shoebox

Test results:

Opti with about 90k miles on it

15" vacuum applied

~1 minute for it to bleed all the way off.

I'd say that is pretty good and would work fine for dealing with the ozone.

Remember that air can bleed through the electrical connector, as well.

divineprime

Thank you shoebox, that proves the point exactly. It also proves that they intended to have a 99% sealed unit, contrary to what RamAir95 tried to assert.

As you point out the wiring connecter can also leak, but on mine it was the shaft area when I had it off the vehicle. You can also find youtube vids showing the same mysterious shaft leak. There are multiple points of entry in a failure condition. Basically mine doesn't hold pressure at all even for a second. The shaft has no end play but whatever seal is in there is leaking. This is the unknown, unspoken about leak when talking about this. BTW my mileage is 105k.

RamAir95TA

Two thumbs up. Can't wait to see dyno results!

divineprime

Are you actually admitting defeat, or are you making a comment to imply that I claimed this was a power mod?

slick1hunting

im curious how shoebox's test results confirm it is intended to be a 99percent sealed unit? If you really want to think about it and have a scientific approach at testing it you would have to measure the volume of air taken from the intake hose side and compare that to the volume of air discharged into the manifold. Air is like water it will travel the path of least resistance. Just because it may not hold vacuum does not mean you can determine the percentage of air being pulled through from undesired locations. If you disconnected the line altogether I would bet you would see minimal if any noticable difference. Now consider even on your opti that wont even build a vacuum I bet still over 50 percent of the air is still coming from the intended air intake it might be closer to 80 percent on yours and 99 percent on shoebox's. My point is you cant use vacuum as a test. In fact if you look at a house vacuum it wont be sealed either but it sucks from the intended tube because it is the larger hole and the path of least resistance. Another proven test is put a hole in a straw it will still pull liquid that is way heavier than air given the hole isnt too big.


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Skedaddle

Testing the opti vacuum leak through the shaft seal, by plugging the air supply line would seem to be unrealistic. It never operates in that condition. Has anyone measured the vacuum in the opti case, with it operating normally?

shoebox

I get about 10-11" of vacuum with a gauge on the inlet line that goes to the intake elbow.

divineprime

Yeah it may pull 50 50 when leaking badly as mine. Thank you for correcting me, I said possilbe full, which would not be possible with an unkinked line.

UPDATE:
I did the mod today, just a few minutes ago, and my car no longer idles rough. Why because I fixed the vacuum leak. Actually is runs much much better when under throttle and kick-down is more precise. No doubt it was running like dog sh** with the distributor leak. The computer accounts for that air, and when not sealed it does not run right. Confirmed.

EDIT:
@ 12:33 in this video
http://www.youtube.com/watch?v=lFCjaz6zHfc
unplug the air inlet line of the from snorkel.
Plug the snorkel, and connect the vacuum gauge to the air inlet line. As the engine runs the vacuum gauge should drop down very near what the intake manifold pressure is.

divineprime

Okay the thread is now resolved, but I am curious as to why Shoebox had 10-11". Was that in hg? Check out my last edit to the previous post.

My manifold vacuum was around 19.9. I would expect a properly working system to be near normal manifold vacuum at the....

shoebox

Yes, 10-11" hg through the filters and restrictors. You can't have full vacuum on an opti. It will suck the cap in (at least on one that is reasonably sealed like they are supposed to be).

divineprime

I totally respect your results and knowledge. Just trying to figure out why it doesn't sound right. In the tech video it only mentions the cap being sucked in when there is a kinked hose. Thus full vacuum. He also mentions it should near manifold vacuum ie 20, while yours is 10-11. Are you absolutely sure that 10-11 is not a clogged check valve? He mentions that too.

I really am just trying to sort this out. Thanks for the extra time you have taken in this thread.

shoebox

I probably should have taken a reference vacuum reading at the manifold. I have a small cam in my car, so vacuum is not going to be like stock. As time permits, I'll try to check the valves for any clogging.

From real world observation of board threads, people that used a straight vacuum hose to the opti got cap interference problems. The inline orifice is not going to limit vacuum?

The FSM says the opti should hold 10" Hg of vacuum under test conditions.

divineprime

That's good enough for me.

Skedaddle

Was the gauge blocking air flow through the inlet line? Or did you have the gauge "teed" into the line? If there is any impediment to flow added with the gauge, the vacuum will be increased beyond normal operating level.

The inline orifice will only reduce vacuum if there is flow through the line. With no flow, it does nothing. That why you need to have the air supply line from the intake elbow unrestricted to fully replicate the actual operating condition.

shoebox

I guess that makes sense that you can't actually control flow if there isn't any. I had the gauge attached to the end of the hose-no tee.