Yes, sorry, dump valve installed and now tested for about 600miles. Very pleased I did it and actually should have fitted this from the get-go.
1. I went for a simple Bailey Dump to Atmosphere valve, which claims to be able to handle any amount of boost. My car only makes 10psi, so this will hardly provide it with a challenge. I went for a dump-to-atmosphere as I needed to lose a lot of air and the general view was that these offer the highest flow for venting the excess to the sky. Remember that the s/c pumps air into the engine all the time, unlike a Turbo that has a wastegate to control boost. So the dump valve has to work pretty much full time on a s/c engine, as opposed to only when changing gear on a turbo.
2. Install was easy and I used a simple T-connector into the main intake pipe to mount the valve, nice and near the throttle body. I T-'d into the feeder pipe for my boost guage and made sure the valve was flexibly supported.
3. I remain amazed at how much air that Rotrex pumps even at a 900rpm idle. You can hear the air being vented when running on an even throttle at lower speeds, but at higher it disappears into the rest of the wind and tyre noise. As you increase throttle, manifold depression decreases, the Bailey starts to close and the venting rush becomes more or a hiss as the hole through which the air was passing closes up as the piston rises. By the time the gauge shows atmospheric, the Bailey is closed and the engine sees the full effects of the Rotrex. And then when I change gear, vacuum momentarily returns, the Bailey opens and dumps the pressure to air and off we go again. Works a treat.
4. Should have done this months ago. Without this valve the s/c was constantly pressurising the entire inlet tract from the s/c outlet, through the pipework and the I/C and right up to the butterfly valve in the Throttle Body. Not only has this build up of pressure now gone, but so has that slightly stressy feel to the engine when cruising fast but at a constant speed. This scenario has the TB butterfly only slightly open so the charged air has nowhere to go and just tries to stall the compressor. None of that any more. The engine is smoother all round and actually feels stronger and more responsive. The CHUFF when changing gear remains amusing and I really love the extra character to the engine as the throttle position now affects the venting noises as you drive. The chap now talks to me....
SUSPENSION UPDATE:
I also got round to fitting my Eibach Camber Bolts to the top hub mounts on the front suspension. This has had a quite remarkable affect on the front end grip as it now runs 1.5deg -ve camber rather than what was broadly 0 or even slightly +ve. Front end grip is now stronger than the back, so a deft lift-off on a wet roundabout is now properly good fun. Tyre wear so far is not impacted, but they've only been on for a couple of hundred miles as yet, so jury still out. But together with the Bilstein B4 shocks all round, I now have suspension and grip appropriate to the power and chuckability of the car. Bloomin' love it - it seems to get better every day!
