Wastegate Overboost Question: Are They Fail Safe or Not ?
07-22-2011, 05:37 PM
#1
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Wastegate Overboost Question: Are They Fail Safe or Not ?
If the lines to the wastegate were improperly installed, can I be in danger of over boosting?
Is there any other scenario that can cause an over boost failure.
Or, are there built in fail safe mechanisms in place.
Is there any other scenario that can cause an over boost failure.
Or, are there built in fail safe mechanisms in place.
07-22-2011, 05:55 PM
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Yes, if you install the lines wrong the WG will not open. Remember that the fitting at the top of the WG is only a vent line (stock configuration has a line attached to it that just deadends somewhere in the engine compartment, since it's only a vent). The side port fitting on the WG is the one that must receive the pressure signal. If that line is not connected or seriously leaking boost pressure, then expect a sluggish or non-working WG.
The only other failsafe in the event of overboost is the overboost sensor which will shut off both fuel pumps if your boost exceeds around 1.4 bar...possibly less as the sensor ages. If that sensor is shot, or the wire disconnected from it, and if your WG does not open, then you can boost to the moon and just flly down the road until your heads blow off or the pistons liquify.
The only other failsafe in the event of overboost is the overboost sensor which will shut off both fuel pumps if your boost exceeds around 1.4 bar...possibly less as the sensor ages. If that sensor is shot, or the wire disconnected from it, and if your WG does not open, then you can boost to the moon and just flly down the road until your heads blow off or the pistons liquify.
07-23-2011, 10:26 AM
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Wow,
My shop did install a new Intercooler, K27 and headers and then I cracked a cylinder right down the middle in less than 100 miles after my shop did the change out installation of the IC, new turbo and headers.
The pistons looked fine but the cylinder was wasted.
I'll try to post a photo. Do I have to subscribe to post a photo or maybe I can't find how to post a photo while using my iPhone.
Is it possible that my shop missed something?
What should I think?
My shop did install a new Intercooler, K27 and headers and then I cracked a cylinder right down the middle in less than 100 miles after my shop did the change out installation of the IC, new turbo and headers.
The pistons looked fine but the cylinder was wasted.
I'll try to post a photo. Do I have to subscribe to post a photo or maybe I can't find how to post a photo while using my iPhone.
Is it possible that my shop missed something?
What should I think?
07-24-2011, 05:51 PM
#4
Burning Brakes
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Glenn, I'm getting a bad case of computer mouse carpal tunnal navigating between Rennlist and Pelican forums on your issue
I have never heard of a cylinder cracking down the middle, not that it can't happen I suppose. If you're concerned about overboost or other fueling issues, usually it's the piston that melts or a ring the breaks. Hmmmm....hard to point the finger at your shop without knowing whether or not your tune and fuel delivery were correct or not. What is (or was) your boost gauge showing when she crapped out on you?
I have never heard of a cylinder cracking down the middle, not that it can't happen I suppose. If you're concerned about overboost or other fueling issues, usually it's the piston that melts or a ring the breaks. Hmmmm....hard to point the finger at your shop without knowing whether or not your tune and fuel delivery were correct or not. What is (or was) your boost gauge showing when she crapped out on you?
07-26-2011, 01:51 PM
#5
I've had the exact experience that Mark mentioned above. After having a new turbo installed I (Big Dummy) adjusted the boost up way to high and destroyed 2 cylinders in the process. Unfortunately, the rings disintegrated which resulted in the destruction of the barrels, pistons and rings...
This was my first major lesson in understanding turbo charged engines and the impact of over boost. And boy what an expensive lesson. So at the recommendation of my mechanic, I've removed the Dial of Death...good luck with the P-CAR...
This was my first major lesson in understanding turbo charged engines and the impact of over boost. And boy what an expensive lesson. So at the recommendation of my mechanic, I've removed the Dial of Death...good luck with the P-CAR...
07-26-2011, 02:58 PM
#6
RL Technical Advisor
I have never heard of a cylinder cracking down the middle, not that it can't happen I suppose. If you're concerned about overboost or other fueling issues, usually it's the piston that melts or a ring the breaks. Hmmmm....hard to point the finger at your shop without knowing whether or not your tune and fuel delivery were correct or not. What is (or was) your boost gauge showing when she crapped out on you?
Besides the issues mentioned by others, boost creep caused by poorly designed header systems is also responsible for these situations and thats something to consider, based on your configuration.
