upper plenum porting
Thread Starter
Drifting
Joined: Jan 2002
Posts: 1,606
Likes: 1
From: Las Cruces NM
upper plenum porting
Has anyone siamese ported the upper plenum and gotten any dyno or track results? I'm just curious what can be done with the stock TPI since I don't want to go to a super ram until after I rebuild the current motor or build a new one and budget-wise, it's not going to be too soon. I'm running stock heads/cam.
Chris
Chris
Melting Slicks
Joined: Feb 2003
Posts: 2,770
Likes: 0
From: Construction Sucks! MI
Cruise-In V Veteran
St. Jude Contributor '03 & '05
Re: upper plenum porting (okinawa86vette)
i've only heard positive things. more power in the 2500-5000 RPM range. i'm working on doing this next month along with porting and polishing my heads. do a search and maybe check out some of the f-body sites. there are some nice links out there, here's one of them.
http://www.thirdgen.org/newdesign/te...meseport.shtml
http://www.thirdgen.org/newdesign/te...meseport.shtml
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: upper plenum porting (okinawa86vette)
I don't think the results will show up on the SOTP dyno or even if on an actual dyno but you can port two areas of the plenum and one in the runners:
-open up the path way where enters the plenum by cutting back the sides, grinding down the two rectangles and narrowing the center bulge.
-flute the openings in the upper runners in the upper mounting flange
-port match the fluted upper runners into the plenum and round off these openings inside the plenum.
The first mod removes restrictions to air flowing into the plenum; the next two allow more air to flow into the runners as the stock right angle bends tend to effectively narrow the openings (air doesn't like to flow rapidly around sharp corners).
The other thing that can be done with stock TPI is to siamese the intake base about 1"-2" deep. This provides more air at high rpm with not much low end torque loss.
You can check out the dyno results of the siamese intake base on my site but only an "after" dyno of the plenum porting along with many other mods.
Of course you will benefit most from the above mods if you have a free-flowing exhaust along with modified air intake system. And some 1.6:1 RRs wouldn't hurt either.
-open up the path way where enters the plenum by cutting back the sides, grinding down the two rectangles and narrowing the center bulge.
-flute the openings in the upper runners in the upper mounting flange
-port match the fluted upper runners into the plenum and round off these openings inside the plenum.
The first mod removes restrictions to air flowing into the plenum; the next two allow more air to flow into the runners as the stock right angle bends tend to effectively narrow the openings (air doesn't like to flow rapidly around sharp corners).
The other thing that can be done with stock TPI is to siamese the intake base about 1"-2" deep. This provides more air at high rpm with not much low end torque loss.
You can check out the dyno results of the siamese intake base on my site but only an "after" dyno of the plenum porting along with many other mods.
Of course you will benefit most from the above mods if you have a free-flowing exhaust along with modified air intake system. And some 1.6:1 RRs wouldn't hurt either.
Melting Slicks
Joined: May 1999
Posts: 2,037
Likes: 0
From: Sarasota FL
Re: upper plenum porting (okinawa86vette)
I doubt there's any gain in siamesing the plenum. It'd be interesting to see though - cut out the dividers and radius the exposed runner flange.
There's a lot of improvements to make in the stock TPI. Most of the good work is in the intake manifold. The plenum work has been gone over. There are ridges where the runners are welded that can be smoothed. Port match everything. Pre crush your gaskets and check your port and gasket matching - that 1/16" wall of steel that crushes that squeezes into your intake track when you tighten down the runners hurts airflow.
There's a lot of improvements to make in the stock TPI. Most of the good work is in the intake manifold. The plenum work has been gone over. There are ridges where the runners are welded that can be smoothed. Port match everything. Pre crush your gaskets and check your port and gasket matching - that 1/16" wall of steel that crushes that squeezes into your intake track when you tighten down the runners hurts airflow.
