Secondaries
#1
Instructor
Thread Starter
Secondaries
91Z stock... Have a well maintained car, new injectors, pumps, and filter and everything, verified the secondaries open up, no vacuum leaks, have Mark's chip, no codes.
How much of a power increase when the secondaries kick in? I can feel a difference, but not much. Can't turn the secondaries off when in power mode when I am flooring it, guess the computer is prohibiting it. Sometimes I can get the rear tires to slip in 2nd gear, sometimes I can't. I live in Florida with the humidity.
Thinking of getting Mark's chip to eliminate secondaries, maybe the valves are sooted up or something, would this effect it greatly? And also headers and exhaust, the stock system which by the way is garbage: there are tool marks at every bend, the resonator was hammered in a little to clear the seatbelt bolt, and it looks like the mufflers were painted by throwing a bucket of paint on it.
The way you guys talk it should pull more, it is nothing compared to my 2002 Viper although it has way more torque. Thanks everyone.
How much of a power increase when the secondaries kick in? I can feel a difference, but not much. Can't turn the secondaries off when in power mode when I am flooring it, guess the computer is prohibiting it. Sometimes I can get the rear tires to slip in 2nd gear, sometimes I can't. I live in Florida with the humidity.
Thinking of getting Mark's chip to eliminate secondaries, maybe the valves are sooted up or something, would this effect it greatly? And also headers and exhaust, the stock system which by the way is garbage: there are tool marks at every bend, the resonator was hammered in a little to clear the seatbelt bolt, and it looks like the mufflers were painted by throwing a bucket of paint on it.
The way you guys talk it should pull more, it is nothing compared to my 2002 Viper although it has way more torque. Thanks everyone.
Last edited by blownrunner; 01-05-2017 at 05:06 PM.
#2
Zs usually are not torque monsters.....Your 2002 Viper should have way more torque than the Z.....I mean it's a ten cylinder motor and there rated at over 500 ft.lbs or am I reading it wrong?
#4
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If you can't tell a difference with key on and key off between 3-6k RPMs something is wrong. If you want more power headers and exhaust are just the first step
#5
Le Mans Master
Key Off is about 250hp
Key On is 375hp+
You should be able to notice that difference.
Your Viper has 2 more cylinders and 150cu.in. more. I can guarantee u that if u drove modded LT-5 w similar displacement, you would be impressed.
Key On is 375hp+
You should be able to notice that difference.
Your Viper has 2 more cylinders and 150cu.in. more. I can guarantee u that if u drove modded LT-5 w similar displacement, you would be impressed.
Last edited by Dominic Sorresso; 01-05-2017 at 09:08 AM.
#6
Pro
You should definitely feel them open up. I have essentially the same setup you do, other than full Stainless Works 3" exhaust, headers to tips. With Marc's chip and secondaries "not" working due to a faulty check valve, the car only made 239 rwhp. I got the check valve fixed (allows the secondary vacuum pump to keep the secondaries open at WOT when manifold vacuum is low), the car put down 344 rwhp on dyno.
I am doing my own tuning now and brought the curve down (RPM) where secondaries begin to open. This allows me to "feel" the power surge earlier in moderate acceleration driving. You can definitely feel them engage.
Is your secondary vacuum pump cycling when you turn the key to "on" without starting the car? It should not cycle. If it does, you should look at the check valve, which unfortunately is under the plenum in a stock setup, and replace it. Very cheap part, but can definitely affect wot performance.
I am doing my own tuning now and brought the curve down (RPM) where secondaries begin to open. This allows me to "feel" the power surge earlier in moderate acceleration driving. You can definitely feel them engage.
Is your secondary vacuum pump cycling when you turn the key to "on" without starting the car? It should not cycle. If it does, you should look at the check valve, which unfortunately is under the plenum in a stock setup, and replace it. Very cheap part, but can definitely affect wot performance.
#7
Instructor
Thread Starter
You should definitely feel them open up. I have essentially the same setup you do, other than full Stainless Works 3" exhaust, headers to tips. With Marc's chip and secondaries "not" working due to a faulty check valve, the car only made 239 rwhp. I got the check valve fixed (allows the secondary vacuum pump to keep the secondaries open at WOT when manifold vacuum is low), the car put down 344 rwhp on dyno.
I am doing my own tuning now and brought the curve down (RPM) where secondaries begin to open. This allows me to "feel" the power surge earlier in moderate acceleration driving. You can definitely feel them engage.
