Top End Porting
The plenum ports are 33 mm diameter on the '90 - '92 engines. They are 34 mm diameter on the '93 - '95 engines. The ports are enlarged to 36 mm. This is an increase of 19% in port area for the early engines and an increase of 12% in port area for the late engines. The injector housing ports are enlarged to match the plenum ports. The fuel injector bosses are reduced in size. On the '90 - '92 engines the primary fuel injector bosses are removed. The throttle body is enlarged from the stock 59 mm to 63 mm. In the air horn, intrusions related to the alternator and air conditioning compressor locations are reduced in size. Finally, the air box is ported.
A plenum with one port left to compete. It's the fourth port from the right. A 36 mm circle is scribed on the port.
After the porting, tuning runs are performed on a Dynojet chassis dynamometer. The fuel and ignition timing calibrations are customized to match the requirements of the particular engine.
Low rpm torque is maintained.
This is an example of the results on a '90 that is stock except for a Corsa exhaust system and the porting. The typical power increase is 35 HP.
This is an example of the results on a '93 that is stock with a Corsa exhaust system. Note that the '93 - '95 engines begin with a 1 mm larger plenum port before the porting. The typical power increase is 30 HP.
The cost is $2800.
The top end parts can be shipped in for porting. This package includes performance calibration chip programming with tuning to support the porting. It includes all new gaskets trimmed to the new port sizes. $2600.