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Boost controlers.


rallyruss
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OK so I hope this is the proper location for this thread. now that I am running the TD04 and the boost is actually controlable(no more overboost) I am curious as to what types of boost control methods people are using and what you think about it.

as of now I am at stock levels and rather happy. but there is always that little bit more.

 

I have seen the little manual boost controlers and they kind of scare me. I do have a boost gauge with an audible warning but I would really like a nice electronic boost control device that taps into the knock sensor and o2 signals. Then if you were to run lean and/or detonate it can back off the boost according to the signals recieved. not to mention that the wase gate cracking open before its needed would be eliminated.

 

I hear you all talking about 12lbs 10lbs 14lbs. how? whatever you run how do you manage it? is your motor stock? intercooled?(what type) compression? water injected?

yeah thats a bit more than just boost controlers but I think that the boost level that can be safely run is related to those other mods also.

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My one turbo ru, not the one in the sig, has a small strong spring. The wastegate actuator still deals with spikes well and I boost about 12-14psi. The spring connects to the actuator arm and the oil feed line, this method is referred to as "shadetree" but works great. I think it actually works as good as my manual boost controller on the wagon in the sig, I'd like to have a remotely adjustable one so I can turn it down going up really long mountain passes fully loaded but that's some $$$. The features you mentioned ie knock sensor and timing etc would be the schiznit but I feel that I can do without, I keep spare motors ready to dropped in not that i've needed to yet.:brow:

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I've got the GReddy PRofect B-SPec II and I love it! I run ~14 PSI on the high side, and stock on Lo.

 

The RX is now IC'ed with a WRX unit...and I also have the TWE pipes. ECU and junk is stock otherwise.

 

My only problems is the REAL fuel cut, and the gremlin fuel cut that i have issues with.

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Oddcomp runs a SAAB APC unit that controls limits max boost based on knock sensor input. Cheap JY parts. IIRC, the main drawback is that it allows boost as high as turbo will go, but its boost floor is set by whatever the stock wastegate is setup for. (I.E. - it won't go below stock boost limit.) The SAABs were set for something like 4psi base boost.

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Is that what a plug and play unit goes for?

 

Its as close to buy it and plug&play as you are going to get...the price is an estimated budget that I would allow myself to do a complete MS+DIS conversion....but I think I would get all new DIS stuff, so that figure might be $600 for me... :-\

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This got me to think'n. My brother had an 87 turbo wagon, but had to junk it, I took some parts off of it. One of the parts was the boost control silinoid....

 

Here is what I am planning.

 

I have rigged up the silinod to work as so:

Silinoid on = normal wastegate function so like ~ 6 psi

Silinoid off = waste gate to const. vaccum pre-turbo intake = gives max boost

 

Now is where it gets interesting, using the overboost switch on my 86 twagon or any ajustable pressure switch I guess "hobbs" has a nice selection I will control ground the silinoid.

 

I think overboost is like 9psi so

P>9psi switch completes circuit silinoid on = takes boost down

P<9psi switch opens circuit silinoid off = takes boost up

 

Incorporate this with the gear shifter switch (james bond button) and I will be about to pick my boost.

 

I guess that kinda sounds like what oddcomps setup is with the SAAB APC.

 

Feed back always welcome.

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  • 2 weeks later...

ok so junk yard hunting today. pulled a bunch of parts. now im broke.

 

found an 88 saab900 turbo. could not rember what parts were needed exactly so I just pulled what I did rember. got almost everything. now I need to figure out how to wire it. I did not pull the harness as that looked like a pain in the rear I just loped off connectors.

 

I am missing the pressure transducer and did not get the knock sensor as I hoped to use the stock one.

 

so I did some reading up on the APC units and am curious if any one here has a fully functional set up?

 

I know a few of you had talked about it. the volvo 240 guys seem to be all about it.

 

boost control here I come:brow:

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what saab has a apc boost controller??

gosh i never knew..

ahem cough cough

wait.. is tha the black box i have in mine tat says says saab on it?

:brow:

btw it will pretty much be useless with out the transducer that is located under the dash of the car its a small silver canhas 2 spade terminal on it

one is smaller than the other

and sadly you cannot use teh suby knock sensor as far as i know

the saab sensor is onthe back side of the motor on a 9000 turbo under the intake and on a 900 its same plae but withthe motor not sideways just look under the intake

 

i assume you got the boost solenoid also right? small brownish thing 3 vacum lines 2 wire connector? on he 9000 its screwed to teh radiator support

on teh 900 not sure but i imagine it will be near the turbo

 

btw maserati had a simular setup for the bi-turbo motor they have

 

also you do not nee the knock sensor for the unit to function

you just lose the knock sensing boost reduction is all

also i think its wire 11 .. i will have to look again but there is a terminal that if you do have the knock sensor you can wire that terminal to a small light or whatever that will light up if you get knocking or detonation

 

oh also...the saab knock sensor is just a bolt on thing i have mine bolted onto one of the heads using a unused bolt hole

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more things i forgot

stock saab apc setting will result in a max boost of 10-10.5 psi

 

also the saab wastegate opens at 5 psi and can be adapted to put on the suby turbo reason you would want to do this

is since the suby wastegate opens at 8 or something psi

well.. when teh apc is activ and it reduces teh boost incase of detonation or something like that

then you will only drop to what ever the stock suby wastegate will open so with it working at like 8 psi by itself..

thats not alot of change

 

and just cause the saab wastegate opens at 5 psi does not mean that the wastegate will creep open from exhast pressure it has a rather large cana nd spring on it to prevent that

 

blah blah blah yadda yadda

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cool good stuff. I have not completely finished reading up on it yet but I get what your saying for the most part.

 

still a couple of confusions.

 

first why do you think the stock knock sensor will not work? all knock sensors generate the same type type of signal. they work like an O2 sensor sort of. they generate a signal with out needing any kind of voltage supply to it. The signal is rather weak though so it requires shielding roung the wire to prevent flse signals.

now I can see that if I were to use the stock one for both the stock purpous and the aditional output to the APC unit then mayby it would pull down the signal too low for it to be read properly. hmm could be wrong but just throwing out a an idea.

 

ok so no I did not grab the pressure transducer if its under the dash. I did get the little three way switching valve.

 

guess I need to go back and pull some more pieces. the volvo site recomends the whole harness:-\ . too much work for me. I would rather cut and splice.

 

it would be sweet if we could make a page documenting install on a subaru like the volvo guys have.

it seems like its a simple thing that is made to sound complicated.

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well i did it.. so it is simple

who wants to translate my insructions to legible reading?

i reall have no idea if it would or would not work witht he stock one

but i am fairly certain well sorta that they are "tuned " abit diffrent from maker to maker but its just a guess

 

and then yeah you lose the ignition retarding as i don't think they would share well

 

and besides teh saab unit just bolts onto a handy spot on like say a cylinder head or teh main block

 

btw early night off so you know where to find me

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