can you run E-85 on the rs4?

[low_qu4ttro]

I'm sure this topic has came up a few times. but I'm a new rs4 owner. my last Audi was just an A4. so is it possible to run E-85 on the rs4 or mix fuels to get something better than E-91? in California it's not as easy to get E-95

[Peter1.8t]

For starters you'd need a different tune. E85 requires something like ~30% more fuel, and I don't think there's currently any tunes available on the market. On top of that you'd probably different fuel pumps as not all fuel pumps do well with e85.

[SkyDude]

I was talking to United Motorsports about a tune for my rs4. They were prepared to create a tune for E85 but then I'd need to always run that. The fuel system can handle it. There may be a little to gain but not much and the 250 miles I get on a tank will drop to below 200...

[forbiddenbeat]

IIRC from other cars, to switch to E85 you need to change fuel lines, injectors, fuel pumps, and also get a new tune. It's not cheap.

I believe some folks here are running meth injection, which is inferior to E85, but probably a lot simpler.

[Peter1.8t]

I was talking to United Motorsports about a tune for my rs4. They were prepared to create a tune for E85 but then I'd need to always run that. The fuel system can handle it. There may be a little to gain but not much and the 250 miles I get on a tank will drop to below 200...

I'm sure they are capable of making a tune. E85 has an octane rating between 100-110, so there probably is some benefit to running it on a higher compression motor.

[BenSti]

IIRC from other cars, to switch to E85 you need to change fuel lines, injectors, fuel pumps, and also get a new tune. It's not cheap.

I believe some folks here are running meth injection, which is inferior to E85, but probably a lot simpler.

I'm assuming this is due to E85 having a tendency to break down the rubber in fuel lines and seals?

[Seerlah]

From my understanding, e85 can be ran on any fuel or direct injected vehicles. Not sure about carburated (sp?), but google is at the tip of your fingers. With e85, no matter what vehicle this pertains to you would need to first find out what stock components are compatible and which ones aren't.

Or is that you really want to know, and worded your inquiry too vaguely?

[Quattrors4]

I'm doing a e85 flex fuel set up as we speak ,it requires a lot of upgrades

[low_qu4ttro]

well I had a buddy of mine mix fuels to make E-85 and he says it makes his 550i run better and it's a noticeable difference in power. I was just wondering if it's possible to do this with the b7 rs4. my other question is if it's possible to mix fuels to make E-95. sorry for wording it so weird.

[LINDW4LL]

On the B8 chassis, there are many people who mix in a little E85 with their 91 to allow for more timing and better knock rejection.

I'm not sure if the effect is greater on a boosted engine, but many have logged a nice increase in timing from just a couple gallons of E85 (say 3, to a full tank of 91). That's not near enough to push the fueling limits (on the B8, at least).

[forbiddenbeat]

I'm assuming this is due to E85 having a tendency to break down the rubber in fuel lines and seals?

Correct, E85 will break down certain types of rubber over time. I believe you need to run PTFE (Teflon) hoses and seals made of specific materials with E85. I'm not sure what our fuel lines are made of, but it's definitely something one would want to check. :D

Perhaps E85 injection is easier since the kit would be built for it?

Also, some interesting info here: http://injectordynamics.com/articles/e85/

Seems like a huge pain to me, to be honest.

[Quattrors4]

Correct, E85 will break down certain types of rubber over time. I believe you need to run PTFE (Teflon) hoses and seals made of specific materials with E85. I'm not sure what our fuel lines are made of, but it's definitely something one would want to check. :D

Perhaps E85 injection is easier since the kit would be built for it?

Also, some interesting info here: http://injectordynamics.com/articles/e85/

Seems like a huge pain to me, to be honest.

yes it will destroy rusting the stock fsi injectors very fast if you leave the car sitting for a few days
basicly to it right you need to switch your injectors that are made for e85 ,fully custom tune the engine with a flex fuel sensor,change all fuel lines ,larger cap low pressure pump,upgraded hpfp and so on ,not worth for na rs4 but worth for boosted rs4s

[zmw]

yes it will destroy rusting the stock fsi injectors very fast if you leave the car sitting for a few days
basicly to it right you need to switch your injectors that are made for e85 ,fully custom tune the engine with a flex fuel sensor,change all fuel lines ,larger cap low pressure pump,upgraded hpfp and so on ,not worth for na rs4 but worth for boosted rs4s

