Manifold Porting

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Wastegate and Manifold Port Service

During recent winter months the air density has contributed to what most call "boost creep" in my Galant. Prior to this year, I thought that boost creep was some sort of fictional problem that only manifested in email postings. Well, for the last 3 months I've had uncontrollable boost. The pressure was set to 15psi and would spike to over 20 at open throttle. The "creep" is caused by gas flow that is flowing at a rate that exceeds the wastegate's ability to dump exhaust from the turbine. The turbo spins faster and faster as the gas cannot escape the turbine's path and go through the wastegate as instructed by the boost controller. The mechanical solution is to make the path to the wastegate smoother and larger to encourage flow of waste gas. If you want to spend some money, buying an external wastegate with a true 35mm opening will also solve this problem. I chose to go to work on the stock 16G turbo housing with a bunch of grinder bits. Below are some pictures of the work and the resulting outcome.

This is the collector side of the Evolution 3 manifold. The inside ring is going to be removed with a grinder bit to improve flow. This won't help the boost creep problem at all but It's good practice to port the manifold so I'm going to do it.

A picture of the entire manifold after porting and cleaning. The ring is now gone and the collector is much larger. On to the wastegate housing...

This is a picture looking down on the car over the front bumper. The oil is penetrant spray. The wastegate housing was removed without disconnecting any water lines or oil lines by removing the center ring that holds the two halves of the turbo together. The ring is clamped with one 10mm bolt that's easily accessible. Start by removing the manifold-to-cylinder head bolts and then the downpipe nuts. Move onto the (4) 14mm bolts that secure the turbo to the manifold, disconnect the wastegate actuator arm, and you've reached the step pictured above.

Bill Washburn of Werks Rally lends a much needed hand with the die ginder. He did a great job on the manifold. (wear glasses!)

This is a picture of the wastegate housing off the turbo centersection. Presently, I'm making a notch in the back of the wastegate flapper to allow it to swing open to it's maximum potential. This is recommended by Tom Stangl's VFAQ.com and is very helpful. The flapper can open an estimated 30% more with this modification. The bit on the grinder is not a good bit to use. Make the investment and buy one carbide bit and one sander bit to smooth the work over. This bit lasted 5 minutes.

After the porting is finished, the turbo can be carefully reassembled and aligined using the clevis pin to orient the two halves before clamping them back together with the band. If you look closely, you can see the larger wastegate hole to the right of the turbo collector. This was ported to make a "funnel" effect to the flapper, allowing maximized flow to the wastegate. (I can email a larger photo for more detail)

The top of the new manifold. Two of the manifold-to-turbo bolts stripped so the threads need to be tapped. Use HIGH TEMP antiseize on this and all other hardware in the area to avoid this. I used regular antiseize the last time this was apart and it didn't work.

Another place to port is the O2 housing where the wastegate dumps. This is important but I bought a ported housing instead of doing it myself. TRE sells them. Mine is a TRE but I bought it used.

So, in conclusion you need:

Die Grinder
Power source (air maybe)
Carbide bit
Sanding bit
Werks Rally assistance
Paul Oakenfold 4 hours nonstop on the stereo

To port:

Back side of waste gate flapper
Wastegate hole on the turbo
Wastegate exit on the o2 housing

Good luck! This worked wonders. I can finally drive the car hard after 4 months of watching the boost gauge touch 22psi. This problem can be averted by buying a 7cm housing with an internal 34mm wastegate from Team Rip Engineering or the like for $300. or a Tial 35mm gate for $250, manifold work to attach it for $150 with a dump tube from Road Race or for about $40 bucks and 4-5 hours of time on a Saturday.