924Board.org

[-nick]

Hey folks,
An interesting result has come out of my ball bearing & socket boost controller (aka Reliaboost / Grainger valve). At WOT and full boost I can see variations up to 2.3psi in the MAP signal. All signs point to the on/off nature of the grainger valve as being the culprit.

So I'm thinking about alternative controllers to keep the boost more constant. Who is familiar with the electronic controllers out there?

Do they control the amount of air the wastegate sees by opening / closing an orifice gradually? This would obviously help keep the boost constant.

What about all these "learning" features / etc.? What exactly do they do?? I could care less about traction control junk (that's what the accelerator pedal is for...), I just want as much boost as I can get as soon as possible and with a constant & consistent peak.

Would an electronic controller be able to keep the pressure signal off the wastegate completely until the boost setting is reached (to avoid wastegate creep)?

Any info is appreciated!
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[Min]

If you do some looking into this subject on the megasquirt forums you'll find your megasquirt can control this sort of thing for you. May require a bit of work to get it working though. If you look at the current implimentation of ebc that extra has you can get an idea of whats availible.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[bass gt]

Nick,

I tried a GReddy Prospec boost contrller on mine. Verdict? Bloody useless!!! I think these systems are made primarily for integral wastegates, which operate on a very small volume of gas to function. I found that the valve as supplied with the GReddy unit, although a big one, just didn't seem man enough to reliably control the pressure. If you look inside our WG's, there is a large vlume differential between the open and closed positions. These valves just don't seem right in my opinion. The destruction manual that comes with it says it works with a standalone WG, but if you look at a common model, such as the Tial, the volume is much smaller than ours, hence better response.
I tried the same setup, in so far as send air to the top of the WG to eliminate creep, and then blow the vent at a set level. I found it just didn't have a suitable response and ability to vent the quantity of air required to prevent overboost. Put it another way, during trials, mine overbosted to 39psi and blew the head gasket, pressuried the cooling system and exploded the electric water pump. I wont go back.
In my opinion, the best way to go is to fit a choice of springs such as 1 or 1.1 bar into the WG and go from there. I've tried a 1.1 bar in mine a couple of weeks a go and it made a steady 15.6psi, no spikes, no issues.
Just my 10pence worth of course.

Steve

[Min]

Here is a link to a boost controller install using the msI etra code. This functionality will be in the MSII/extra code as well I suspect.

http://forums.turbobricks.com/showthread.php?t=80599&highlight=extra+boost
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[flosho]

Nick, just curious if you can see these fluctuations on the boost gauge itself? I have the simple ball bearing MBC and from 3-6k RPM the boost is constant; no spikes or dips or anything.

The electronic boost controllers usually use a solenoid to send a signal to the wastegate, but more often these wastegates are INTERNAL.. Like my roommates SRT-4 and my other roommates Eclipse GSX. Both of these guys see their boost spike say 17 or 18 psi and then fall off towards redline to ~15psi.

Alot of the electronic ones, will limit boost in first gear to allow for traction(instead of flipping a switch with dual stage manual boost controllers) and do other nifty things that really are neat, but not really needed. I would maybe look at a decent namebrand mbc and see if it still flucuates.
_________________
[This Space For Rent]

[-nick]

Thanks Min, I forgot about the MS talk on these. I'll look into it some more.

Flosho - I'm not really watching the gauges, so I'm not sure if you can see the fluctuation there or not. This comes from datalogs of the MAP signal. My Grainger valve was from Boost Engineering and uses the ceramic/lightweight ball bearing / etc. Not a Home Depot piece. I don't get any spikes, just the fluctuations. A bleeder style controller shouldn't do this, it's just because the ball & seat valves are really just on/off.

Maybe a simple combo of the Grainger (to keep the signal away from the wastegate until the last minute) and a bleeder valve (to keep the max boost steady) would be the ticket. I could set the Grainger to 1-2 psi below max boost to avoid most of the wastegate creep when the bleeder valve would take over.

Or just plumb through the MS & a solenoid, although I'm not sure if there is any real benefit there as long as the boost is constant and comes on as quickly as allowable.

Bass - thanks for the info on the fancy EBC piece. You would think that they would do a better job for the $600 pricetag!
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[Min]

and if what megasquirt can do doesn't interest you, you can always go this route.

part 1 http://www.autospeed.com/cms/A_2541/article.html
part 2 http://autospeed.drive.com.au/cms/A_2542/article.html

Just means you gotta solder together another board. From my view the megasquirt will provide similiar functionality.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[WEASEL149]

I fitted a Blitz dual solenoid EBC (Spec R) to my S1 931 and it works like a dream.

Initially I had problems plumbing it in correctly as I had imported it from Hong Kong to save some cash and instructions were in chinese hehe.

There's a switch on the control unit that sets it to external wastegate operation. All you have to do then is leave your wastegate control line plumbed in as normal but take another line from the charge tube to the valve controller, then take one from the valve controller to the top of the wastegate (I used another spare wastegate control line that I had for this).

Plumbed in like this means that if the valve controller stops working you revert back to standard boost.

Only problem I had with overboosting was when the controller had a 'scramble' boost set (basically an overtaking setting controlled by vacuum). Make sure there's no scramble boost set and there are no problems. Set the controller conservatively, then gradually increase settings.

I have 4 different boost levels set that I can select from the dashboard and the digital boost readout is useful too.
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1979 UK 932

[jamie924]

this might help keep an eye on your boost levels have a circuit for a basic electronic boost controller circuit but i cant work out how to post the pic let me know if you would like the file

http://homepage.ntlworld.com/dgace/diy_boost_gauge.htm[/img]

[JSMotors]

There is an article on this in the Janaury 2005 issue of sport compact car. Some electronic controllers, such as the early Greddy, are no better than the ball bearing controllers, but some are almost dead nuts on and even improve boost response(minimally- .1 of a second) by keeping the solenoid shut completely while building boost and anticipating full boost situations so that it can open the wastegate just before full boost and thus never spike over. The newest Blitz and the Apex'i can be programmed for different boost at different rpm, gauge modes, data logging and playback.

Here is a review of a few controllers SCC tested. The Apex'i goes for $375 on ebay, $400-450 or so in the DSM community. Check DSMTuners.com and DSMTrader.com

http://www.sportcompactcarweb.com/tech/0207scc_boost_control/

Not mentioned in the online article is the Power Enterprise boost controller/gauge. There are comparison graphs in the Jan. '05 issue and they show it working really well. No spikes and that minimal decrease in lag.

[bass gt]

Nick,

I am looking into exactly the same thing. Car was on the dyno the other night. 230BHP at 13 psi.
Now how about something a little out of the box. All the controllers people talk about on here are either the grainger valve type, or a rice electronic controller.
Just as a discussion point, how about this. Rather than try to limit/bleed the air pressure feeding the W/G, why not uprate the internals of the W/G? i don't mean buy a 1.1 spring ect. Why not use the M12 port at the top, and fit a thraded rod down into the W?G, and place a plate on top of the spring. Now , by winding the rod down, you are increasing the preload on the spring, effectively increasing the W/G threshold. Obviously, an additional vent port would need to be made in the top of the W/G, but why would this not work? You could even possibly mate the rod to a flexidrive, and route the controller into the cabin.
Thought please gents,

Steve

[Raceboy]

I have this mod done on my 931 WG. Wrenching the boost up with 19mm "special tool"
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[bass gt]

Raceboy,

So how did it work?? Did you find the boost more stable? For my money, this seems the most obvious, simple and effective method. Unless I'm missing something????

[Paul]

It reduces the amount that the valve can open.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[bass gt]