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#1
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Turbocharger Boost Pressure
Has anyone tried checking and adjusting the boost pressure of their turbocharger?
It is my understanding that over time, the boost pressure control valve looses its factory setting (0.6-0.8 bar) and opens too soon resulting in reduced power. Supposedly, the KKK brand is adjustacle but the AE brand is not.
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the sooner you start... the sooner you'll get done If it ain't broke, don't fix it.. Its always simpler to tell the truth... 2007 Honda Accord EX 2007 Honda Accord SE V6 96 C220 97 Explorer - Found Another Home 2000 Honda Accord V6 - Found Another Home 85 300D - Found Another Home 84 300D - Found Another Home 80 300TD - Found Another Home Previous cars: 96 Caravan 87 Camry 84 Cressida 82 Vanagon 80 Fiesta 78 Nova Ford Cortina Opel Kadet 68 Kombi Contessa |
#2
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I found the SD to have 8-9 psi when tested. When the turbo was out of the vehicle, I removed the cover and adjusted the wastegate by 3 turns. The boost is now 13.5 psi. The Garrett can be done on the vehicle, but, it's a PITA. Most folks opt for the boost controller to make their life easier.
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#3
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Quote:
Is 13.5 psi within the .6-.8 bar? What is a boost controller? Did doing this impact performance?
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the sooner you start... the sooner you'll get done If it ain't broke, don't fix it.. Its always simpler to tell the truth... 2007 Honda Accord EX 2007 Honda Accord SE V6 96 C220 97 Explorer - Found Another Home 2000 Honda Accord V6 - Found Another Home 85 300D - Found Another Home 84 300D - Found Another Home 80 300TD - Found Another Home Previous cars: 96 Caravan 87 Camry 84 Cressida 82 Vanagon 80 Fiesta 78 Nova Ford Cortina Opel Kadet 68 Kombi Contessa |
#4
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A boost controller is a device that will regulate the wastegate and is easily adjustable. You can do a search. There's plenty of discussion on it. Here's the procedure for adjustment of the Garrett: Turbocharger Wastegate Valve Spring Tension Adjustment for 617 Engines Introduction Garrett Turbochargers If you have a Garrett turbocharger (w/ wastegate adjustment inside cover), removing the cover takes some time and perserverance. It is not particularly difficult, just tedious. Make sure that the turbo area is cool (use a fan between adjustments) and when re-installing the spring, "squeeze" it to reduce its diameter before inserting. Then, with a screwdriver push on the flat part of the spring until it seats. KKK Turbocharger If you have a KKK turbo, the adjusting screw sticks right out of the top (sideways on engine) of the wastegate chamber and does not require removal of a cap. Caveats Remember both of these turbos are capable of over 40 pounds per square inch of boost and they run against an open wastegate all the time so these adjustments are really critical. Don't get carried away or you are going to buy a motor. However, please note that it is hard to get a tremendous amount of boost (i.e., well beyond safe ranges) from an original 617 turbo now that the cars have a few years on them now and the springs are fatigued somewhat. Still, confidently proceed with caution. If you have an exhaust temp gauge in-line you can carry the boost procedure a little further, but even at 0.9 bar (upper limit of factory specifications) they just fly. Preliminary steps necessary before adjusting wastegate valve spring tension Prior to adjusting the wastegate valve spring tension, there are two necessary preliminary steps that need to be taken, each of which is provided at this web site: http://hsb.baylor.edu/html/easley/mercedes/mercedes.html and is referenced below: The first step is to ensure that the injection pump is timed correctly. This procedure is described on the following web page: http://hsb.baylor.edu/html/easley/iptiming.htm Checking the boost sensing lines and overboost sensing switch is the next step in this process and is described on the following webpage: http://hsb.baylor.edu/html/easley/boostchk.htm After successful completion of the above two steps, you are now ready to adjust the wastegate valve spring tension (i.e., boost adjustment). Tools needed for adjusting wastegate valve spring tension on turbocharger High quality vacuum/pressure gauge (needed for checking boost pressure only) "T" fitting for vacuum gauge and 6 - 8 foot length of vacuum hose for monitoring boost pressure while driving vehicle (needed for checking boost pressure only) Phillips screwdriver 10 mm socket and 1/4" drive ratchet and extension for removing air horn Pliers for removing sensor hose clamps at turbocharger Small mirror for clarity during cover removal High powered flashlight or shoplight Instructions Remove the u-shaped air intake and the intake to the air cleaner. Make sure to re-install before testing boost pressure. Cool the turbo area with fan. Spray the cap cover "spring" area with Liquid Wrench or other similar solvent. Using a couple of small screwdrivers (a very thin bladed 5-8" shafted one is great), "spin" the spring around until it starts popping out. Pull out the spring with needlenose pliers or fingers. Remove wastegate valve cover. Be careful not to damage the rubber seal behind cap (but attached to body of turbocharger) when removing. There will likely be a small quantity of oil that will leak out when the cover is removed; this is normal – not a problem. Completely remove locknut on wastegate valve. Make a note of measured length of exposed threads on valve. Turn spring assembly (it has flat, thin edges for wrench) clockwise. Begin with 3 full turns - it sounds like too much, but it isn't! If our approximations are correct, for every 1/8" of threads exposed (by screwing spring assembly in), this equates to 0.15-0.20 bar of boost. Reverse disassembly procedure. To reinstall spring as easy as possible: Make sure that you've thoroughly cleaned the groove where the spring resides. Make sure that the spring is thoroughly clean. Lightly file or grind the flat side of the spring at each end so that it's shiny. This enables you to manuever better when inserting 'cause shiny end shows. Make sure that rubber gasket is firmly seated before replacing cover. Compress spring with fingers to reduce diameter when placing in groove. And, push cover hard simultaneously. Then, push spring with biggest screwdriver that you can use. Tap screwdriver with rubber hammer. You should "feel" spring seat. Do this only on fan-cooled turbo area. Road test using Stu's guidelines: having the boost gauge in the car, start driving a fully warmed up motor and engage "S" and go up to 4,000 rpm and full throttle, read the boost. Good luck and hold on to your hat. If further adjustment is needed, cool turbo area with fan. Finally Please let me know if you complete this procedure successfully; it took a while to type this, and I'd appreciate knowing when each person has completed the repair! Please e-mail me at richard_easley@baylor.edu ©1998 Richard Easley, Waco, Texas and Stu Ritter, Denver, Colorado. |
#5
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I would reccomend the boost controller (google it). In thoery, it reduces turbo lag, and its much easier than adjusting the wastegate.
