I got round to fitting my new forge DV (off MABR's group buy) a few days ago and last night I had a late run over to Tamworth and back. This gave me the opportunity to try the acceleration and take the revs up to near the red line.
Now with the standard DV I always got a very metallic (Bee in a tin can) noise just before I came off the throttle to change up a gear.
Now the noise has gone and I seem to have smooth quiet boost up to the change (nice).
It was a nice cool evening and so I seemed to have plenty of power and it was running so smooth.
I tested the old DV for leaks after I took it of and it was fine.
So what was going on before ?
Was I losing boast through the valve before time ?
Or was the standard DV supposed to release boast at lower pressure for safety ?
What ever it is I'm more than happy with the results

P.S Does this mean I,m now on the rocky road of engine modding
Tim

the standard bosche valve was a single piston dv and will let off boost very early but a forge will hold onto boost until you come off the accelerater or clutch pedal

^^Not trying to sound rude mate , but that doesn't make sense to me. It's not supposed to let off any boost ever until the throttle is closed. The Bosch valve is even fitted "backward" so boost pressure works with the spring pressure to keep the valve closed while on boost. The only time the valve should open is when the vacuum in the manifold pulls the valve open.

Sinlge piston or not, If the Bosch valve was leaking boost there was something wrong with it.

Yes - welcome to my world

My thoughts exactly
The old bosch seemed ok,
The test I did was pushing in the valve and putting my finger over the vacuum connector which then held up the valve.
But I suppose that just checks the vacuum hold.
Could the pressure have been getting past the seating at high boost ?
What ever the noise was, its 100% gone now.
Tim


P.s Nigel..Now I've entered your world, how long have I got before for my first rebuild ?
I need to warn bank , wife , motormech

I'm pretty sure the Bosch valve has rubber diaphragm as opposed to a piston, so maybe there was a pinhole leak in it. That's the way diaphragm dv's usually fail.

P.S. In answer to your question to Nigel. Warn them now so they can be mentally/financially/logistacally prepared!

Oooh a dump valve, I'll give it 6 months tops.

Yes it does - and it perishes, resulting in leaked boost.