AlpineRAM

RowJ- Yes those were diesel engines we tested. The runtime on the test stand was up to a simulated year of truck usage. (Some bio and veggie oil research we did then).
I left out an important part- the Fitting to the exhaust was quite thick (like 8mm ID) and after about 5cm (2") the tubing was necked down to 1mm ID, everything made from high temp copper tubing, about 1.5m of the small copper tubing going across the engine to be in the airflow of the fan and well supported by brackets, then to the nylon hose.
The connection to the exhaust manifold was vertical, like the EGT probe usually is.

AlpineRAM

RowJ

Sounds like your right then, as you usually are.
Full time drive pressure gauge would be nice... but IMO, kind of like the oil temp gauge I had. A little boring.
Never felt the need for full time read out because once you know your DP is safe at WOT for a given set up, should not change. Change your setup....check your Turbine Inlet Pressure (DP)... and that's it.

I'd have to give up my differential temp or my primary boost readout.... both of which I consider more usable.
My $.02.

RJ

AlpineRAM

We had the drive pressure gauge to get the data for some stuff related to biodiesel in EGR equipped engines, partially with VG turbos. You are right about the "boring" gauge, but it would be interesting to plot the ratio TIP to boost for different altitudes and temperatures. I think it would also be interesting to see the influence of a camshaft, of timing (or EGT to boost to TIP) there are a lot of interesting things to be learned.

AlpineRAM

Forrest Nearing

I've been running a drive pressure gauge full time for about 6 months... 1/8" copper from the manifold to about the brake booster, then nylon into the cab. Every once in a while it'll get stuck... it's happened maybe 10 times... just run it up over the stuck level and back off easy... usually comes unstuck.

it's never been stuck for more than a few minutes

I'll never run another truck without a drive pressure gauge

Ph4tty

Why do you say that?

Forrest Nearing

just another tuning aid... can show you a boost leak before a boost gauge will... helps you set up the wastegate, etc. after driving around w/ one for this long, I can't imagine being without one

RonA

I ran a drive pressure gauge for a while. The soot travelled up the tubing, clogging first the copper tubing, then the gauge itself. If you take a short piece of 3/8" pipe, roll up a piece of a stay free mini pad, stuff it into the pipe, put the proper fittings on the ends to splice it into the line, no soot problems. I'm sure there's another way, but it works. I don't monitor drive pressure any more. I am easily confused by too many gauges and lights.

Tiger Rag

Wonder if a cigarette filter would work as you describe?

Tiger Rag

Same exact thing that my buddy said. Run it up there and it'll come unstuck.

pmtg

are venturi effects ever a factor when plumbing in a drive pressure gauge? i would think at WOT the exhaust velocity might create it and throw off the reading.

just curious...

Forrest Nearing

I doubt it because there's no "flow" though the tubing... I mean, we all use boost gauges and trust them, right?

BIGHEAD

OK , for the sake of my ignorance, what is Drive Pressure? How does it relate to performance? Thanks

G1625S

Drive pressure is a measure of restriction before the turbine inlet--basically in the exhaust manifold. It's how hard the pistons are pushing or 'driving' the exhaust out of the cylinders/manifold and into the turbine. Like an intake manifold pressure gauge, a drive pressure gauge (as Forrest said) is an excellet tuning tool. For instance, if it takes, say, 40psi drive pressure to make 30psi at the intake manifold, you know something's wrong. By comparing drive and boost pressures, it's easy (and fun) to see how timing, wastegate setting and so on affect engine output.

RowJ

The proper term is actually 'Turbine Inlet Pressure'.... which tells you pretty much what it is. It is the pressure of the exhaust gas, from the cylinders, on the inlet of the turbine wheel.
The ratio of TIP to Boost can be a critical factor in determining performance and in determining how safe a head gasket is. Most important, IMO, it is directly proportionate to, and tells you a lot about, cylinder pressures created during combustion.
Ideally, at WOT, you want a ratio of 1:1 or less (drive pressure same or less than boost).

Woops, G1625S types faster than me.

RJ

BIGHEAD

OK, so I can unscrew my pyro guage & put in another pressure guage & see what kind of pressure I have? The drive pressure should be less than the boost? Is there a guage on the market that you can buy that won't soot up, or just use a set up like previously mentioned above?
I noticed on the a chevy website, they kept talking about drive pressure issues, but I didn't know what they were talking about.