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Flex-fuel vehicles are approaching it wrong

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  Perhaps the trick that is needed here is a 2 stage turbo. If that's what they've done

with the Bio-Power Saab it would allow the high compression necessary to optimize

ethanol fuel, even at low rpm,  AND back off on the boost when running Unleaded 90 octane

so as to avoid knock.  That would allow 9.5:1 compression  for just loafing around town

on Unleaded, without the turbo, and still get decent mileage and low emissions.

So their effective compression ratio WITH the turbo could be maintained at about 15:1

whether low rpm or high rpm, when running E85.  That might be how they get the high

mileage AND high HP.  With all that boost going on , I wonder what the lifespan of this

engine would be?? Even with a nice soft fuel like E85, there are alot of heat cycle issues

to contend with..

 

 

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I vote that 1outlaw forgets the warranty and modifies the ECU and turbo and optimizes his Saab for E85. :);) ;D That way we can get the facts first hand. I drove my brand new VW TDI home a year ago and immediately spiked the fuel to B50 using my homemade brew---way above the approved B5. I'm hoping if the alternator tanks that it is still covered. Also, I asked Alcohol a question about three hose blenders on the other site.

Marty

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rufus- the Saab link says in the small green print under the data something to the effect of:" performance data is based on E85, mileage data is based on petrol"

 

cessna- I have a kid in college, one starting college in Jan, and one 2 years from starting--I am a poor man :'( :'(

 

Greengenes- Saab claims to have used a more durable valve and seat in these- yet from what i have found my USA version really only lacks the ECU programming and other turbo setup. BTW- my turbo does not spool up until about half throttle so it just lopes around until you need it--with the manual trans and clutch conserving driving, I would not beat anyone off of the line...even grandma ::) but it will develop some nasty torque steer as the turbo comes up if you are not anticipating it. Not sure about durability- back when Saab was pre-GM owned they made a car that was retired just last winter in running condition (in a Wisconsin museum now) with over a million miles on it-engine untouched -but of course that one was not likely on steroids ;D

 

 

 

 

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Perhaps the trick that is needed here is a 2 stage turbo.

 

What you discribe could be very easily done, as the same sort of functionality already exists in some aftermarket tuning solutions, OEM ECU's and electronic boost controls. All you have to do is change the settings on the boost controller as fuel octane changes. No highly complex dual stage turbo systems. If the ECU sees a  High indicated octane, use high gain and duty cycle on the waste gate, low octane open the waste gate sooner and limit boost to lower levels.

 

I currently do it with the twist of a dial on my electronic boost controller. It has 4 channels you can preprogram to give different boost profiles. I usually turn the boost down when just putting around town, but just a turn of the knob bumps the boost up to its highest setting.

 

OEM ECU's currently do exactly what you are discribing as a safety function called limp mode. If the ECU sees to much detonation, it will add fuel and pull timing. If it can't get detonation under control with those changes it drops to a very conservative fuel and ignition map.

 

All they would need to do is have two base maps one for straight gasoline and one for pure E85 and then have the ECU interpolate between those two maps based on its estimate of the actual fuel mix/octane.

 

Larry

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Hotrod, Is this turbo tuner the type of thing you are talking about?

It is some sort of piggy back module that is car model specific, that probably cooks the manifold absolute pressure signal the ECU sees. (real manifold pressure x, what he ECU sees x-y)

 

Here is a list of some of the common electronic boost controllers and a brief description of how they work.

 

http://www.splparts.com/doc/tech/EBC.htm

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

 

As mentioned in the page above the turbo has a spring loaded waste gate that begins to open anytime the supplied air pressure to the waste gate actuator exceeds a given pressure (typically 7-8 psi). Boost is managed by how much pressure actually gets to the actuator. If the pressure it sees is greater than the waste gate spring pressure if forces the waste gate open and bleeds exhaust gas off (sends it through a bypass passage) before it passes through the turbine.

