quick question about NA2T

[SATAN]

Dweezil wrote: WOT= 0 vacuume. They use check valves so you have assist in the event of a sudden stop.

K so you have wot wich = 0 vacume(or close to 0) then you let off the gas and slam on the brakes. how is this assisting the booster? Does the check valve keep the maximum engine vacume in the booster untill needed? will it hold it that long? then the only time the check valve opens again is when it sees even more vacume than what is allready in the booster?

Yup that makes perfect sence! thanks Dweezil.

[OR-Zman]

^well that makes sense. I think.... :shock:

Are you sure that an NA is pulling 0 vac at WOT? Somehow that seems counter intuitive to me. I have no info to dispute but...WOT on an NA would seem to me that there still has to be a considerable amount of vac to supply the cylinders just like they would need at 3/4 throttle.

Like I said, I am just thinking of this intuitively, but not sure how it makes sense.

[SATAN]

OR-Zman wrote: ^well that makes sense. I think.... :shock:

Are you sure that an NA is pulling 0 vac at WOT? Somehow that seems counter intuitive to me. I have no info to dispute but...WOT on an NA would seem to me that there still has to be a considerable amount of vac to supply the cylinders just like they would need at 3/4 throttle.

Like I said, I am just thinking of this intuitively, but not sure how it makes sense.

right thats why I said " 0 vac (or close to 0)" Its never an absolute 0 vacum unless it is force fed or your atmopheric pressure is above 0 which can happen.

If it did happen then you engine would have a volumetric efficiency of 100% or more

[OR-Zman]

^gottcha. Thanks for that. My brain was starting to hurt. :?

[Chris86NA2T]

[quote]SATAN wrote:

every NA i have seen has a check valve on the brake booster line.. in fact i cant think of ANY car off hand that i have seen that doesnt have one..
Hmm, but why on NA's? I cant see a reason for needing it? Booster works off of vacume which is allways happening on an NA so....?

the same reason that NA cars have a vacuum canister.. there is little to no vacuum at wot.. bypass the vacuum canister and run a straight vacuum line to the hvac.. as soon as you hit the gas the vents will all default to full defrost and full heat. they need vacuum to operate. every car with vacuum operated hvac will have a canister and check valves to keep vacuum in the system.. people with NA cars and big cams (much lower vacuum at idle than stock) often add a vacuum canister in the line going to the master to hold vacuum and keep the power booster operating..

[Az4u2c]

Thanks for all the advice so far. I'll just get a check valve for that vacuum canister. I don't remember seeing a check valve on the brake booster, but I'll make sure there is one there before long. I could really give a shit about the emisions stuff. Does it matter if I feed them boost? I mean surely they won't work correctly but as long as they don't leak it won't cause any fuel troubles so i'm happy with it. I'll throw some valves on there if i feel like it. The vents were what i was worried about. I know vacuum quickly drops to insignificant levels at hard throttle. There are some long hills out in the sandhills where you stay nearly WOT for a long time and on a hot day you'll quickly notice it gets really bloody toast and the defrosters dry out my eyeballs. I think i can find the big line that goes to the vac canister and check valve it and be okay. Or at the very least no worse off than I am now. Also, where the heck to I buy check valves? Can i just waltz into AdvanceAuto and ask for one....or?

[Jason84NA2T]

Az4u2c wrote: Thanks for all the advice so far. I'll just get a check valve for that vacuum canister. I don't remember seeing a check valve on the brake booster, but I'll make sure there is one there before long. I could really give a shit about the emisions stuff. Does it matter if I feed them boost? I mean surely they won't work correctly but as long as they don't leak it won't cause any fuel troubles so i'm happy with it. I'll throw some valves on there if i feel like it. The vents were what i was worried about. I know vacuum quickly drops to insignificant levels at hard throttle. There are some long hills out in the sandhills where you stay nearly WOT for a long time and on a hot day you'll quickly notice it gets really bloody toast and the defrosters dry out my eyeballs. I think i can find the big line that goes to the vac canister and check valve it and be okay. Or at the very least no worse off than I am now. Also, where the heck to I buy check valves? Can i just waltz into AdvanceAuto and ask for one....or?

You seem to have a vac leak somewhere in the climate control system if your car exhibits those symptoms.

yes, they have them at any good parts store.

[Az4u2c]

Jason84NA2T wrote:
You seem to have a vac leak somewhere in the climate control system if your car exhibits those symptoms.

yes, they have them at any good parts store.

That very well may be. I've got a big bunch of silicone hoses lined up. When everything is all torn apart i'll go back with all rubber. I can always tell when a new hose cracks because it starts to idle shitty. All this old rubber just seams to be falling apart, so it's definatly time for new stuff. Just one of the many things i hope to fix starting Saterday.

[G-E]

I ca't be the only one who's thought of this but....

what if you seperate the vac lines from the engine and have a closed loop with the vac pump ? constant vac without relying on the engine, and if you have no leaks the pump shouldn't run very often at all

[Az4u2c]

Can somebody throw me a bone and direct me to the sites where I can find the vacuum line routes again? I know i found that information with the diagrams and hose info before, but now i've lost the links somehow. I know gary's site and few more had some good info...info i'm probably going to need soon.

[chronic]

I dont know if this is the one you're saying you already have. But here you go anyway, http://users2.ev1.net/~jboykin/vaclines.htm

[bmanz]

G-E wrote: I ca't be the only one who's thought of this but....

what if you seperate the vac lines from the engine and have a closed loop with the vac pump ? constant vac without relying on the engine, and if you have no leaks the pump shouldn't run very often at all

thought and decided somewhat against that. Some things like cruise control and the EGR also monitor changes in vac using a pressure switch to determine if it's active or not. Running a constant vac may alter their functionality in an undesirable way. Ideally a one-way valve to keep boost out, and a pressure switch to turn on the vac pump when vac is less than , say 10.

[MrwassmanNA2T]

Then you could have the vaccum sensitive lines run to the plenum right?

[Az4u2c]

[quote]bmanz wrote:

I ca't be the only one who's thought of this but....

what if you seperate the vac lines from the engine and have a closed loop with the vac pump ? constant vac without relying on the engine, and if you have no leaks the pump shouldn't run very often at all
thought and decided somewhat against that. Some things like cruise control and the EGR also monitor changes in vac using a pressure switch to determine if it's active or not. Running a constant vac may alter their functionality in an undesirable way. Ideally a one-way valve to keep boost out, and a pressure switch to turn on the vac pump when vac is less than , say 10.

That is a very good point. However both the EGR and the cruise are worthless to me since my car didn't have it as an option it seams and i have no incentive to hook it up.