I think 15-17 psi is about the max anyone that's modified a 617 runs. There may be a very small # of exceptions, but in order to use that extra psi you'll need to alot of things beforehand.

Anything over 20psi will require better valve springs.

At least in the exhaust. Once you get over 30psi exhaust pressure the valves start to get pushed open.

Springs shouldn't be much of a problem to get if you want some. Take a pair to a performance shop (a real machine shop, not a ricer parts-swap shop) and see if they have or can make anything to match the spring rate needed.

I'm running a Holset HX30 with wastegate that opened (when new) at 27psi. The gauge I currently have only goes to 16psi, but it goes waaay off the deep end of that one all the time... Maybe I should get a bigger gauge. Should I worry about my valve springs?

I would look for a lighter wastegate, no way you need 27 psi of boost, and your turbine inlet pressure is probably around 50 psi.

You are likely floating your exhaust valves, which cause a power loss and can erode your valve seats.

As well as piston-valve collision.

Is there any way of knowing that you are floating your valves from too much pressure?






In a side note I have to tell... this is the 1,500th post in this forum!:D

High RPM misfiring, black smoke or piston contact.

Baja,

I did some test fittings this weekend. How were you able to clock the turbo up and still use the stock diaphragm? Also what did you do for the oil lines? Also, did you use 2 of the accordians to fit the exhaust manifold up?

Yes, but it was tight. Are you planning on using a 115 intake or modified 123 intake? Basically I clocked the compressor housing so that the actuator rod would just clear the oil supply, and adjusted accordingly. Also, my exhaust flange adapter was made of 3/4" so that gave me an extra 1/4" if your using a 1/2" adapter.
I made my own with a combination of parts. I happened to have some 1/4" SS tubing with swagelock fittings. For the 12 mm banjo (oil filter end), I used an old one I had laying around and reworked the threads so that the swagelock fitting would thread on. The other end I welded a 3 AN fitting on and used this from there to the turbo
No, just one and my adapter. There's a pic of the adapter early in the thread.

Unfortunately, something gave out yesterday, and now It sounds like there is air escaping somewhere when I get to about 12 psi. I thought at first that one of the hoses came off, but they are all intact. I haven't had time to pinpoint the problem yet.

I finally got around to finding the problem. Turns out I developed a hole in the resonator. I have never heard this type of sound coming from an exhaust before, just like air coming from a spray nozzle... I was driving myself nuts trying to find a problem in the intake. I replaced the resonator with a straight pipe, and can tell no difference in noise level.

So the 10mm hole is the fill side and the flange side is the drain?

Whats the blue hose to copper line for in the pics?

Well, you guys scared me, especially forced talking about black smoke, high rpm misfiring, and bashing holes in pistons, so I guess I'll turn the boost down to 15-17psi from the 20-25psi its been running.. Although I haven't had any complaints from the engine pulling 23ish psi at 4800rpm... yet... although your points are all well-taken, and the extra stress is not productive as far as the engine is concerned. Sorry to jump in with a side topic.

BTW: What might tighter valve springs do as far as cam wear is concerned?

correct
That's for measuring exhaust pressure. I wouldn't worry about it if I were you.

what manifold is that?