We all know that stock rotary engines come with a lot of unnecessary, complex “stuff” on and around them. Metal vacuum spider, air pump, brackets, control valves, hoses, and just “stuff”. Most of us live in areas where we don’t have to pass emissions visual or sniffer tests. For those who do not, you have the option to remove all the stuff. Generally you don’t gain much if any horsepower from doing so, but you get a nicer, clean engine and enginebay, and often a better running engine as far as reliability and response. Most importantly you gain the ability to work on the remainder of the engine in as little as 25% of the time it would have taken you with all the stock stuff in place.

For the FD engine, half of the junk under the manifold is for emissions, and half is for the sequential twin turbo control system. In my mind, there isn’t much merit in removing only half of the stuff under there, so I usually recommend that people ditch it all, or leave it all stock. That is, go with a no-emissions AND non-sequential setup and eliminate all the hoses/solenoids/etc. possible. IT is possible to JUST remove the emissions while leaving sequential controls intact. It is possible to JUST remove sequential controls while leaving the emissions intact. I suggest that you read up on my writeup about the non sequential turbo conversion elsewhere on this page for details about that, so you can make a more informed decision.

When I do emissions removal, I do the following pretty much standard on all engines:

••		remove vacuum spider and hoses
••		remove air pump, hoses, and brackets
••		remove air control valve (acv) from intake manifold (the funny looking part with wires and round pieces on it above your exhaust on the intake manifold)
••		remove double throttle control plates from upper manifold
••		I usually leave the idle speed control (ISC) motor intact
••		remove EGR valve.
••		remove accelerated warmup valve
••		everything that is now open gets capped off with vacuum caps or aluminum blockoff plates (I purchase mine from an online supplier).
••		remove twinscroll system on 87-88 turbo engines
••		everything that is now open gets capped off with vacuum caps or aluminum blockoff plates (I purchase mine from an online supplier).
••		remove cold start thermowax. This is a device on the throttle body that is fed by 2 coolant lines. It is a cylinder filled with wax, and when cold, the piston is retracted into the cylinder. An adjusting screw rides on the cylinder, and by way of a pivot, rides on a cam which is connected to the throttle plates. When cold, the setup holds the plates a hair open all the time (as if your foot were on the gas) to keep the cold engine idling a bit higher. As the engine and coolant warm up, the wax melts, the cylinder expands out, and pivot moves off the cam, and the plates close up to normal position (slowly) and normal idle speed. Removing the thermowax is not a great idea for everyone, but it does get rid of a couple of coolant lines. If you like to start your car in the morning and let it warm up without you being inside, and you live in a colder climate, you probably need the thermowax left in place. The benefit of removing it is the lack of coolant lines connecting the intake to the engine, meaning it is much easier to remove it if need be.

You also have a few other options at the same time:

••		remove stock oil metering system **to allow user to run 2-cycle premix in the gas at all times**. The benefit to this is a cleaner engine externally, less oil consumption by the engine, and cleaner 2-cycle premix burning internally (necessary to lubricate the apex seals, which is what the OMP system did with crankcase oil) leaves fewer deposits on the internals and probably does a better job of even lubrication internally. Note that you will have to religiously pour in premix with your gas, without fail, after removing the system. OMP, oil lines, vacuum lines and oil injectors get removed and blocked off. Note that you cannot remove the OMP from a car with a stock computer.
••		remove a/c and p/s. Hardcore owners often wish to clean up the engine bay and remove weight and complexity from the car by doing this. You remove the p/s pump and lines, and leave the stock rack in place. You remove the a/c compressor and lines, and in some cases the drier and condenser. Then you take the bracket off the engine, and you’re left with a very basic engine block and intake/exhaust manifolds, water pump and alternator, and that’s about it. Note that I can perform any or all of these modifications to anyone’s car, but they’re best done during an engine install, such as while your car/engine is here for rebuild. Keep this in mind when considering a rebuild, even if I am not doing the install, I can still set up your engine this way while it is here.