After reading through the "More Power" thread I'm a bit confused by this bit about the dump valve - sorry I'm new to turbos.
Quote:
You can just cap off the blow off valve at the front of the manifold and gain a few psi. The dump valve opens around 10 to 12 psi. If yours is like mine, it opened and the boost went down to 8 psi. Easiest thing to do is just find some kind of large rubber cap and slip it over the outlet tube, and clamp it there. If you still have everything connected to the stock turbo inlet, you can reinstall the stock hose back over the cap and clamp the hose over it. You should have a boost gauge before doing this, as this was the point at which I found out my wastegate was bad and with the dump valve closed, the turbo was pushing 25lbs of boost! From here, you can install a manual boost controller (ebay has them cheap) and turn the boost up more. Depending on how good of shape your head gasket is in, you may or may not be able to hold much more boost than stock, so do this at your own risk. Assuming things are in good shape, 15lbs of boost is probably max for a non intercooled engine with stock bolts and head gasket. I have been told engines with a good gasket and properly torqued heads that haven't been over heated will hold 20 to 25lbs of boost with an intercooler. If you don't know the history of your engine you could be taking a risk pushing it to the limit. If you really want to push some boost and keep the head on, step up and install a set of ARP studs. They have been shown to hold 40psi with a stock 3 notch head gasket.
Speaking of that dump valve, I found on my engine that after it was capped off it leaked boost between it and the manifold, and after I fixed that, between the two pieces its made of where it is crimped or glued together. I would remove the whole damn thing and get a 1-1/2" rubber plumbing cap from Home Depot to cap off the manifold. When I did this the turbo spooled up MUCh faster, it was a night and day differnnce. I highly recomend removing it!
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Can anyone explain this a bit more for me please?
I have a boost guage and at the moment get 10psi on full boost - not yet installed a Boost Controller but will be soon. Looking to take it to 15-18psi as I have factory intercooler, MLS gasket and Monark nozzles.