Deleting secondary throttle plates? - ZR-1 Net Registry Forums

Paul Workman · 01-08-2008

Still climbing the leaning curve here...

Just learning more about our LT5s, I see that in some cases the secondary throttle plates are removed for improved performance (presumably). I found this interesting, as at first blush there seem to be several possible locations for trouble to develop - what with having 4 discrete signals required from the ECM to the respective injector (pair) relay to allow the secondary injectors to work (in pairs), the mechanical issues inherent with the secondary throttle plates and the acuation thereof, etc, etc.

The obvious advantage would be the "kiss principle", I recon, but I would appreciate some enlightenment on this particular procedure, and how it is accomplished e.g. are all injectors running "full time"? What does this do to the torque curve by comparision, etc, etc?

In other words...What is the problem and how well does this procedure address it?

P.

bradslt5 · 01-08-2008

I would love to do this also. from what i hear you lose just a little low end but that is all i know . i would sure like to learn how to do this i get so tired of messingf with and spending money on this set up the way it is . i wouldnt mind the little trade off in low end for the simple operation of no secondaries .

petefias · 01-08-2008

You need a new chip that runs all 16 injectors. Any good tuner could do that for you. Give Marc Haibeck a call. He could do a 415 for you to help out on the low end.

You may give up a little on the low end on a stock motor, but you won't have to deal with all the vacum lines, actuators, trouble codes.

01-08-2008

Well it's easy, but it's not. You can do a couple of things.

1) Remove the scondary butterflies entirely and you will have to fill the holes where the shafts go. But you can open up the ports a bit more as a result.

2) Zip tie the secondary system open and leave the butterflies in.

Then you need to go in and turn all 16 injectors on, but you still need to run a vacuum line to the solenoid so the system "thinks" it's still operational. Plus a few other small tuning tricks.

Rob and I were going to do a write up on it, but he grenaded his rear end. So it got pushed a little down the line.

GOLDCYLON · 01-08-2008

Is there really that much HP gained on a base 350? I would not think so?

We Gone · 01-08-2008

See if you can get ShawnZR1 over on CF to post his views... he took his out a while back.. 350 P&P with headers..

kenthompson · 01-09-2008

Quote:

Originally Posted by Jeffvette

2) Zip tie the secondary system open and leave the butterflies in.

Then you need to go in and turn all 16 injectors on, but you still need to run a vacuum line to the solenoid so the system "thinks" it's still operational. Plus a few other small tuning tricks.

Jeff, why do you need to turn them on, would they not still be active if the switch is on, RPM is met, TPS is far enough, etc, etc? I don't remember a switch or a position sensor on the secondary system. I agree that the solinoid must remain active for the system to work reasonably well.

KT

Pete · 01-09-2008

My testing resulted in 5 RWHP gain and cleaned up nicely under the plenum.
Use Dorman freez plugs #555-108.

You won't feel the difference,espacially with stock small ports.
I felt no differance and my ports are huge for a 350ci,come drive it yourself.

On a totally stock chip our secondaries will open as low as 1500 rpm at WOT.

Yank them.
Benefits: FREE HP
Drawbacks: Nothing you will notice.

Pete

ShawnZR-1 · 01-09-2008

Quote:

Originally Posted by Pete

My testing resulted in 5 RWHP gain and cleaned up nicely under the plenum.
Use Dorman freez plugs #555-108.

You won't feel the difference,espacially with stock small ports.
I felt no differance and my ports are huge for a 350ci,come drive it yourself.

On a totally stock chip our secondaries will open as low as 1500 rpm at WOT.

Yank them.
Benefits: FREE HP
Drawbacks: Nothing you will notice.

Pete

For the most part, I agree. All other things being the same, you probably won't feel a difference one way or the other. I can't really say I've lost low end torque. I can still pull in 6th gear from 55 on up.

IMO, the biggest advantage is losing all of the moving parts and vacuum lines under there! Fewer things that could go wrong is a good thing in my book!

lbszr · 01-13-2008

Is the outboard end of the throttle shaft hole a deadend or does it need plugged as well as the inboard end?

And can they be removed without removing the breather box?

Quote:

Originally Posted by Pete

My testing resulted in 5 RWHP gain and cleaned up nicely under the plenum.
Use Dorman freez plugs #555-108.

