Lorax

Rolex... LOL. Yeah, the Yaris was more car than I am driver so I decided to get a measly 951 instead. I'm really going to miss the jaw dropping acceleration of the Yaris, but it is just too scary for me. This 951 with Vitesse stage II is much more manageable.

Duke

ivai

Hmmm.. I bet I know where to find pics..

RolexNJ

Oh ok, so now onto the new 951!!

Keithr726

doesn't your car have a vitesse stage II?

Porschefile

Is it a Greddy Type R? If so, those are known to leak, and 14psi seems to be about the limit before they can start seeing issues. Technically, the BOV shouldn't leak or open at all until you let off the throttle on boost. With it leaking, that is causing added lag.

By tightening the spring in the BOV, you are causing it to open up later, so at low rpm or partial throttle and while building boost, it won't open or will barely crack open so the car will act as if you have no BOV/BV basically causing the intake air to back up and surge the compressor. With smaller turbos it really shouldn't be doing it hardly at all. Big turbos are a completely different story as the stiffer wastegate and BOV spring pressures you'd typically see will make surging the compressor fairly normal at low rpm partial throttle and building boost under the WG spring pressure.

Here's a video to give you an idea: Link

tedesco

for some time I run the greddy type r BOV as well but decided to discard it after some driving. What I found not to be ideal is simply the large diameter of the BOV and the resulting big T you need to have in the intercooler pipes. My intercooler pipes are 60mm and you joint the 40mm tube from the BOV to it. The resulting joint I suspect to be quite lossy (in case of the BOV beeing closed under boost conditions)for the charge air flow as it will see a big (and in my case sharp) step. I don´t know if its clear but maybe you get an idea. I would now rather use several small BOV for which I think it is easier to join the recirculation line back to the intercooler pipe nicely.

Lorax

Its the greddy type RS. How can I see if its leaking? I have a forge BOV unit as well, but unfortunately the SFR intercooler pipes are flanged for the type RS only

Porschefile

Well, the type RS is supposed to be a better one. A friend of mine is running some 22-24psi on his and it seems to work just fine. Are you 100% sure you don't have a leak somewhere else?

Lorax

I honestly don't think its leaking at this point... I think that the relative pressure just dropped a bit due to the loss of backpressure from removing the cat, as well as the increase in volume of the new hard pipes. car is boosting fine to 15psi now, and i turned it up to 17 for a bit and that was fine too. Is that what is happening? seems to make sense in my mind.

black944 turbo

Did you buy that beautiful red one with 968 seats?

Lorax

Nope, It's white. Pics coming tomorrow ....

Duke

Less backpressure (e.g. a removed cat) results in higher boost pressure with no other changes.

Think of backpressure as a resistance that the boost must overcome... the less resistance, the less the turbo has to work.

Lorax

Alright that makes sense... but then how do I explain my issue? Just the increase in volume from the hard pipes alone? I would say the drop was .75psi

special tool

that is the way it should be!
It is the opposite of decreased resistance after the turbine.
The old pipes were a restriction - congradulations, you will now make the same same hp at this lower boost setting.

I had temporarily used a 2.5 inch ic outlet pipe on my 3in/3out ic after my last round of mods.
So it TEMPORARILY went from 3 inch ic outlet, DOWN to 2.5 inch pipe to 3 inch throttle plate!! (no ballbusting please)
When I finally putthe 3 inch ic pipe on, I gained about 1.5 psi at same temp.
My turbo is as big as a pumpkin, but you get the idea.