trim out fuel in the middle as it seemed to me (whilst watching the AFR) that it was quite fat in the middle relative to the throttle position. But from what you both are saying, I'd be better off backing that tension back off as I'm not able to affect what I'm looking at by tension alone, and I'll be able to bring back in a lot more power if I can get it optimized.

Partly for this conversation I guess is that I would take it to a man with a dyno, if I could be sure that he was prepared to tune the truck to optimize the bolt on bits that I have. Obviously XXI and gturbo provide a lot more of everything, and I'd want to be sure that the tuner was prepared and capable of getting the most efficient power out of it. I can dial the thing up to 11 and then drive it on the throttle to not blow it up, and it will be great, but I want it done properly, and I'm not convinced any of the local tuners would be brave enough to try with someone elses truck (and not OEM turbo and pump etc) Maybe I'm wrong... Fair risk to try I guess.

So I guess I'd probably be best going and resetting the pin at max throttle up a big hill, given that I'm going to struggle to get the economy tuned in the fashion I'm trying. Give it the best chance of power at the top end, and let the pedal position sort out the rest of it.... That sound about right?

 

[Dougal]

So dougal, I guess what I'm trying to get at is some sort of figure to chase. So basically the only figures I know is 16:1 is basically raw wet fuel and 40:1 is too lean to be pushing a 3t truck economically. I've managed to make a difference with the pin tension in the area I'm talking about, so what would be a (extremely rough and subject to variation of course) figure to chase? What sort of numbers do other people in a similar situation see, as AFR is basically all I have to tune it off. Whilst I don't know where the star wheel was set when the pump was delievered, I'm at about 70 clicks tighter on the star wheel to get me to the figures I'm seeing, and to me that seems excessive (I've done it in about 10click sessions). That was progressively done to reduce the amount of fuel at full load, as it was getting a LOT of fuel... But recently I've been trying to trim out fuel in the middle as it seemed to me (whilst watching the AFR) that it was quite fat in the middle relative to the throttle position. But from what you both are saying, I'd be better off backing that tension back off as I'm not able to affect what I'm looking at by tension alone, and I'll be able to bring back in a lot more power if I can get it optimized.

Partly for this conversation I guess is that I would take it to a man with a dyno, if I could be sure that he was prepared to tune the truck to optimize the bolt on bits that I have. Obviously XXI and gturbo provide a lot more of everything, and I'd want to be sure that the tuner was prepared and capable of getting the most efficient power out of it. I can dial the thing up to 11 and then drive it on the throttle to not blow it up, and it will be great, but I want it done properly, and I'm not convinced any of the local tuners would be brave enough to try with someone elses truck (and not OEM turbo and pump etc) Maybe I'm wrong... Fair risk to try I guess.

So I guess I'd probably be best going and resetting the pin at max throttle up a big hill, given that I'm going to struggle to get the economy tuned in the fashion I'm trying. Give it the best chance of power at the top end, and let the pedal position sort out the rest of it.... That sound about right?

I have no idea what you're trying to acheive. If you want the absolute best fuel economy then you start by reducing load (get rid of external bolt ons, fit smoother and narrower tyres etc). Then get better driveline efficiency (manual gearbox) and drive slower.

Then once you're down to the minimum load you have to fit a turbocharger that provides only the required boost at the best compressor and turbine efficiency for that boost and find the best spot for injection timing to get the peak pressure just after TDC.

Notice how I haven't mentioned fuel pump AFC tuning? That's because outside injection timing it doesn't matter.

Tuning an automotive engine is a massive bag of compromises. You can't have it all and you've got some heavy compromises already with an automatic pushing 33" rubber.

As far as AFR at cruise. It isn't critical at all. I have one AWD diesel car which runs ~25-27:1 at 100km/h (5psi boost, 400C EGT) and uses under 6 litres/100km. I have a 4BD1T powered 4wd which runs 35-40:1 at 100km/h (7-8psi boost, 380C) and uses ~10 litres/100km.

 

[rebuilt80]

So there always seems to be two stories to tuning - the school where you try and modify the pin to a preset bunch of pressures (ie grinding etc with the bike pump to set pressures) and the school where you use the pin tension to basically just set max fuel and don't worry about what happens in the lower pressures as its so variable dependng on engine load that you're wasting your time...?! I know mark said in as many words, just use the spring tension to set max AFR and that all that needs doing. I've done a couple of long highway runs and the eco has been up, and after a quick chat to XXI, the figure of 50 was used as a cruise AFR. I'm nowhere near that (but I suspect that would be best case, manual, diff gears etc etc) so I'm trying to work out if thats something I should be heading towards, or its not applicable to my situation.

That fair to say? I seem to be a bit confused. I guess I wasn't that clear in the fact I'm not trying to make massive fuel economy gains, I was simply trying to optimise what I have, but I don't have any benchmarks to work towards. Its fairly clear that if you lean it off, you need to use more boot to get it to go, so thats locked in. My question came more from the other direction - is it possible to allow an excess of fuel to be added via the BC or will it only bring in what it wants regardless of the boost pressure?

