Secondary Remove guide?

[Funracer]

Thanks to all for the help on this thread. I accomplished the deed
on Saturday and followed the pics and advise above closely. Removed
all the secondary vacume lines and associated hardware as well as the
the evap purge lines. Left the vacume pump under the right side headlight
in place and just unhooked the vacume line and disconnected the electrics.



Still deciding whether to wire open the secondaries or remove them. More
on that later.

Thanks

[5ABI VT]

Funracer what year is your z?

[Paul Workman]

Originally Posted by Funracer

Thanks to all for the help on this thread. I accomplished the deed
on Saturday and followed the pics and advise above closely. Removed
all the secondary vacume lines and associated hardware as well as the
the evap purge lines. Left the vacume pump under the right side headlight
in place and just unhooked the vacume line and disconnected the electrics.



Still deciding whether to wire open the secondaries or remove them. More
on that later.

Thanks

I'm assuming your calibration was changed for NO SECONDARIES, yes?

90s require a hard electrical connection (switch) to be left in FULL POWER mode. However, if the contacts get corroded or oxidized, the connection could become "sketchy" or even open. That is a BAD thing in a 90 secondary deleted motor.

I would suggest hard-wiring (soldering a shunt between the wires), effectively taking the switch out of the circuit. That way no gremlins can turn off the switch: gremlins imaginary or real (called kids).

Just sayin...

[dcarroll95]

Another valid reason to remove the secondary valves is the secondary intake valve gets massive carbon build-up from not running all the time. I'm in the middle of removing the butterflies and can see the intake valve and my car with just 19k miles has major carbon build-up on the intake valves. I'm going to try to clean it up before I put it all back together.

I hemmed and hawed about ditching the secondaries as I hate to make a low mileage car non-OEM but I feel I can justify it to a future buyer based on this. There's a great article on secondary intake valve carbon build-up on Marc Haibeck's web page:
http://zr1specialist.com/HAT%20Web/f...20deposits.htm

He doesn't specifically state that a solution is to remove the secondaries but doing so will ensure fuel is flowing over the secondary intake valve and keep it just as clean as the primary intake. It's pretty astounding looking at the build-up on the secondary intake valves on my car vs the primaries.

[dcarroll95]

Also, can I test run the car with the valves open before I chip it or is that a huge No No = engine lean and blow up? Hopefully someone responds before I get it back together. Kind of want to drive it 1-2 miles before I send the chip off, but won't do it unless I hear affirmative.

[Paul Workman]

Yes, you can, but why bother??

Total air flow into the motor is controlled by the throttle body, and not by the SPTs. Normal fueling will be supplied by the primary injector only up until the rpm and throttle position triggers the ECM to command the SPTs open. Then the necessary fueling amount is split/shared between the primary and secondary injectors.

You might (maybe?) be able to notice a slight decrease in torque after the secondaries are tied open, compared to stock operation. But, as soon as (power demand) opens the secondaries anyway, tied open or not would not matter, far as performance goes.

IMO, deleting the secondaries is a "no brainer". Less "stuff" to ever break down later, and BOTH intake valves get washed (and thus) clean in normal driving.

NOTE: And, for what its worth, the second gen LT5 did away with the whole primary-secondary arrangement anyway. I and others consider this as validation for removing them in the first place. The LT5 is starving for air; proven by the gobs of performance increase w/o the significant loss of low end torque seen after intake porting of many 2-valve motors.

.

[rkreigh]

a few tips


stuff some paper towels down the ports


do indeed take the linkages and flappers out, while the don't hurt flow much, they are worth some $ and "in the way"


DO look at porting and opening up the secondary ports, without the flappers you can go bigger now which is one of the real benefits.


make sure you use the new chip as all injectors will need to run at all times except idle where it steps down to 1 injector at tps 1%


try to do the head porting to really take advantage of this mod. Otherwise it's nice, but not that much gain.



unlock the gain with 4.10 gears as you will "pull through" the small area in the power curve under 2000 rpm where the flappers pick up some low end torq


with the gears you are almost "never there" and will get up over 2500 where the no flapper mod really starts to gain over having them closed.


this engine has a "myth" of being down on low end torq and this doesn't help down low but honestly I only notice the good and I've been flapperless for many years now. DO IT!!!