I'm thinking about porting the whole TPI setup. The base, plenum and runners. It is untouched now, and I can't run any better than 13.4
It hits the brick wall at 4800-5000RPM.
How much higher should I expect it to pull after FULLY porting it all?
I just want to know if it's worth the trouble.

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AKA Pony Punisher II on all other boards.

89' Iroc-Z
ZZ3 short block-355 TPI ZZ9 cam
NOS 150 shot.
blah...blah...blah..
95' T-56, 6-speed
99' Z' rearend w/ 4.10's
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1997 black Trans AM
A4, bone stock except for the Flowmaster.

 

You arent going to see much difference in it, because the runner size will be the same, and the overall length isnt changing either. It will get you some HP, maybe from 10-20 if its done well and done right, but its not a major change. Its a ****-poor setup anyway IMO. Take a look at a TPI intake sometime from the top view with runners on/plenum off, pay close attention to where the runner transitions to the base.

 

Just buy the edelbrock and runners hi flow TPI setup from Summit or direct from Edelbrock. It's the same one as Accel by the way.

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'92 Formula
305 TPI 5speed
1LE package
Mods: SLP headers,SLP catback,SLP air foil,ported plenum,Crane AFPR (47psi),MSD6AL,AC delco cold plugs, Bosch O2sensor, homemade cold air,K&Ns,3:73s,JET fan switch, Macewen white face gauges

 

I can't speak before and after,, since I hogged the intake out before I put the engine together for the car (bought with the engine out of the car). I fully ported the stock base, used basically stock SLP runners (I cleaned them up just a little) and gutting the plenum,, the engine will pull easily to 5700 rpm (about what the cam in my sig should pull). However,,, as stated in the previous post,, the runner size and length adds / tunes in so much midrange torque,, that I can run the times "short shifting" at 5200 rpm (to take advantage of the torque)as I can shifting at 5700 rpm. However,,, knowing what I know now, I'm sure I could have gone with a smaller cam and run a better time (especially with the exhaust I'm running). Saying all this,, I'd still spend the time and effort (took me about 14 hours)porting the intake - if you've done some porting before. I'd think that a heavily ported stock intake (ported all the way from entry to exit) would flow as good or better than the off the shelf Edelbrock and the Accel unit. There's even a post out there backing this up with flow bench info - I think his flowed within a few CFM as an aftermarket intake.

Use the search function there are a number of good threads available on this topic.

I guess it depends on your time and money available!!! Good luck.

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86 IROC - 9.8:1 - 355, TFS twisted wedge heads, 218/228-110, fully ported GM base and plenum, SLP runners, 52mm BBK, 24# SVO, 1 5/8" Headman headers, 2.5" Dynomax, TH350, 2200 stall, B&M Megashifter, 3.23 peg leg, 245/45ZR17s on 212 Eagles