Is your secondary vacuum pump cycling when you turn the key to "on" without starting the car? It should not cycle. If it does, you should look at the check valve, which unfortunately is under the plenum in a stock setup, and replace it. Very cheap part, but can definitely affect wot performance.
I am doing my own tuning now and brought the curve down (RPM) where secondaries begin to open. This allows me to "feel" the power surge earlier in moderate acceleration driving. You can definitely feel them engage.
Is your secondary vacuum pump cycling when you turn the key to "on" without starting the car? It should not cycle. If it does, you should look at the check valve, which unfortunately is under the plenum in a stock setup, and replace it. Very cheap part, but can definitely affect wot performance.
#8
Pro
Just to "feel" the secondaries, I believe you can run your experiment in reverse. Turn the power switch to Valet mode, take the car out on a safe road. Get it in 4th gear and from 2000 rpm, smoothly, but rapidly hit WOT. At 4,000 rpm, switch Valet switch to full power. You should feel the secondaries open up. Best evaluation is on a dyno, not a butt meter, but going this way, valet switch off to on, you should feel it. When you put on headers, you should retune your VE tables to get most out of them. Marc will reflash your chip to add a bit more fuel and add anti backfire as well. Just ship the chip to him and tell him what fuel you will be running (octane). VE tables are more involved and can't be done without driving the car and capturing fuel trim data.
#10
Marc had a method on his website to activate the port throttles manually for diagnostic purposes, and see with a flashlight whether they are opening. Not while driving, of course, but a worthwhile check anyway.
#11
Pro
The ECM contains an upper RPM limit, whereby the power key will not change state above 4000 rpm. For our safety, I'm sure. So, the experiment you describe won't work above 4000 rpm.
Marc had a method on his website to activate the port throttles manually for diagnostic purposes, and see with a flashlight whether they are opening. Not while driving, of course, but a worthwhile check anyway.
Marc had a method on his website to activate the port throttles manually for diagnostic purposes, and see with a flashlight whether they are opening. Not while driving, of course, but a worthwhile check anyway.
Won't contest the RPM limit in the stock tune (I'll look at mine to see how it's set). I have performed the test I described, possibly switching at 3000 RPM and definitely felt my secondaries open after i repaired the check valve. The "test" before I fixed it and on the dyno proved they were not opening at WOT, despite the ECM command to open being received.
I would expect the OP has secondaries that are working fine. Best test is indeed on a dyno, not simply driving.
#12
Le Mans Master
91Z stock... Have a well maintained car, new injectors, pumps, and filter and everything, verified the secondaries open up, no vacuum leaks, have Mark's chip, no codes.
How much of a power increase when the secondaries kick in? I can feel a difference, but not much. Can't turn the secondaries off when in power mode when I am flooring it, guess the computer is prohibiting it. Sometimes I can get the rear tires to slip in 2nd gear, sometimes I can't. I live in Florida with the humidity.
Thinking of getting Mark's chip to eliminate secondaries, maybe the valves are sooted up or something, would this effect it greatly? And also headers and exhaust, the stock system which by the way is garbage: there are tool marks at every bend, the resonator was hammered in a little to clear the seatbelt bolt, and it looks like the mufflers were painted by throwing a bucket of paint on it.
The way you guys talk it should pull more, it is nothing compared to my 2002 Viper although it has way more torque. Thanks everyone.
How much of a power increase when the secondaries kick in? I can feel a difference, but not much. Can't turn the secondaries off when in power mode when I am flooring it, guess the computer is prohibiting it. Sometimes I can get the rear tires to slip in 2nd gear, sometimes I can't. I live in Florida with the humidity.
Thinking of getting Mark's chip to eliminate secondaries, maybe the valves are sooted up or something, would this effect it greatly? And also headers and exhaust, the stock system which by the way is garbage: there are tool marks at every bend, the resonator was hammered in a little to clear the seatbelt bolt, and it looks like the mufflers were painted by throwing a bucket of paint on it.
The way you guys talk it should pull more, it is nothing compared to my 2002 Viper although it has way more torque. Thanks everyone.
The real advantage is simplicity (and combatting alzheimers forgetting to "key" the car). You can also now open up the porting on the heads too. While the ZR-1 will not shove you in the back like the torq monster viper, it will sure keep up with it with a bit of TLC for the Z
#13
Instructor
Thread Starter
Thanks everyone so much for the reply's, going to bypass the secondaries before I start goofing with the exhaust. On a plus side, it is cooler now in Florida with less humidity so it should be making a lot more power.