Boxster 98 2.5 Twin Turbo

[socratic]

How loud is the turbo whine? I'm hoping there would be little to no whine because I do a lot of commuting with the car and having it whine all the way to work would be annoying.

[Gerardo de Kort]

If you are driving with the top down you will faintly hear the turbo's. If you have the top up or hardtop you will practically not hear it (period).
Which is the way I want it too. The boxster 2.5 tends to have a whine by itself (stock).
Especially in traffic (slow speeds) I don't think you will notice anything.
One extra sound which I have noticed was a slight whirl wind like sound coming from the air intake (left side). This happens when you let go off the throttle.
I didn't install any blow off valve. The kit doesn't come with one (although it seems really easy to install). Plus I think once people hear that it will be a dead give away that the car is "charged".
I like it being a sleeper.

[eric95]

I'm not sure if your Turbo kit came with mandrel bent piping; if it did, I find that from outside the car when you get on the throttle, the car sounds like a jet plane sucking in air.

Pretty much a dead giveaway right there!

Never understood not having a BOV, even in low PSI cars. I guess when the throttle plate slams shut the air gets fired out the air filter? Not enough charge to cause compressor surge?

[Gerardo de Kort]

Hi Eric,

Honestly, I've never had somebody revving the car while I stand outside to listen to it. I have revved it while leaning over the engine but off course it's loud with the engine cover removed.
I do have the mandrel bent piping.
Friend of mine who's experienced at turboing cars did not sound too concerned over me not having BOV given the fact I was boosting 5-6 psi. He has a mean RX-7 3-rotor (turbo off course).
Never cared for checking but do you know if they make quiet BOVs?

P.S.
Do you also carry twins?

[Kirk]

Originally Posted by Gerardo de Kort

Never cared for checking but do you know if they make quiet BOVs?

Sure, the stock BOV on my '01 WRX was quiet. Rather than blowing air off to atmosphere it would recirculate it around to the inlet before the turbo. If I recall currectly this helped to keep the turbo spinning too.

Originally Posted by eric95

I guess when the throttle plate slams shut the air gets fired out the air filter?

The idea of a BOV is relieve pressure when you lift off the throttle so that the turbo keeps spinning rather than stalling as pressure builds for a second. It also keeps things from going over pressure when you lift - which might cause an intercooler or piping to break. I doubt you'd have pressure going back out the air filter, as to do that you'd have to get the turbo spinning backwards or something...

[Gerardo de Kort]

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[edevlin]

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Ed