rat wrote:
Draco i agree with your thinking that it should be lean.
Break thrue!!!!!!!! I thought I was typing in Korean 😳
It makes sense that it should be lean....
Bigger turbo means lean mixture?
The turbo will flow more over 1 bar. The T28 is designed with under a bar in mind.
rat wrote:
The turbo will flow more over 1 bar. The T28 is designed with under a bar in mind.
Remember the T28 has a AR60 compressor housing...thats bigger than a normal T28...the new turbo is also an AR60, phisicly the same size as the T28 compressor housing....obveously the compressor wheel differs.
All this talk of boost pressure is daffed.
Powder 0.5bar boost does not mean it flows the same mass of air as 0.5bar in another application. You are only thinking about pressure and not tempreture. A bigger turbo will flow 0.5bar boost easier so the air should be cooler which mean more mass. Remember boost is only a measure of the engines inablity to swallow the air the turbo is supplying.
Now Draco I agree in theory yes you are right it should be leaner but it doesnt always work out that way. Get the car tuned again and put on dyno and then see if you have made any improvements or you have made it worse.
Maybe your new exhaust manifold is the problem...
Gary57 wrote:
Maybe your new exhaust manifold is the problem...
I will get to the tuning as i did before, just wondering why...
Why do you think it might be the manifold? Do you think it flows worse than the other one?
I cant say it is the manifold because I havent seen it but maybe it is restricting the motor...
Gary57 wrote:
I cant say it is the manifold because I havent seen it but maybe it is restricting the motor...
Gary57 wrote:
All this talk of boost pressure is daffed.
Powder 0.5bar boost does not mean it flows the same mass of air as 0.5bar in another application. You are only thinking about pressure and not tempreture. A bigger turbo will flow 0.5bar boost easier so the air should be cooler which mean more mass. Remember boost is only a measure of the engines inablity to swallow the air the turbo is supplying.
Now Draco I agree in theory yes you are right it should be leaner but it doesnt always work out that way. Get the car tuned again and put on dyno and then see if you have made any improvements or you have made it worse.
Maybe your new exhaust manifold is the problem...
Hi Gary, this now not being to argue, but rather to understand ur thought pattern,
I fully agree that a change in manifold can definately cause a diffirence in performance, taking into account possible easier flow or more restricted flow, but not change in turbo, unless there has been a change in flow regulation, and fuel mapping is off, this type of thing u see with MAF sensors when introducing atmospheric bov's that will cause overfueling, and even then not to this degree that it smokes.
What you are proposing would be the diffirence between a cold and hot day, does ur car smoke on a hot day or cold day? Or even the diffirence of driving in JHB compared to the coast, which is a diffirence that a MAP sensor recognises as the name indicates (Manifold Absolute Pressure) which is the Absolute pressure in your manifold at any given time. I mean in this case we would be talking about changing air density from like 14.7 (example) ot like 11 or so...
A change in impellor size or housing size would mean a change in compression rate sure, but it is still regulated by the wastegate down to 0.5 or 1 or what ever ur std boost level is set too. The rate at what ur cylinders can swallow air has not changed
I don't know, maybe I am highly confused, but that is how I see it, if I am somehow wrong, please show me to a airpressure for dummies guide I can study, I know for one, that is a subject I would appreciate to know backwards.....
I'm not going to get into any arguments but 0.5 bar is still 0.5 bar, this is the reason you can run a T28 at the same boost as a T25 on a standard map without problems. But what's the point of that?
As for the overfueling, I would look elsewhere (ie. not the turbo) if it is deffinately running the same boost. I'm not sure what other mods you have so take it to the dyno and get it checked out with a wideband. It could be that the standard management is trying to compensate and is over-doing it as the boost characteristics are different from the T25, but still the same boost.
Tell me, is the car smoking throughout the rev range, only on boost, on WOT, on light acceleration, etc?
When it's cold it already starts in negative boost when driving, when warm, idle settles and on light throttle not in boost no smoke..as soon as you get close to boost and into boost it starts blowing black/dark smoke...heavily...the more throttle you give the more it blows smoke.
It is obveous that I need to retune because it's obveously over feulling, I just wonder why because it should be underfeuling with the "bigger" turbo.
I can only think that the standard management over-compensating is to blame then, but a tuner will be able to tell you on the dyno. Only so much can be diagnosed on the net.
Good luck dude! 😉
djtreble wrote:
I can only think that the standard management over-compensating is to blame then, but a tuner will be able to tell you on the dyno. Only so much can be diagnosed on the net.
Good luck dude! 😉
I am running full management, no maf, wolf 3D with map sensor.
And running at the same boost as before? That makes me think there is a leak somewhere post turbo (or even at the turbo). Was it a new/proven turbo?
I was running 1 bar boost according to wolf, according to guage a bit more.
With the new turbo I am not taking it so far...the boost pics up and will boost to and over 1 bar if I keep giving throttle....but the black smoke starts just before boost if you give throttle and gets worse the more you give throttle.
I have not tried to drive it hard because I know the feulling is off...
I'm not a mapping expert but in theory I'd say that the black smoke is because your turbo is more laggy and the car is recieving too much fuel too early. The boost curve will be different to the T25.
When I start mapping I will be able to give you a more in depth diagnoses.
Maybe it is as simple as that...to much to soon...thanks for the help in anyways...
No prob, let us know what the problem was when you find out.
Will do thanks.
What you are proposing would be the diffirence between a cold and hot day, does ur car smoke on a hot day or cold day?
Yes this will cause your car to smoke on a hot day if it was tunes on a cold one, this is why you should have a IAT sensor if you are running MAP.
Simple formular of PV=mRT, use this and see what the difference in mass of air per 5 degrees of air temp... 😉
I'm not going to get into any arguments but 0.5 bar is still 0.5 bar, this is the reason you can run a T28 at the same boost as a T25 on a standard map without problems. But what's the point of that?
This is because the standard map uses MAF which measures the mass of air, not the pressure. 8)
0.5 bar is a pressure reading isn't it? So the MAP would see the 0.5 bar on both turbo's
The MAF measures the air before the turbo anyway so wouldn't the turbo be sucking in the same mass of air to build up 0.5 bar pressure in a system of the same size despite whatever turbo is on there?
Basically the air mass and air pressure would be the same at 0.5 bar no matter what turbo you use? Or am I totally wrong? 🙄
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