Drive pressure Gauge
- Thread starter LarryJewell
- Start date
Was the dash kit an overlay, or a complete replacement? Where did you purchase that unit from? Looks good
. Thanks:hello:
. Thanks:hello:
Wow....Larry, with that many gauges your truck should look like a plane cockpit at night.
It makes me want more gauges...what else can I monitor
It makes me want more gauges...what else can I monitor
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can someone explain drive pressure to me please?? wanting to get a gauge set up going for my truck soon. thanks!!!
wanting to get a gauge set up going for my truck soon. thanks!!!
Drive pressure is reading the pressure that builds up in the exhaust manifolds and up-pipes - the pressure that is driving the turbo. Knowing drive pressure allows those of us with Variable Vane Turbos (04.5+) to tune our trucks effeciently. If you are getting 40+ PSI from your stock turbo but it is taking 80+ PSI to get it that's not at all effecient and you will make more power with less boost and alot less drive pressure. The general rule of thumb is that you want to remain at or under 1.5:1 drive pressure to boost pressure ratio - the closer to 1:1 you can get the better.
But say for those with Fixed-wheel turbos, if you take a drive pressure reading before, say, doing bigger manifolds and/or up-pipes and it's really high. then you install the parts and it's below 1:1 somehow, how would you then correct it (aftermarket turbo such as an S64X
) tuning? or just changing the turbine wheel? injectors? water/meth an easier fix (more dense?) I know next to nothing here, but it seems if your tuning is make to be effective at 45psi of boost and lowering DP lowers boost to 35 psi, more power isn't just there, tuning needs to be altered too, right?
Gots to be careful thinking of DP as only an exhaust tract phenom. The shaft connects the turbine (exhaust) to the compressor (induction). All induction loads show up on the DP gauge also.
But say for those with Fixed-wheel turbos, if you take a drive pressure reading before, say, doing bigger manifolds and/or up-pipes and it's really high. then you install the parts and it's below 1:1 somehow, how would you then correct it (aftermarket turbo such as an S64X
Installing bigger manifolds and/or up-pipes shouldn't lower your max boost, if anything it should raise it some. They will lower drive pressure by getting rid of some of the pressure created by the restrictions in the stock pieces. Getting rid of these restricions allows more of the air coming out of the motor to act on the turbo, driving it harder and getting you a little more boost. If you go too big they can add lag, you have just made that much more volume of air that you have to pressurize before it acts on the turbine. If you have a 10PSI drop in boost pressure after installing manifold/headers and/or up-pipes I would be looking for leaks. When I installed mine I got the same boost with 10PSI less drive pressure because the ECM was using less vane position to get the desired boost.
BTW on a fixed turbo drive pressure readings can be used to get the wastegate adjusted to keep the turbo in it's map.
Hence the word "drive" in the name drive pressure. You are driving the compressor side of the turbo using the turbine side. If there were no induction loads drive pressure woud be next to nothing (it would only show the restrictions in the exhaust).
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Nice echo. :hug:
Induction load is the bulk of DP. It is all energy required for adiabatic boost compression, plus the energy thrown into heat producing innefficiency. In short, it can measured using just the turbo compressor temperature delta, COT-CIT, and multiplying by the MAF, and the heat capacity of air.
Induction load is the bulk of DP. It is all energy required for adiabatic boost compression, plus the energy thrown into heat producing innefficiency. In short, it can measured using just the turbo compressor temperature delta, COT-CIT, and multiplying by the MAF, and the heat capacity of air.
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so by reducing exhaust restriction, drive pressure lowers say 10 psi, but boost may increase, adding to induction load, correct? therefore circulating the supposed better system efficiency?
On Edit: i may have just realized i could be thinking of these two separately and not as DP= exhaust restriction + IL or something similar
On Edit: i may have just realized i could be thinking of these two separately and not as DP= exhaust restriction + IL or something similar
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cool thanks
yes but your going to need to add some tubing of the manifold to them put the sense in the end of that. move guys use copper tubing because you can bend it.
I used about 2 ft of copper tubing coiled up and the actual sensor was mounted to my fuel filter housing.
do your guys drive pressure gauge reading fluctuate quite a bit?
i've got an autometer cobalt 0-60 psi mechanical gauge, and im useing 5ft of coiled 1/4'' copper tubing. gauge is almost impossible to read, when im getting into hard the needle fluctates +- 20 lbs and the needle moves so fast you can hardly see it. (like i'll see a high of 45 or 50 psi, and it will move to as low at 25 or 30 psi, so fast you cant see the needle moving lol)
is this normal for the needle to be fluctating this much? seems like a liquid filled gauge would maybe solve this problem, or is it because im useing a mechanical gauge?
i've got an autometer cobalt 0-60 psi mechanical gauge, and im useing 5ft of coiled 1/4'' copper tubing. gauge is almost impossible to read, when im getting into hard the needle fluctates +- 20 lbs and the needle moves so fast you can hardly see it. (like i'll see a high of 45 or 50 psi, and it will move to as low at 25 or 30 psi, so fast you cant see the needle moving lol)
is this normal for the needle to be fluctating this much? seems like a liquid filled gauge would maybe solve this problem, or is it because im useing a mechanical gauge?
I don't get the flucuations you are talking about but I have a few big differences from your setup:
I have a VVT, you have a fixed geometry wastegated turbo
I have an electric gauge
My best guess is that your waste gate is flucuating as much as your gauge.
I have a VVT, you have a fixed geometry wastegated turbo
I have an electric gauge
My best guess is that your waste gate is flucuating as much as your gauge.