Turbo Pressure - PeachParts Mercedes-Benz Forum

Phil · #1 04-11-2005, 10:39 AM

I connected a test guage on the line from the intake manifold to the alda then drove the car. I was getting 8psi boost. I then adjusted the waste gate but could only bring the pressure up to 11psi. In all my searching it looks like I should be able to get much higher pressure. I was hoping to raise it to the 13-15 range. Does anyone have any idea why I can't get more pressure.
Thanks

tangofox007 · #2 04-11-2005, 10:45 AM

The 617 engine manual calls for 0.7-0.8 bar at full load. Be happy!!!

Phil · #3 04-11-2005, 11:41 AM

Quote:

Originally Posted by tangofox007

The 617 engine manual calls for 0.7-0.8 bar at full load. Be happy!!!

Thanks for the info but what is the conversion from bar to psi? I haven't found that formula as of yet.
A list of this as well as other pressures, vacuums etc. would be a good idea on the DIY page someday.
The more I do with this car the more I like it. It's been a long time since I had a car that was designed with the idea that someone would be working on it someday.

tangofox007 · #4 04-11-2005, 11:49 AM

In round figures, 1 bar = 14.5psi. So 11 psi is right on spec.
http://justchil.net/psitobar.html

dannym · #5 04-11-2005, 12:35 PM

Quote:

What is barometric pressure?

A: Barometric pressure is the pressure of the air that's pressing in all directions. In regular weather forecasts, the meteorologists are almost always talking about the air's pressure at the ground. The air's pressure is caused by the weight of all the air above the ground pressing down - gravity pulls air toward the earth just as it pulls everything else. It's called "barometric" pressure because an instrument called a barometer is used to measure air pressure.

--------------------------------------------------------------------------------

Q: What does a barometer measure?

A: barometer measures the pressure of the air pushing on it. On the average, at sea level, the air has a pressure of 14.7 pounds per square inch. This means a square one inch on each side has 14.7 pounds of air pressure on it. We don't feel it because the pressure is pushing with equal force in all directions. Instead of using pounds per square inch, barometers in the U.S. measure the pressure in inches of mercury. This is how high the pressure would push mercury into a tube that has the top sealed off from the air. A reading of 29.92 inches of mercury is the same as 14.7 pounds per square inch.

Gotta love the internet. You can find anything!

Danny

d.delano · #6 04-11-2005, 12:36 PM

11 psi=0.7584233022 bar

I'd leave as-is. Can't go much above that without introducing the possibility of engine harm.
Main problem I have is turbo spoolup. I too am reading 8-8.5 psi turbo output and I'm OK with it for the time being, but the turbo lag is pretty bad. Is it a sign I may need a rebuild i.e. new cartridge or something like that?

Phil · #7 04-11-2005, 01:13 PM

I took out a lot of the turbo lag by adjusting the alda. You have to play with it a little to get just where you want the turbo to come in but it's an easy adjustment.

tangofox007 · #8 04-11-2005, 01:34 PM

Quote:

Originally Posted by dannym

Gotta love the internet. You can find anything!

Danny

Except that what you found has to do with the pressure unit known as an "atmosphere," not the "bar." One bar(14.5 psi) does not equal one atm(14.7 psi.)

dannym · #9 04-11-2005, 03:59 PM

Quote:

Originally Posted by tangofox007

Except that what you found has to do with the pressure unit known as an "atmosphere," not the "bar." One bar(14.5 psi) does not equal one atm(14.7 psi.)

Ok, how about this one?

Click Here
Danny

engatwork · #10 04-11-2005, 07:38 PM

Quote:

Is it a sign I may need a rebuild i.e. new cartridge or something like that

It is a sign that the alda is not adjusted as well as it could be but it may not be worth fooling around with. The acceleration feel should be pretty seamless through the turbo coming up.

Hit Man X · #11 04-11-2005, 07:41 PM

Quote:

Originally Posted by Phil

I took out a lot of the turbo lag by adjusting the alda. You have to play with it a little to get just where you want the turbo to come in but it's an easy adjustment.

Yeah, crank it up... makes it a LOT better to cruise about.

#12 04-11-2005, 10:11 PM

Quote:

Originally Posted by Phil

I connected a test guage on the line from the intake manifold to the alda then drove the car. I was getting 8psi boost. I then adjusted the waste gate but could only bring the pressure up to 11psi. In all my searching it looks like I should be able to get much higher pressure. I was hoping to raise it to the 13-15 range. Does anyone have any idea why I can't get more pressure.
Thanks

The Garrett will only make 11psi without modification. The KKK turbo on the other hand will be at 20+psi before you know it, if adjusted incorrectly.

After recently tearing apart my Garrett this week I found a few things. The wastegate diaphram won't go above 11psi because it is bottomed out on it's threads (On the valve). The only stock way to go above 11psi (With pyrometer or intercooler) is to cut more threads on the valve. This will allow more spring tension and more boost. The other way is to use an external Boost Controller to the wastegate hose. I think this is cheating the easy way out, plus it looks goofy.

I also found the valve stem seal to be VERY loose and allowing soot to enter under the diaphram.

If you can live with 11psi, good for you. I'll keep my KKK turbo and 13psi.

boneheaddoctor · #13 04-11-2005, 10:17 PM

Quote:

Originally Posted by 82-300td

The Garrett will only make 11psi without modification. The KKK turbo on the other hand will be at 20+psi before you know it, if adjusted incorrectly.

After recently tearing apart my Garrett this week I found a few things. The wastegate diaphram won't go above 11psi because it is bottomed out on it's threads (On the valve). The only stock way to go above 11psi (With pyrometer or intercooler) is to cut more threads on the valve. This will allow more spring tension and more boost. The other way is to use an external Boost Controller to the wastegate hose. I think this is cheating the easy way out, plus it looks goofy.

If you can live with 11psi, good for you. I'll keep my KKK turbo and 13psi.

Umm you got that backwards...the KKK starts building boost at a lower RPM but peters out early...the Garrett will easily do enough to damage the motor.

I am running 14 PSI boost on my W116 right now with a garrett T-3....and and experimenting eith turning up the full load stop to get egt's up to max under full load to get most power.

And by the way....10 psi or 14 psi..you will make the same power without the IP being adjusted to increase fuel output. Don't sweat 11 psi unless you are doing other mods.

Hit Man X · #14 04-11-2005, 10:23 PM

Quote:

Originally Posted by boneheaddoctor

Umm you got that backwards...the KKK starts building boost at a lower RPM but peters out early...the Garrett will easily do enough to damage the motor.

I am running 14 PSI boost on my W116 right now with a garrett T-3....and and experimenting eith turning up the full load stop to get egt's up to max under full load to get most power.

And by the way....10 psi or 14 psi..you will make the same power without the IP being adjusted to increase fuel output. Don't sweat 11 psi unless you are doing other mods.

What are EGTs stock? And what's in the "acceptable" limits of safe being nonintercooled?

#15 04-11-2005, 10:31 PM

Quote:

Originally Posted by boneheaddoctor

Umm you got that backwards...the KKK starts building boost at a lower RPM but peters out early...the Garrett will easily do enough to damage the motor.

I don't know about that. I have adjusted my KKK to 20psi (By accident) and it WILL shoot up to that by 3500rpm.

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