I have been wondering....can a car that starts running lean cause a slight increase of boost because of the velocity the gass is pushed out of the combustion chamber?
if not, why would boost increase without setting it, it might be actuator related, but if boost pushes the wastegate open because of a bad actuator spring boost will then decrease....not increase....am I right?
it will lag from the wastegate opening early before the full boost setting
Running lean wont increase boost, running rich with very little timing will increase the spool up of the turbo and make the boost come in a few 100 rpm sooner.
If you are leaning the car out in load the boost can very well increase due to the increased efficency of the motor.
I have been wondering....can a car that starts running lean cause a slight increase of boost because of the velocity the gass is pushed out of the combustion chamber?
Becuase its leaner that doesnt mean the gasses flow faster...
Running lean wont increase boost, running rich with very little timing will increase the spool up of the turbo and make the boost come in a few 100 rpm sooner.
What would be rich and what are little timing?
timing would depend on the load and rpm, rich would be down in the low 10s.
Gary57 wrote:
timing would depend on the load and rpm, rich would be down in the low 10s.
So you dont adjust the timing on idle then, you just slow the advance rate down?
I cant explain this kinda thing on here it takes time, rather just get your dyno tuned properly and dont fiddle you will break things. It would need to be richer than 10s anyway...
Hay Draco… Rising EGT's could add extra energy to the exhaust gasses decreasing spool-up time but I think we are talking engine killing glowing manifold lean here.
As Gary said a lot of guys dial out timing in the boost transition area’s and add fuel to get the mixture burning slower to lower lag by a few 100RPM but its normally drag cars as the tune makes the car lazy in those area’s of the map because of the decrease timing and plug fouling AFR’s..
Have you changed anything on the Z could there be a loose pipe? How are you controlling boost?
Rising EGT's could add extra energy to the exhaust gasses decreasing spool-up time
How can a increase in exhaust energy lower the spool up time??
Spot on about the drag cars thing. I have done 2 cars which needed this, it also helps getting off the line...
How can a increase in exhaust energy lower the spool up time??
? Did I use the wrong word? Pressure difference with higher EGT Exhaust Temps that’s why you wrap or ceramic coat manifolds. Higher temp gas want to expand by having higher EGTs there is more energy in the exhaust gasses making the pressure difference across the turbo more resulting in a lower spool up time maybe not much a few RPM.
When running rich with retarded timing you relying in the slower burning fuel to exit into the exhaust manifold and continue to expand creating the same pressure difference.
The more the difference to quicker the spool , it has it down sides but that’s no needed here
No quite sure where this pressure difference is but and increase in entropy is an increase the energy transfered to the turbine wheel. This increased energy transfer will cause the turbine wheel to generate more power. Basically an increase in exhaust gas will cause the turbine hweel to spool faster.
If you are talking about the pressure difference aross the turbine wheel then the difference the increased EGT will make is neglegible.
We add fuel and retard timing to put more energy into the exhaust. The mixture is still burning and therefore is transfering its energy into heat and work done on the turbine, instead of transfering it into work done by moving a piston down.
Pinkfluffybunnys wrote:
Hay Draco… Rising EGT's could add extra energy to the exhaust gasses decreasing spool-up time but I think we are talking engine killing glowing manifold lean here.
As Gary said a lot of guys dial out timing in the boost transition area’s and add fuel to get the mixture burning slower to lower lag by a few 100RPM but its normally drag cars as the tune makes the car lazy in those area’s of the map because of the decrease timing and plug fouling AFR’s..
Have you changed anything on the Z could there be a loose pipe? How are you controlling boost?
At the moment the boost is controlled by the actuator....which I suspect because even before I got it tuned I was unable to either increase or decrease the boost by normal means("tapping" air from line to actuator).
Before the tune it barely boosted 0.9 bar because of overfueling, after the tune it went up to a bar. As in the post about the Z I had fuel pressure problems, put in the pump and it was sorted, car stopped pinging, but did not tune yet. A week ago I put in fuel to take it for a drive and directly after I put in fuel it started pinging and boosted to 1.3 bar, checked fuel pressure but it was where I set it, I could see nothing funny.
After the fuel pump install I took it for a drive plenty times and had no problems and as I said, directly when I put in fuel that day I noticed the change, car aslo felt lazier than normal.
I have no doubt that I got bad fuel from the garage, but why would the car suddenly boost 1.3 bar?
but and increase in entropy is an increase the energy transfered to the turbine wheel. This increased energy transfer will cause the turbine wheel to generate more power. Basically an increase in exhaust gas will cause the turbine hweel to spool faster.
If you are talking about the pressure difference aross the turbine wheel then the difference the increased EGT will make is neglegible.
We add fuel and retard timing to put more energy into the exhaust. The mixture is still burning and therefore is transfering its energy into heat and work done on the turbine, instead of transfering it into work done by moving a piston down.
Basically what I just said, now with added Vitamin B and C and Engineering lingo. 😉
At the moment the boost is controlled by the actuator....which I suspect because even before I got it tuned I was unable to either increase or decrease the boost by normal means("tapping" air from line to actuator).
Before the tune it barely boosted 0.9 bar because of overfueling, after the tune it went up to a bar. As in the post about the Z I had fuel pressure problems, put in the pump and it was sorted, car stopped pinging, but did not tune yet. A week ago I put in fuel to take it for a drive and directly after I put in fuel it started pinging and boosted to 1.3 bar, checked fuel pressure but it was where I set it, I could see nothing funny.
After the fuel pump install I took it for a drive plenty times and had no problems and as I said, directly when I put in fuel that day I noticed the change, car aslo felt lazier than normal.
I have no doubt that I got bad fuel from the garage, but why would the car suddenly boost 1.3 bar?
Have you check all the vacume lines already?
Basically what I just said, now with added Vitamin B and C and Engineering lingo.
Hehe, that is pretty good I like 😂 .
Draco an increase of 0.3bar means something else has changed not tuning. Check vacuum hoses, actuator, WG not seizing up,etc.
I have checked vacuum lines, even the vacuum on my guage shows no diffs, normally I could see a vacuum leak on my guage.
The WG might somehow stay closed....I will take the actuator arm off and see if it moves easy, that is all I can think of and the vacuum hose between compressor and actuator seems fine, although, before I could take it off completly and the boost would not increase at all(that is why I stated I need a new turbo), why now suddenly increase....
It is just funny that all this happened directly after I put fuel in....
Draco wrote:
I have checked vacuum lines, even the vacuum on my guage shows no diffs, normally I could see a vacuum leak on my guage.
The WG might somehow stay closed....I will take the actuator arm off and see if it moves easy, that is all I can think of and the vacuum hose between compressor and actuator seems fine, although, before I could take it off completly and the boost would not increase at all(that is why I stated I need a new turbo), why now suddenly increase....
It is just funny that all this happened directly after I put fuel in....
Maybe you shouldve tried using fuel before. 😀 😀
Wise ass 😀 😀 ....ok when I put in that spicific fuel on that spicific day... 😉
Last night I checked the wastegate, not stuck, opening and closing properly....
I just need to understand something....when I said that my boost increased you guys suggested that I check for vacuum leaks.....the way I understand it is if there is a leak under boost, the turbo might boost more because there is air escaping.....but that does not show on your boost guage....if anything your boost guage will show boost then decrease.
How would a boost leak(vacuum leak) cause your guage to read more boost and keep it there?
I have never seen it when I had vacuum leaks nor other cars....
You can have an air leak and your gauge wont even pick it up because your turbo can supply enough air. A vaccum leak on the lines going to the actuator will cause the boost to increase.
Its either a faulty gauge or your actuator is damaged.
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