i heard awhile back that a ported stock base flows as well as a non ported edelbrock base. Is this true?? I need to know whether the 350 dollars is worth it this early in my build up. It is basically stock, save the sig. The plenum is coming off for port and a AFPR, sooooo i need the guidance. thnx in advance

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'89 SHAGGY IROC
L98 7r4, all free stuff,T.E.S.,HOOKER CAT BACK,KYB,ACCEL8.8,JET fan sw. etc.
so much to do , so little money

 

Absolutely, a ported stock base will flow as well as a Edelbrock TPI base(as cast). The aftermarket people won't tell you that, but they are trying to sell you something. I recently met a guy who builds lots of TPI motors and ports his own manifolds and has put them on the flowbench. He tested one of his ported GM bases against Edel, TPIS, and Accel all on the same flow bench and the GM base was the winner. Now if you take a Edel base and port and extrude hone it then that might be different but I have not seen that type of comparison done on the flow bench.

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Dave Zelinka

 

But don't the stock units get really thin when you port them to flow like the aftermarket units?

 

Yelofvr...Do you have the flow numbers for his ported stock base? I would like too see them if you do.

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

I wouldn't worry about it too much Aaron, for the intake, a thin wall won't affect anything.

 

Here are the numbers I have. They come from a TPI article written by Ray Bohacz(My Hero) in GM high tech performance. All tests done on same day, same bench:

Runners
stock tpi 203cfm
Accel large tube 242 cfm
Extrude honed Accel 275 cfm
SuperRam 289

BAse manifolds
stock 222 cfm
Accel 251 cfm
Accel extrude 276 cfm
Edelbrock perf RPM dual plane 286

This tells me the ported GM manifold must have outflowed 251 cfm, but I do not have the exact data. In terms of wall thickness I personally ported my manifold and spent over 30 hours on it. I used calipers to measure wall thickness at all points I could get to and it was plenty! beleive me. I compared my work to a manifold done by AirFlow Research and my dimensions met or exceeded theirs at all point so I know I did a thourough porting job. I cc'd all runners afterward and matched the volumes.

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Dave Zelinka

 

Can't compare the following numbers to the May 96 Hi-Tech Performance info above,, however looks like he's got his own comparison numbers. I have no doubt this is accurate. There is a lot of potential,, and you can really open the stock base up (it's not that thin). There are just a couple areas you need to watch for. Check out the following post by super chevy.

super chevy
Member
Posts: 45
From:
Registered: Jul 2000
posted September 25, 2000 07:41 AM
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I have ported several intake bases, plenums, and runners. I use a die-grinder with a carbide bit to cut/enlarge the ports to whatever gasket I am matching to, usually a Fel-Pro 1204 or 1205 intake gasket and a set of TPIS large tube runner gaskets. By taking your time and using care, you will be able to not only enlarge the intake/runner ports, but you will be able to radius the ports to give the incoming air a straighter shot at the head, and remove some restrictions/casting flash in each port. I then use an 80 and 120 grit sanding roll to smooth the ports, and finish by hand sanding the ports with a 400 grit to get them as smooth as possible. By utilizing all these elements, the most recent intake I ported (an '86 casting) flowed an impressive 200cfm @ .400 lift (28") on the flow bench. That is only 2cfm less than a TPIS Big Mouth base!
It is my experience that if you port and gasket-match all three TPI induction components (plenum, runners, intake) you will see a signicant increase in horsepower/torque, and peak RPM.
Good luck with your porting!
Super Chevy

 

I dont have any quantifiable numbers yet, but I've done two sets of plenum/runner/intakes for people. There's a lot of potential in the intake, IMHO. so far, both people have liked the result. Here's some pictures of the work I've done on the intake, runners, and plenum:
Dan's TPI project

I'm porting TPI intakes for $275 if you are interested. If not, use the pictures as food for thought and give it a try yourself! Like Dave was saying, it takes a lot of time, but if you go slow and do it over the course of a couple weeks, it is quite straight-forward.


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Daniel Burk http://www.isthq.com/~dan/fcar.html
'84 Trans Am WS6/L69
KB SFC, Moser axles, Torsen Diff. PST suspension, Braided stainless brake lines, Koni struts, 11-inch rear disks,Spohn Adj. torque arm,
Ported 305 heads w/1.94"intake valves, Comp Cams XE262H, Griffen alum. radiator,
Turbine Technologies 2500 stall converter, underdrive pulleys, Crane Hi-6 & more.
1.05g skidpad verified.
New best E/T! 14.039 at 100.82 MPH in 41 degree air at Stanton, Michigan.

[This message has been edited by ws6transam (edited November 03, 2000).]