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Extreme 280zxt page

Waste Gate

The pictures above are a HKS waste gate and the Turbonetics(Delta Gate) waste gate. These units are about the same rating, and will handle about a 300Hp engine. The Turbonetics (Race Gate) is the unit to get for the higher Hp applications.
The lower picture is an excellent install of the Turbonetics Race Gate. The turbonetics Race Gate will handle very effectively an engine producing well into the 500Hp range. Note the location of the unit, an excellent location that will not get in the way of any other bolt on parts, including the air conditioning compressor in any zcar. I would highly recommend this install. The gate exhaust can easily be fed into the exhaust downpipe or run seperate. Note the unit is installed center of the exhaust manifold to ensure a smooth dump of exhaust and relatively even spacing for consistant exhaust flow.Very nice.
The characteristics of a insufficient waste gate is over boost, meaning the boost will not be controlable at the lower boost settings. A good test of the waste gate with a high output turbo is to set the boost controller to off, or disconnected, and run the engine under load to the high rpm ranges. Note the ability of the waste gate to bypass the excessive air to keep the boost levels to minimum, if you get to a point that the boost increases with the engine rpm, then you need a bigger waste gate. The majority of over boost cases, are not a problem, however, a full blown race engine running to the edge of detonation will have to have an accurate boost level to ensure the maximum boost setting is stable throughout the rpm ranges, as more air flows the insufficient waste gate will again show it's ugly head in the higher rpm ranges. The next problem is a spike in the boost upon first spool up. This situation is most commonly caused by a less then desirable boost controller. When the turbo spools up you will see a max boost level of say 15psi and then level off to say 13psi across the rpm range. to combat this problem you will set the maximum boost lower then you could normally run to ensure the engine doesn't run lean with the turbo spiking. The spiking will create a situation of a few pounds of boost lower then the engine can actually handle, and that means an overall loss of power over the RPM range, which in turn means slower drag times. Two pounds of boost with an engine running 20psi is significant. I myself have noticed with the stock turbo engine a seat of the pants difference from 11psi to 13psi of boost.
Myself, I am still running the Nissan Stock waste Gate, and that appears to be working well in my car. I do have a slight overboost challenge, but I am not spending 100k plus on a race car I am running in competition, and for about 450.00 dollars for a race gate and the costs of fabricating the gate exhaust and welding the inlet flange on the exhaust manifold, I can live with it. I am also utilizing a Blitz boost controller, a very good unit, and it regulates the boost very well. I would expect a 450.00 dollar unit to do just about anything for that price.
You can see the price of just these two components is significant, not for the do it as cheap as possible builder. The old adage still applies here, you play, you pay. Call me cheap, but I am not prepared to lay out that kind of money yet for a car I run just for my own fun and pleasure. A further note on waste gate selection: A good rule of thumb is what ever turbo you are utilizing in your system can be checked to ensure the waste dump is sufficient for the system. Generally, if you set the waste gate to minimum boost levels, in most cases with the controller off, and the boost can be controlled at the minimum level, the waste gate is sufficient for your application. A waste dump that will not enable the turbo operate at minimum levels indicates the need for a bigger waste flow and possibly an external waste gate. Ensuring the correct operation of the stock system and finding it is sufficient for the system is well worth the time and testing as the external gates are again, very expensive, and require engineering to incorporate in the system.

Here is a picture of a Tial 46mm waste gate. This is the unit selected for my final turbo build. The Tial waste gates are extremely high quality made from stainless steel and aluminum. The 46mm gate will bypass 1.3 bar of boost so that is excellent for my application, and will enable me to run stock boost if I want to. The boost is being controlled by a Blitz controller and is adjustable on the fly from inside the car while driving. Tial waste gates are easily servicable as the valve and the seat are replaceable. I like the compact size of the gate and the ease of install.