I have already done the usual porting work behind the throttle body, and have installed the runners. I saw a magazine that cut out the section between the holes on the plenum to match the siamesed runners. Is this worth me taking it back apart and doing? Thanks.

 

If I were you I would take it off, and port the plenium to match the runners. It isn't going to hurt. Depending on your motor, it might help alot.
Fbird

 

Yeah, I think it is probably worth doing. I am probably going to get the TPIS Big Mouth intake shortly anyway. I was considering Holley's stealth ram, it is priced right, but I think I will rarely spin the motor upwards to 6000 rpms. I think I am going to stick with the low end torque the tuned style runners provide. Thanks for the reply, where in N.C. are you?

 

I don't think you will loose too much lower torque by porting the plenium. I agree with you on the ltr setup. I don't think my engine will ever go past 6000 either. But porting the plenium might help you get there faster! I'm in Jacksonville by the way. Well, for another couple months anyway. I will probably be moving to SC then.
Later

 

I go to Jacksonville dragstrip occasionally with my 87 Grand National ( 11.55@116 ). I did however take my Z28 last time just to see what it would baseline, it went 14.34@95, and was able to take the street class trophy that night. It ran very consistent times. I have alot of work to do though if it wants to stay near the Buick!

 

Do not Siamese the plenum. An engineer at SLP told me to port the plenum to the big mouth gaskets, but do not knock out the wall between ports because doing that will throw more air to the back tube of the runner which in turn causes un-even airflow distrubution.

I ported my plenum TB ports to 58mm, knocked down the EGR walls behind the throttle bores, port-matched the plenum's runner ports to big mouth gaskets. THen I port-matched the SLP runners to the big mouth gaskets and cleaned up some cast flash inside the runner. Then I ported the SDPC base to match runners and slightly enlarged intake ports that meet the heads.

By doing all of that, My car pulls to 5,600 with no loss of power. I've pulled it to 6,000 a few times and it still felt strong. It didn't fall on it's face like I expected it to eventhough peak power is probably closer to 5,400 - 5,500 rpms.

Hope that helps!

 

 

Thanks for the info Bad91z, from the looks of your mods I have some catching up to do! You have an awsome third gen. By the way how do you like the vortec intake and heads?

 

That makes alot of sense. Hey Sharp, I have only been to the strip here once. I haven't ran my car at all. I don't think I will get a chance to do it before I leave. Maybe I'll get some times on it when I get home. Good luck keeping up with that Buick. Sounds like a killer ride.
Later