In terms of matching turbines, housings, pumps etc, well thats all already locked in, those are the parameters I have to work with.

And when you say absolute best economy, to me that means best economy possible with the existing setup. I'm not building a prius...


"Boost compensator adjustment is a bit like programming a power chip on an electronic injected engine. It let's you adjust how much fuel is added and when.
You can change power output, and also change the drive-ability of the vehicle by having fuel available when you need it."

This is where I get confused again. So if I can determine if the AFR is high at a certain boost setting, why can't I alter when the pin moves at a given pressure?! So if I was to run it up on a dyno, and saw a spike in the AFR curve at a certain boost (hypothetically) could I not adjust the pin tension to delay the fuel a touch, hence lowering the AFR at that boost pressure?

Or do I just flat out, set max AFR/fuel at WOT using spring tension and leave it completely alone...

 

[Dougal]

So there always seems to be two stories to tuning - the school where you try and modify the pin to a preset bunch of pressures (ie grinding etc with the bike pump to set pressures) and the school where you use the pin tension to basically just set max fuel and don't worry about what happens in the lower pressures as its so variable dependng on engine load that you're wasting your time...?! I know mark said in as many words, just use the spring tension to set max AFR and that all that needs doing. I've done a couple of long highway runs and the eco has been up, and after a quick chat to XXI, the figure of 50 was used as a cruise AFR. I'm nowhere near that (but I suspect that would be best case, manual, diff gears etc etc) so I'm trying to work out if thats something I should be heading towards, or its not applicable to my situation.

That fair to say? I seem to be a bit confused. I guess I wasn't that clear in the fact I'm not trying to make massive fuel economy gains, I was simply trying to optimise what I have, but I don't have any benchmarks to work towards. Its fairly clear that if you lean it off, you need to use more boot to get it to go, so thats locked in. My question came more from the other direction - is it possible to allow an excess of fuel to be added via the BC or will it only bring in what it wants regardless of the boost pressure?

In terms of matching turbines, housings, pumps etc, well thats all already locked in, those are the parameters I have to work with.

And when you say absolute best economy, to me that means best economy possible with the existing setup. I'm not building a prius...


"Boost compensator adjustment is a bit like programming a power chip on an electronic injected engine. It let's you adjust how much fuel is added and when.
You can change power output, and also change the drive-ability of the vehicle by having fuel available when you need it."

This is where I get confused again. So if I can determine if the AFR is high at a certain boost setting, why can't I alter when the pin moves at a given pressure?! So if I was to run it up on a dyno, and saw a spike in the AFR curve at a certain boost (hypothetically) could I not adjust the pin tension to delay the fuel a touch, hence lowering the AFR at that boost pressure?

Or do I just flat out, set max AFR/fuel at WOT using spring tension and leave it completely alone...

You're missing the point completely. The whole AFC assembly only does one thing. It sets the max fuel curve based on boost.

Because at cruise you aren't using max fuel, the AFC is irrelevant there. Trying to test economy on different drives is going to have a massive variability anyway. It's simply not reliable to go on the same drive twice and fill up with slightly less. My own vehicles can give me +/-10% between tanks with no vehicle changes.

As for 50:1. That's bollocks and attempting to push AFR that high and EGT that low will push your drive pressure too high. The only thing the AFC has in common with EFI is limiting fuel based on boost.

Fuelling is set by your right foot all the way up to the max the AFC (and governor) will allow.

 

[gerg]

Whether your AFR at cruise is 25, 35, or 50 has nothing to do with the required fuel to move you, but rather how much air your feeding it. You require a certain amount of energy as in fuel to move your truck at a set speed and unless you screw with your timing to optimize it, that doesn't change. As you ask more from your turbo, hence higher AFR, you increase drive pressures to achieve it and use more fuel in doing so. Your thinking like this is a gas engine or something. It's all backwards. With a gas engine you use fuel to control egts. With a diesel you use air. Use the minimum air to control your egts and you will have max power. If You want max economy at cruise, use the least amount of air you can.

 

[rebuilt80]

ok. so how does this sound. max (or min, as it were) AFR set at about 18/19 at full load, and everything else will just be what it will be...?! Economy comes from the right boot, and thats that.

 

[Dougal]

If You want max economy at cruise, use the least amount of air you can.

With the added condition of burning completely clean.

 

[mudgudgeon]

ok. so how does this sound. max (or min, as it were) AFR set at about 18/19 at full load, and everything else will just be what it will be...?! Economy comes from the right boot, and thats that.

This has gone from over complication to over simplification

My EFI analogy was probably a bit clunky.

My possibly clunky understanding is something like this . . .

Max fuel screw setting dictates the absolute maximum fuel available.

Boost compensator restricts how much of the available fuel is being delivered and allows more fuel to be delivered when boost is high enough to overcome the boost compensator diaphragm spring AND engine load/throttle position demands more fuel.
If throttle position isn't demanding more fuel, boost compensator/fuel rod position is irrelevant.

