How to Raise Secondary activation?

[chris89]

I would really like to know how to raise the activation of the secondaries to around 4800-5000rpm where the torque comes in so there's not a "flat spot" in the power band.... torque comes in at 4800rpm so the secondaries should activate into Short Runner mode for high rpm power to 6,000rpm where the horsepower is made. Just wondering if there's any way to Adjust?

 

[johnathan1]

Are you talking about the ACIS?

 

[chris89]

Well yes.

 

[IJ.]

If ACIS is functioning correctly there shouldn't be a noticable jump.

 

[bigaaron]

VTEC controller? :biglaugh:

 

[IJ.]

VTEC controller kicked in Yo? :biglaugh:

Fixed

 

[chris89]

I hate the flat spot in the power band, 4,000rpm is to early because it doesn't start pulling until 4800-5000rpm where the Torque comes in... it's like pull to 4k then Flat spot... until 5k then it starts pulling again, Secondaries should open later for a better power band.

 

[IJ.]

If ACIS is functioning correctly there shouldn't be a noticable jump.

 

[Ma70.Ent]

I don't really know if you read the stickies since no one seems to read them, so here's a link to one

http://www.supramania.com/forums/showthread.php?t=41390

 

[BorHor]

I guess some NA's want to feel the "Turbo" kick.

 

[Midnight Dorifuta]

I wonder if I should troubleshoot my ACIS... my engine does seem to lag a little around 4 grand.

I wonder -how- I should troubleshoot it. Check all vacuum lines first?

 

[CRE]

Yeah, start with checking the vacuum lines, then test the VSV, then pull the upper intake manifold, clean it out real well and test the valve and the actuator.

Chris89, there really shouldn't be a flat spot. My car pull fine at 4000 (granted I really don't remember how it was when the system was stock anymore). If your ACIS is functioning properly the easiest way to control it would be trying to find a variable tachorelay to control the VSV with (if one exists that goes that high). Otherwise, I suspect you'd need to add a controller between the tach signal and the VSV. If the signal is converted to a variable voltage signal (instead of a pulsed signal) you'd just need to add a comparator.

I'm pretty sure that moving the engagement up so high may cause other issues though.

 

[chris89]

there's no reason for them to activate so early, the engine is designed to make maximum torque at 4,800... I can tell that there no gain having them activate at 4,000rpm because it doesn't start pulling until 5k... I guess since it's gonna be that hard i'm not gonna worry about it.

 

[mickyg]

Chris, my understanding of the ACIS system is that it's there to enhance LOW end torque. The engine runs out of breath if you delay the valve till later in the revs. If anything that would make things worse as the engine would be running outside the "tuned" range at those revs.

I think the designers of this engine did a pretty good job with the system as-is. Unless you've done something to alter the stock intake tuning, you're likely to be disappointed with any fiddling.

HTH

 

[chris89]

well with Honda's vtec and the nissan 350z etc... The transition goes into Short runner once the engine's done producing it's torque... vtec is at around 5k right where the torque ends, 4800-5000rpm is where they should activate.... there's no point it in kicking in early... I have a feeling that it'll make a pretty noticable difference with it activating later in the power band.

 

[johnathan1]

Yea, just get it back to stock form, and working correctly. It helps create more low end torque. If you can "feel" a boost in power around 4k rpms, then the system isn't working properly...

 

[CRE]

well with Honda's vtec and the nissan 350z etc... The transition goes into Short runner once the engine's done producing it's torque... vtec is at around 5k right where the torque ends, 4800-5000rpm is where they should activate.... there's no point it in kicking in early... I have a feeling that it'll make a pretty noticeable difference with it activating later in the power band.

True, but we've also got a shorter power band. Also, there are MANY other differences between our engines and theirs, all due to numerous technological advancements since our cars were rolling off the line. But comparing our engine to a 4cyl Honda with a much higher redline and that's also 10years newer is pointless.

I've explained the basics involved. If you just can't let this go, then try it, dyno the car before and after and show us how it comes out. I'm curious to see how how the system reacts to different settings. BUT I really don't see how even a whopping 5HP increase (at the crank) is even worth all the speculation, much less the time it would take to build a controller for it.

 

[SupaMan]

from what ive read and asked people about it it doesnt kick in its on when you get on it low rpm and then it turns off when you get in the higher rpms that kicking in is your acis not working, or so thats what ive been told. Id have to agree with micky and CRE on everything else theres a possbilty that itll work and give a lil more power but it wouldnt be worth it and theres more of a chance that it wont work and youll take away power.

 

[CRE]

SupaMan, I agree with you agreeing with me 100%!

 

[chris89]

It would be way to big of a pain in the ass to mess with anyway, there's no point. I just thought it might be more easily adjustable since it's Not as complicated as other systems. It's a very effective system in helping produce better low end torque, and high rpm power, Pretty High end technology for the 80s! I wonder what people thought of it when it was first introduced...