Dump Valves (part 2)

[pezza]

I just saw the other thread started by Ritch about Dump Valves but thought I better not hijack that one for a change :)

Still modding I see Ricth :lipsrseal ..or thinking about it /yes :thumbsup:

What dump valve you thinking of buying?

I was wondering what guidelines people normally follow in setting these up?
Are there any issues in pressure settings (which will vary from car to car)?

I have been running with a standard re-circ valve from a FQ-340 and it seems ok mostly when driving in full auto mode but symptoms more apparent in tip mode , revvin close to the red line and quickly backing off the loud pedal completely and then shifting up a gear quickly, I get a jolt, similar to a fuel cut jolt or where you drop the car from neutral back into drive, when you forget that you are back in full auto mode :oops:

Early evo 8 dump valves had problems not shutting off completely between gear changes and this had the effect of not allowing revs to drop off completely when stamping on the clutch... With an auto car am wondering if that would cause my gear change to be jerky?? :inquisiti /help

This morning it did happen in auto mode too in 2nd... but at around 4000 revs... its almost like a flat spot, before accelerating hard again.. (The more I explain it, the more it sounds like fuel cut). When this happens, the boost gauge is showing about 0.7 - 0.8 bar tho...

This has only started happening either because:

upping the boost a very slight tadge.. (Boost gauge peaks between 1st and second about 0.85 bar)

changing induction to cylindrical / BMC filter/induction

relocating the manual boost controller (but not changing length of piping)

or maybe recirc valve not too well?


ANy ideas folks?

I am going to tweak the boost controller down again and have a run this lunch time to see what difference it makes..

I would also like to try with the original recirc valve (if anyone has one kicking about :) as mine was blitzed, by the previous owner I must add!)

Cheers and thanks for reading :)

DeK

[pezza]

Pez .. If your thinking of changing your Dumpvalve , why are you going for a recirculating one .. ?? :inquisiti

The FQ340 device is already in there, been in there since december.. Got it off a mate when he changed his... But now there are recalls for early FQ340 recirc devices due to low pressure and the fact they don't shut off quick enough between gear changes. Not sure how to check mine.

I would like to try swapping back to original but my original is not a dump valve... its just a pipe surrounded by silicone in a bodged repair job. the previous owner must have driven over or hit something to blitz it, along with the bumper bracket which was twisted and eventually punctured my intercooler!!!!

I need to get hold of a stock device to try..