Interesting Paper On Crs And Ethanol Fuel Blends .

[discopotato03]

I came across this article when searching for info on lower ethanol fuel blends .

http://delphi.com/pd...010-01-0619.pdf

I have not had time to read it it all but what looks interesting is the table on page 5 and how the octane rating and knock resistance of E85 and E50 are very similar . Whats more interesting is the stoic AFR which means in their tests they think E85 and E50 (US fuels) do much the same thing , only you'd use less E50 which would extend your range .

As I said I have not read it all but if interested in ethanol blends its worth a look .

Cheers A .

Edited November 11, 2012 by discopotato03

[wedge_r34gtr]

I've just had a quick browse - very interesting papaer. The 20% better fuel consupltion of the E85 at the higher comp was a bit of a suprise - i expected a little , but not that much.

It would be interesting to get hold of someones flex tune for E50/E85 and see exactly what has changed - i.e.fuel consumption, power/torque difference etc.

[Lithium]

I did some flex-fuel tuning on an S14 a while back using Virtual Dyno (unsure how well it compares with a real dyno yet - we were more or less testing the process but dyno will happen) and right off the top of my head I recall it did seem to drop off in gains quite substantially after E60, and I was also pretty surprised at the amount more fuel usage required to meet targets on E85 as well.

Something which we discussed but never really formed a solid conclusion on but interestingly enough (whether this is placebo or not) despite Virtual Dyno not suggesting there was much of a difference there seemed to be a reasonable sensation of quite a lot snappier performance... not exactly a scientific observation, but it did seem like it got up and went more impressively on E85 somehow. When I next do a session of the sort (will be doing one within the next couple of weeks) I'll see if can log a few curves from different ethanol contents and put across the fuel requirement differences.

[simpletool]

Like you said DP it's interesting that the E50 and E85 has similar timing for lower compression but the highest compression scenario shows significantly higher timing allowable for the E85, along with higher power.

At 9.2CR and 11.85CR the E85 makes only 1% more power, and is limited to the same ignition (or less) - at least at these low revs. However at 12.78CR the E85 makes 3% to 4% more power than E50 and runs the same timing at 1500rpm, 1° more at 2000rpm and 3° more timing at 2500rpm. I can only imagine that higher revs plus forced induction would show this gap to be even greater.

I'm not sure how RON and MON are measured but it's clear that for high compression and higher revs the E85 clearly outperforms E50. For lower compression conditions they are equivalent - at least in this test.

[Lithium]

Had a chance to read that - very interesting stuff, cheers for sharing. Glad they posted IMEP, there is a bit of a myth that I encounter which suggest there are only performance gains to be had using ethanol on knock limited setups and its nice to see an independently researched paper which isn't some workshop or whatever showing off their 1337 tuning which shows some of the general benefits from using eth blends. Shame they chose to use "91" as the base petrol.

[discopotato03]

Well I think it was a good datum to start with 91 ULP though in our measurements I think thats more like 95ULP . Correct me if I'm wrong but I though their 87/91/93ULP was similar to our 91/95/98ULP .

What I read out of that paper is that for any meaningfull engine speed and load there is an optimum AFR and timing setting and if for whatever reasons you have to retard the ignition timing the torque falls and exhaust temp rise .

With higher compression ratios the temperature and pressure in the chamber increases the chance of detonation and with real high CRs only high ethanold content fuels resist detonation and nock retard .

I think its more a case of running the optimum timing than running any extra over that .

For our less sophisticated RB engines it's probably a case of working out how often you end up running a lot of boost and how much the extra anti nock properties of high ethanol content fuel are worth the cost and set up hassles .

I'd say any worthwhile amount of E100 you could throw at 98ULP would make it more nock resistant but lower amounts are easier than higher amounts particularly if you didn't need much help to make the 98 workable .

A .

[Lithium]

They have RON/MON/AKI specs on the fuels tested and the base is 91RON - same as ours, so imho too low to relate to the E85 we'll get downunder.

