zinx

iTrader: (3)

I think you are going to run out of fuel before you get to 25 psi. I would upgrade the pump, fuel lines, replace the dampener with a 1:1 FPR, and replaces the primary 550 with 1000cc or higher. I don't know that that would get you to 25 psi, but it would be a much better start.

c_mart_28

iTrader: (1)

Alright, well, went ahead and made the switch last night. Before making the switch the car had been searching a little bit for an idle and would lean out a bit and then settle, then lean, then settle while on regular pump gas. I had just thought it was a tune issue and that I would be able to square it away when tuning for e85.
Well...with the extra fuel and fuel pressure needed the surging idle and irregular AFR's just got worse. The car will start and I can keep it running but I don't think I'm keeping a regular fuel pressure. I'm pretty sure my pulsation dampener took a dump on me.
Time to finally install my FPR and possibly bigger primaries (as recommended above..) and see if that takes care of it. I'll post an update as soon as I get it squared away.

fritts

iTrader: (5)

Why don't you check your fuel pressure first before you assume its the fpr or the dampener. Then replace your dampener and check pressure again. Just get your car sorted out before you go to far. I would have run the car on gas with a new fpr and injectors then switched over. Also you should not just assume you need 30% more fuel. You should actually tune for your idle afr's rather than assume at 30% its correct. Coolant correction I needed much more fuel to keep my car running well along with adding more fuel up to engine temp. I don't believe E85 likes to run in a cold engine. I have noticed that once warmed up completely (oil and coolant) I can idle and cruise much leaner than I could on gas as well. Even in part throttle conditions that would cause my car to lug with gas the E85 seems to run fine.

c_mart_28

iTrader: (1)

Thanks for the advice.

I do understand that 30% is not a solid number, more just a starting point for tuning. No biggie.

My issue actually ended up being just a matter of simple tuning. I did though install an Aeromotive 1:1 FPR just to be safe. After a bit of dabbling I'm now running quite well and ready to start fine tuning. I also can say that with E85 my car does seem to be much smoother, even in the very early stages of tuning.

On a side note: any recommendations on what to run for fuel pressure?

moremazda

iTrader: (4)

^^^ I am running 45psi base pressure with 1600cc primaries and a check valve on the regulator so I run a constant 45psi throughout the vacuum range.

Dane

The 15% gasoline blend is the cold starting agent. E85 came about as a deal between the government and the automakers. Explanation: The small amount of gasoline is the required minimum to start flex fuel vehicles down to sub zero temperarures. Otherwise, all flex fuel vehicles would have had to have been produced with cold start assist units (like many FC have) if pump ethanol would have been primarily E98. However, above 50 degrees or so, piston / flex fuel vehicles will start using pure E and E98 blends. Of course the RX7 is a somewhat different beast than a typical 10.5 compression piston vehicle...so one may need to supplement the E85 even more (as was touched on above).

Interestingly, cold start assist units of FFV's would have only cost automakers an additional $40 average per vehicle...but when you look at milions of cars built, I guess that was enough reason for them to lobby for gasoline blends.

If you are curious, E98 (w. 2% gasoline) is also a government mandate, even if one makes his own ethanol for fuel. This is done because otherwise ethanol would be drinkable (well to a mountain man, lol), therefore would techincally be considered as bootlegging, or would lead to the potential of it. So if you own a (legal) still or a even if a station sells E98, there better be some gasoline in there in case of a spot check.

AnthonyNYC

iTrader: (3)

I've been running E85 for about 2 months now. This past weekend was about 15 - 25def F in NY, I had no issues starting it and driving around. It idled as soon as it started. I had to crank a little more but I just need to add some more fuel on cranking for that temperature. Intake temps were 30deg F.

I'm starting to fine tune the car, I added 30% more fuel than when I used gas. I just added 7% more fuel this weekend and AFs are in the low 11s. I figured it was cold so I might as well be safe. I am not sure if we are running E70 where I am but so far all seems normal with starting in cold weather.

Anthony

gusfd3s

There has been alot questions about oil contamination with E85 in rotary engines, atleast here in sweden.

Some people claim 300km is an absolute maximum before changing oil..

I sent a bottle of oil to Motul a couple of weeks ago letting them analyze my oil which was used 1500km+ and 3 dynos.

It is in french, but you might get some info out of it

SPEED_NYC

iTrader: (3)

translation?

jacobcartmill

iTrader: (6)

i think it passed

fritts

iTrader: (5)

Google translation of lower right box

We reflect a good engine. Wear general is a correct level for this vehicle. There were no abnormal clogging oil depots by burning or dust or liquid cooling.

c_mart_28

iTrader: (1)

Just a bit of an update on my FC (1660pri, 550sec, FPR, walbro, stock otherwise..)

Very solid and improved idle from 93 oct tune.
18psi form T04e.
Noticeably improved torque throughout the rpm range.
No real issues to date.
Lots of weird looks at the gas station for pumping e85 into a 21 year old car..

Anxious to hit the dyno now to see what kind of power it really makes (my guess is around 360rwhp..) and if my semi stock fuel system can handle a few more PSI. Dunno if I'll try to squeeze out a full 25psi or not. Likely not, I don't want to get too greedy.

wankeltrim

13B REW GT4202BB 32PSi boost

gusfd3s

Congrats Jörgen, this is awesome news!!

