04smoker

just use a regular cheapo oil pressure guage with 3 to 4 feet of copper tubing and then adapt it to the nylon tubing. Have someone ride with you to see what the pressures are. However, do make certain that you pour about 10 or 12 drops of regular oil into the copper tubing or it will get plugged with all the souit. Also this does need to be plummed into the exhaust manifold before the turbo. If you may have an ats or similar manifold, they come with two pyro bungs so just plug into one of them.

wap

Does DP varry? Like, if I am runnin full fuel and I make a 0 to 100 run WOT and hit max boost, some where I should hit max DP, right?

The reason I am askin is because I have 2 pyros and I was thinkin of makin a guage, doin some test runs to know what kind a DPs I am runnin the adjust or not depending on what my pressures are then reinstalling the pyro prob.

Make sense?

XLR8R

There's a bunch of things that aren't on the site yet, Will!

Been pretty busy building parts in the shop...

As soon as we get an idea of how much demand there is for this, I can decide how many kits to carry in inventory.

You'll definitely attain max TIP on a WOT run; they are fascinating to monitor under a variety of driving conditions - I was surprised at how dynamic it is.

Lots of us carefully watch our boost gauge so the HG doesn't get hurt, but the HG is also subjected to the exhaust-side pressures... the overfueled stock Holset can generate at least 75 psi TIP on the '05 (who knows how much higher it would climb - Big Blue watched it peg the meter several times during testing last weekend ).

Since temperature and pressure are so closely related to volume, I like to monitor them simultaneously - that's why I plumbed the pyro & the pressure tap into the same SS fitting in the manifold (no reason to drill another hole if you don't have to!)

I agree that it makes sense to use the TIP gauge as an effective tuning tool.

wap

Ok, I am gonna have to get on the phone and we need to work somethin out. I am not that concerned with my drive pressures, just cause I dont think they are that high but I dont KNOW that. Keep me posted and like I told ya the other day I will give ya a call when I get a chance.

Keep up the good work.

trik396

I cannot comprehend how drive pressure can be detrimental to a headgasket?
I know it can be hard on the turbo itself. That seems pretty evident. But 75psi or whatever is nowhere near the pressure of 17 or 19to1 compression squeezing 45+ pounds of boost then firing the injector. That pressure has to be in the thousands of psi.
Am I looking at this the wrong way? Please school me if so...

Raspy

Yeah, I'm lost too.

How does the drive pressure compare to the boost? Say at 30 PSI boost, what would the drive pressure be?

John

trik396

This is dependant on which turbo you have and where you are at in it's efficiency range I believe. A bigger turbo will have lower drive pressures at 30psi boost because the exhaust turbine is larger and letting the gasses pass easier. A smaller (stock) turbo will be approaching the end of it's efficiency at around 30psi boost and the further boost you make the more you'll heat up the air and the higher the drive pressures will be. I also know how this is hard on exhaust valves and springs, but headgaskets??? Someones gotta have an answer...

Raspy

The only thing hard on head gaskets, that I an think of, is more and more power. Finally, they'll blow with the extreme heat and pressure in the cylinders. Only indirectly related to drive pressure. It's hard to see how the drive pressure could ever be lower than boost. Excxept for an instant, during a bark, when the power is cut and the boost is already up.

John

Raspy

trik,

I agree but I'm just wondering as a general idea of it. The drive pressure must always be higher than boost under power. I'm wondering just how much. Maybe a stock truck, maybe 20 PSI boost. What 25 PSI drive? 35? I've never measured it and have been curious. Of course there are a number of variables.


John

Need95-00CTD

The exhaust gasses don't escape well with a high drive pressure, because they will only equalize the pressure between the exhaust manifold and in the cylinder while the valve is open, so if drive pressure is 30psi the cylinder pressure after the exhaust valve opens will be close to 30psi (slightly higher due to airflow restrictions), but if your drive pressure is 75lbs, cylinder pressure will be 75lbs as well. Remember, the exhaust valve doesn't close right at TDC, so there is still a fiar amount of gas in the cylinder. Once the valve closes and intake air is let in, it again equalizes the pressure, but because all of the exhaust didn't escape, your air charge is hot, dirty, and pressurized, meaning not enough cool clean air can enter the cylinder compared to lower drive pressures. This hot air is what kills head gaskets, because it even further raises EGT's and cylinder pressure, not anything a HG wants to see.

Did this help?

trik396

Yes it did. Makes perfect sense too. Thanks...

Need95-00CTD

No problem...now I have to go check what mine is...

XLR8R

TIP isn't detrimental to the HG - it's merely an indication of how other things are affecting it...

after all, who cares what the EGTs are? EGTs don't melt piston crowns - combustion chamber gas temperaures do!

The HG "sees" the intake boost psi the same way it "sees" the TIP - through the valve seat windows when they're open; since boost pressure is used as a common rule of thumb for determining HG longevity and supporting mods, it follows that TIP pressure would carry at least the same weight in knowing the level of stress that the HG is being subjected to... especially since TIP certainly appears to act as a preview of what's occuring inside the combustion chamber in real-time.

With any increase in accelerator pressure, the TIP always responds before the EGT or boost gauges... the only gauge that exhibits the same degree of dynamic response is the rail pressure - sure makes sense if you think about what's going on inside the CTD from moment to moment!

Since we can't directly monitor the cylinders' internal conditions during the process of combustion, we make do with watching reflections of the event...