[discopotato03]

As I said I think it was a base line to demonstrate how different fuels react to increasing compression ratios and nock .

I think it may be some time before we see static compression ratios that high and I reckon there would have to be a lot more high ethanol fuel available and being used .

The trouble is that at the moment few vehicles here are OE flex fueled ones and those that are were not designed to specifically use E85 , I think it was mentioned that engines set up for straight ULP/E10 give poor consumption with E85 because they can't take full advantage of its usefull properties .

I sense consumer resistance here to garbage grade E10 and its hard to promote something that decreases your fuel consumption and makes your engine run slightly lean . Its easy for people to think that if 10% is bad how bad must 70-85% be . If their Engines were designed to burn straight ULP/PULP and are getting a bit tired they are not going to give any worthwhile returns with E10 or possibly E anything - particularly without any retuning .

Later model cars designed to cope with at least E10 and have some ability to self learn via wider band 02 sensor will cope better especially if their static CRs are on the high side . I get the feeling that direct injection holds some answers but thats beyond what most people here have or can probably tune anyway .

There needs to be more E85 marketed and engines designed to properly use it before it can take off in the market place , because there is no easy transition strategy its going to be a long drawn out process . Its not like when unleaded fuel came in and every car after a certain date had to use it by law . Most people are not that concerned with the green aspects of Ethanol fuels and will only voluntarily make the change if there is something it it for them - meaning some cost incentive . People tend to remember the increased consumption more than the power they gained in something like their "Spark Ignition Direct Injection" Commode Door and if they weren't specifically focused on the power aspect having to fill the thing more often is a drag in their busy lives . Why would they bother . If they were a bit of a car nut and wanted to play with different blends of say 98ULP and E85 it could be interesting but I doubt thats your average Commodore buyer .

Ultimately some car nuts and a few bent greenie rat bags are the small number leading the ethanol wave , the rest prefer it in glass .

A .

If I was setting out to build specific E85 engine it would have a higher static CR ie 9.7-10:1 and possibly the typical 1-1.2 bar boost that many use in road cars .

Edited November 12, 2012 by discopotato03

[Dale FZ1]

The abstract and conclusions give sufficient detail for the average punter to understand what they investigated.

The direction for production engineers wanting to use flex-fuel technology and hitting on performance, fuel range and emissions targets is (to me) heading towards cam-less valve actuation, and perhaps throttle-less spark ignition engines. I think that is effectively what the BMW Valvetronic system is all about (??).

I tend to agree with Adrian regarding the any consumer swing to E-fuels until/unless the popular opinion is that they are getting something for nothing. If their car goes further on less fuel, or the unit cost for fuel means their transport costs are lower, then watch them pick up usage.

It is quite clear that the knock limitations of straight petrol do not allow mechanical optimisation (ie higher end static CR) when multi-fuel strategy is the target. But early or late inlet closing events seem to pull back the defict when no E-blend is being used. Without research, I suspect that strategy is aligned with the Miller Cycle process and may be directed towards improved fuel efficiency and/or emissions so perhaps a win-win for future production engines,

Meanwhile I don't see sufficient evidence that the average Skyline/RB punter will benefit from playing with multi-fuel blends. E50 might yield most of the benefits, but who wants to muck around with making their own blend when E85 is commercially available in what seems to be reliable proportions. Again I agree with Adrian that the evidence points towards benefits for someone planning on dedicated E85 use with a new engine build. Not sure that just playing with static CR is the answer, though it would seem 10:1 and 1.2-1.5 bar could be a very effective combination.

I don't have the engineering know-how, but reckon the best solution might lay with cam spec/timing in tandem with higher static CR. The effective dynamic CR should be the focus, really just as now for people running straight petrol.

I would be interested to get some reliable information from engineers involved with the swap to ethanol fuel for the Supertaxis on what was the change-trend in cam spec for them. I'm not really interested in that category, but there aren't many recent instances where they have had a mandated change from petrol to alcohol fuel and give engineers the chance to see what (if any) mechanical detail of the engine could be changed in tandem to get the best from it.