What are peoples view on this.

Can we get a discussion going?

Some people say its dangerous, some people say its completely safe.

Obviously by doing this you have the famous waste gate flutter but what functional benefit does this setup offer?


Si

 

anyone?

 

compressor surge will wear out the bearings in your turbo much quicker than with the dump valves which allow the additional air to effectively purge out of the system on throttle lift, also you may affect driveability of the car on part throttle from bucking and throttle hesitation. The dump valves are designed to be routed back into the intake, your tunes take this into account.

why would you ever want to run without?

 

Grand National never had them and they drove fine. A proper sized turbo shouldn't flutter IMO and I don't think out turbos will surge. Spool would likely be effected in an off on throttle situation and I agree the bearings would wear more.

I'd also ask, why do this? I'm swapping to a MAFless setup with a larger y-pipe but keeping the small bypass valves venting to atmo. What situation are you in that you cannot run a BOV?

 

Keep in mind that a grand national is also an automatic, the turbo stays online throughout the gears, and the recirc is only really needed when the throttle is released. On a 996 there are quite a few gear changes and the throttle changes are much more abrupt.

 

True and a good point! I still don't think it's that big a deal but t does beat up the turbos more.

 

Yea no reason to do this at all IMO....not if you don't have to. A BOV is cheap insurance and should help boost response vs none...especially in a manual car. Turbos are rotating at speeds north of 100,000 rpm, having air slam back into it without surge housings/bov would be pretty rough on a turbo after time.

I will say that I remember my old 12v Cummins turbo running 40+ psi of boost on/off throttle all the time. Amazed that turbo didn't grenade itself every week.

If you want cool sound along with performance...do it right and go mafless and big a@@ 50mm BOV. This will make all kinds of good sounds.

 

I seriously considered a large BOV or even a pair of them. I've skipped it, at least for now, as I think the two stock bypass vented will be enough - we shall see. I like the look and sounds of the big valves but the cost is nuts and the volume unnecessary IMO. If I'm wrong I can upgrade later so stay tuned!

 

I'm sure they are enough and if you're still planning on running the factory y-pipe and intake setup..might as well run'em. I'm building a new 3" y-pipe now so decided to go with one big vs two.

 

Nope, not running the factory Y-pipe anymore. Just couldn't quite justify the big valves, I'll wait and see how these perform. Did you go with Tial?