lowering boost pressure to add adjst boost knob

[mickster8888]

i want to be able to control boost within the cockpit with a manual boost control to lower boost pressure.i know that they only increase pressure so i would want to have it at .5bar then use the boost control to raise it to the current delivery of the 1.0bar spring. i want to do this in case i have a driving event and its wet. would like the boost range to be between .5 and 1.0 bar. engine is 3.3 with k/27/29 turbo, rarelylate houligan exhaust, bigger intercooler, b&b headers, with cis injection(which i know is the most limiting factor). i would really like to dial things down when it gets wet cause it's a handful even when dry as the boost comes on like a freight train. the suspension is extremely stiff(23 frnt 33rear torsion bars with revalved bilsteins) which is not the best setup for wet but it is what it is. is there a .5bar spring i can put in in place of my 1.0bar spring in my stock waste gate or do i have to get a tial waste gate to bring the boost down to .5bar. any advise on matter would be greatly appreciated as usual guys. thanks in advance, mick

[RarlyL8]

I believe the 931 (924T) used the same waste gate but had a 0.4bar spring. Don't know where you would purchase one however.

[quattrorunner]

Can a spring be butched? I have one of the springs from a 3.0 turbo but am keeping mine for the same purpose.
Mine is tired and only boosts to .45bar which I like. It's shorter.
So can the springs be cut to reduce tension?

[Dr J]

Cutting a spring makes it stiffer.

[quattrorunner]

O good to know Perhaps heat one?

[16Volt]

Why wouldnt you just run a Greddy Profec-B? I had one on my previous turbo car (not a 930) and it has a programmable hi and low boost setting. You could also adjust the "hit" and it would feed boost slower.

[fredmeister]

I have made a few adjustable wastegates by modifying the OEM wastegate housings for my own vehicle and a forum member previously.

My design does not use electronic boost control but is fully mechanical with an adjustment screw on the top cover housing.

Works great for me and allows roughly .7bar to 1.1bar boost of range the way I have mine set up.

Let me know if interested.....I have been trying to drum up interest so I can have more parts machined in a batch order to a machine shop and then I can build some more.

PM me as I might be able to help you out otherwise as well.

Fred

[930/66]

Originally Posted by fredmeister

I have made a few adjustable wastegates by modifying the OEM wastegate housings for my own vehicle and a forum member previously.


Fred

I have the same solution, works well

[TurboKraft]

For lowering the base boost pressure:

Option 1: 924T spring in the stock wastegate.
Good luck finding one, nearly everything for that car is discontinued/NLA.

Option 2: install a Tial F46 wastegate.
Available with spring pressure from 0.2 - 1.4bar in 0.1bar increments, bolt on with no mods to exhaust required.

Connect your adjustable regulator and raise boost again for dry conditions.

[mickster8888]

thanks for the info guys. definately food for thought. now if i could just find a 935 stlye manuel boost controller i'll be stoked. anyone?

[TurboKraft]

Long since NLA, but we are sourcing suitable (and better) replacement control valves to assemble packages.

[mickster8888]

how long before they're available?

[TurboKraft]

Several weeks. Getting the valves in, will test thoroughly before selling to public. Going to make it in the style and spirit of the controller used in the factory Turbo racecars.

Not going to skimp and use the junk pot metal & plastic regulators as are typically used in MBC kits.

[mickster8888]

awesome. can't wait. any idea on price?

[TurboKraft]

Not at all.

[mickster8888]

can't wait till it's available. thanks for your guidance.