I know Vader has a link to an article on porting your plenum, can I have that link? Also, I'd like to port the base manifold on my TPI set-up, can somebody give me some directions on doing that? I am going to be taking the engine appart this week to put in my new LT4 Hot Cam, so I figured I might as well port these parts while they are out of the engine. ------------------ 1987 Chevy Camaro IROC-Z L98 TPI 350 (5.7L) TH 700R-4 Transmission with 2.77:1 Rear End Current Mods: LT4 Hot Cam, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires. Best ET (w/o LT4 cam): 14.32 @ 97.7mph (corrected for elevation)

Dan,

You want to remove the EGR walls just behind the TB holes in the front of the plenum. The TB holes are 52mm at the face, and cone inward to about 48mm. If you're using a 52mm TB, you'll want to open these holes to 52mm all the way thru. Smooth all of inner contours you can reach, feeling the thickness of the walls to assure you don't cut thru. I also radiused the exit holes of the plenum as much as I could on the inside. You'll want to match everything well, in other words if you're using aftermarket runners, open the plenum holes to match. Do the same thing on the intake bores where the runners attach. You want to match the intake to the heads and blend this back into the round portion of the intake bores. Try to maintain a consistent diameter thru the intake runner bores down to where it blends into the rectangular exit port. Stock runner tubes are so thin that all you can to do them is smooth out where the tubes are welded to the plates - you'll see a "step" there where the tubes don't perfectly match the plates. Since this only flows air, you will get the best flow if you polish the intake bores and plenum inlets after porting them. Note that even a fully ported base won't flow as much as an aftermarket intake, although you probably know that by now. I asked this stock vs aftermarket question on here a few days ago, and the consensus is that aftermarket is the way to go. Clean everything including the intake egr passages very well before reassembling - have it hot-tanked if possible. If you any questions, or have cast aftermarket runners (SLP or Edelbrock), e-mail me and I'll send pic's of how I siamesed the runner inlets and plenum recently, if you're interested. This helped increase the usable RPM's, making it pull harder to redline.

Hope this helped,
Shawn

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87 GTA, auto w/2075 stall, 3.27 rear, L98 .020 over,Comp 269HR cam & 1.5 roller tips, ported heads w/3 angle vj & brnz guides, 52mm TB & airfoil, SLP runners, ported plenum, ported intake, Edelbrock TES, AFPR, MSD 6A/Blaster coil, MAF screens, cold-air induction, vortec muffler, heated O2, Ed Wright Fastchip.

Thanks a lot, does anyone else have any suggestions or pics?

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: LT4 Hot Cam, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Gutted Catalytic Converter, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, Fully Ported TPI Plenum and Base, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

http://www.isthq.com/~dan/efi.html

http://www.tribal-treasures.com/cars...-port/port.htm

Hope these help.

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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
Best run - 12.53/112.4 on 26x11.5 ET Streets.

[This message has been edited by BadSS (edited January 14, 2001).]

Hey since your 90% of the way there and youve got the dremmel handy, pick up a pair of thin head gaskets and pocket port those heads.

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1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Lunati roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat

http://y42.photos.yahoo.com/tonysams72

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1991 banditt2 firebird #130of#600

Anyone have any more advice on porting the base, I am sure there is more power there than in the plenum.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: LT4 Hot Cam, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Gutted Catalytic Converter, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, Fully Ported TPI Plenum and Base, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Watch the thickness. Don't go thru like I did. PITA to fix. I'll have pics in the future, but nothing soon.

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Bob '89 Formula CC350
Last(lost)Member of the Elusive Great Lakes Crew
My car's homepage