924Board.org

[ericj001]

whats the low down on boost controllers in a otherwise stock set up? been looking at a few, single and dual stage units. the electronic ones are "neat" but may be a bit much for a stock engine, and a bit pricey. I have intercooler aspiration, but thats a long way down the road..
pros, cons, suggestions would be appreciated..
thanks,

[Smoothie]

They were talking about boost control under "Let's Play: What does this do?" - very technical stuff there.
I've played a bit with boosting my boost in a less expensive and less intrusive (easier) way.
1) I put an adjustable air pressure control valve inline with the control line (hose) that runs from the pressure pipe to the wastegate. It's a $15 item from Northern Tool & Equiptment (formerly Northern Hydraulics), but I think I've seen something similar at Home Depot either near the air compressors or power tools. Installed, it sits right on top of the valve cover inside the engine compartment. Would be better and more convenient to add some hose and place this control in the passenger compartment because it would be subject to less heat and vibration and it takes quite a few test runs (drive, stop, get out, adjust, get back in, drive, etc.) to get it adjusted. Once it's adjusted though, you just leave it alone, so; having it in with the engine helps to keep you from playing with it. You adjust the valve to limit the pressure flow back to the wastegate and thus keep the wastegate closed longer resulting in more boost.
2) Being a guy that likes to be nice to his engine, I thought of adding an intercooler, but; being also a guy that likes to spend as little as possible, I decided to go with water injection and came up with my own simple design. My '82 924 Turbo has a place at the bottom of the windshield wiper reservoir where a headlight washer pump can be installed. I did this. The pump was about $70 and was the most expensive part. I then drilled a hole into the left side (looking from the front into the engine compartment) of the top half of the air cleaner housing and attached a barbed hose fitting on the outside and a small piece of copper tube (about 4 inches) to the inside of the aircleaner. I then bent the copper tube into an "L" shape, but; with a gradual bend so it wasn't kinked. Then crimped down the end of the tube to seal it off, then used a small finishing nail held in visegrips to drill a tiny hole in the tube in the position where it would spray water back toward the CIS injection air flow metering plate. Then I attached a piece of hose between the headlight washer pump and the barbed fitting and spliced a small plastic fuel filter into the hose at a position where it wouldn't interfere with the headlight's up-down motion to keep the sprayer from getting clogged. So, we now have boost and we have detonation supression, but; we don't want the water injection to run constantly, so:
3) To have the water injection come on only when needed, I used a pressure switch. This is a switch with 2 elec. contacts and a small hose fitting. You tee it in with a hose to a vaccuum line somewhere that will give it pressure when the engine's intake is being boosted. Mine is non-ajustable and closes its' switch contacts at about 5 psi, so; from 5 psi boost and up, the switch is on. Just wire it in series with the electricity to the headlight washer pump and you're set. I think it cost about $50 and don't recall the name of the place I got it. Should be able to find something similar from most turbo retailers.
With this setup, it's sufficient to top off the windshield washer reservoir at each gas filling. I just use regular old blue windshield washer fluid. If the reservoir does get empty on you, you'll hear a loud sound from up front when the turbo is producing >5 psi. It's only the the headlight washer motor running dry and screaming for more water. First time I heard it, I thought oh S, the turbo charger is going (again). It's not that bad, but; does need attention because the washer pump gets destroyed if you run it dry too long. (I'm on my second pump now.)
I've had this setup operating in my car for >6 years with no engine damage. Without any alterations, my boost gauge read about 8-9 psi max. With the valve installed I have it adjusted to give about 12 psi max. Doesn't sound like much, but; it's enough to press you back in your seat and make you want to go, "weeee!".

[ This Message was edited by: Smoothie on 2001-09-20 11:45 ]