Running without a BOV?

[WydRyd]

Thanks, Nathan. I plan to use two of these billet type BOV's... one on the up-pipe from turbo to i/cooler and one post i/cooler.

[NathanUK]

I don't really know, but I thought it would be nice to get the cooled air back into the system and then it is cooled again.
By placing a blow off / recirc. before the IC you are pumping hot air round the turbo

Just a thought.

[WydRyd]

Good point actually. I wonder how much of a difference it would make though? Probably minimal?

[NathanUK]

I was thinking it would be kinder to the turbo and the IC.

[Porschefile]

Many older turbocharged cars also didn't come with intercoolers, then there is CIS, etc, etc. That really doesn't mean anything in and of itself. At the time most of those cars were built, turbocharging was in it's infancy with gasoline automobiles. Even at low pressure it is still entirely possible and actually more likely (lower than WG spring pressure that is) that you will see compressor surge. At the moment I'm only running 7psi on my Carrera temporarily and I still see surge at partial throttle and building boost pressure below the WG spring pressure. I've seen the same thing on my 951 running around the same boost, so it's not just high boost applications that will cause it. If you are running less boost pressure than the WG spring pressure (such as in partial throttle conditions) all of that pressure has to go somewhere unless you have some way to release it. My 60-1 is dying a slow death because of it. Oh well, it's just an excuse to upgrade.

Patkeefe, rubber in your intake (unless there's maybe a bellows/accordion style intake pipe somewhere) isn't going to absorb all or much of the backpressure and you are still likely to see compressor surge.

Just FYI but those plastic bosch BV's aren't all that great. With greater than 14psi they tend to leak pretty badly. Also, over time, due to the relatively light spring rate inside of them they can start to leak which will cause slower boost response. IMO, it's not even worth messing with them when you can just buy a billet BV or aftermarket BV/BOV and have a better unit.

[WydRyd]

Originally posted by Porschefile
Just FYI but those plastic bosch BV's aren't all that great. With greater than 14psi they tend to leak pretty badly. Also, over time, due to the relatively light spring rate inside of them they can start to leak which will cause slower boost response. IMO, it's not even worth messing with them when you can just buy a billet BV or aftermarket BV/BOV and have a better unit.

Yeh I know, it was just an example. The one I have is a billet aluminium unit which looks similar. I just wanted to confirm that the side pipe is the inlet

Here's the one I'll use pre and post i/cooler:



I plan to use two because I run max of about 1.3bar, so I want quickest possible venting as I can

[BoxxerSix]

Originally posted by WydRyd
Yeh I know, it was just an example. The one I have is a billet aluminium unit which looks similar. I just wanted to confirm that the side pipe is the inlet

Here's the one I'll use pre and post i/cooler:



I plan to use two because I run max of about 1.3bar, so I want quickest possible venting as I can

Looks to be a Forge BOV(or a good knockoff of it). Forge makes great stuff, I use their products on damn near every turbocharged car here.

This is the BOV I had on my 965 before I sold the car last year. Fully adjustable and adaptable to any fitment necessary. I now have two of these for my current project And yes, that's a quarter right below the BOV.....one of these valves will flow as much as two of the smaller Forge units, but requires some custom-fabbed intercooler/charge piping work to make it fit properly(doesn't come close to fitting stock location)

[930Turbolader]

I know I'm coming in a little late in this thread but here is my own experience with no BOV. I ran with out one for 2 years. Hammered the throttle many a times and heard my turbo stall and chatter occasionally (the sound was just like the 935's I watched at the IMSA races years ago). Never had any issues. I'm not advocating for anyone else to do it, I took the chance on my own. I chose to leave it off for a couple of reasons....1. I got a LOT better throttle response without it. 2. The race cars back in the day (935's) didnt run them. Yeah, I know they rebuilt the turbo's or whatever after every race but from a performance standpoint they were not needed. 3. If I damaged my turbo from not running one then I would buy another turbo AND reconnect the BOV and never do it again! But as it turned out.....nothing happened.

[WydRyd]

930turbolader, that's the same experiences some of the ricer boys have had with their Japanese imports and running BOV-less... they also experience significantly better throttle response and almost no lag whatsoever.

It's interesting the 935's never used them, especially considering how much boost those monsters use to run Goes to show how tough the KKK turbo's are I guess

P.S: Doesn't matter anyway, because tonight I'm installing the BOV. My welder has just called me and told me he's done the job for me

[930Turbolader]

Merv,
I have one now, a Tial I believe. Stephen installed it when he converted my CIS to EFI. Whatever it is, it works pretty good and is hands down better than the 965 set up I had. It does make noise when the pressure is released but I'm used to it now and in fact dont even pay attention to it anymore.

[WydRyd]

Yeh, I had a TiAL 50mm unit too... I sold it with my old turbo system. It worked great, but it annoyed the hell out of me and my mates would always say "How's the rice cooker going?"... got to me after a while, so I want to go with a quieter stealthy solution

[WydRyd]

I just tested this billet BOV down the FWY and damn it's so much quieter & softer than the TiAL...lt tends to vent fairly quickly too, at the very lift off the accelerator. I like it. I haven't even recirc'd it back to the intake yet and already I'm pleased with the reduced noise levels