I guess this is calculated flywheel hp?

wankeltrim

Yes it's flywheel hp.
We run out of fuel at 7500rpm so we decide to stop and do another fuel setup

RXTASY57

iTrader: (2)

The key to high power fuels is the specific energy that is available during combustion. This is not something that should be confused with the heating or calorific value (the heat generated by burning a test sample). For instance normal gasoline has a typical heating value of about 43 whereas for ethanol the figure is only around 27.1. Taken at face value ethanol is therefore obviously a very poor fuel so there must be other reasons why it can produce more power than gasoline from an engine. The answer is that the specific energy, not the heat value, determines the potential for a fuel to generate power. If more fuel can be burnt effectively with a given amount of air then more power will result, but this should not be taken as meaning that just adding more fuel necessarily always means more power. The stoichiometric (chemically correct) air/fuel (A/F) ratio for gasoline is approximately 14.7:1 but best power is achieved at richer A/F ratios around 12.7:1. This is partly because of the charge cooling effect of the extra fuel and also because the presence of slight excess fuel means all the air in the charge will be burnt. Further enrichment beyond this point will cause power to fall. With ethanol the stoichiometric A/F ratio is 9.0:1, therefore it is possible to burn more fuel and the specific energy of the charge will increase accordingly. Maximum power is obtainable at the very rich A/F ratio of around 6:1 so the usable specific energy (12.7 / 6 * 27.1 = 57.4) is much higher than gasoline, although of course fuel consumption will be dramatically increased. Ethanol has an octane rating in excess of 110 RON permitting use of higher compression ratios or higher boost pressures.

Another property of a fuel is it's specific heat of vaporization or how much heat it will take to vaporize a given amount of fuel. For gasoline it is 140 and for ethanol it is 361. The amount of heat removed for ethanol is (12.7 / 6 * 361 / 140 = 5.4) times better than gasoline. To put a temperature value to these numbers, gasoline will lower the intake charge temperature by 50F while ethanol will lower the intake charge temperature by 270F.

Now the bad. When using E85, expect fuel milage to drop by 20% during cruise and up to 50% during high boost.

Now the good. E85 can be as cheep as $2.15/gallon. When run down to 6:1 A/F ratios it allows very high boost pressures and optimal ignition advance.

Dane

A 5-10% fuel economy loss is the range that most people see in normal daily driver use. Some with higher compression (piston) vehicles cannot tell a measurable difference at all. To achieve the numbers you quote, you would have to increase the fuel to air ratio substantially, and by design. If so, this would indicate that you should be achieving higher power levels via increased boost that are not possible using 20/50% less gasoline. If this is the case, pointing out an increase in E85 consumption is splitting hairs.

Additionally, current pump gas will not achieve the fuel economy of yesteryear...for example when our cars were EPA tested, or when junk ethanol comparison studies were done by Chevron in the 80's. This is due in part to the amount of benzine in current gasoline, especially in higher octane gas, or in fuel labeled "100% pure gasoline". So if you were to do a back to back (tank to tank) comparison, I highly doubt you will see such a difference given the exact same driving habits on both tanks.

So imo, 20/50 is unique to your situation, a miscalculation, or something you read and took as fact. For reference, mileage figures of current/recent FFV's only show a couple percent difference between fuels. If you really want to split hairs, since E85 can be used in engines with compression ratios as high as 18:1, the potential is there to greatly increase fuel mileage over gasoline, even if this doesn't apply directly to a low compression rotary engine.

RXTASY57

iTrader: (2)

Just trying to point out the performance factors. Not to concerned with consumption, but that is good news Dane!
Now I can't find anything that's "bad" about converting to E85.
I personally haven't done it yet, but am in the process!
Have gathered all of the essentials minus the surge tank I will be using.
2 X 044 Bosch pumps, 4 X 2000cc injectors from Injector Dynamics, and a T72 BB Turbo. Hoping for 600 RWHP @ 25 PSI.

Dane

Fwiw, I have not seen a noticeable fuel economy loss in my tired, stock 89 240 using a 50% E70/E85 splash blend. This may be due in part to me not using an E85 "fooler" device or any other related parts that would ramp up the fuel rate. Even with the puny stock injectors, pumps, etc. I have slightly more power...but this is because I am using the maximum advance the distributor allows.

Interestingly, when I switch back to straight pump gas when not near a station that has "E", I actually loose power due to the knock sensing system. Admittedely, if I put the distributor back to the factory setting, I would surely see a slight loss of power / economy on E85 versus pump gas.

Regardless, I am not looking for performance in this car anyway...just a fuel that will clean out (and keep clean) the internals of a mildly driven 21.5 year old, low compression car. Other side benefits I have found is a smoother idle, and less stinky exhaust. But if I was building something for serious power, it would be silly not to use 105 octane fuel that is readily available in many areas and costs slightly less than gas (much less $5 p/g race fuel).

RXTASY57

iTrader: (2)

From all the posts I have read on this forum, people increase their fuel maps by 30% when converting from regular gas to E85.
That alone tells me ther is no way you would get just as good of gas mileage.
You might with a piston engine, but this is a rotary forum and most people talk about rotarys when talking about technical stuff.
E85 is comparable to Q16 which is $15 a gallon. If you are talking performance, you would go with E85. It only makes sense.

1bigfella

Just my experience with E85 and my setup. Car is pretty much track orientated. FD 13b BP, T04z. Had to run intank sard 280lph fuel pump, going to surge tank, then bosch 044, with 10mm fuel lines to engine bay. 4 x 1750cc fuel injectors. Car is running a conservative 16psi at puts out 425rwhp. Fuel consumption I could not care less about as long as the fuel is the same quality every time I put it in the car. Have not had any issues so far except for great gain in HP and cooler fuel temps for induction. I run 150ml of Castor oil with every 20litres of fuel. My tuner is very switched on with this product and swears by it. 25 years as Rotary mech and engineer. Cant see many drawbacks, you just have smash the fuel into it and make sure it doesn't run out of it.

Jason