slowcorrado

Hi Rennlist, long time lurker, not much of a poster here...

I've been researching any info I can find on boost regulation issues because my 86 951 is going into overboost protection all the time. All obvious/easy fixes have been done (visible vacuum lines, diverter valve was shot, etc..) and I'm ready to progress to further diagnosis. My end goal is to pickup the Rogue A-tune as my software solution and only minorly (14-15 psi) increase the boost.

My issues/questions are what seems to be a recurring theme on all Porsche forums related to the 951s. The problem is that I'm only finding OLD (2002 to 2010) information related to products or solutions to my issues. So many broken links, companies that aren't in business, products not being produced any more, (ex: Laust vacuum manifolds) etc..

What is the latest info or solutions we've come up with in the fight to improve and repair our cars! :-)

1) Venturi delete: I see a few vendors still sell the kits to delete this. Is it smart to go this route, or do a fully custom vacuum setup? If the CV gets deleted, isn't it basically useless to buy all the stock formed venturi delete hoses since the end product will need to be all custom anyways?

2) Boost regulation: For the sake of argument let's stick with only manual boost controllers or stock. It looks like everyone thinks the CV should be ditched. I ask: Why? Can it be programmed to just have a higher boost threshold and be kept stock otherwise? If removed, what is a current boost controller that works well and uses the latest technology? (I see lots of choices on eBay that look neat, but keep seeing folks referencing the 'accuboost' or the Lindsey one in posts from like 10 years ago)

I'd love to see this post evolve into something that can update the current state of these issues on our cars.

*** LOL, after posting this, I notice that it's officially my 1st post since I joined in March of 2012. I've probably been lurking for 4 years before that. Heh! ***

Dougs951

Are you looking for a manual or electronic boost controller?

And many of the problems relating to the CV are age related. They simply disintegrate.

And yes with a CV delete it is pretty easy to make your own hoses under the intake

slowcorrado

I'd like an electronic one, but was thinking that manual would be more reasonably priced and simple/durable. If there are good new electronic options, please enlighten me! All the older threads are showing Apexi as the choice at around $600. (from 2008 or so) It's funny, a quick conversation with Joshua from Rogue piqued my interest in possibly upping the boost using the stock CV. He mentioned that it's possible to get up to 14 lbs out of it with some type of software change. That sounds like an amazing solution because it keeps your stock vacuum routing and failsafes, but I didn't think about asking him for further details at the time. I haven't see any info about this anywhere. (Its also possible I misunderstood him!)

mahoney944

you need the venturi delete kit, or at least its recomended while your in there)

remove the cycling valve, remove any lines attached to the venturi system leaving (you can grind the small metal line fitting they connect to), plug the j boot with a bolt and hose clamp, remove the jet screw inside the banjo bolt attached to the "L" shaped hard pipe and run a line from the hard pipe to the wastegate with a boost controller positioned on that line where ever you want. and your done set the controller to any level of boost you want. you will also need a chip set to remove the boost limiter.

Single port wastegate


duel port wastegate


vac routing for duel port wastegate (If your using single port refer to the wastegate connections above)

Mangonesailor

The venturi delete hoses do not tie into the CV valve. At least from what I've seen. The Venturi Delete kit is just for extra insurance "in the event" and cleans up the underside of the intake manifold. Less stuff to break/bust. The Hoses for your new boost controlling method will have to be custom cut and fitted. Not a big deal. 944online sells bulk 6mm and 10mm hose. Don't forget to get the hose going to the AOS that will be receiving a relief valve. I've read somewhere that if you do not update this hose as well your car will smoke under boost. I Personally would like a clean car... even though mine's black.

I noticed on the CV valve that there is a restriction jet in one port that possibly prevents this possibility.

I'd prefer to have an electronic controller after I install a manual boost controller. I don't want to be messing with too many crazy settings after initial install and a manual controller can be "bench tested" to 13-14psi and then installed... so you don't start driving around at 2.5psi and think you screwed up. However, I'd like to see some information on what people are using too.

Don't forget the "while you're there" maintenance and such. I have new AOS seals and dipstick o-rings waiting on me for when I get state-side. I pretty much have everything for the venturi delete sans AOS hose/relief valve. I will purchase the M-tune and fabspeed exhaust and be in about the same boat you are come Christmas time. Stay tuned for my thread and pics.

PS: If someone would like to PM me and explain how to upgrade to the 2-bolt flange for the wastegate dump for the Fabspeed exhaust, I'd be grateful.