You won't feel the difference,espacially with stock small ports.
I felt no differance and my ports are huge for a 350ci,come drive it yourself.

On a totally stock chip our secondaries will open as low as 1500 rpm at WOT.

Yank them.
Benefits: FREE HP
Drawbacks: Nothing you will notice.

Pete

01-08-2008	#1
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,493	Deleting secondary throttle plates? Still climbing the leaning curve here... Just learning more about our LT5s, I see that in some cases the secondary throttle plates are removed for improved performance (presumably). I found this interesting, as at first blush there seem to be several possible locations for trouble to develop - what with having 4 discrete signals required from the ECM to the respective injector (pair) relay to allow the secondary injectors to work (in pairs), the mechanical issues inherent with the secondary throttle plates and the acuation thereof, etc, etc. The obvious advantage would be the "kiss principle", I recon, but I would appreciate some enlightenment on this particular procedure, and how it is accomplished e.g. are all injectors running "full time"? What does this do to the torque curve by comparision, etc, etc? In other words...What is the problem and how well does this procedure address it? P. Last edited by Paul Workman; 01-08-2008 at 03:48 PM.

01-08-2008	#2
bradslt5 Join Date: Oct 2007 Location: lone pine and mammoth lakes ca. Posts: 544	Re: Deleting secondary throttle plates? I would love to do this also. from what i hear you lose just a little low end but that is all i know . i would sure like to learn how to do this i get so tired of messingf with and spending money on this set up the way it is . i wouldnt mind the little trade off in low end for the simple operation of no secondaries .

01-08-2008	#3
petefias Join Date: Aug 2005 Location: Lancaster, PA Posts: 147	Re: Deleting secondary throttle plates? You need a new chip that runs all 16 injectors. Any good tuner could do that for you. Give Marc Haibeck a call. He could do a 415 for you to help out on the low end. You may give up a little on the low end on a stock motor, but you won't have to deal with all the vacum lines, actuators, trouble codes.

01-08-2008	#4
Jeffvette Guest Posts: n/a	Re: Deleting secondary throttle plates? Well it's easy, but it's not. You can do a couple of things. 1) Remove the scondary butterflies entirely and you will have to fill the holes where the shafts go. But you can open up the ports a bit more as a result. 2) Zip tie the secondary system open and leave the butterflies in. Then you need to go in and turn all 16 injectors on, but you still need to run a vacuum line to the solenoid so the system "thinks" it's still operational. Plus a few other small tuning tricks. Rob and I were going to do a write up on it, but he grenaded his rear end. So it got pushed a little down the line.

01-08-2008	#6
We Gone Join Date: Apr 2004 Location: ATL. GA. Posts: 2,170	Re: Deleting secondary throttle plates? See if you can get ShawnZR1 over on CF to post his views... he took his out a while back.. 350 P&P with headers.. __________________ Steve 1990 Steel Blue/Black #2355 1990 Red/Red #1473 1991 Quasar /Black #118 Sold 1991 Turquoise/Black #766 Parted Out 1993 Yellow/White #179 Sold 1990 Black/Gray #1361 Headers/4:10s Sold

01-08-2008	#5
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,155	Re: Deleting secondary throttle plates? Is there really that much HP gained on a base 350? I would not think so? __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V

01-09-2008	#8
Pete Join Date: Dec 2003 Location: Chicagoland,IL Posts: 2,679	Re: Deleting secondary throttle plates? My testing resulted in 5 RWHP gain and cleaned up nicely under the plenum. Use Dorman freez plugs #555-108. You won't feel the difference,espacially with stock small ports. I felt no differance and my ports are huge for a 350ci,come drive it yourself. On a totally stock chip our secondaries will open as low as 1500 rpm at WOT. Yank them. Benefits: FREE HP Drawbacks: Nothing you will notice. Pete __________________ '91 #1635 PoloGreen 350 LT5 11.09 @ 129.27 11.04 @ 128.86 474RWHP 400RWTQ http://www.youtube.com/watch?v=SFNFOhGGlR4 http://www.youtube.com/watch?v=ZlRIOMwaDYY https://sites.google.com/site/peteszr1garage