Question for those with superchargers

[halistan]

Got the SVX just before Christmas and I'm still using the 9psi pulley. Everything seems to be running well (albeit the engine seems unusually loud when i'm inside the car but that's another story) but I've got a few questions about tuning.

I'm using the ECUTune Stage III and it does run well but everyone keeps telling me I need to get a wide band sensor or i'm going to burn it up yada, yada, yada.

First of all, i'm not sure what I would burn up if the car is running too lean and I can't seem to find any posts that talk about that.

Can anyone give me some insight as to what that does and how to tell if the car is running lean? I know this can't really be 'tuned' until I get a Hydra or something but I wanted to know if there are some things I could do to make it run a little better while I save up money to do that down the road.

My other question comes from the fuel pressure regulator that was installed with this kit. Apparently the gauge on it is broken and when AWD Tuning checked it, it was set at 80psi. Now, when it was set that high it ran FANTASTIC. I mean, it really had some get up and go and I liked it.

When Collin was fixing the car though after my little fire mis-hap, he said that was way too high and would damage my fuel pump and set it back down to 40psi. That's fine and all and I'm glad he did but it does seem to have less power now.

That being said, does anyone know what the fuel pressure should be set at for these things? Is 80 going to screw something up? I have the 12psi pulley but haven't put it on yet because I want to make sure its in stable condition before I ask AWD Tuning to put it on.

Any thoughts? Please edu-ma-cate me

[Conn SVX]

Mine is 35 lb.

[Tapani]

Originally Posted by halistan

i'm not sure what I would burn up if the car is running too lean and I can't seem to find any posts that talk about that.

http://en.wikipedia.org/wiki/Engine_knocking

The air to fuel ratio is enrichened to cool down the compression and combustion peak temperatures - mainly as a means to control "knock".

Knock in any otto engine is detrimental, but especially so in a force fed one.

End result may be melted / holed pistons, fractured rings and the shock loads may even cause big end bearing failure - i.e. total engine failure.

Easiest way to detect a lean condition is to install the said wide band oxygen sensor and gauge. With this you will real world quantitative data of your AFR.

Spark plug color is not very handy - you have to do long WOT runs,shut the engine immediately, remove plugs and analyze. Not very easy - especially with a boxer engine.

If you have a diagnostics/analyzing interface and software you may be able to make educated guesses from the fuel trim parameters in the ECU, but this is not easy and requires more experience than I have.

A permanently installed wide band is a cheap answer and you can use it to monitor the fuelling and other issues in real time.Very handy, highly recommended.

You may want to widen your search outside the forum postings.

/T

PS Since the photo was taken I have replacedthe boost gauge with a tranny temp gauge. The wide band is still very much in use.

[fasteract7]

As already mentioned a lean AFR with forced induction increases thermal stress, knock, et. al. 11.0-11.5 range is usually considered safe in a setting of not too aggressive timing..certainly many turbo tuners are happy in the high 10's at load/WOT.

As far as the fuel pressure, what injectors are you running, have they been flow tested? You will get more fuel per spray with a higher pressure load but an intact O2 sensor feedback system will tend to mitigate things back to the base map settings. Maybe your ECU map is happier with the richer numbers and not tending to lean out (shorten injector duration) like a stock ECU.

A wideband setup would certainly clarify things...they have dual sensor setups with a switch so you can read both banks, of course, more costly. You can go the more labor intensive route and switch the O2 sensor manually to the lt/rt. OEM sites and take readings or assume both sides are near identical and only read one bank.

[Tapani]

Originally Posted by fasteract7

.....OEM sites and take readings or assume both sides are near identical and only read one bank.

Just to clarify: Ít is better to leave the stock O2 sensors in place and drill +weld extra bung(s) for the wide band sensors upstream from the cats. The bungs are only a few dollars each.

If you take the stock sensors out the fuelling will not be correct because the ECU relies on the closed loop info.

For a ton of force fed (and other) Subaru chatter see here: http://forums.nasioc.com/forums/index.php

/T

[svxfiles]

You can now get a decent wideband single side for $200.00, maybe less.
What fuel pump are you running, stock or a Walbro 225?
With those giant injectors you should have a 225 to supply them.
And for tuning peace of mind, a wideband.
I do agree with all of the above statements.

[halistan]

Thanks for the info everyone The fuel info was very insightful. I haven't had any knocking since I got all the vacuum leaks fixed. Since then its been pretty stable to be honest. Again, its a little louder than I expect when sitting in the car but i'm not sure how much noise I should expect now that it has a supercharger.

I decided to look for a dual sensor but they run $500-$800 so that's not doable but the single one might be within budget.

I am running the stock fuel pump. How much is the 225? Are they hard to install? I've always heard the fuel pumps are a little hard to install on these cars.

