I was watching a video series from The Tuning School in which the tested several different fuels in a supercharged C7 (93, E85, Ms103, c9, c85, etc) and they stated that when using ethanol that anything above E40-E50 had negligible gains as far as power goes. Rather than take that as gospel I wanted to see if anybody else seen this in their experience/dyno testing?

 

Yes I agree with that 100%. I run my car on E70. I'm running 15 lbs of boost and 19 degrees of timing. I've tried from E65 through E85, with no noticeable difference in performance. The advantage of E85, is pump and don't worry about mixing. The advantage of running E70 vs E85, is it lowers demands on the fuel system, and you get a little better mileage. E70 is made by mixing 1 gallon of premium gasoline (E10) with 4 gallons of E85. The driver for me doing this was this, I buy my E85 from Speedway, and it is often lower than E85 in the winter. I've tested it as low as about 73%. If you have the car tuned on E70 and you get fuel that tests 85% out of the pump you can always drop it to E70 with a little gasoline, it is usually right there beside the E85 on the same pump. If you have your car tuned to E85, and the E85 tests 72% that day there is nothing you can do about it, your just going to be running rich. Not the end of the world, but not optimum tuning. I made 714 RWHP on the E70, with an unlocked converter on the stock LS1 bottom end. So far so good, its lasted almost a week so far.

In the hottest part of summer, and running high inlet air temps the E85 may make a more noticeable difference, because of the higher fueling requirements, it will cool the intake charge a little more. When summer comes around I may go to strait E85, it can be done simply by changing the stoich from 10.7 down to 9.8. E70 and E85 are close enough that any difference in the timing and VE tables will be negligible. I wouldn't feel that way going from like E40 to E85 though, I'd need to retune it to verify that big of a difference in E content.

 

Good info. I'm going to start tuning my SBE LS1(59 cc patriot heads, 224 cam) on 91 first while i learn hptuners then switch to E85. Might consider doing E70 if my fuel range is too limited.

How long have you been running that set-up at 700+?

 

Thanks for the info Scotty...I'm moved up to Michigan from Pa and E85 is everywhere up here...I am gonna be running MS3 with a content sensor so that will help, but if I can run lower % of ethanol in order to lower fuel system requirements and still get advantage of E than it will help out. I'm only shooting for like 5-550 rwhp out of my L33 through a manual with a 380lph and 80# and -6, but I from my research and calculations it should be attainable without upgrading anything.

 

Arizona recently switched to E54 from E85 at many stations and I've had to deal with this a LOT lately on all sorts of different combos. General rule of thumb I've found is that on many common combos E54 took a few degrees less timing before knock compared to E85 and it made less power in the process as to be expected when running less timing.

 

I believe some of the problem with the E54 comes from the Petrie companies reducing the ethanol content with regular gasoline base stock which has little to no octane enhancers in it. Basically the extra 31% they are adding is about 85 octane stock, and they are counting on the ethanol to carry the octane of the E54 to a reasonable level. It's is not as good as if you made your own E54 using 93 octane gasoline and E85. All lower E levels are not equal.

 

All E levels are equal in the same area as they use regular octane fuel to mix with and this comes directly from the fuel distributors who actually do the mixing for stations. They don't use a lower octane base fuel to mix with than regular for the area as that's all they have. Sure you can make your own mix using E98 barrels with 93 octane or even MS109 if you wanted to but I think most are concerned with what you actually get out of the pump.

 

I do get my lower levels of E out of the pump, but as I said I select the 93 octane to blend with it, as they are normally side by side on the same pump here, a green hose for E85, and next to it a black hose that can be selected 87, 91 or 93 octane, I just chose to mix with 93 for the gasoline portion. As well I've not ever tried to go below E65.

I have seen some blender pumps, where you can chose the mix you want, and they pump it all at once, out of the same hose. At a "Mother Hubbard's" I've seen one, but that's the only one I've seen like that. You select the % ethanol content, and can select the gasoline portion to mix with it. It may be a little complex for the average consumer though who just wants to grab a hose and squeeze. I wish all fueling stations had that.

What Arizona is doing probably makes good sense for the standard flex fuel vehicles, just not when we are using it as a substitute for race fuel. In that case I may consider using methanol injection with it, just like 93 octane.

I am a chem eng and have worked in the petro chemical industry. The reason I said 85 was because you are right they have a base stock, that is shipped to these distributors you speak of, from the refinery, that do the blending for the stations, is often lower than the standard fuel pumped. If they add 10% ethanol to an 85ish octane base it will meet the 87 most stations pump, and some places in high altitude go lower than 87. The base stock typically ranges from 84-87, and the distributor ensures that it makes the octane rating that the station is going to sell, before it is shipped to the station. It is often blended as it is pumped into the tanker that is going to haul it. They also add any custom packages of cleaners etc that the individual brands of fuel advertise. "Techron" etc. They also make the higher grades from this base stock, through blending octane enhancers with it. When I was involved in this it was MTBE that was used frequently, along with a few chemicals, however I think that has been discontinued for environmental reasons. If the base stock is below the 87 they can also use these enhancers to make sure it meets the 87. The base stock will always be low to keep costs down, and they will add as little as possible to it to meet the minimum requirements.

I suspect that when they are making ethanol blends, they use the lowest cheapest stuff possible because the ethanol content will take care of the octane requirements for just about any stock vehicle on the market. And probably the cleaning requirements too, I doubt any other enhancers are added. If the base stock were 85 octane, just using my calculator here adding 54% ethanol (ethanol is typically considered 106), you'd end up with about 97 octane. If you used 93 octane for the gasoline portion about between 99-100, like I do at the pump. A minor difference, but that could make a degree or 2 of difference.

Speaking of timing, my car on 15 PSI of boost, and 11.4 compression makes best power at 19 degrees, using E65 through E85. Just for reference. You don't loose much power dropping it to like 18, like maybe 5 hp, but if you drop it to 15 or 16 it becomes more like 30-40hp, significant.

Probably more detail than some would want, but some may enjoy the read.

 

Yeah as I said the main distributor out here blends ethanol with regular 87 octane at the plant and ships it off to the stations and it routinely takes a few degrees less timing on E54 vs E85. Depending on the combo this is typically anywhere from 15 rwhp to 50 rwhp and I see it every week. Mixing your own fuels obviously makes a difference and the sky is the limit at that point.