I'm not sure where you're getting your information on e85, but it's just incomplete at best. As someone who has run e85 since 2002 and exclusively when possible, I've had none of those issues and except on my Supra, I took advantage of stock fuel system components, pumps, lines, etc. I would guarantee every component on the RS4 is compatible with ethanol and would cause no problem, the unknown may be the fuel pumps. Ethanol does not cause rusting, it is not acidic, it does not eat or consume rubber. To do it properly you would need more fuel, but my understanding is that rebuilt HPFP's from APR or anyone else is more than capable of pushing that much fuel.

Now with that said, the BIGGEST problem with ethanol and direct injection is really the lack of lubricity in ethanol, which has caused pump failures in the BMWs, in fact the early 335s had pump failure from standard e10 93 octane fuel where supposedly the small amount of ethanol was washing down the walls of the cam driven pumps.

E85 can do magical things even on NA motors, first off it runs much much cooler, it burns cleaner, likely would eliminate or grossly deter carbon build up, there would certainly be values for ethanol on an NA car, I agree with you though that cost and performance upgrade may not be worth it.

[LINDW4LL]

I'd agree. From what I understand, most cars produced in the past decade (if not longer than that) can handle E85 without issues. From a corrosion standpoint, that is.

[zmw]

I'd agree. From what I understand, most cars produced in the past decade (if not longer than that) can handle E85 without issues. From a corrosion standpoint, that is.

since 96 actually, ethanol was designed to replace MTBE which was added to fuels to help completely burn, and reduce emissions in the late 80s, in the early to mid 90s MTBE was turning up in drinking water in significant quantities enough that MTBE was outlawed, ethanol took it's place. It certainly has some odd properties, and storing it can be problematic, and vehicles sitting for weeks with very very high values of ethanol (say 80% and up) may experience starting issues or eventually clogged injectors, but simply changing the way you treat your vehicle, ocasionally running a take of 93 through fixes those issues - For enthusiasts, the value of e85 is hard to ignore, it's 1.29$/gal right now and provides 110 like octane, and for boosted applications it goes really well with high lvls of boost because it's damn near impossible to pre-detonate, and provides more exhaust energy, spools turbos earlier, and generates less heat - it's basically magic pixie dust for boosted cars.

[low_qu4ttro]

since 96 actually, ethanol was designed to replace MTBE which was added to fuels to help completely burn, and reduce emissions in the late 80s, in the early to mid 90s MTBE was turning up in drinking water in significant quantities enough that MTBE was outlawed, ethanol took it's place. It certainly has some odd properties, and storing it can be problematic, and vehicles sitting for weeks with very very high values of ethanol (say 80% and up) may experience starting issues or eventually clogged injectors, but simply changing the way you treat your vehicle, ocasionally running a take of 93 through fixes those issues - For enthusiasts, the value of e85 is hard to ignore, it's 1.29$/gal right now and provides 110 like octane, and for boosted applications it goes really well with high lvls of boost because it's damn near impossible to pre-detonate, and provides more exhaust energy, spools turbos earlier, and generates less heat - it's basically magic pixie dust for boosted cars.

now what about a non boosted car? would I see a difference in the way the car runs if I put E-85 in my b7 rs4?

[zmw]

now what about a non boosted car? would I see a difference in the way the car runs if I put E-85 in my b7 rs4?

With tuning... yes - without tuning, all it will likely do is either NOT run or run so lean that it's going to be unstable or throw lean codes. As I said in my first post, there ARE values in running e85 on an NA non boosted car - cooler, cleaner burn, virtual elimination of carbon depositing, etc - you could also have a much more agressively timed tune even on NA, but I wouldn't do it without a proper tune.

-Z

[forbiddenbeat]

I'm not sure where you're getting your information on e85, but it's just incomplete at best. As someone who has run e85 since 2002 and exclusively when possible, I've had none of those issues and except on my Supra, I took advantage of stock fuel system components, pumps, lines, etc. I would guarantee every component on the RS4 is compatible with ethanol and would cause no problem, the unknown may be the fuel pumps. Ethanol does not cause rusting, it is not acidic, it does not eat or consume rubber. To do it properly you would need more fuel, but my understanding is that rebuilt HPFP's from APR or anyone else is more than capable of pushing that much fuel.

