So finally, after 3 months with the SR swap, I get my car to the drap strip...

Stock SR, except Manual boost controller set to ~10-11 psi (spikes to 14-15), ACT street clutch, Greddy RSPL FMIC, etc....

So, first launch ever with an SR....I get a 2.24 second 60' (not great, but not horrible for my first time with the engine), and of course, I COMPLETELY miss 2nd......end up with a 14.8 @99.3 mph.....the 99mph was pretty good, considering I spent a long time screwing around with the missed shift.....

So, second and third runs, something seems obviously wrong....my 60's are 2.2 and 2.4, but I run 15.3 @ 90 mph.....

ughhhh....so in the staging area, I pop the hood, and tap the throttle, it revs up, then almost stalls...and the BOV is making a whistle noise (like a quiet whistle)....I look in, and can see that it isn't shut all the way...just wonderful....

So, it starts to rain, and they call a delay, so I come home, take off the BOV and take it apart inside my room.

Sure enough, the rubber seal between the top half and bottom half of the head (where the spring is compressed) was somehow getting slightly caught as the plunger closed, not allowing it to fully close.

It's amazing how a <1mm opening in your BOV can completely ruin what should have been a fun night at the track :-(

I was at least hoping for something in the 13.5 range :-(

 

my condolences. thats unfortunate. what brand was the BOV?

 

It's a Greddy RS....it's really strange how the rubber piece is "sticking" and getting caught up....it's kinda the same type of piece that goes around the rear brake pistons....I am thinking of putting some grease on it so that it doesn't catch....

 

yeaa...maybe its the cold? lol.

 

ive many many problems with my rs as well man, i hate it..never had it get cought like that but it seems to whistle a lot and i find myself tightening it more that i should have to be...def upgrading in the future..

 

That plunger seal area is where a good BOV is determined in my opinion. As that is really all that is important on a BOV. Springs should hold up fine but the seal if it is *** then you have a turd for a BOV.

 

i agree, but i haven't explained the problem well enough....

On the other side of the plunger (top side, between spring and housing) is a rubber diaphragm, that seals the area on top of the plunger (where the spring is housed, and where the pressure FROM THE HOT PIPE goes).

It is this rubber diaphragm that is getting slightly bunched up a bit i guess..

nonetheless, you are right...anything causing the plunger not to seal is not good....


on a positive note, i bought an AVC-R today!

people say it's a hard install, but it sure looks easy....a few vacuum lines, and a few wires spliced into the harness...

 

that is the part I am talking about. That is where a good BOV and a bad one really show.

 

interesting....i assumed a $200 Greddy BOV would be "good" haha

 

Yea I would have to. In my RB25 S14 I had a Greddy. It turned out to be a **** of ****. I only use ARC or Tial now.

 

i want a sard r2d2 so badly...

 

I would think they might be good also.

 

Well if you are looking for a 13.5 time there will be more tuning than just boost problems and leaks with the BOV. Granted that you were having problems with the BOV, but I think that it is a minor problem to worry about. Running high 14's regardless of BOV problems just shows that you may need better reaction with your launch (for grip and skid) and also quite possibly better traction control (VLSD, and Z rated tires) open diffs suck for launch and traction on the 1/4 mile, not to mention you need more HP.
I see STI subaru's hitting between 13.0 and 13.5 at the track those engines are relatively in the 300HP range and more depending on the driver and boost levels of the engine.
Now if your using a BASIC t25 (ASSUMED by me since you just had an SR swap), then mid 14's is pretty much to be expected.
Humidity and weather temprature will also change HP output dramatically.
Theres so many other factors besides the BOV that you need to take into effect.
In other words good job just do it better next time, don't worry about it. If by chance you slip into the 15 second range then if I were you I would start to worry.

 

Thanks.....

Like I said, the 14.8 was with a completely missed shift from 1st to 2nd....

Also, the subsequent runs in the 15s were 100% without a doubt a result of the BOV not closing....I mean I could hear the air pouring out of the BOV at full throttle, and my boost was building absurdly slow...

This was at 10 psi, with spike to 14ish

I am installing AVC-R this weekend....with 14psi, I should easily be in 13s....


Also....when you talked about reaction time, I am assuming you meant with respect to slipping the clutch on launch, because obviously, real reaction time (w.r.t. the tree) doesn't affect the time.

My 60' was a 2.2.....not great by any means, but definitely not abyssmal at all

 

if you ever want to get rid of it i suggest you go with a 1g dsm