924Board.org

[Zuffen]

Here is a topic which for the turbo guys will get the most gains.

IS it better to raise boost by spring, compression, or wastegate controller or a combination.

Discuss....

Innovate if your looking at controllers. Think what is the best way, besides the regulator type (my opinion not effective) is there a better "race" engineering method.
_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[81turbo]

I vote for the Boost controller. I like the adjustability. I eventually plan to track my car and on cold days at sea level I would like the ability to raise it up a little. Plus I would probably use a little more boost for the track than I would for the street. I wouldn't care about the pistons since the turbo lag doesn't bother me that much, as far as the spring, I really wouldn't want to run 1 bar all the time. On a hot day I would be scared.

[Zuffen]

what kind of boost controller
_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[jazz guy]

I agree with 81turbo and vote for the wastegate controller. The flexibility to raise and lower boost comes in handy. I can run 12lbs. boost easily and almost always 14lbs. (depends on air temp.) when I want up it. I have been able run higher boosts but that involves octane boosters or special brews like toulene. I think toulene is a separate issue here. I am under the impression that it allows you to run higher boost but doesn't necessarily make more boost in and of itself. I also want the "Big Bang" to continue to be a theory, so I keep my boost levels under control.

Bob, I am curious as to why you don't feel that the "regulator" version is the way to go? Have you had a bad experience using one? I would also like to find out if there are better alternatives.

Right now I do use a pressure regulator system plumbed between the turbo intake tube and the top of the wastegate. I have run it for years with no problems. It is easy to adjust, holds boost levels steady, and is very cost effective even adding in the cost of a good boost guage.

I'm always open to new ideas though, maybe there is a better way to do it?

-Brian

[924RACR]

I'm for a wastegate controller, due to more advanced/intelligent control algorithms available. Go figure - I make my living working on computer controls for cars.

OTOH, I like the failure mode associated with John Heaney's boost regulator. Then again, it still doesn't get around the response curve of the old wastegate, while a controller does.

No idea which one to go with, though - haven't bothered researching them yet... still trying to get the cars running properly!
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[81turbo]

I am using a boost controller that I purchased from Huntley Racing. Turbonetics, I believe. It is a manual style controller plumbed on the wastegate return line right on the pressure pipe. I just purchased some brass fittings and ran flexible boost lines to the controller mounted to the firewall. This way I can remove the entire assembly for smog testing. It works great. I recently took it off top get the car ready for smog and I REALLY miss it. I have been running about 10.5 to 11psi (no intercooler. . . yet). I have been hesitant to try more until I get my air/fuel gauge set up. I am sure that the car could easily run more but it is very fun where it is. Although, my car may have a spring or shim in the wastegate since without the controller it runs about 8 -8.5psi. The extra 2psi really makes a big difference. .

[Zuffen]

correct me if I'm wrong

but with a regulator style your just delaying the signal, at some point the signal will level out and not really be a long term boost. So for a variable amount of time depending on conditions you will have an overboost condition, which may be long enough for street peak applications.

The factory used a regulator for the GTS and 935. But they also ran higher rated springs in the wastegate. So your looking at .78 and 1 bar from the wastegate and then a peak and delay with the regulator.

A controller on the inline side does the same thing by holding the signal until it reaches a preset spring load at which time the signal then hits the wastegate. Your getting your set boost level without signal bleed until it hits the limit.

That is more effective but not easily adjustable on the fly as the regulator style. There is one controller from Australia that has a turnable knob, with each rotation being 1 psi.

I want a 5 to 6 preset controller with no bleed and a knock sensor/safety back up set to retard the timing as well as enrich the mix to help cool off the chambers. At least that is what I'm thinking at the moment. Killing the fuel pump is too harsh on the motor, but you don't want it to lean out by restricting fuel. And you sure don't want to kill the spark on a CIS car, imagine all the fuel. What would be cool is to maybe alternate the spark and let the cylinders richin out to help cool. But then what if you have a hot spot and you dump extra fuel will it detonate worse or squash out the fire.

Just thinking outloud
_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[Lizard]

I am suprised that raising the CR wasn't that popular as raising the CR would boost power even when the turbo hadn't kicked in, although I guess it is abit more risky of blowing a head gasket
_________________
3 928s,

[81turbo]

[dwak]

Why doesn't some bright spark do a 'boost controller kit' article for the tech section like was done for the 'Hot start problem fix'.
With photos.
Especially since I'm ready to do a controller.

dwak

[Peter_in_AU]

if you're looking at a boost controller, head over to autospeed.com and do a search on "controller" they have lots of info and DIY controllers.

Here's a cheap commercial controller from the site http://www.autospeed.com/A_1465/page1.html
_________________
1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you

[jazz guy]

After reading some earlier posts I have determined that I am running a setup like John H. described to Vaughn. It is a very simple operation to install because it doesn't require any mods to the wastegate plumbing.

Here is what I did. I've had the controller on for years, so I'm doing this from memory:

Remove the sound baffle/breather fitting on the top of the wastegate and insert a nipple/hose barb fitting in its' place.

Run a small diameter hose from the nipple through firewall into the cabin.

In the cabin you plumb the hose through an adjustable air regulator mounted within easy reach of the driver. Mine is located just below the dash between the steering column and the center console.

(I used a Craftsman reg. that I got Sears. It was made for one of their small air compressors. Small hose barb fittings worked great for running the hose in and out of the reg. It may vary with the brand of regulator used.)

Next remove the upper intake tube (the one that says 924 turbo on it), tap a hose barb fitting into it, and run the hose from the regulator back thru the firewall and onto the intake fitting.

I ran a tee off the hose between the requlator and the intake tube to go to my boost guage.

Button up the intake tube and your back in business.

I have used this setup for a long time with no problems. It's cockpit adjustable. Easy to use. And boost holds very steady from initial full boost all the way to redline.

The downside is that unlike some of the newer boost controllers, this setup can't be tuned for different boost patterns. Some other controllers allow you to program in more boost at different rpm ranges. A cool feature.

[Zuffen]

So it seems most 931 guys running a controller are running off the vent side of the wastegate.

So full signal is making it to the wastegate and the delay is on the other side to atmospheric vent.

Jazzguy

But by rerouting the return line to the manifold your actually doing what?

Are you pressurizing both sides so at some point your killing the signal to the wastegate and running without the wastegate?
_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[jazz guy]

Zuffen,

It has been a very long time since I tackled this job. When I did, it was with a close friend who owned the twin to my silver w/ black leather interior 931. His had the m471 package, mine didn't originally so I upgraded mine to it. Together we worked on our cars and driving skills a lot.

Thinking back on it, it is my understanding that system I used doesn't delay the boost signal to the wastegate. Instead, it pressurizes the back side,holding the wastegate closed longer to build more boost. It is in effect, acting like a stiffer wastegate spring, only it can be adjusted stronger, more boost, or weaker, for less boost.

One additional benefit is that if my system fails, for example if one of the fittings leaks or a hose gets nicked, it will revert to stock boost because none of the wastegate component's functions are physically altered by the addition of the system.

Brian

[wdb]

whats the benefit of using a 2 stage boost controller , as seen here .
http://pages.cthome.net/gus/mike.html

for more mods see links at bottom of this page
http://home.earthlink.net/~turbogus/index-old.html

after reading more, the benefit is : That way I could leave the line on 5 lbs. without spinning the tires, then flip the switch up to 13 lbs. while under way. This produced a 2.38 launch, & a quarter of 15.766 @ 85.86 mph.. A little practice with the HI-LO switch= 2.28 60', and 15.558 qtr mi