Now with that said, the BIGGEST problem with ethanol and direct injection is really the lack of lubricity in ethanol, which has caused pump failures in the BMWs, in fact the early 335s had pump failure from standard e10 93 octane fuel where supposedly the small amount of ethanol was washing down the walls of the cam driven pumps.

E85 can do magical things even on NA motors, first off it runs much much cooler, it burns cleaner, likely would eliminate or grossly deter carbon build up, there would certainly be values for ethanol on an NA car, I agree with you though that cost and performance upgrade may not be worth it.

I'll defer to you since you've actually run E85. :) I just recall hearing of fuel lines breaking down over time running E85, but perhaps that was on older cars.

[mpdbrown]

I'll defer to you since you've actually run E85. :) I just recall hearing of fuel lines breaking down over time running E85, but perhaps that was on older cars.

I know first hand that some fuel trucks (tankers which deliver fuel to gas stations) would complain about the ethanol corroding their hoses when it was added to gasoline years ago. Here in my lab ETOH is shipped and stored in plastic bottles, but apparently it takes a larger toll on rubber over time.

[zmw]

It is true that ethanol can eat up some kids of rubber, but the fuel lines and coatings used on a fuel system since 96 should be completely resistant or immune to it. The concern comes when you let ethanol SIT, it is hygroscopic by nature which means it wants to collect and retain moisture (water) - that is the primary concern when ethanol sits. The result is that when sitting it CAN lead to rusting or break down of materials - the fix for this is to try not to let the car sit. This is most often seen in marine applications where there is significant moisture around and in the fuel.

Don't get me wrong, e85 isn't without it's faults, and certainly some care should be given when using e85, the best solution is to have a true flex fuel capabilitiy which means you can pump in e85 in any quantity and your tune is auto adjusting, I have no idea if this type of functoinality exists for an RS4, my gut says it does not. In other enthusiasts cars, tuners like Cobb have been able to enable the factory ECU to understand and read ethanol content (via a sensor and the fuel return line) and then adjust the fuel and timing maps accordingly. For an RS4 my guess is you would have to run two static maps, one for ethanol and one for regular pump fuel, but I doubt the RS4 has the ability to blend maps based on an input of an external sensor.

[zmw]

I'll defer to you since you've actually run E85. :) I just recall hearing of fuel lines breaking down over time running E85, but perhaps that was on older cars.

There are two issues that are most common with older cars and ethanol. One is metal/steel fuel tanks that have significant corrosion or sludge build up. E85 has the tendency to CLEAN this, the result is clogged fuel filters, potentially clogged injectors and lines - this is not the fault of E85 though, this is sludge that is built up in the system and e85 is causing it to break down and loose. It'd be like blaming the dental floss for breaking off a piece of plaque on your teeth rather than blaming the plaque itself. Steel or alloy tanks that have an iron quantity in them are prone to rusting, because e85 wants to collect water you can certainly accelerate the rusting of a fuel tank. The easy way to prevent this is to NOT let the vehicle sit with ethanol, OR if it's going to sit let it sit with a FULL tank of fuel in it so you are minimizing the amount of surface that has contact with water and air allowing rust.

The next primary issue is similar, if you have an old car with hundreds of thousands of miles on it's fuel system and old rubber lines, ethanol absolutely can accelerate that break down, ethanol does not have the oil content of standard fuels and similar to using rubbing alcohol on a dirty spot it will want to pick up and remove oil deposits that have permeated into the fuel lines themselves, the problem with this post fuel filter is the sludge it is freeing up is going straight to the injectors.

The reason you read about teflon coated fuel lines is because they do not absorb ANYTHING, not oil, not ethanol, nothing - you can be assured that what's flowing through there is only the fuel. I admit when I redid the supra fuel system I used all teflon lines, but it was just an extra measure of comfort in an already expensive project so it was fractionally more expensive. You could do the same by using stainless steel hard lines or even regular fuel line now which is all ethanol rated. Teflon also allows you to consider running race fuels or M1 which are much more corrosive to standard fuel system components than e85 would be.