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1976 BMW 2002- 100k 1995 BMW 325i 175k 1984 Mercedes Benz 300D Turbo Diesel- 270,000 mi 1981 Mercedes Benz 240D- Estimated 300,000+ mi Returned to the earth |
#6
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Quote:
One thing I'm not totally sure of though, is this: does a boost controller reduce lag as much as adjusting the waste gate manually as Brian describes?
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1998 E300D, 287k, barely broken in. |
#7
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I T'd in a $3 15 psi pressure gauge in my car. hooked it up with some 1/4 poly icemaker line. no lite, but it works fine all day. push 9.75 psi WOT. that is without adjusting anything. I havent even installed my voodooo boost controller.
good word- overboost can cause all sorts of problems. from headgaskets to overheated EGT's. dont mees with it without a gauge.
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1984 123.193 372,xxx miles, room for Seven. 1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven. |
#8
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Wow, mobetta. Trouble with the keyboard? You usually type much more clear than that.
I'm running 14psi peak boost right now on my high setting, 8psi on my low setting. |
#9
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When the springs get weak in the wastegate, it allows the wastegate to creep open as the turbo builds boost. With a boost controller, the boost signal doesn't reach to the wastegate until the preset pressure. The wastegate gets the boost signal in one big surge, therefore keeping it closed until full boost is reached.
I'm a bit fuzzy on my turbo stuff, but that's the basic principal. BTW, I had my 300 spiking at 12 PSI and settling to 11 PSI. I believe cruising at 80 MPH produced 10 PSI. A friend of mine ran it up a mountainous region-in the summer-with the A/C on- at 80-95+ MPH-with 3 passengers and a loaded trunk. It still runs very well with over 250,000 miles, and doesn't burn any oil between oil changes. I think the high end of the MB spec is around 11.X PSI.
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1976 BMW 2002- 100k 1995 BMW 325i 175k 1984 Mercedes Benz 300D Turbo Diesel- 270,000 mi 1981 Mercedes Benz 240D- Estimated 300,000+ mi Returned to the earth Last edited by mbzkid; 02-19-2007 at 11:11 PM. |
#10
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'85 300SD (formerly california emissions) '08 Chevy Tahoe '93 Ducati 900 SS '79 Kawasaki KZ 650 '86 Kawasaki KX 250 '88 Kawasaki KDX200 '71 Hodaka Ace 100 '72 Triumph T100R |
#11
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Quote:
Quote:
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#12
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When you put more air in you need more fuel.
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'85 300SD (formerly california emissions) '08 Chevy Tahoe '93 Ducati 900 SS '79 Kawasaki KZ 650 '86 Kawasaki KX 250 '88 Kawasaki KDX200 '71 Hodaka Ace 100 '72 Triumph T100R |
#13
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The ALDA didn't make much difference for me after adjusting turbo because not much boost is produced until about 2400 RPM anyways. Sure I was more responsive off idle but not 15 MPG worth.
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1985 CA 300D Turbo , 213K mi |
#14
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You are misunderstanding how the ALDA works.
The bellows inside the ALDA automatically adjust to air pressure. Adjusting the screw only increases the fuel given off the line. |
#15
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The ALDA enriches the fuel delivery in response to altitude and intake manifold pressure.
The higher the manifold pressure (higher boost)=more fuel needed (ALDA adjustment) http://dieselgiant.com/mercedesaldaboostsystemservi.htm
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'85 300SD (formerly california emissions) '08 Chevy Tahoe '93 Ducati 900 SS '79 Kawasaki KZ 650 '86 Kawasaki KX 250 '88 Kawasaki KDX200 '71 Hodaka Ace 100 '72 Triumph T100R |
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