924Board.org

[bureau13]

When I have the wastegate off for repairs, I'm going to run a line to the top port for eventual boost controller purposes. Is there any issue with running a stock spring and (eventually maybe some day) running higher boost e.g. 1 bar perhaps?* I was reading somewhere and they were saying you should choose a spring that gives a boost pressure close to what you want to achieve. Well, right now I think I should achieve stock levels, or thereabouts, but eventually with some other mods I'd like to get up to a bar or so. Should I get a spring so it's at stock Euro levels (10 psi) instead? Or am I OK keeping it about 6psi and then turning it up later, with appropriate additional mods?

I am trying to avoid having to take the wastegate off twice.
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1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)

[chuck21401]

Are you going to replace the valve guide on the WG? Any interest in arbors I used to push out out the old valve and push in the new one? I'll mail them to you if they would help.



I don't know if there was anything even wrong with my valve guide (or the fat gasket between the hot/cold site), but there seemed to be some play...and that was tightened up with the new guide. In any case the WG works as it should now. Anyway, send me a PM if you are interested.

re: boost controller.

I am running a manual boost controller on my car now, but I did not run the second line to the top of the wastegate.

I bought a Turbonetics MBC and installed it temporarily in the engine compartment. I didn't want to modify the control line so I bought metric adapters to connect to the pressure pipe and the stock control line.



Couple of observations. The inner diameter of the hose that came with the MBC was too small. I bought different hose. The barb fittings (bellow) were also too restrictive. Just something to think about when you get around to installing the MBC. I understand why folks run the dual port WG but haven't noticed any issues with the way I have it set up.



Here is how it is set up now. I'll have to rethink it where to mount it when the intercooler arrives. I suppose I can mount it in the car, but I'd like to have it out of sight, maybe in the glove box?



With the way I have it set up, turning the dial to the (+) setting actually decreases boost...so dialing (-) increases boost since air to the WG is being restricted.

I've found that that this MBC is very sensitive. A 1/4 turn is the difference between 7psi and 10psi. Crank it too far and you are 15psi ++. Right now I'm running 10psi. With the intercooler I think I'll start at 12psi and see how it goes.

Re: WG spring or MBC

From what I've read, adjusting boost via MBC gives you the most flexbility. If you get a 10psi spring you'll will not be able to go lower than that without changing the spring obviously. On a really hot day you might want to dial it back. Also I'm not sure how easy it would be to source such a spring from what I've read in different forums.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler

[Cedric]

Put a hose to the top port, it's very simple and it works brilliantly. I skipped the bling boost controllers and bought a high precision pressure regulator from a pneumatic store designed for lower pressure levels, super quality and well priced. It works perfectly, boost is flat up to redline with good controllability. Good luck
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1980 924 Turbo
www.instagram.com/garagecedric/

[bureau13]

I am actually going to probably go with a Tial. By the time you add up the diaphragm and any of the rebuild kits that deal with the valve guide, etc the Tial is not that much more. However, I do plan to go over the one I remove carefully, so it's possible I will decide to stick with the stock one. In that case, I will check back with you on this. Thank you for the offer!

[bureau13]

Yes, that's what I'm leaning towards. Ideally, I would be able to have it adjustable between stock (i.e. stock spring pressure) and up to 1 bar to be future proof, but I just wasn't sure if having a spring pressure so far below that higher boost pressure was an issue.