Greddy Type S Question Options

[turbohcar]

Just picked up a Greddy Type S second hand. Now, this thing has two vaccum ports on it. One is on the black "hat" cover and the other is in the aluminum casting part right under the first. Which one do I plug into the intake manifold boss and do I leave one unplugged or not? Pics to be posted later if we need them. Thanks

[TURBOWHT]

USe the one that goes into the side of the top cover. The other small little on that comes out at an angle just stays the way it is. Nothing goes over that one.

[turbohcar]

Well..... after work I bought some parts from the hardware store and made myself a BOV tester. What I basically did was took a T-fitting and cut some silicone hose too. I hooked my boost gauge, air compressor, and BOV to it using the T-fitting and hose. On the SOFTEST setting the top straight fitting did not respond until about 30psi and even then it barely even opened. Now, when I put the hose on the small fitting it opened at just over 18psi. Which one of these is correct? I figure the smaller one since the top one doesn't respond as fast. Comments?

[turbohcar]

Well, I'm lost. I must be testing it wrong because I even took the unit apart and took the smaller spring out (there are two, the smaller is inside the larger) and it still does not respond. The Type S is designed just like the stock BOV. It has a spring in the upper cap portion that is on top of a plate connected to a shaft which controls the valve at the bottom. Down around the bottom of the plate that the spring sits on it is surrounded by a rubber gasket that seals the bottom portion from the top. Now, the upper boss on the unit feeds the upper portion of the cap and the lower angled boss feeds air underneath the rubber gasket just like the small hole on the gasket surface of the stock unit. Any ideas?

[wortdog]

Well..... after work I bought some parts from the hardware store and made myself a BOV tester. What I basically did was took a T-fitting and cut some silicone hose too. I hooked my boost gauge, air compressor, and BOV to it using the T-fitting and hose. On the SOFTEST setting the top straight fitting did not respond until about 30psi and even then it barely even opened. Now, when I put the hose on the small fitting it opened at just over 18psi. Which one of these is correct? I figure the smaller one since the top one doesn't respond as fast. Comments?

They aren't supposed to open under pressure, they open from vacuum generated when you let off of the throttle. Your tester doesn't seem to make any sense, unless I'm picturing it incorrectly.

[turbohcar]

Hmmmmm.....vaccum you say Sherlock? Well then my testor is wrong.

I assumed that when you let off the gas that there would be pressurized air backed up against the valves when you let off the gas in the intake manifold (where the boss for the BOV line feed is) which would slowly bleed off as the car slowed down (while the car is slowing down in RPM). Why is the intake manifold in vaccum while the intercooler pipes, before the throttle body plate, have positive pressure?

[wortdog]

The engine is in vaccuum because at higher RPM the engine flows way more air than the closed throttle blade can supply. If the intake manifold stayed under boost, the car wouldn't slow down when you let off of the throttle.

Testing a BOV is a little hard, you have to simulate your normal boost pressure on the valve of the BOV(where it attaches to the I/C piping) and then pull a vacuum on the upper nipple.

[turbohcar]

Nipples??? I love nipples!!!!

In any case, I tried putting a little pressure with my thumb on the valve to simulate a bit of pressure on that side but we both know how accurate that is. I suppose I'll just have to test it on my car then when I get the clutch pedal back in. I don't have any way to create vaccum. Thanks Eric!

[turbohcar]

Well, I guess my next question is if there's no way to test it, then how to I adjust it correctly?

[wortdog]

When adjusting a BOV, you're looking for a balance between compressor surge at low boost and leaking at high boost. Do a boost leak test at your normal boost level or a little higher, then back off the spring pressure until the BOV leaks. Then tighten it back up a little past the point where it stops leaking and you should be good.

If you're planning on running over 20psi, you'll probably end up with some surge at low pressures, but that won't hurt anything.

[natedogg]

This link might help some. I have the greddy S on my Evo. Works great once you have it adjusted.

http://www.roadraceengineering.com/instruc...nstructions.htm

[turbohcar]

Nice link Nate! I'm still working on mounting it right now. It's kind of hard thinking about drilling right into my HKS upper intercooler pipe but what has to be done must be done. I'm still waiting to get my clutch pedal back from the guy that's making some bushings for me so as soon as I get that back and put back in I'll be able to test the new BOV.