Just wondering if there's any risk in using gas with ethanol in the HT4100. Right now, MN mandates 10% ethanol, some legislators want to raise it to 20% (stupid politics). Is this amount of ethanol in our gas a risk to the HT4100?

i would say it is indeed a risk going over 20%

also i belive someone here said not only will the computer be unable to compensate but the risk of damaging the rubber compnets in the fuel system is also great ...

So what can I do if it ends up in all our gas?

that im not sure of to be honest ....hopefully someone can tell us more ...

Funny you should mention this topic....

I have been discussing this at length with a friend of mine (hot rodder, mech engineer who has converted 3 cars to ethanol)

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More conversation below in red - I worked on 3 gas to ethanol conversions from 1998-2000 so when you get serious, let me know and I'll tell you what worked and what didn't in real world application over lunch or something.

-----Original Message-----
Subject: RE: E85 Conversion?

Good thoughts to ponder.

E85 is 15% gas, 85% ethanol, so I would expect mixing ok. I have read some on distilling my own and it never mentioned it.

I forgot the regulator has a rubber diaphragm. Fuel pump shouldn't care, but the rubber line to it (all the ones I have looked at have a short rubber line) might deteriorate faster, and yes, the injectors, if they are not viton already. Any way to know? The issue on the pump (at least the one in the IIT 1998 Ethanol conversion Malibu which burnt out after 12k miles) was arcing between hot and ground tabs on the pump housing. When we pulled the dead unit there was significant carbon build up and corrosion on the tabs indicating arcing. 35% of schools saw the same problem during competition with similar or more miles. Other teams saw no problem at all but may not have pulled the tank to check. On the fuel injectors, I would guess that a call to the manufacturer or even a contact at a fuel injection specialty shop could tell you but I don't know for sure. At IIT, on both Ethanol car and truck programs we used Bosch ethanol injectors and they had all the specs for everything… We had part#'s but all we needed to tell them was engine size and year and they were all over it.

I forgot that getting too far out will just trigger a SES code, indicating that too much BLM correction is needed. I don't know the actual fail point, but I agree, the larger injectors will "fix" some of that. On the IIT Malibu conversion we did not have access to the computer (1st gen OBDII came out around 1998 so no aftermarket computer device existed and we had 6 months to do everything). We swapped the injectors and filled it up 100% E85 without issue. GM tech2 programmer showed identical O2 sensor operation. The key here is sizing the fuel injectors as closely as possible for 9.8:1 AFR and making sure the injectors operated identically to stock electrically. The O2 sensors don't care what fuel you use or what injectors you use. As long as the ratio is balanced (stoich) you can keep the same zero point when you convert. Another way to state this via chemestry is that O2 sensors measure free O2. If your AFR is stoich (for any fuel) than the O2 sensor will measure the same amount of free oxygen. If you wanted a true flex fuel car without calling GM for a duel fuel map ECU get an injector that can handle the added volume for ethanol but shoot for an AFR between E85/Gas. Then you are relying on O2 compensation but you aren't pressed to the outer edge of the table for either fuel. It could work, we were looking at something like this for our Ethanol truck at IIT but we ran out of time to implement it. I guess if I can see what I can tweak, then I would know better. I need to get LT1-Edit or the competition to it to learn more anyway.

A friend of mine knows a guy in WI who runs a 455 Pontiac with 12:1 and E85, running 9's. He runs 31 degrees timing with E85, and 30 with 110 race gas for best power, 1/4 times are nearly identical with either fuel. Not a street car though…. E85 should get give you 3-5% power increase compared to gas just due to chemical properties concerning the latent heat of vaporization. Ethanol cools significantly compared to gas during phase change from liquid to vapor thus lowering the air charge temp and increasing air density in the chamber. On the Malibu with no other mods besides conversion, we got a track tested 2 tenth quarter mile time reduction and a 2.5 MPH increase in trap speed. I am curious about the Octane numbers for E85. Pure Ethanol (E100) is 110-112 octane. E85, 85% Ethanol - 15% other (possibly gas or indolene?) is 99-100 Octane which evidently is safe on your friend's car at 12.5:1. The burn rate/pattern for E85 is better than 93 octane gas but not as good as 110 octane race fuel.

