How too controal boost level?

[jimbixjr]

I have a 745i turbo setup. I believe the boost is set at 8 psi. on the stock application. I have heard that it can be changed with a new spring inside the wastegate. I have also heard it can be changed with a standard boost controller. Can anybody with experience in this tell me how it can be done. I realize that with changing boost level I will need fuel upgrades. thanks for your help

[RDAvena]

I chopped off the cap on my wastegate and made it adjustable with the stock spring. Welded it back together and it has run at 10PSI without issues.

You could use a grainger valve for further fine tuning.

[russc]

I thought the ECU stock has a fuel cut if you go over 9psi? Check over at the 745i.com

RussC

[RDAvena]

I thought the ECU stock has a fuel cut if you go over 9psi? Check over at the 745i.com

RussC

If you are using the 745i ECU.

[jimbixjr]

what about the ecu out of an 86 535i 3.4l manual car? I have heard its around 10 psi but you can do more with an fmu and a chip that retards timing without getting a full standalone system for fuel and spark..??????

[Tjn182]

Yeah - the 745i ecu only causes troubles...

I'm running 10psi flat right now, but my wastegate has begun to wear a little. I tapped the top chamber, sealed it off, and now I blow boost into there -- it keeps my boost right at 10psi. I'm pretty sure I can bump it to whatever I want... but I'd rather have a more "mechanical" way of adjusting it.

[russc]

what about the ecu out of an 86 535i 3.4l manual car? I have heard its around 10 psi but you can do more with an fmu and a chip that retards timing without getting a full standalone system for fuel and spark..??????

Look at my website, the 059 DME is scalable to 1000hp. But it doesn't monitor boost like the m106 system.

RussC

[Monotalonawd]

I haven't seen a 745i wastegate but if it's activated via a pressure hose, you can use an "adjustable check valve" as a cheap manual boost controller. I used it with great success on my turbo dsm!

http://www.gusmahon.org/html/boostcontrol.htm

Take a moment to visit the site; it's about the old turbo Mopars!

[Tjn182]

I haven't seen a 745i wastegate but if it's activated via a pressure hose, you can use an "adjustable check valve" as a cheap manual boost controller. I used it with great success on my turbo dsm!

http://www.gusmahon.org/html/boostcontrol.htm

Take a moment to visit the site; it's about the old turbo Mopars!

The 745i wastegate acts quite different from other wastegates...

@ 10 psi it will open and no boost controller will change that.

[russc]

More than some might know, its a pulsed design, the valve is pulsed a 10 or 12hz which sets up resonace in the exhaust system to enhance flow, and made more low end torque. In much the same way N/A cars tune intakes and exhausts.

RussC

[jimbixjr]

RussC, what is your website address?

[russc]

I just updated my profile again. It seems it keeps getting lost!

My page is in the profile now.

I really need to make some updates, especially to the tuning pages.

RussC

[papajetta]

i have a stock 745 wastegate plus a " home depot" boost control, i've run anywhere from 8 psi to 15 psi,
every turn past 8psi is 2 more psi
totally shut is 15+ psi

[jimbixjr]

Do you have any pics of your setup?

[jimbixjr]

I wouldnt mind running my setup at around 15-17 psi.