Do not over look porting your upper and lower plenum.. Just cleaning them makes a huge difference. I then took my dremel and an aluminum cutting bit and gasket matched them. I then used sanding wheels and my finger and polished the holes smooth.


Cost under 10 bucks for dremel parts
Time 2-4 hours
Gain noticeable on the top end, after this my MPH went up in the ¼

At this time you can also polish the outside of the plenum since it is all off or have it powder coated like I did..


Gosh I miss my 2.8… Anyone in Orlando with a 5 speed RS 2.8 or 3.1 for sale cheap…Or trade for some stuff…

 

Porting the plenum and runners alone seems wimpy to me

 

Lets face every 1/10 or 1/100th counts when you have a 2.8/3.1... It is easy to do....

 

The problem is if you do not know what you are doing you could make things worse. If you take out too much metal or cut away too much you could cause airflow problems. Cleaning to me seems the best way unless you are experienced in porting and polishing.

 

Actually it opened up 2500+ in my car. Barely ported too, maybe 1/8" overall.

 

never had any expereince.. Just chatted with those that did.. Leanr by gasket matching first... Simple, easy and worth it..

 

Yea, but when you think about it you arent going to hurt airflow anymore then the factory did in the first place.

Port it to match the gaskets and cut as many imperfections out as possible and smooth the runners. If you dont dig holes you will be all right. It's basicly simple, people screw up the most when thier porting and polishing the combustion chamber on heads or totally hogging out the intake ports.

 

I was watching Popular Hot Rodding TV or Horsepower TV on TNN and they were doing porting and polishing to heads. The guy doing it was from Wyotech a trade school. He said if you mess up it could hurt airflow and he tested his flows on the head using a machine. I still think unless you know what you're doing and have a good book on it just clean it. More power to you though if you do it and it doesn't mess anything up.

 

Yeah, if you go beyond cleanup and into "Hey, I think if I grind this curve away, it'll give me more air!", that's when you can do damage. All we can really do is remove sharp edges or "casting flash"- left over metal shards from GM that "obviously" stick out into the ports.

See http://www.sa-motorsports.com/diyport.htm for a cool do-it-yourself guide on head porting. I'm surprised that page is still up; it's been around for as long as I can ever remember ('97/98..)