vrus

I know a popular item to upgrade on these cars is the diverter valves because the stock ones supposedly cant sustain boost (on modified cars) and cant recover as quickly as the solid billet versions.

Do the majority of you guys run the stock plastic Bosche Diverter valves or have you upgraded to the billet versions?

I had a lengthy talk about various upgrades with a very knowledgeable Porsche tuner who said his experience was that the billet versions didnt perform as well as the Bosche plastic ones..

Just want to hear some end-user feedback.. What is your opinion on this ??

TB993tt

Ditto -RS Tuning advice is stay with Bosch plastic

WHB Porsche

Are the billet valves able to be used as divertor valves or do they simply become blow-off valves?

AndyT

they are diverters

vrus

Perfect.. One more thing to scratch off the list.. LOL..

I'm basically going through a list of service items that I want to check when the TT shows up so that it is in perfect working order before I start modifying the engine.

Kevin

Sure, and is the service tech going to replace your turbocharger after it just ate the diaphram that was once in the shreded Bosch bypass valve?? Leaving 12 year old bypass valves on your engine is reckless. Running 1.2bars of boost on stock Bosch valves are also running a risk. I see it at least once every two weeks a set of turbochargers that come across my bench with the compressor wheels wiped out..

The problem is, rubber doesn't mix well with engine oil. As our cars have aged blowbye and the frequent over fill or oil gets passed thru your dear Bosch bypass valves.. TB is the poster child for having engine rebuilds every two -three years.. His engine is nice and tidy with very little blowbye and I highly doubt that he overfills his levels.. The rubber weakens and breaks apart. When dislodged it gets sucked into your turbochargers whenever you release your foot off the gas pedal..

I have tried all the different bypass valves and like the Forge valves because of the quality and precision machining that has been done in the UK. A benifit is that one can tailor the spring seat pressure with there spring kit, and every other year you can take the valves apart and clean them and relube the viton orings. Is this a sales pitch for Forge.. No, you folks can buy the valve that you want.. It's just my observation and recommendation.. The last time you seen your I/C full of oil, or you had a overfill, just remember your Bosch bypass valves..

vrus

Hey Kevin,

I apprecaite your input and advice.. I was going to contact you to ask you questions about your Turbo packages..

With respect to the diverter valves.. My decision was to either buy NEW factory Bosche diverter valves or buy aftermarket Billet ones.. I was going to buy a new pair for the car.. i just didnt know which way to go.

I have a list of service items that I want to inspect & replace on the car once it arrives and this was one of the items (along with cap, rotor, plugs, wires, filters, etc,etc).

Do you think the billet valves respond as well as the plastic ones? Do they recover as quickly? Really interested to hear your side of it.

Of course, not trying to start anything hear, just like to hear different opinions . We all learn from eachother.. that's the whole point of these boards.

Spartan

I've always had trouble with my Forge or Bailey diverter valves in my audi. Stock is fine, actually audi 710N's are better, many many many guys run them on cars runing over 2bar with zero issues (myself included) for years.

Stock 993tt diverter valves with an 8.8 lb spring are bosch number 0 280 142 108. You don't want that one. The upgraded version (audi 710N) is part number 0 280 142 114 and has a 14.4 lb spring as well as beefed up internals to withstand the heat.

JJayB

Let see plastic or metal. I've had one of the Bosch units go bad. It just seemed that the performance was a little off, after sustained track sessions then it really dropped off. Unfortunetely the diverter was the last thing we thought about.

When I took the Bosch apart and compared it to the billet diverter, it seemed that the O ringed billet was better designed than the diphram in the Bosch. Who really believes that plastic holds up better under heat and pressure than metal.

sfl993t4

I've been running Forge valves on Kevin's recommendation for a couple of years and have been very happy with them. Re-lubed then last year and they still seemed perfect.

Steve

GIA

Steve,

I am planning to buy one, and I know there are several springs in this Kit. Can you please advice which spings to use. Or its depends on the boost that I have.
Anyway, I am tryibg to understand the interdependance of Boost and Springs rate.

Thanks,

Gia

badabing

i just replaced my 12 year old stock OEM valves will Billet ones I got from Pelican Parts which they list as EVO Motorsports brand. I run a stock motor on the street only so racing application was not a consideration but they did get rid of that honking noise coming from the engine bay every time the boost hit .3 bar.

zweistein

I replaced my diverters with OEM stock ones. Honking is also gone, and Porsche should know what they fit to their cars, so I don't see a point for modifications here on a stock car.

sfl993t4

In answer to the question about Forge Springs.

Having experimented with the green spring, I now use the yellow spring without any additional shims. This seems to work fine.

Steve

GIA

Thanks Steve.