996tt: recirculation (dump) valve - necessary?!

[benzito]

I will very soon be making changes to the exhaust and also remapping my 996 turbo; a friend of mine who does car tuning gave me some sound advice re: the stock Bosch dump valve. Apparently at higher boost its not as reliable (esp on earlier cars so leaking may become a problem) so an aftermarket option is recommended e.g the Forge DV.

I don't doubt any of this because on my old sl55 I had to change the stock Bosch intercooler pump which was useless (and virtually all earlier sl55's have had this change now) , so:

1. Has anyone changed their DV and is it necessary if you're aiming for 500+bhp?

2. Does anyone know where they can be sourced cheap, the cheapest forge DV I've seen is on fleabay for about 100pounds each.

3. On the forge website there are a few with different finishings/styles. Does anyone know which is recommended or which would be best for the 996tt?

[sportsandclassic]

Hi,

You will benifit by changing both valves and their connection hose called an "F" hose. I would also get the valves with adjustable port ontop of the valve as you can turn this any direction you need. We can source you a kit for around £225 with hose.

Mike

[markcoznottz]

sportsandclassic said:

Hi,

You will benifit by changing both valves and their connection hose called an "F" hose. I would also get the valves with adjustable port ontop of the valve as you can turn this any direction you need. We can source you a kit for around £225 with hose.

Mike

Noone makes a silicone 'F' pipe on its own do they?. It is available in some turbo hose kits though apparantly.

[sportsandclassic]

Forge motor sport do the hose.

[maxpaul]

How easy are they to get at? Is it bumper off etc?

Paul

[davek_964]

Bumper off won't help you get to the DVs - they're at the top of the engine (at the "back" as you face the engine bay, slightly to the left).

I certainly wouldn't want to change them myself - it looked rather tight to get in there. I've heard one is much harder to get at than the other.

[EvoSlayer]

maxpaul said:

How easy are they to get at? Is it bumper off etc?

Paul

A bit awkward but doable, I've had them in and out a few times for various jobs. If you don't mind a few scraped knuckles it can be done without lowering engine, it's just a case of getting stuff out of the way.



Have fun

Btw, the stock spring clips on the hoses are a bh, throw them away and replace them with stainless hose clips!

Edited by EvoSlayer on Wednesday 12th October 16:56

[markcoznottz]

My F pipe burst like a banana skin, replaced at home, what a job, wouldnt wish it on anyone, I used jubilee clips when refitting its downright impossible to get the oe clips back on.

[benzito]

sportsandclassic said:

Hi,

You will benifit by changing both valves and their connection hose called an "F" hose. I would also get the valves with adjustable port ontop of the valve as you can turn this any direction you need. We can source you a kit for around £225 with hose.

Mike

Thanks for sourcing the kit for me Mike, its made things much easier! I am hoping to fit it soon, I've been told it could take at least 2-3hrs as the valves aren't easy to get to...