For those with Greddy Type S
I have the one spring mod. I was just curious because some people have fluttering, while the rest have whistling (including me) when they let of the gass at partial boost/throttle. Which one is the correct way?
FYI,
I have been running a Type S on my DSM for a couple of years now. I would like to point out a couple of things that I have noticed:
Even though it may seem like it is working fine, I would highly recommend putting some RTV or sealant around the stud that comes out of the top (where you adjust the nut on the top of the BOV). I changed out to a Tial BOV once and since I had the Type-S off I did some pressure testing with a MityVac hand pump. The Type-S only held 10psi! You may not notice it when on the car because the turbo is flowing enough air to get past that point, but it just makes the turbo work even harder and maybe fall off more than usual on the top end. Anyway, after I put some RTV on the stud between the washer and the top of the BOV the Type-S held 30+psi without any problems.
Also, I'm not sure what any of the Evo guys are doing, but if you get the flutter when you let off to partial throttle, you can connect the bottom nipple on the Type-S to a boost source such as the upper IC pipe. Doing this will allow you to tighten the BOV more to hold even more maximum boost and still allow blow off at release to part throttle. At part throttle, when the throttle plate closes partially, the pressure going to the lower nipple will be greater than the pressure going to the upper and allow the valve to open. If only the upper nipple is used, at part throttle, you may still have some boost pressure or not enough vacuum going to the upper nipple to open the BOV and that's what causing the surge. Sure, you can loosen the BOV a ton or modify it with only one spring, but that doesn't completely slove the part throttle issues and may allow the BOV to leak more at WOT.
Eric
I have been running a Type S on my DSM for a couple of years now. I would like to point out a couple of things that I have noticed:
Even though it may seem like it is working fine, I would highly recommend putting some RTV or sealant around the stud that comes out of the top (where you adjust the nut on the top of the BOV). I changed out to a Tial BOV once and since I had the Type-S off I did some pressure testing with a MityVac hand pump. The Type-S only held 10psi! You may not notice it when on the car because the turbo is flowing enough air to get past that point, but it just makes the turbo work even harder and maybe fall off more than usual on the top end. Anyway, after I put some RTV on the stud between the washer and the top of the BOV the Type-S held 30+psi without any problems.
Also, I'm not sure what any of the Evo guys are doing, but if you get the flutter when you let off to partial throttle, you can connect the bottom nipple on the Type-S to a boost source such as the upper IC pipe. Doing this will allow you to tighten the BOV more to hold even more maximum boost and still allow blow off at release to part throttle. At part throttle, when the throttle plate closes partially, the pressure going to the lower nipple will be greater than the pressure going to the upper and allow the valve to open. If only the upper nipple is used, at part throttle, you may still have some boost pressure or not enough vacuum going to the upper nipple to open the BOV and that's what causing the surge. Sure, you can loosen the BOV a ton or modify it with only one spring, but that doesn't completely slove the part throttle issues and may allow the BOV to leak more at WOT.
Eric
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TruckSkinJoe
Evo Engine / Turbo / Drivetrain
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Jul 18, 2007 12:25 PM