I have also read that the fuel sensor in the new FFV cars is solely to tell the ECM what timing to run, gas gets less, E85 gets more. E85 is 110 octane or so, so it can use more ignition lead. This will also help power loss of the lower BTU of E85. It is lower but not low enough to hurt you - chemical properties more than make up for it (see above). Your fuel economy will definitely suffer though. Figure on 2/3 energy economy compared to gas (due to lower AFR). Emissions output should be comparable to gas.

Might have to make a still and make some at home! Even 20 gallons a week would help the bottom line with my drive significantly! Now, you're talkin'! If you make it, I'll purchase from you!



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Subject: RE: E85 Conversion?

Relying on the O2 sensors to compensate for a non-stoich AFR is a bad idea in my opinion. In this case (gas to E85) you would use up the full tolerance of the sliding scale to compensate. Environmental changes such as temperature/pressure/humidity would push the system outside of range. Furthermore, it has been proven (and I am sure designed that way by GM for cost reasons) that O2 sensor tolerance resolution becomes increasingly unstable and inaccurate when you get above/below 14% compensation (thus the lower fuel economy and performance + other unknowns like what effect the extra richness has on cats long term).

Three parts that may need to be changed or may burnout prematurely (15-50k miles instead of 150k) are the fuel injectors fuel pump and regulator. All have rubber gaskets/o-rings/grommets that need to be changed to Viton which is not affected by E85.

Two ways to change the AFR without relying on the O2 sensors is to swap out the fuel injectors for larger capacity identical voltage/load units and do nothing else. This effectively works around the computer by making it think you are at 14.7:1 when you are really at 9.8:1. The other way (assuming your fuel injectors have the bandwidth) is to use LS1 or LT1 edit to change normal operating AFR to 9.8:1. You can do this for OBDII, don’t know if you can do it for OBDI. Since 9.8:1 is stoich for E85, Cats/O2's/etc… are operating normally and your O2 sensor zero point is preserved so you get the added benefit of tight emissions controls/response/performance.

Given points above, obviously 50/50 mix gas/E85 would give you better results if you didn't change anything. However, I am not sure whether E85 is 100% soluble in Gasoline so you should make sure of that before you do it. Lastly, the Reed Vapor Pressure of Ethanol is substantially lower than Gasoline so it won't start you car well in temps below 35 degrees F.




-----Original Message-----
Subject: RE: E85 Conversion?

If the O2 sensor measures O2 content, wouldn't it just adjust if there is enough bandwidth in the injector flow rate? What would really need to be adjusted? I can see if you need more bandwidth a set of higher flow rate injectors would do the trick.

From what I am reading a lot of people are getting good results (although lower fuel economy) just just driving with it with no mods at all. Is there much if any rubber lines left these days?

Wondering if a 50/50 mix of E85/gas would be a comprimise. I can get it in Rockford easily. Tell me, please, why on earth is E85 the same price as gas, when it is coming from corn? Sounds like a profit maker to me…..

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Subject: RE: E85 Conversion?

Really?! I just checked the station by my house and they are quoting $2.15… It's not worth my effort at that price.

You need to make sure parts that are in contact with Ethanol are compatible with it. It's a solvent so it corrodes rubber and it's conductive so you could have a problem with an in tank fuel pump burning out etc… You also need to adjust the AFR from 14.7:1 to 9.8:1. There are several ways to do this but make sure you have enough fuel injector bandwidth to cover approx. 30% more fuel all around.



-----Original Message-----
Subject: E85 Conversion?

What is needed to convert to E85?

I can get it in Rockford for $1.549!

In a nutshell, the O2 sensor reads free O2, it doens't know and doesn't care what fuel is going down the pipe. (my previous posts on here are incorrect, if I can find them I will correct)

So, given a does of ethanol E85 (85% Ethanol, 15% gas) the integrator will swing way high, the Block Learn will start going low until the Integrator gets back in the range of 128 (which is stiochiometric, not just 14.7 absolute, but where the amount of oxygen is in the range it is expecting). BLM will be way off, possibly enough to set a code, but after a lot of reading on the internet, most don't. So it tells me that BLM won't set a code, only the Integrator will. But being Integrator is back to where it should be, it is happy about it.

Now, draw backs, Ethanol eats rubber, so your fuel pump will likely live around 1/3 time. Regulator and rubber O rings on the injectors all will live less. Fuel economy is less. Typically on a Tahoe with a 5.3L V8 but not a FFV, mileage went from average 15.8 to 12.3. Owch. So it is a wash on saving $$ at the pump. Unless you make your own E85.....

Food for thought! And the gas tank!!!