Exactly how crappy is the stock TPI intake manifold? Is it worth it to get a new one or should I just port the stock one?

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"Though I cruise through the valley of Rice I shall fear no turbo, for torque art with me."
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1985 IROC-Z w/T-tops, 305 out and 350 L98 TPI engine in, Hooker Super Comp Headers, 3" Hooker Super Comp Cat-Back, 3" CatCo Cat, Rebuilt TH700R4 with Shift kit, 3.73 Richmond gears, Auburn differential, Accell SuperCoil, Accell 8.8 racing wires, BBK AFPR, Homemade Ram-Air (thanks to Andris Skulte), MAF screens removed, Dropped A/C, TB coolant bypass, Hurst Dual-Gate Shifter, Air Foil, K&N filters, Holley performance fuel pump, Spohn Subframe Connectors, Re-located Spohn Lower Control arms, and more to come.

 

They aren't too bad imo. The entry angle into the head is wrong and aftermarket intaks are just as bad... You don't want to port the floor too much and DO NOT flatten the bottom port radius where it enters the head, this will make airflow worse. There isn't much meat in the roof to raise the port (which you want to do), but you can go up as far as possible... I had a buddy of mine tig across the ports so I could raise them up as much as I could, then siamesed the round entries. Aftermarket intakes have more meat in them and are already "cast ported" but for the money there's alot of potential left in the stocker.

 

when big dan on here ports them, they flow a little more than a big mouth manifold........ but he also charges 275, but you also gotta remember, what would happen if big dan fully ported a big mouth manifold??

 

Get a new one. The Edelbrock or Accel have alot of room to cut if you want more. The TPIS manifold is a ported Edelbrock.

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1991 Z28 ZZ4 with LPE superram base, SLP runners, LPE 58mm T-body,Random Technology ramair,TES headers,24#svo injectors,ZEX nitrous,Walbro 255lph f-pump,Accel AFPR,Random Technology catback,!cats,and mutch more.

 

Do any of you guys have any flowbench numbers of before and after ported lower intakes?