Is too much boost for a given fuel bad?

[UnderPSI]

I thought this was common sense.... my bad.

[libbydiesel]

Ok, but how are you magically increasing boost? I turned down my fuel, and as a result I can't produce as much boost. Sure I could make more power for a given mass of air by increasing the fueling, but it doesn't feel like the added boost affects power either way (waste-gate connected or not) for a given volume of fuel. For the test, my setup is an AAZ with a K14 turbo, stock boost pin, stock everything, with a minor adjustment of fueling, and pump timed to .90mm. With the waste-gate connected, it will generate 9psi boost consistently (enough to put the boost pin on the step). Without, it tops out at about 19psi with my current fueling. I'm only using the butt dyno, but it doesn't feel any different, except it's quieter with the waste-gate disconnected. To quell this argument, we need someone to run a few dyno pulls with consistent fueling and variable manifold pressure.

You can 'magically increase boost' by adjusting the wastegate opening pressure or vane angle of a VNT. 

Are you intercooled?

There are dyno apps for smart phones.  You could do the testing yourself in a more conclusive manner than the butt dyno.  Please report back your findings.  If for the same fueling there is no difference in power between 9 psi and 19 psi, then the most appropriate fuel to air is somewhere between the two. 

[BillyWillicker]

Anyways, 8v-of-fury, does your M-TDI do the daily drive yet and run as intended or are we keyboard cruising still?

[Smokey Eddy]

If the wastegate on my turbo opened (or maybe i just need to adjust the controller RadoTD(Matt) made me) I would run 16-20psi.

[8v-of-fury]

I thought this was common sense.... my bad.

How to only reply when you have something helpful to post, that is common sense.

Sorry for utilizing the forum for what it is there for.

[R.O.R-2.0]

ok.. final nail in coffin..

my turbo makes 25 psi with the LDA hooked up, or un hooked, but it makes WAY more power with the LDA hooked up, at the same 25psi boost..

plain and simple, if you have too much boost for a given fuel, it reduces power and efficiency..

[JamesT]

ok.. final nail in coffin..

my turbo makes 25 psi with the LDA hooked up, or un hooked, but it makes WAY more power with the LDA hooked up, at the same 25psi boost..

plain and simple, if you have too much boost for a given fuel, it reduces power and efficiency..

That's not a nail in the coffin, despite bringing this back from the dead. The LDA regulates fuel, not airflow. What you're saying is that with more fuel for a given boost, you make more power. That's already a given here. What you need to do is disable the LDA and see if there's any significant change in power by adjusting manifold pressure.

[R.O.R-2.0]

ok.. final nail in coffin..

my turbo makes 25 psi with the LDA hooked up, or un hooked, but it makes WAY more power with the LDA hooked up, at the same 25psi boost..

plain and simple, if you have too much boost for a given fuel, it reduces power and efficiency..

That's not a nail in the coffin, despite bringing this back from the dead. The LDA regulates fuel, not airflow. What you're saying is that with more fuel for a given boost, you make more power. That's already a given here. What you need to do is disable the LDA and see if there's any significant change in power by adjusting manifold pressure.

if the LDA is un-hooked, how is it NOT disabled? im completely aware of the functions of the LDA.. it regulates fuel. the wastegate regulates air, and if neither are hooked up, i can still make 25 psi boost..

were talking about keeping the same quantity of boost, and changing fueling..

im saying that it IS possible to make HIGH boost numbers, and still have marginal fueling..

god, im almost sorry i started this thread..

[8v-of-fury]

So if you can make 25psi with everything unhooked?

How do you manage this?

[R.O.R-2.0]

So if you can make 25psi with everything unhooked?

How do you manage this?

how the hell should i know? my boost gauge doesnt lie tho.. pressure reading taken DIRECTLY from the turbo outlet..

the exhaust coming out of the engine is still hot, and it takes heat and pressure to spool a turbo, not fuel..

heat and pressure are present in ANY exhaust stream.. my TD pump is cranked up enough that even with the LDA un hooked, it still smokes..

[8v-of-fury]

heat and pressure are present in ANY exhaust stream.. my TD pump is cranked up enough that even with the LDA un hooked, it still smokes..

Sounds like your car needs some better tuning? How do you have so much exhaust pressure and heat with WAY less on-boost fueling?

[R.O.R-2.0]

heat and pressure are present in ANY exhaust stream.. my TD pump is cranked up enough that even with the LDA un hooked, it still smokes..

Sounds like your car needs some better tuning? How do you have so much exhaust pressure and heat with WAY less on-boost fueling?

i have a CRANKED UP PUMP.. it pours coals with or without the LDA hooked up.

the collar on the fuel screw, its gone, and the fuel screw is threaded in like 3 full turns past the collar..

and like libby mentioned.. the MAGIC way to increase boost without fueling, is to adjust the wastegate.. durr..

[8v-of-fury]

I unno man.

Why are you running that much fuel? To smoke that bad on boost aswell ? why?

[UnderPSI]

...the exhaust coming out of the engine is still hot, and it takes heat and pressure to spool a turbo, not fuel..

With out fuel, you wouldn't have heat or pressure. Heat is not needed to spin a turbo, it does help though.

[JamesT]

Ok, so I was playing again today. I disconnected my LDA, and set my fuel screw so it could smoke off boost, but not on. Kept my waste-gate disabled, and did a 60-90km/h pull in 4th gear up a bit of a hill. Set the wastegate to open at the stock 9psi, then did another 60-90 pull up the same stretch of road.
No LDA, no wastegate 5.9 seconds maxed out around 24 psi boost (hard to tell exactly because I was paying more attention to the speedometer and the road).
No LDA, waste-gated  6.0 seconds maxed out at 9 psi.
With LDA, no waste gate, I backed off the throttle when the needle headed towards 30psi.

That doesn't actually mean that 24psi is good for that fueling, just that the most efficient would be closer to 24 than 9. I would conclude that I have a well matched turbo for my setup, and have a hard time attaining too much boost for a given fuel, but if I could reach too much boost for this fueling, it would be a bad thing. If I turn the fuel down, 24psi would be too much, but I likely wouldn't be able to make that much with my setup.

Oh, and you shouldn't take the boost pressure from the turbo outlet, only the wastegate control. The pressure you should measure is the  plenum pressure. Temperature drop from the intercooler and restrictions in intake stream will affect your readings otherwise.