I had a long standing issue that was causing a slight hesitation as the boost rose between 1-4 psi. This wouldn't happen all the time, mainly between fast gearchanges, so it was very hard to trace. I assumed it was a boost leak of some sort but on a boost leak test there was no leaks.
The noise as boost started to rise has been there since I built the engine and I assumed that having a dump valve it was normal. I decided to do some research on the valve I had, as it was a part that i hadnt tested/checked. The valve second hand from e bay and advertised as a bailey dv24.
By chance I found a website that showed how you can service your dv24. I also found alot that said how bailey valves were no good but replacement wasn't an option at the moment so I thought I'd give it a go.
http://www.evilution.co.uk/432I followed the guide and 1st thing I noticed was I didn't have a dv24 single piston valve but a dv26 dual piston. This was a bonus as I prefered not to have unfiltered air entering the engine.
The next thing I noticed was the piston was very stiff and took some effort to remove and was a bit sticky In its bore.
I immediately knew this was my problem as the valve had a dry black non greasy substance inside that wouldn't allow the piston to move freely. (I used silicone grease as I didn't have lm grease)
After reassembling, the piston movement was checked and was smooth with no tight spots.
A test drive proved that this was the cause and now it seemed to be dumping differently too.
I may need more mapping now though.
