Hey I am taking the upper plenum off to replace the injectors and install a Fuel Pressure regulator. Do you guys have any ideas on anything else I can do when its apart to boost power a little bit? Give me any ideas!!!!


Brian Felts

 

You could port the plenum

 

Cool I know I need to knock down the EGR walls just inside the TB, anything else. Will there be any need to gasket match the runners? Or will there be any gains if I open them up like you guys do with the SLP runners.



Keep them coming

 

The EGR walls are the biggest issue, While its off of the car i would open up the TB holes to 58mm Just so you dont need to remove the plenum (more important on lt1's and other intakes) if you ever go with a bigger throttle body. Also the divider between each runner is kinda blocky, I cut mine down and smothed them out to make a nice airfoil style divider, If you've got the money you can buy some TPIs bigmouth gaskets and gasket match to those.

 

As for porting the plenum, here's the keys to hit.

- EGR walls inside the throttle bores (obviously)

- gasket match and radius the entry from the TB. I wouldn't worry about increasing the size of the openings beyond this. The plenum is gravy to pull off, so if/when you move to a bigger TB down the road you can always do it later. Also, opening a stock plenum up for a 58mm TB is quite a piece of work from the pics i've seen and would be a HUGE waste of time if you don't need dot do it.

- A lot of radius work can be done on the runner entries as well. Also, usually at least a couple of the holes really need to be gasket matched as well. You can easily check the plenum to runner junction for problems by putting a runner on one side, and using the runner holes on the other side to look through. Again, i'll differ from tpi_iroc here in my advice and say to only gasket match the holes to stock runner gaskets if you're using stock runners. Opening up to big mouth gaskets would give you a nasty 1/8 lip aroud the entry to each runner. The stock gaskets match nearly perfectly with stock runners. Again, pulling the plenum is so easy (and also part of a runner swap anyway) that opening the holes up for large tube runners later is no big deal.

- And don't go nuts trying to get it spotlessly clean. Carbon in the plenum is not going to cost power or driveability. Just throwing this in here because i've seen some people ask it in a quest to be ultra **** and make it look like a new casting.

 

I'm not any kind of expert on this stuff yet, but I ported my plenum and runners. I wasn't much more to get the runners off and if you look into the mouth of the runners you will see a big lip there where the tubes end. I just smoothed the lips down and cleaned the inside of the runners with carb cleaner and an old terry cloth towel. I sprayed a bunch of carb cleaner into the runners, let it soak and then forced the towel into the runner tubes with a screwdriver, and then pulled it out the other end of the runner. Did this several times and got 99% of the carbon out of the runners. Was really easy cleaning them this way. I had my plenum put in a jet washing machine and it got a lot of the stuff inside it, but not all. Like Ed said, I didn't get **** about cleaning the inside of the plenum. Something else I did when porting my plenum was after I finished grinding down the EGR ridges, there were two large grooves in the front of the plenum just before the ridges, so I used JB Weld to fill these depressions, then ground the JB weld down so there would be a smooth flow of air across this section. I hope I didn't screw up by doing this. If I did then it's my fault. But those grooves were pretty deep and filling them in can't hurt air flow. I've also got a pdf file of a plenum porting how to sheet I found somewhere. I can't tell you where I found it, but I do have the pdf file I can email to you. It's by Vader and is pretty complete. Details everything you need to know to get the job done. Let me know if you would like me to send it to you.

Dan