This article deals with the common problem of turbo stall and turbo surge experienced by many modified Powerstroke diesels. The condition known as turbo surge or stall occurs under heavy load conditions where boost pressures are elevated. The root cause is generally an imbalance of essures between the turbine side and the compressor side of the turbo. When the forces on the turbine are no longer strong ough to drive the compressor side of the turbo adequately, stall occurs. Often on Powerstrokes the stall will manifest self as a surging and the boost pressure in the manifold will fluctuate as the vehicle surges and you can hear an dible cyclic sound which corresponds with the surge.

The truck used for this article is my own 2001, F250 Powerstroke, crew cab, long box 4x4. The truck has a 4" exhaust, aFe intake, gauges and Banks Big Hoss 120hp chip. I uld experience turbo stall/surge when towing a 30' travel trailer weighing about 10,000# over the passes at highway eeds of 65-75mph. When the boost would reach 17-22psi the stall/surge would be very strong and the boost would oscillate 4psi while making a wooh-wooh sound. If the throttle were pressed further so the boost would climb to 23-28psi boost the rge would go away, but its hard to explain to the state patrol why you are pulling a trailer at 90mph up hill.

The following is some information about our experience with this problem, its causes and how to fix it.  The fix self was quite simple, we installed a Banks quick turbo and compressor wheel and a Big Head actuator.  This resolved e problem completely.  The following are some photos and things which were observed and changed while the truck was art.

When the truck was driven with the Banks turbo housing, compressor wheel and Big Head actuator no apparent performance in was recognized. In fact the turbo comes on slower in the low end than the stock unit and we experienced considerably re turbo whistle than the stock unit as well. Mid range and high end performance seems about the same as stock with the me top boost pressures experienced at about 28psi. Under load towing where severe surge was experienced, absolutely no rge with Banks.

Next we tried the Banks Turbo housing with Big Head actuator and the stock compressor wheel. This duced the whistle and helped bring back some of the low end. However under heavy load conditions an audible surging sound present, but the boost gauge does not fluctuate. We suspected that the sound was being caused by the waste gate ying to open so a ball was placed in the tube leading tot he actuator to plug it. With the ball in place a noticeable duction of the sound previously heard under heavy load conditions was present. The plugging of the Big Head actuator d not completely stop the sound but reduced it by more than half.

From this experience it would appear that the jority of the turbo surge or stall experienced with modified trucks especially those using large horse power chips which oduce high boost pressures is associated with the waste gate. It would seem that the exhaust pressure against the ste gate is at least a contributing factor in unseating the waste gate allowing it to flutter effecting the pressures in e turbo charger.

The combination of the Banks turbo housing, compressor wheel and big head actuator work together resolve the surge because the turbo housing is larger and flows more reducing the back pressure behind the turbine. The mpressor wheel reduces the amount of drag on the wheel reducing the load on the turbine. The Big Head actuator with its larger, stronger spring helps to keep the waste gate shut.  Since this was initially done we have found most cases of turbo strall can be resloved by replacing the stock compressor wheel with the Banks wheel and either plugging the actuator line to the waste gate or replacing it with a Banks Big head actuator.  It is probably best to use the Banks Big Head so that control for opening the waste gate is not dependant soley on exhaust back pressure.

This is a photo of the original turbo housing waste gate. It is evident in the photo that the waste gate sealing is rough and has been leaking around one side. We suspect that the waste gate opening and closing against the spring of the stock actuator was at least part of the problem causing the surge and stall problems. Under high load conditions exhaust pressure builds up behind the turbine would act to try and open the waste gate and the stock actuator spring was just not enough to keep it closed. The new Banks Big Head actuator has a much stronger spring and holds the waste gate shut much tighter than the stock one. Also the waste gate seat area of the Banks quick turbo housing is better and seals tighter than the stock one.

This is a picture of the intake manifold where it connects to the compressor housing.  It is hard to see in the photos but the interior surface of the intake manifold was very rough so it was decided to smooth it out while the truck was apart. Stock intake manifold before smoothing.   The stock "Y" pipe that connects to the turbo is very rough inside and the passenger side makes almost a 90 degree turn into the turbo, so we decided to smooth this part as well. This is a top view of the turbine and turbo charger mount.  The exhaust gases enter the turbine from the mount side and exit the turbine towards the bottom of the picture.

Intake manifold after a little work to smooth it up. The intake manifold is actually fairly easy to do this to as it is aluminum. We used a die grinder with course tootsie rolls to knock off the big bumps, then followed that with a flapper.   Intake manifold after smoothing.  The grinding and smoothing of the entire intake manifold took about 1 hour. This is the "Y" pipe after smoothing.  I don't think I would do this again.  The "Y" pipe is very difficult to get out of the truck and even more difficult to get aligned properly with the turbo when putting it back. This photo is the inside of the compressor housing.  The center opening is the intake to the compressor and is where the compressor wheel is located.

This picture shows the difference between the stock compressor wheel on the left and the Banks compressor wheel on the right. Every other fin on the Banks compressor wheel is shorter than the fins on the stock wheel. Also the Banks wheel is made of a different alloy than the stock wheel to resist bending under heavy load. The Banks wheel does whistle more than the stock wheel and whistles through a larger boost range as well.

The combination of the Banks quick turbo, compressor wheel and Big Head actuator gave about the same performance as the stock parts with a slight increase in turbo spool up.  The main thing is that the turbo stall and surge were completely eliminated.

Article by Dave Meheen of Diesel Power Products.