ACIS assistance please.

[Gimpster]

Gentlemen,

When I was at the track a couple weeks ago, I did a few back to back runs. For two I left ACIS as it was, no vacuum and "open" in its sprung position... which happens to be butterfly UP joining both compartments.

I trapped ~~77mph both times (1/8th mile).

I then ziptied the ACIS closed, and I lost about 3mph.. the car did feel a little slower.

SO, I'm a bit confused here. Is that what you guys would expect? After reading on clublexus and toyotanation, they make it sound like it should be the other way around. However, except for the butterfly in the way, I expect when it was open to have more power, and it did.

SO#2, does it make sense to totally remove the butterfly and machine off it's mount from the side cover of the intake?

Today I just put a vacuum hose on the ACIS -> strong port in intake. Those Camry guys claim its the next thing to string cheese, but I can't tell a lick of difference. I'd like to see if my milage goes up/down though having that flapper closed.

I need to get a VPW capable OBDII logger (my old ELM only does ISO) so I can see airflow #'s, that would put the nail in the coffin.

---

Conor, this is why I want to get a second intake... to do some experimentation on the dyno I would like to get a few "experiments" ready and back-to-back pull them. I'm friendly with the local dyno owner, so the time would be pretty cheap.

[Weasy2k]

I have done a fair bit of research about the 2 way and 3 way ACIS systems and i happen to find that if you are running n/a do not pull a toysrme and remove it (turbo i would follow his lead for sure).

Toyota put that in for a reason and that is to help midrange and i would like to say high range but when i say high i mean upto like 6000rpm

When you have the flap OPEN it turns your intake manifold into a short runner plenum intake setup. You now have about a 9" runner intake manifold (not including the lower plenum). This helps you with "upper" rpm range and is generally what you want for turbos as well, however this lowers torque numbers in the lower end and the get up and go power is lost (where you loose your time on the track).
Now when the valve is closed you now have a 15" runner intake setup with the left and right bank having there own mini plenum at the 9" mark, but since 1 intake valve is pretty much open at a time on each bank its safe to say you have ONE 15" runner per cyl.
LONGER intake runners help with your get up and go torque...(this is why the 5vz has a 26" long intake runner setup :O) if anything i would have the low end torque setup on all the time (which you did) as at that point you will see gains.

If you are dragging and never see below roughly 4500rpm then having it open is the better way to go.

The 3mz dual TB intake manifold helps this even more because now you have a 3 way adjustable intake system which will help the bottom end even more as each bank get their own TB.

[Gimpster]

Thank you sir, I feel much more educated about how it works now!

Maybe I'll have to find me one of the twin TB intakes one of these days.

[conor]

I have a copy of Toyota's ACIS training sheet on my home PC.. I'll post it up later. Explains how the system works in OEM terms and even has basic dyno charts. There's a visible difference in power/torque production when the ACIS valve(s) actuate

I want to find out if a later model 3-way ACIS manifold can be fitted to our non-VVTI engines.. it'd be a nice (and easy) little pick-up, if it's it not too much of a PITA, anyway. Dunno if the TPS is compatible or not.

[Weasy2k]

^ yea i have that too somewhere around here...i lost it but thats where i did most of my research from.

[DaveMush]

my website....

Index of /manuals/Toyota Technical Training

[Toysrme]

There's a half dozen of them for all different engines.
Know what ACIS is worth a shit? The 1uz-fe's.



LoL thanks for AIMing me weasy LoL!

Besides making a new manifold, the best thing you could ever do is take a long neck plasma torch and hack the entire god damned middle of the pleumn out, front to back.

[Weasy2k]

Originally Posted by Toysrme

Dont listen to me

Ok!

[Jason.MZW20]

The 1MZ doesn't see much of a gain with the short runners because of the relatively conservative cams. Now let's say we had a system like VVTL-i, and the low range lobes were tuned for the long runners, and the high range lobes were tuned for the shorter runners and ACIS and the cam switchover point occured at the same RPM. Guess what? BIG power boost.

The high lift, high duration cams in combination with the short runners creates excellent top end power, but we don't have a variable lift system.

The shorter runners combined with the stock cams at low revs effectively bogs the motor. Motors need the intake tumble effect to create any real usable power at the low end, and that's just what the longer runners do.

In effect, you're handicapping the ACIS system (and the motor) by statically inducing a fixed intake runner. The longer runners work best from 1000-4000rpm (or whatever range the ECU is tuned for), and the shorter runners from there on.

The 3 stage system offers mid-range torque improvement from 3000-4500rpm, but can only be found on the pre-DBW VVT-i 1MZ. I think it's funny that every Toyota V engine gets an ACIS system, but all of the 4 cylinders, with the exception of the 3SGE, do not.

[Weasy2k]

Then there is the 5vz motors...with its 20ft long runners :P

BTW great explanation Jason

[conor]

Originally Posted by Toysrme

Know what ACIS is worth a shit? The 1uz-fe's.....

Besides making a new manifold, the best thing you could ever do is take a long neck plasma torch and hack the entire god damned middle of the pleumn out, front to back.

Dunno, I think I'm going to trust the OEM engineering/testing/tuning rather than disable the system. Maybe it gets in the way when you're doing custom turbo 3VZFE builds.. but in general I don't see how it's anything but a good thing.

Even if it's primary intent is fuel efficiency (and I don't see why that's a bad thing), it still switches over to "short" runner mode at an RPM that you're going to be at/above the whole time if you're racing.. so why bother disabling it at all? Expecting to do a lot of stop-light racing between 1000-4000rpm? heh

Originally Posted by Jason.MZW20

In effect, you're handicapping the ACIS system (and the motor) by statically inducing a fixed intake runner. The longer runners work best from 1000-4000rpm (or whatever range the ECU is tuned for), and the shorter runners from there on.

The 3 stage system offers mid-range torque improvement from 3000-4500rpm, but can only be found on the pre-DBW VVT-i 1MZ. I think it's funny that every Toyota V engine gets an ACIS system, but all of the 4 cylinders, with the exception of the 3SGE, do not.

Yes! It's tuned to work with ACIS. Again, there's no reason to disable it unless you're doing some whacky custom build.

And I wonder why they don't really use it on the 4-cyls.. You'd think that they would be looking for every gain possible, there.

[Weasy2k]

For those 4bangers they used T-VIS and i think thats about it or just use the cams to alter the airflow for different portions of the powerband. IE: vvti-l