Engine Porting
 

Can anyone advise on engine porting for my 3rd gen (1993) RX7. What is involved and what are the costs? Are they different grades of porting and will this make a big difference. Where are the best places to go? I guess what i am asking in a round about way, is it worth it?

Many thanks
Gregg

http://www.mazdatrix.com/engsptb.htm

http://www.mazdatrix.com/faq/portbp.htm

If the engine is already out of the car and torn down, it will be the cheapest horsepower you will ever gain with the exception of your downpipe and midpipe. It is definately worth doing while the engine is apart for a rebuild.

Here are some pics I recently took while porting while at different stages of the port for people to see the progress. The tape is to protect the face of the iron if the bit is to skip out of the port. This is something if you ever try porting on your own that is a must to do. You would be surpised out how some people continually skip across the face of the iron while porting.

These ports were for one of my personal cars so I didnt take the finish down as smooth as I do for customers. Take the finish down smoother than what I have done here is not necessary or really beneficial in any way but some people like to have the polished look. To port an entire 4 port turbo engine and exhaust ports will take about 4-5 hours if you are just doing the ports and the "bowl" of the port. If you want the runners ported and polished then add more time on for that.

Some people simply just port the port opening and dont clean up the factory castings which have can have severe cast marks left behind. Porting is more than just opening up the port, the opening edge of the port should be ported at an angle into the direction of the runner to allow smoother airflow. Every person ports differently and has there own ways they do things. Some bevel the closing edge of the intake port and others dont. However, I think it is necessary to bevel the sides and closing edge of the exhaust ports. This has been long winded enough at the moment. If you have any other questions let me know.

As far as pricing, a basice street port including exhaust porting will start around $250.00 and some shops charge up to $500.00. Other types of degrees of street porting costs more. If you are going to port the engine there is no reason to do a small street port unless you have emissions to pass. IMO there is no sense in doing it unless you are going to really improve the flow.

pics

These pics are when the ports are finished or close to finished.

Here are a couple different sized exhaust ports. Nothing crazy but it the center housings is a stock port so you can get an idea.

Keep emissions in mind when deciding on which porting you want (and how large)

Many thanks for all the replies. It's all very helpful.

Can anyone advise how difficult it is to do. Although I have never done this type of work before, I am quite handy with engines etc and i seem to have the tools to do it (according to the web site information). How do you know how much to remove with the porting. Read about templates. Are these any good?

Thanks again
Gregg