Exhaust  
 

 

The standard exhaust on the Corolla is relatively free flowing, however two large 180 degree bends at relatively tight radia can be seen in the back box (muffler to some). This helps to limit the flow of the exhaust, allowing for greating fuel economy as the engine cannot expel exhaust gases rapidly. This is often called back pressure, many believe that back pressure is required in a N/A car otherwise you will lose most of your torque. This is partly true, having too large an exhaust on a N/A engine will degredate performance but it isn't back pressure that is wanted, it is a channelled exhaust velocity. Simpley put the thinner exhaust allows the exhaust to travel at low speed high pressure, and a wider exhaust lowers the pressure and raises the speed, to a point. Too little pressure and the exhaust gas velocity will also drop considerabley.

 

  
   
So for the 1587cc of the 4A-FE 2" diameter is the ideal exhaust bore. this will give the lowest exhaust pressure at the greatest exhaust gas velocity.
   
The above exhaust was custom bult to my specifications by the people at the Performance and Modified Car Centre (PMCC). Mandrel bent stainless steel, to allow from maximum flow, even with the catalyst still there a very noticable difference can be felt and heard. The back box was to my personal taste but is functional as well as good looking!
   
On the over all finish, the exhaust isn't too garish or loud. 'Off the shelf' exhaust are available, but as far as the AE111 goes, in europe only the hatchback is catered for and only mongoose make an exhaust for it. In japan they don't have the 3dr hatchback, but they do have a coupe which we don't have here, and a few manufacturers in japan make exhaust for the coupe. They could possible be converted to fit a different model (still i think would be cheaper to go custom than import from japan then start chopping it up!)
     
The AE111 has many parts that don't need modification, or could be used on earlier models to improve performance, the exhaust manifold (or 'header') is one such item. From the factory it is a Four to Two, mandrel bent stainless steel setup, very impressive piece of kit really! One thing that could be done to improve this is to remove the aluminium ply heat shield and wrap the pipes in exhaust wrap (more commonly found on rally cars). This will keep the engine bay temperature down and keep the gas inside the manifold hot, therefore expanded so no reduction in pressure until the gases reah a point underneath the car where there is no wrap. At the point the heat dissipates harmlessly onto the road. Decreasing exhaust manifold temperatures will allow better cooling by the radiator and reduce hot air absorbed by the air intake. Ergo, increase performance!
   
So this is what needed to be done next then! Firstly remove the gastly heat shield, then remove the manifold, careful not to damage any radiator fins which is very easy at this point. once having removed the heat shield there should be a manifold like the one at the top of this page (if not go and find an AE111 engine and get the exhasut system from that, its good!). With the manifold free from the vehicle get your angle grinder out, cut off the mounts (as best you can) then proceed the grind down the remained of the mounting. When finished it should look something like this.
   
Now that you've cut of all the mountings and smoothed the pipes, back to a round shape, you can move onto heat wrapping. Remember you can cut the wrap too long but not too short, its a pain when you run out if wrap and there is an inch or so not covered. beginning from the top or bottom is ultimately personnal preference, I began from the bottom. You must wrap it tightly or it will not be as effective, cover about 1/2 or so of the previous winding. Terminate the ends either with locking wire or stainless steel cable ties, I used the latter at the top and the former at the base. When finished and replaced it should look something like this.
         
4A-FE Power!