Jahoo88

Ok i know how i will be making my MBC. I will use a pressure relief valve and a pressure regulator.

Heres my question: The pressure regulator is basically a bleed valve that bleeds off excess pressure right? Will this not cause a boost/vacuum leak?

The only way to solve this would be to plumg the pressure regulator exhaust (bled air) into the TID after the AFM.

Or am I all wrong on this one?

breesej

Not all pressure regulators are bleed valves...

read this tech article... it should help you out.....

http://www.autospeed.com/A_0670/page1.html

Jahoo88

Thats the one i want to make, but i was under the
impression that the only way a pressure regulator works is by bleeding air off.

kleetuz

iTrader: (2)

Go to www.mcmaster.com and get part #48935K25
You have to get 1/4 nipples welded onto the ends to run the lines off of. Simple ball and spring type, works great.

2kwik4u

I know you want to make your own and all but for a shade over $50 you could get this one---> http://www.boostvalve.com/pricelist.html

i have heard nothing but good revies from it...Even heard of one guy using it on his new Turbo 4cyl honda jetski!!!

breesej

Not all pressure regulators are bleed valves...

read this tech article... it should help you out.....

http://www.autospeed.com/A_0670/page1.html

breesej

Damn, I clicked on the wrong button and I double posted the same response.... 6 hours later.

If you have a S5 TII then just start with the pressure relief valve between the boost pressure pick up and the wastegate. S5 TII's have a pressure regulater called the Turbo Boost Duty Solenoid which bleeds off boost pressure.

Certain types of pressure regulators will not bleed off pressure. Think of air tanks in your garage or at the mechanics, they all need pressure regulators to regulate pressure to the air tool. All it does is lower the air pressure from the inlet of the regulator to the outlet. Think of SCUBA gear..... you have a couple hundred PSI of air in the tank, and you regulate it down so you can breathe. Would you want it to bleed off air when you are under water?

Now these are all examples of a regulater being between (inline with) the source and the destination. The stock S5 TII regulator is an example of a bleed valve type regulator which is located after the source, parallel to the destination.

Yeah, I've probably made it more confusing. Not all regulators are bleed valves, think SCUBA and you'll get it.

Jahoo88

Thanks everybody. Kleetuz, that www.McMaster.com site is really good, i wasnt able to find any site with such products that lists specs and prices for so many products. Everybody building an mbc should definetly check out.

2kwik4u, it looks ok, but i will be making my own that should be better then the one they sell.

Breesej, of course.... the scuba thing is right, they would be bleeding off like 99% of tha air if it was a bleed valve haha. I just have to get a real pressure regulator.

BTW it is an S5 but i have no solenoids and no emissions so my wastegate is hooked to the compressor outlet nipple. I boost 5.5 psi (wastegate spring sressure) in 1st. Only starts to creep in the higher gears. I want it to get to 12 psi RIGHT away.

Now if i get a relief valve set to 12 psi, the wastegate will be closed till then. I will likely be seeing 12 psi around 2700 - 3krpm in some higher gears. I will by then have:
680cc secondaries
walbro 255lph pump
fcd
new fuel filter

Will it run lean between 3krpm and 3800 rpm when the 550cc primaries are working alone?

Jahoo88

Also, I think i will get part
# 99045K22 - Adjustable Polysulfone Back-Pressure Relief Valves 0 -10psi

Should i get 10/32 female screw thread or 1/8" NPT female? Whats easier to get nipples in?