Snack

well to be honest a design like that will have a big effect on the rotary scene but when it comes down to it, i think most of us will just use the old school method and continue to premix. friction isn't a selling word. you got to take into effect the housings.

peejay

Octane loss from oil injection is minimal.

Carbon is more a problem of overrich fuel mixtures than oil.

Anecdote:

My latest RX-7 came with a weak engine with poor cold start and worse hot start characteristics. To help compensate, I was mixing oil with the fuel on the order of 1 quart every 10 gallons or so, in addition to the oil from the oil metering pump and whatever the engine got from the obviously worn oil control O-rings.

This is widely considered to be excessive.

After 6,000 miles of driving like this, on top of an unknown number of miles (odometer showed just under 150k when I got it, but it was far more worn that that would siggest), the engine died. When I pulled it apart, extreme wear of the apex seals and especially the seal slots were noted. (The rear rotor, which is what I drove home on, had one broken seal, three flat springs, and the corner pieces were almost round. You could fit the spring between the seal and the slot. WORN OUT) The front rotor, which failed, was a bit worse This engine had horrible compression when I got it and didn't seem to degrade very much, so I, and the previous owner, had been driving it like this for a while.

However, there is minimal carbon deposits, certainly not what one would expect from an engine burning a quart of oil every 250-300 miles by design and an unknown amount of oil due to blowby. I credit that to what is unfortunately an unorthodox approach to carb tuning: run it extremely lean under cruise and just rich enough under idle conditions to not stumble.

The engine came with a RB Holley carb setup, which was removed as part of the purchase deal. On its new home (a good '83 12A in a '79 S-model), it runs extremely rich. Tuning Holleys to run extremely rich seems to be the only way to get them drivable, rotary or not I have pulled rich running engines apart where you practically had to spoon the carbon out.

FC3Sdrift

iTrader: (5)

if your worried about octane loss from premixing, just add 1 ounce of Toulene for every 10 liters of fuel ...that'll boost 93 octane to around 100 octane...there's already toulene in gas your just adding a bit more

check out on the internet for more information on it ....its safe and its cheap

patman

iTrader: (3)

^ HAHAHA

you, sir, are grossly misinformed

toluene is 114 octane.
when mixing fuels, octane numbers roughly average. therefore if you mixed 1 gallon of toluene with 1 gallon of 93 octane gasoline, you would have 2 gallons of 103.5 octane.

if you mixed 1 gallon of toluene with a tank of 10 gallons of 93, you would have a tank of 95 octane.

if you mixed 1 ounce of toluene with 10 gallons of gasoline, you would have wasted 10 minutes. (fyi it would be 93.08 octane, but the tolerance on high grade in the US is .6, so you could only be getting 92.5 octane)

pat

RETed

WTF?
They shouldn't allow people who can't do basic math to post in here.


-Ted

patman

iTrader: (3)

oops, i didnt notice that you said 10 liters not gallons. just for clarity, that would be 93.49 octane, ie still less than the tolerance on the pump spec.

now, if you want to mix toluene by the gallon, go for it, it will increase octane rating as well as power output since toluene has a higher specific energy content than gas. The problem is that it is hard to get hold of large quantities of it, and also it is a potent carcinogen and will probably kill you in a few years if you mix up that many gallons of it.

slo

iTrader: (1)

regular plain old gas is also a carcinogen, I have a friend that died of leukemia at age 29, the cancer was believed to have been caused by cleaning the hands with gas, apparently one too many times where he grew up on a farm.

If one where to treat it like one should treat gas and keep body parts out of it and head out of fumes etc then they would be fine.

FC3Sdrift

iTrader: (5)

I was just saying to mix a bit to offset the octane loss from premixing


heres a quote from the gasoline digest page
http://www.idavette.net/hib/fuel/page2.htm
in the paragraph below the picture of burt renolds

"Do it with 91 and 100 unleaded gasolines, you mix 3:7 for $32.05. Because a 1:1 mix of toluene and pump gas costs you performance and throttle response due to slow burn speed"

I didn't mean go make your own race fuel ....its cheaper to just buy the real stuff
but starting in 2009 leaded fuels are banned in Canada

toulene is 103.5 octane....if you mixed 10 gallons of 91 octane with a 1:1 ratio of toulene it would give you 20 gallons of 97.5 octane (thats right off that page too)
my numbers were off thats why i said look on the internet for more information

peejay

Actually, if you actually read what you quoted, it says to mix 91 octane with 100 octane, because high amounts of toluene could hurt.

Octane enhancers react differently depending on the base fuel's blend. There is no sure way of calculating octane rating because, quite honestly, despite giant heaping huge mounds of cash poured into research (especially in WWII), we don't know how to chemically figure out a composition's resistance to knock. To this day we still physically *measure* knock characteristics with a special variable-compression engine.

It's fascinating stuff, really.

An old trick used to be to combine certain unleaded fuels with certain leaded fuels (before leaded fuels were banned... in 1986) because the different chemical interactions could result in an octane rating greater than either fuel alone.

FC3Sdrift

iTrader: (5)

mixing it at 1:20 ratio should make up for any octane loss from premixing and then some
its about 10-15 bucks for a 4L jug

patman

iTrader: (3)

at that price why not just buy c16?

peejay there is a decent way of calculating knock based on the percentage content of different compounds in the fuel, this is known as the research method. The method using the engine you refer to is called the motoring method. In the US all octane ratings are R+M/2, in other words the average of the two methods. One reason for this is because both methods produce errors for different conditions- the motoring is accurate with regard to specific engine variables, but lacks accuracy in relative environmental conditions (kinda like a dyno must be corrected to SAE specs based on current temp and pressure). Research includes environmental factors but is unable to compensate for real world combustion situations. The average of the two provides a number that is more relevant to all situations.

Badfish

I think you are missing the point of what fcs3drift was orriginally saying. He was simply offering a solution to the 'octane level' lost due to introducing premix into the fuel mixture. And what I really think he ment by bringing it up is that the "octane" loss caused by premixing is so small that it is negligable.

As far as mixing up your own concoctions and putting them into your tank, I say good luck not blowing up a motor (or your garrage) or breaking some other internal component. Just go buy some preformance fuel and leave it to the pros with the labs and the funding.

P.S. this whole octane thing is only relevent to high preformance turbo or supercharged engines, and i doubt that even the stock turbo rotaries would have any problem detonating premium fuel (93 octane)


I'm sure theres 50 reasons I'm wrong, so let me have it, i can take it!

peejay

Er, no.

Research method (ASM-D2699) tests the fuel in a standardized test engine under "mild" conditions. Motor method (ASM-D2700) tests the fuel in a standardized test engine under "severe" conditions. In both cases, the fuel is being measured in an actual running engine, being compared against known control fuels.

The reason for using the average of both tests is that some fuels are more sensitive to "severe" conditions than others, so unless you are running a Waukesha CFR engine, a single test cycle is kinda pointless. If a fuel gets similar results from both tests, then it is less sensitive to operating conditions, and less likely to knock under wildly varying operating conditions. That's why in the US the difference between the two cannot be more than (IIRC) 7 numbers.

Toluene, incidentally, is kinda sensitive. Its RON is 120 but MON is 109.


ASTM D2699 abstract: http://www.astm.org/cgi-bin/SoftCart....htm?E+mystore

ASTM D2700 abstract: http://www.astm.org/cgi-bin/SoftCart...758+1202694634

patman

iTrader: (3)

i stand corrected.