When you combine high enough boost pressures, AND enough right foot, the boost compensator allows an increase in fuel delivery (within limits of max fuel screw setting).

Back off the throttle (demand less fuel) and the throttle position reduces fuel delivery.
If boost drops below the compensator spring rate, fuel pin restricts fuel delivery again as there is no demand for it.

Some examples
High load, low boost, low rpm (as mentioned by dougal ) represents early acceleration (idle or cruise to maybe 1800-ish rpm). Boost has not built high enough to overcome the boost compensator spring, therefore boost compensator is restricting fuel delivery because inceased air flow is not yet available to burn additional fuel cleanly. Restricting fuel is therefore keeping EGTs and smoke in check.

High load, high boost, low RPM.
Under acceleration or climbing or towing a load. As boost builds, it will overcome the compensator spring and progressively deliver more fuel until the fuel rod is fully depresses. Max fuel is now dictated by throttle position and the max fuel screw setting.
Star wheel position changes spring preload and affects how quickly the boost compensator feeds in more fuel. The pin profile also affects the rate at which extra fuel is fed in. This is what is tuneable.

Low load, high rpm, any boost.
Cruising, not much throttle. Throttle position controls fuel delivery regardless of whether boost is high enough to depress the fuel rod spring/diaphragm. Fuel rod position is irrelevant. right foot controls fuel delivery to meet your demand for power.

The boost compensator allows you to tune how quickly the turbo and engine can reach full boost/full power.
More fuel equals more energy to drive the turbo. More drive pressure equals more boost equals more air flow, which in turn let's you feed in more fuel.

Tuning boost compensator spring rate/preload and fuel rod profile allows you to feed in more fuel earlier, bringing on boost earlier and more torque at low RPM. This is what gets you moving quickly, and makes your rig more enjoyable to drive.

Tuning it to work optimally with your set up is where the benefits are.
Things that affect this are. . .
Turbo
Intercooler and intercooler efficiency
Exhaust system
Snorkel /intake tract
Auto or manual
Tyre size
Your appetite for power vs risk (how far will you push the limits)

 

[Dougal]

The most you can simplify the process:

Set max fuel to max boost with the AFC right open.
Set the AFC to match reduced fuel to reduced boost during spoolup.

"Set the AFC" can be a huge process with many, many, options.

 

[ForealBoreal]

Keep it simple.
Set desired full load/boost AFR.
Set low end AFR.

Exactly what dougal said

 

[rebuilt80]

Cheers;

I understand where everyone is at with this. To come around full circle to my initial question, I guess we can say that I can trim a bit of fuel out of the mid range if I like by moving the pin tension but ultimately its (fueling at cruise) determined largely by other factors. At cruise, so basically a steady state, the BC is not affecting fueling much at all, and hence tinkering with spring tension in that area is done at the detriment of other settings.

Simple is fine, I was just trying to refine the settings I have to ensure that I'm doing as well as possible with my current setup, and without another vehicle or dyno to do a direct comparision, its hard to get fine settings correct. So thanks everyone.

 

[Dougal]

Cheers;

I understand where everyone is at with this. To come around full circle to my initial question, I guess we can say that I can trim a bit of fuel out of the mid range if I like by moving the pin tension but ultimately its (fueling at cruise) determined largely by other factors. At cruise, so basically a steady state, the BC is not affecting fueling much at all, and hence tinkering with spring tension in that area is done at the detriment of other settings.

The pin shape, spring rate and tension will change your max fuel based just on boost. Below that it's all down to your right foot.

 

[Lumpskie]

Hi Guys! I'm a total Landcruiser and diesel noob who just bought a diesel converted FZJ80, that has a Grunter turbo on it. The previous owner said that he had a 1HZ in this rig originally and, when it died, he swapped the 1HD-T into it. As a result, this turbo was set up for the 1HZ. My question is this. Is the only difference between the 1HZ and the 1HD-T model the waste gate spring? From my googling, I saw that the 1HZ setup was 14psi and the 1HD-T is 18psi... does that sound right?

If that is right, can I just swap the spring out and run the truck? Or do I need to add more fuel to match the increase in boost on these?

Sorry for the total noob questions. I appreciate any information you can give me.

Thanks,

 

[Tapage]

1. 1HZ it´s a NA engine

2. PO probably using HD-T exhaust manifold and grunter turbo on the NA 1HZ

3. stock boost on 1HD-T it's about 9PSI

4. you gotta tune your actual setup on it's own ..

 

[IanB]

@Lumpskie Does your injection pump have a boost compensator? If not, your tuning options are very limited.

1HZ being a non-turbo diesel has a higher compression ratio than the 1HD-T, which will be one of the limiting factors as to how much boost they can handle compared to the 1HD-T. I'm not sure that GTurbo provides different wastegate springs based on the engine the turbo is to be mated with, I would expect that to be accomplished via boost controller.