Just curious, because this is one of THE most significant "FREE" mods you can do to your V6. The difference is almost night and day.

I dunno how different the V6 in the f-body is from the one in the Fiero, but on the Fiero, the intake pieces (lower intake, runners, and plenum) don't match up very well. In particular, the matching from the tuned length runners, to the intake manifold, and from the intake manifold to the heads.

You can expect to gain anywhere around 5-6 horsepower on an otherwise completely stock motor. Even more with other modifications.

The good thing about our motors is that the EGR system is piped in through underneath the plenum right after the throttle body. This is good because the exhaust gasses coat the entire intake in a thin dark layer of soot / tarnish. Why is this good you ask? Because it can show you exactly where the restrictions are when you dissasemble everything.

When you remove the intake pieces, like for example, the intake manifold (lower part) and you look at it from the top. Where the gasket was removed, it's shiney.. you see the bare metal. Where the RESTRICTION is on the other hand, you'll see the metal is black. Plain and simple, all you need to do now to port match it with the runners is to grind the metal all along the edge where you see the black discoloration. Grind it down all the way until you do not see any more discoloration. That's IT! Some engine builders charge TONS of money to attach the entire set-up to a flow-bench, and then spray dye through the intake for this very same thing, but thanks to GM, they've done it for us with the EGR.

Anyway, I hope this helps people some.. it's a very important mod for this car. It's a well designed motor, but with anything mass produced, money is the important issue, so things like this don't really get the attention they need when they're being built. They make up for this loss of precision by enhancing the motor in cheaper less expensive ways.

I did this to my Fiero and the difference was night and day...

 

I did a "slight" port year? two years ago? and it really picked up after 3K. Depending on what happens with this engine i will be swapping, I may rebuild the V6, and go heavy on the mods then sell it.

 

Yeah, unfortunately for me, I enjoyed this increase in HP only for about a couple of days.

The reason why I did all this work to my Fiero is because it had overheated BADLY.. I mean BAAAAD. The coolant temp went WAAY past the red into the black area. Had I not been using synthetic, my engine would have seized.

In any case, the waterpump (aftermarket, and had a plastic impellar) had failed. I didn't know it was that, and went on to do a complete valve job on my engine. I got it all back together, ran AWESOME for a day (drove about 10 miles) and then the next day, spun a bearing while I was booking down the street with the gas pedal floored. Actually.. it wasn't a spun bearing, it was a worn out main bearing. (the big one).

Oh well...

I've got my 2.8 getting ready to go to the machine shop in the next day or two. It's getting the full 2.8 to 3.1 conversion, with a mid to high rpm cam.

Should be fun. I'm going to go back over my intake and do any clean-up I may have missed.

 

Hm; I've got the top end of the TheWraith's old 2.8 in my basement... never really looked at the plenum closely. I'll have to see if there's any trace marks of that black soot! His engine was FULL of black soot (it died somehow, he thinks a rod went out), so if soot tells us where restrictions are, his plenum would be a great one to look at!

 

You know what, I actually took pictures of an intake with the pieces off, I did close-up shots of the runners and showed just how bad the restrictions are.

To be honest, the restriction up there really is pretty damn bad. When you look at the size of the holes, you're actually ONLY getting about 3/4ths the amount of flow from those holes than you're supposed to.

I can't stress enough how easy of a job it is.

It's well worth the time spent with the grinder.


Todd