Partial throttle boost?
- Thread starter Trav4011
- Start date
johndeere185
475/530 12.50
is it sticking?
I'll take a crak at it....I'm pretty sure its the twin blade throttle body causing it :laughing6:
uh-hem :blink: Sorry
Okay....You now have it plumbed into the midplate and the boost valve is closing when the vacuum drops and then it instantly goes into boost and pins the boost valve shut....so try this. Re-plumb it and run a line from right behind the throttle body to the boost valve so that when you tip in on the throttle the vacuum will drop but the boost valve will only sense that....it wont get smacked with boost...just a vacuum drop. You may find that you can modulate your throttle a little better when setup like this, it won't be as abrupt or quick to shut the valve.
Another idea would be to put a jet in the boost valve hose to slow down the valve action a little. I have never done this and I'm not even sure it would work, and if it did work then what would you do if you wanted instant boost ??
lkatya
built KB 2.6H
I don't think it will close plumbed like that. It will see a huge amount of vacuum only! The vacuum will only increase as he gets into it if I understand this correctly, plumbed right after the TB????
Travis, mine is plumbed into a tee that also feeds my boost gauge and my FPR and works great! I know when I switched to the low vac bypass which I'm pretty sure you have or should have, it does hit a little harder but only jumps to about 2psi and then climbs smoothly. :thumbup:
The bypass pulls the valve open when in vacuum.. bypassing the compressor discharge back into the inlet. When you get closer to atmospheric, the valve should begin to release and start to close the valve. Once at atmospheric pressure, the valve should be closed, no matter if there's boost present or not. And, if there IS boost present, it's only going to function to slam the valve shut once you pass a certain threshold.
So, I think bad as L is correct.. I'll switch it over to vacuum only, and see how that works out. The worst thing that could happen, is that boost could leak back into the inlet.. which I will notice on the pressure gauge.
BTW, I do have the low vacuum version, with the aluminum hose barb upgrade.
Travis
So, I think bad as L is correct.. I'll switch it over to vacuum only, and see how that works out. The worst thing that could happen, is that boost could leak back into the inlet.. which I will notice on the pressure gauge.
BTW, I do have the low vacuum version, with the aluminum hose barb upgrade.
Travis
lkatya
built KB 2.6H
The bypass pulls the valve open when in vacuum.. bypassing the compressor discharge back into the inlet. When you get closer to atmospheric, the valve should begin to release and start to close the valve. Once at atmospheric pressure, the valve should be closed, no matter if there's boost present or not. And, if there IS boost present, it's only going to function to slam the valve shut once you pass a certain threshold.
So, I think bad as L is correct.. I'll switch it over to vacuum only, and see how that works out. The worst thing that could happen, is that boost could leak back into the inlet.. which I will notice on the pressure gauge.
BTW, I do have the low vacuum version, with the aluminum hose barb upgrade.
Travis
I can't seem to wrap my head around this concept! Adding a jet to slow down the response makes sense. But pluming into the intake before the compressor?? How do you ever see atmospheric pressure? It seems like you would have vacuum at idle and even more vacuum as the compressor starts to really feed itself. What am I not understanding here?
When the TB is open, fully, there's no more vacuum in the plenum.. It's at atmospheric pressure, or very close to it.
Bird
Old and tired
True - for naturally aspirated engines - the supercharger changes all that.............
Bird
Well its confirmed....most people don't have a clue how the bypass works.
I have been plumbing Eaton's like this since about '02 but what I was shooting for was a quicker closing, I think in your case Travis it might actaully help you some.
Yes, that's true.. but, only on the pressure side of the system, which would be the lower. Anything before the blower's inlet is going to be atmospheric, as soon as the blade is wide open. You may draw just a hair of vacuum still.. depending on how restrictive your inlet is, and air filter.. but, we're talking very miniscule.
Travis
Bird
Old and tired
I used to try and do everything I could to increase the speed at which the boost valve closed....I only had a 2lb pulley and a stock Eaton so I wanted boost to come in as quickly as possible.
Trying to slow down the action of the valve is not going to be that hard you just have to think in reverse.
A smaller line or a line with a restrictor in it....(I'm thinking some sort of a 2 dollar aquarium valve here) decreaseing the amount of spring preload on the canister. Actually I first said to move the vacuum line to right behind the throttle body but after thinking about it I would move it to the furthest point from the throttle that still had vacuum only. The line diameter might be of interest here....use plastic 1/8" tubing instead of 7/32" ID.
Bird....don't mind me I was just being a morning pre-coffee smart azz.
Not sure what KB is using these days for actuators...most of them are made by Arvin. I know the ones Eaton specs for their stuff aren't designed to be pressurized. You should plumb the vacuum line anywhere behind the throttle plate but before the supercharger.
Adding pressure to the actuator isn't going to close the by-pass plate any tighter - when the plate is in the closed position it rests against a set screw. All you'll do is eventually mess the diaphram up in the actuator.
Adding pressure to the actuator isn't going to close the by-pass plate any tighter - when the plate is in the closed position it rests against a set screw. All you'll do is eventually mess the diaphram up in the actuator.
lkatya
built KB 2.6H
Thanks! That makes sense! I think the low vacuum KB accuator that we are using changes things a little though. I was playing around with it before I put it on and the spring is so light that it seemed to barley close on its own. Nothing like the eaton ones that snap shut with some force! At any rate keep us posted! I'm interesed in trying this as well just to see how it feels!
ldtu: