Turbo not boosting over 10.5 psi - Page 2 - PeachParts Mercedes-Benz Forum

mach0415 · #16 12-01-2010, 02:34 PM

Quote:

Originally Posted by JHZR2

Never seen any fluctutions on my vdo gauge which is taking pressure just before the overboost relay.

If you have no ALDA. The boost line to it is plugged, right? Without an ALDA, how are you increasing fuel to support the boost? Need fuel to get exhaust glow to support more boost, it seems...

I am using the line that goes from the intake (banjo bolt) to my boost gauge.

winmutt · #17 12-01-2010, 02:58 PM

Your ARV could be leaking easily enough.

panZZer · #18 12-01-2010, 03:24 PM

Quote:

Originally Posted by LUVMBDiesels

I agree with the above. Get a boost controller on EBAY or build one. I set the one on my 617 to 13psi.
The engine outlasted the car!

Here's the cheapie I was trying to find a link for http://3barracing.com/product_7.htm

winmutt · #19 12-01-2010, 03:26 PM

If you pay more than $20 you are paying to much. You can make your own for ~$10 at the local hardware store (I always have a problem finding bb;s but I think the stuff they use for slingshots 1/4" or so would do the trick).

mach0415 · #20 12-01-2010, 03:46 PM

Quote:

Originally Posted by winmutt

Your ARV could be leaking easily enough.

The ARV is disconnected from vacuum. So are you saying that ARV may be mechanically hung open? I am not sure how this works. Does it help bleed off manifold pressure back to the turbo inlet?

winmutt · #21 12-01-2010, 04:00 PM

It could be leaking boost easily enough. It recirculates air back into the manifold with the transmission is shifting, for instance, to keep it spooled. KKK is a pretty small turbo. It would take a half a day to replace with a t3.

rscurtis · #22 12-01-2010, 04:58 PM

Quote:

Originally Posted by rscurtis

IMO, if the car runs OK, leave it alone. My '83 300D will only do about 10# with the AirResearch turbo, and runs great.

Making boost that you don't need does nothing but waste fuel. The 617 is not a high -boost engine like you see in a modern pickup or OTR truck.

Winmutt, why would you disagree with that statement? New pickups and OTR trucks routinely run in the 30-40 PSI range. How long do you think your (or my) 617 would last at those numbers?

winmutt · #23 12-01-2010, 05:47 PM

Quote:

Originally Posted by rscurtis

Winmutt, why would you disagree with that statement? New pickups and OTR trucks routinely run in the 30-40 PSI range. How long do you think your (or my) 617 would last at those numbers?

Plenty as long as the intake and exhaust temp and exhause pressure are low. You will get valve float at 20psi but stronger valve springs will handle that.

mach0415 · #24 12-01-2010, 06:45 PM

I did a little tweaking on it this evening after searching for more info on another thread that deals with KKK turbo waste gate adjustment. The Garret and the KKK have a similar psi/bar increase/decrease per revolution of tightening/loosening of the waste gate adjustment screw. It seems that the KKK's need 3 CW turns before it starts to increase boost, per the thread. I verified this, as I turned a total of three turns - took about ten minutes of messing with. I now have approx. 11-11.5 psi of boost under an inclined load. One revolution of the adjustment screw after the initial 3 appears to have an increase of 1psi. So, I am on my way to 12-13psi. More tweaking tomorrow

PS - I wish I would have copied and pasted the thread for reference.

Junkman · #25 12-01-2010, 08:39 PM

Quote:

Originally Posted by winmutt

If you pay more than $20 you are paying to much. You can make your own for ~$10 at the local hardware store (I always have a problem finding bb;s but I think the stuff they use for slingshots 1/4" or so would do the trick).

I found a box of different sized BBs at a bicycle shop. Here's a pretty neat place I've bought stuff from. Search bearings.

http://www.thethirdhand.com/index.cgi

scottmcphee · #26 12-01-2010, 08:47 PM

Since your ALDA is off, any overboost circuit and its cleanliness is irrelevant. Your only protection is keeping your eye on the boost gauge.

However, I think you'd be hard pressed to cause any problem to the engine. Even if the wastegate malfunctioned and it got stuck closed, the IP can only put out so much fuel... you are not likely to have to have a meltdown.

I heard the stock turbo on my 603 could do 3 bar maximum in ideal conditions (no waste full load). But that formula includes sending a lot more fuel than a stock IP can put out.

I guess you *might* be concerned about this if run-away diesel is on your mind and consuming the engine's own crank oil (or nearby propane leak) is a possibility or real fear. If so, put the ALDA back on and get your overboost circuit tested and working.

You know that pushing more air into the engine than is required to sufficiently burn the delivered diesel adds no more power, right? For these reasons beyond 12 psi is for "ego boost" only.

mach0415 · #27 12-02-2010, 03:20 AM

Quote:

Originally Posted by scottmcphee

Since your ALDA is off, any overboost circuit and its cleanliness is irrelevant. Your only protection is keeping your eye on the boost gauge.

However, I think you'd be hard pressed to cause any problem to the engine. Even if the wastegate malfunctioned and it got stuck closed, the IP can only put out so much fuel... you are not likely to have to have a meltdown.

I heard the stock turbo on my 603 could do 3 bar maximum in ideal conditions (no waste full load). But that formula includes sending a lot more fuel than a stock IP can put out.

I guess you *might* be concerned about this if run-away diesel is on your mind and consuming the engine's own crank oil (or nearby propane leak) is a possibility or real fear. If so, put the ALDA back on and get your overboost circuit tested and working.

You know that pushing more air into the engine than is required to sufficiently burn the delivered diesel adds no more power, right? For these reasons beyond 12 psi is for "ego boost" only.

Ditto. I have considered putting the ALDA back on to add over boost protection back into the equation. Its just so much peppier w/o it! My purpose for increasing boost is to see where the sweet spot is. Yeah, I know that 12 psi is the realistic goal and do not need ego boost, so I will probably give another turn to give me a solid 12psi and turn the page to move on from this chapter. Next is paint

winmutt · #28 12-02-2010, 09:54 AM

Anything over 11.5 psi is a waste on the kkk. Just generating heat. You need either a T3 (14 or so psi) or something more radical.

scottmcphee · #29 12-02-2010, 10:13 AM

FWIW, I added a manual turbo wastegate controller ($20) and a pressure gauge.

My digital gauge actually measures absolute manifold pressure taken from a sensor screwed into the manifold.
At the altitude I live, the car (not running) sits at -0.1 bar.

A typical dash mounted boost gauge measures pressure relative to atmosphere, so these would show 0 bar in the same setting.

(Interestingly I've seen the diesel make a little bit of vacuum at the intake at low RPM taking off from standstill, dips to -0.12 or so)

I dialed in my wastegate controller to pop open at about 1 bar absolute, and that's also when a bright blue alarm LED goes on at the gauge.
Only for very hard pushes I see the LED come on. And when this happens, there's just no more to give, she's flat out.. sort of when you'd expect to see max boost.

panZZer · #30 12-02-2010, 06:24 PM

Quote:

Originally Posted by winmutt

If you pay more than $20 you are paying to much. You can make your own for ~$10 at the local hardware store (I always have a problem finding bb;s but I think the stuff they use for slingshots 1/4" or so would do the trick).

So the BB goes under the knurled knob(between it and the skinny locking nut?) --is there a simple sticky about assembling one? Thanks