[cozykat]

You would be okay with a single wideband. You will want to install the sensor, based on fuel delivery, to the hotter/leaner side. I think the fuel delivery in the SVX runs in serial from driver side to the passenger side (cylinders 6, 4, 2, 1, 3, 5), so you'd want to install the sensor on the passenger's side as it will run hotter.
Running a sensor on each bank would be ideal (one in front of each cat as you want the sensor as close to the engine as possible but you can't be too close to the engine because it's too hot). To help with cost, you could simply buy two single kits. Here are some commonly used ones:
AEM UEGO Wideband
Innovate Wideband

The AEM has the controller built in to the gauge which is convenient but means you have to have the gauge to read the sensor. The Innovate has the controller separate so you can choose whether to have the gauge installed and still read the sensor using a computer.

I have not installed my walbro yet and have been told it's not hard to install, just a pain to get to.

Tom has posted some photos but I don't think there is an official write up anywhere. (and Walbro kit here)

[svxfiles]

I like my Innovate Wideband but once I got dialed in it had server its purpose and its currently out of The Claret.

The Walbro's should be about $100.00 on E-Bay.
They are not hard to install but it is a dangerous job!
I did have a really good wright-up years ago, (more than seven) but the important stuff was
1) OPEN ALL THE WINDOWS AND SUNROOF!
2) DISCONNECT THE BATTERY!
3) BE FAR AWAY FROM FIRE FLAMES OR SMOKERS!
4) TAKE YOUR TIME.
5) Since gasoline now has ethenol in it when you make your connectione THAT WILL BE SUBMERGED IN GASOLINE, cover the wires and connections with alcohol/gasoline rated hoses so that they can not short out and go BOOM!
It is a good idea to stagger the connections so that they can not posssible bump into each other, even if the hose degrades.

[svxfiles]

Just for your information;
Fuel Flow After Pressure Change Worksheet

Old Pressure:43.5 PSI
New Pressure:80.0 PSI
Old Flow Rate:550 cc/min
New Flow Rates:745 cc/min
The RC Fuel Injection home page site;
http://www.rceng.com/technical.aspx


There is no way your engine will need that much fuel and its harder on the fuel system.
This is a great site for basic information.

[cozykat]

Originally Posted by svxfiles

Just for your information;
Fuel Flow After Pressure Change Worksheet

Old Pressure:43.5 PSI
New Pressure:80.0 PSI
Old Flow Rate:550 cc/min
New Flow Rates:745 cc/min
The RC Fuel Injection home page site;
http://www.rceng.com/technical.aspx


There is no way your engine will need that much fuel and its harder on the fuel system.
This is a great site for basic information.

^ nice website

[svxfiles]

They do have some cool formulas.

[cozykat]

Concerning fuel flow, if you feel like checking the manual, you might lose your mind a little:
The 92 manual shows the fuel flow going from cylinders 2, 4, 6, 5, 3, 1 but later in the same manual it also shows that the delivery line feeds right into cylinder 6 first. lol

Not sure if a newer manual corrected this discrepancy - or I may be missing something.

[svxfiles]

6-4-2-1-3-5-

[Tapani]

Originally Posted by halistan

My other question comes from the fuel pressure regulator that was installed with this kit. Apparently the gauge on it is broken and when AWD Tuning checked it, it was set at 80psi. Now, when it was set that high it ran FANTASTIC. I mean, it really had some get up and go and I liked it.

This was THE concern for me.

If you feel performance loss that great with your butt dyno there's a chance something is not right. Could be caused by a lean condition itself, but it can, in addition, be due to the knock protection pulling your timing back.

It's time for the wide band installation - and the high flow pump. And fixing the broken fuel pressure gauge (and making sure the FPR works as it should).

Others are more educated on this than me..... But.... When you have fixed all this and have some piece of mind your fuel supply can cope with the engine requirements you may still want to think twice before intalling the "12 PSI" pulley. I trust it's been discussed in the past that 9 PSI is pretty much the max boost level "safe" for a stock engine (piston strength, compression ratio). Especially a high (?) mileage used one.

The EG33 is a tough engine, but like all others it needs to be operated within its limits.

Mine has been blown for 15 years @ 4-5 PSI.... over 100.000 miles. A year ago when I had the engine apart (for HG problems) the only parts clearly worn were the big end shells. Even the ring gaps were still within factory specs and main bearings showed absolutely no wear. Cylinder #6 was oval quite a bit, but not due to wear. The slap from the #6 piston skirt is clearly audible at cold starts, but fades after a few minutes - so I figured a rebore would be an overkill at the time. If I ever plan to increase the performance level I will need to rebore the block and use forged pistons with a lower compression ratio. For now - an old mans summer time daily driver - the midrange is quite satisfying.

Proceed with care and enjoy the ride !

Kind regards from Finland,

/Tapani