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GSP Wastegate Review

In this review I will be testing the Godspeed GT-SERIES 38MM wastegate from GodSpeedProject.com.

Standard 38MM flanges
Ships with 7psi spring
Duel port (reference and controller port)
Six hex bolt design
All mounting hardware, flanges and gaskets included

Looking things over

Out of the package the wastegate has a good look and feel. The first thing I noticed was how compact the design is compared to other similarly priced wastegates. I don't have much room under the hood as it is and my old wastegate just cleared the radiator support by less then 1/4". There are six hex head bolts holding the spring and diaphragm in place which is stronger and provides a better seal around the diaphragm then the V-Band design of other wastegates. The only drawback to this is that getting the bolts started while holding back the spring pressure can be a bit of a challenge sometimes, specially if a higher boost spring has been installed. The spring and diaphragm are isolated from the exhaust heat by three studs. This helps keep the diaphragm from getting damaged as well as keeping the spring from getting weak from heat. The wastegate features 2 ports (reference and controller) to use in conjunction with a boost controller setup. The diaphragm seems good, and has very little stretch, although I really have no way to fail test it, other then real world use and abuse which of course I will do! I vacuum tested both ports and found no leaks. To do this test I applied 15 in-Hg of vacuum to each port separately and allowed it to sit for 30 minutes. There was no loss after 30 minutes meaning the diaphragm had a good seal to both the WG housing and the plunger head.


The Installation was of course straight forward. The manifold I am using already has the WG flange attached so I did not need to use the flange provided. In the near future I will be fabricating a WG dump to my down pipe and the extra flange will come in handy for that. I had been running a manual boost controller with my old WG but I will be bypassing that for the first part of this review, using the spring only to regulate boost pressure. Note: If you do not plan on running a boost controller of some kind I would recommend picking up some extra WG springs. These will come in handy when trying to dial in the boost level you want to run. For an untested street car, start with a very low pressure spring (4psi) and go from there. When installing the hose barbs remember to use some Teflon tape to stop any boost leaks from occurring. Although the leak would be small, they can cause the WG to behave erratically.


Currently I have only put around 100 miles on the WG. I am pleased that everything operated smooth from the start. I found that the gate is a little tight, opening consistently at 10 - 12PSI. This may be due to the fact that I still have my boost controller installed, it is simply turned off. I will have to bypass it completely to see if the levels come down to the advertised 7psi. This is not a problem for me as I run higher levels of boost on a regular basis. For a new untested turbo install I would definitely recommend picking up some extra springs, at the very least a lower pressure spring to start out with.

-09/23/08 Cool Weather Testing

Since the weather has been getting down in the 50's I figured this would be a good time to do some cool weather testing. I also took the check valve for the boost regulator out of the line. This brought the boost down to a more manageable 9psi. I would however, still recommend the purchase of additional lighter springs unless you are comfortable with moderate boost levels.

-02/01/09 Cold Weather Testing

I finally have the car back together after a major suspension overhaul so I took it out for a spin.  The weather being a crisp 20F degrees with snow on the ground makes this a perfect cold weather test.  I am happy to report that the wastegate worked great, even after sitting for 3 months with no use.  With the manual boost controller removed and the boost line directly from the turbo to the wastegate, boost levels stay between 8 - 10psi, the advertised range for this wastegate spring.

-05/14/09 Finally some warm weather

Well, spring has arrived and I have been taking the car out on the weekends and even commuting to work in it on the nice days. I have now surpassed 3000 miles on the GSP wastegate, 3224 to be exact with no problems.  The compact design is great, and its smooth operation makes it a great choice for a street or light drag car.

Final Thoughts

Although I have never personally had a problem with a wastegate failing or sticking, this can be quite detrimental.  A wastegate which sticks closed after a shift under wide open throttle can easily over boost the engine to the point of breaking.  The design of the GSP wastegate minimizes that by use of a large diaphragm. More surface area on the diaphragm means the wastegate valve will open much easier.  The downside to this of course is that the gate starts to creep open before peak boost levels are reached creating a small amount of lag but I personally think this wastegate reaches a healthy balance.

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