Ok I know last year this was hashed and rehashed but I couldnt remember a few facts on the drive preassure gauge and I couldnt find it on search. Wouldntcha know that "drive", "pressure", "boost" and "gauge" are four of the most ever used words.

So Im tryin to setup a few gauges and was wondering if knowing the DP all the time is of any use whatsoever?

So drive preassure is simply the amount of preassure inside the head? Right? But it is read at the exh. manifold.

The boost is different how? I know its preassure read at the intake if using the genos boost bolt anyhow? Where does the computer read it? I mean where is the psi sensor?

Is it worth it just to have a weldelet in the exhaust manifold so that I could install a gauge for DP only when trying to diagnose problems or setup twins or what?

Thanks for once again teaching me the basics of my "cummins air pump".

 

Drive pressure is read at the exhaust manifold and is a meausre of how much a plug the hot side of the turbo is. Essentially psi between the head and turbo. The pressures in the head will easily hit 2000 psi at times.

Boost is a measure of how much air is being squeezed thru the intake by the turbo. The ECU reads it at the MAP sensor, dual function sensor it is.

Do you need to monitor all the time? Probably not but it fills a aguge hole and gives some interesting info at times.

 

Well there wasw alot of people back when I was checkin into it before that said the gauges didnt last very long and the line into the cab still got relativly hot.

 

You have to run a filter and make sure you run copper on the front end of the line. Blow the filter out once in a while and they seems to last pretty well. Where they don't last a long is in cold weather and freezing a lot. Tends to mess the gauge up.

 

so what PSI gauge is best to read it?? 100psi gauge??are you saying the drive pressure gets up to 2000psi!!

 

ur drive pressure should be ideally 1 to 1 with your boost pressure

 

yeah that's what I thought....but the 2000psi head pressure statement had me wondering....so a 100psi gauge should be perfect...

 

Cylinder pressures can exceed 2000 psi, not manifold pressures. Compress 40 lbs of boost and light off the injected fuel, temps get hot and pressures get high.

Once its released into the manifold expansion quickly drops the pressure and the heat. Drive pressure is essentially measuring how much pressure is held in the manifold to spin the turbo.

With these CR engines a 100 psi gauge is needed to see the peaks. I can peg a 60 lb gauge with stock fueling and getting the 3rd event to start firing. The 600 engines run close to a 1:2 boost to drive ratio when the 3rd event is firing. Normal cruise is around 1:1.2 .

When you see the drive pressures its pretty easy to understand how the in-cylinder EGR works, and, how to circumvent it.

 

Thanks for the explanation but what would it tell you to know this variable all the time? I'm just tryin to determine what that would help?

 

As noted above, turbine inlet pressure can approach 1:2 on a HPCR HE351 but with aftermarket fueling - you'll need a 100psi guage for accurate monitoring.

Copper (or aluminum) tubing isn't durable within the CTD's harsh harmonic environment - that's why our permanent TIP Kit uses 304 stainless steel tubing & fittings and a soot filter to protect the gauge from heat, carbon and vibration.

A TIP gauge is a useful tool for both diagnosis & tuning of any turbocharged engine - most folks are surprised to discover how much abuse their HG takes from the hot side of the engine!

 

thanks man so what do you mean for tuning. I'm saying what can I do with that info? I understand the principal just not the tuning part. What could I adjust based on what I learn?

 

For example, say you "knew" that your big ol' turbo was efficient enough to keep up with an ECM crammed full of aftermarket fuel, based on the manufacturer's published pressure ratios, compressor maps, etc. Then you get around to measuring the TIP and are shocked to discover how far it is into the "excessive" range...

Now you know enough to alter your engine's tune through hardware or software changes to maintain a reliable power output, or you can add durability in the form of better parts to keep running the initial power level. Clear as mud?

Although TIP & EGT tend to move together, they certainly don't match. A lot of folks are very concerned about boost pressure vs. HG integrity, yet never consider what's happening in the other half of the engine's breathing tract.

Generally speaking, making best power from any engine boils down to process control:

The more you know, the faster you go!

 

"the more you know the faster you go"

Wasn't that at the end of every episode of G.I. Joe.

Tanks for educatin me

 

Glad to help!




GI Joe episodes?

Must've aired back when I was making babies... but I did have lots of little green army men!

 

come on we all know G.I Joe was...


"Now you know and knowing is half the battle!!!"