 

On my WRX the stock setup has a reference line that runs from the intake manifold to the waste gate actuator which has a small restrictor orfice in the line. Between the turbo and that restrictor is a T that goes to an electrical boost control solenoid that bleeds off air pressure in the line. Due to the restrictor it takes a certain amount of time for the manifold pressure to build up in the waste gate actuator enough to push it open if the boost control solenoid is closed. If the boost control solenoid is open it bleeds off air pressure on the line to the waste gate actuator. Depending on how often and how long the boost control solenoid opens will determine what the actual pressure is in the  waste gate actuator and when it will open.

 

For example the intake manifold is at 15 psi, the actuator has an 8 lb spring. If the BCS (boost control solenoid) is closed the pressure in the actuator will rise in a couple seconds (due to the restrictor is does not rise immediately) to over 8 psi at that point the waste gate actuator will start to bleed off exhaust pressure so drive energy of the turbine (hot side) drops and boost drops and holds at a lower pressure than 15 psi.

 

If you start fluttering the BCS very rapidly at a 50% duty cycle it will now bleed off boost pressure, so the waste gate actuator will take longer to reach 8 psi pressure and manifold boost will continue to climb.

 

All the after market electronic boost controllers are is a more capable control solenoid ( higher opening rate and flow and faster response) and the electronics to control boost but with adjustable inputs from the driver (ie you can set things like your max boost limit and gain-[how agressive you want the boost control] in a dash mounted module).

 

Many of them have additional added features such as logging and other trick displays as well.

 

Larry

 

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rufus- the GM alt fuels people told me that the Saab 9.5 BioPower runs at about 5% added consumption.

      - I have a USA spec Saab 9.3 2T Aero that will bury the turbo needle on e20 (92 octane) but will not on E10 (89.5) octane- it does call for 90 octane so that makes sense. Compression ratio is 9.5:1. Two Saab techs have told me that all factory parts are E85 ready except that on '04's (mine) they cannot use a factory E85 tune in the ECU- i am waiting for the warranty to expire before I take this step. Of course, even after conversion it would still lack the variable pitch turbo of the Biopower model- I do not know what boost is is running now as it is only a non-calibrated guage.

 

I see a very simple solution here.  What I've gathered is your model Saab in Swedish-spec is offered with an E85 tune, and the only main difference is the calibration of the PCM (ECU), but the important fuel system components are already intact.  If I'm wrong, correct me.

 

Who's to say you couldn't find a used Sweden-spec PCM for your exact model Saab that had the E85 tune in it, and swap it out?  If it didn't work, you could simply swap back.  Here in the states, there are several used auto parts locator sites such as www.car-part.com and others.  Common sense tells me there must be something similar across the pond.

 

Only stumbling block you may run into would be a conflict of the vehicle's security system not recognising a chipped key (if your car has such a feature) and not allowing the car to start till the key was programmed into the other PCM.

 

It sounds like you have some rapport with some Saab techs...This may be a question to fire at them and get more input on it. 

 

I did something similar with my '97 Grand Prix...Rather than spend the money on a reprogrammed "performance" PCM, I tried a PCM out of a Chevy Lumina with the 9C1 Police Package.  A bit more agressive advance curve, and the paltry 108 MPH top speed limiter was removed, but it was still regular 87 octane friendly.  Since this car had no chipped key security system, the swap was incredibly simple.  The PCMs VIN didn't match the car's but it didn't seem to care.

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Minnesota has given the okay to "Blender Pumps."  This looks like a "Biggie" to me.  It seems that stations that install blender pumps sell a whole lot more ethanol than when they just sell e85, alone.

 

It, also, should serve to bring some "Blenders" in line.  If they won't pass the tax credit along, the station owner can just install a blender pump, and take the tax credit, himself.  Have I got this about right?

 

Also, was Minnesota waiting on the EPA, or is this strictly a State-specific thing that's had the blessing of the EPA all along?  Can anyone help on this?

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Guest colchiro
Minnesota has given the okay to "Blender Pumps."

 

Cool! (Now that I don't need to blend any more.)

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