Incoming

Me and my friend where talking about nitrous and turbo systems... At one point in time he mensioned putting about 16.00 or 17.00 dollars gas in my car and then goto the local airport with a gascan and get a few gallons of jet fuel... Ive heard of incidents that engines couldnt take it... being that i have a v8 can my car can it handle running that rich gas? get more power that way?

thnx wes

Dzhezkov

iTrader: (1)

I used to work with JP8, which is a mixture of mostly kerosene with some benzene, toluene, xylenes and naphthalene mixed in. I don't think it's good to run, but I know it can run in diesel engines.

Apeiron

Diesels aren't quite the same, they'll run on almost anything.

FSTFBDY

iTrader: (33)

you can run Av gas. 100LL (low lead) 114 116 etc.

anything with lead though isnt great for the 02 sensor.

B4Ctom1

yes just make sure you are running the 100LL instead of the "JP-anything" jet fuel. Yes it does reduce the lifespan of the O2 sensor in the long run. It runs in turbo/nitrous cars fine. Real race gas would be preferred especially if you are paying a premium for it.

88 350 tpi formula

iTrader: (9)

I have run 100LL quite a few times, it works fine and usually is pretty close to the same price as 93 at the pump. usually within 10 cents or so more per gallon

parks911

Jet fuel won't get you no where except draining your gas tank & fixing the problems you created in your fuel system.


Now Av-Gas 100LL as already mentioned is a different story.

Now if you really want to boost of power? Go to your nearest dragstrip & buy that racing fuel they sell. It costs about $5.00 a gallon (did last time I bought it). But mix it with regular gas. it will boost your octane to well over 100.

Apeiron

And that will give you a "boost of power" how, exactly?

B4Ctom1

I agree, it is well known that engines running more octane than needed will be sluggish and lose response.

anesthes

iTrader: (12)

1) Jet fuel isnt gas, as mentioned in this thread.
2) Higher octane gas will make you run slower, unless you tune your car. Its called running rich.

FSTFBDY

iTrader: (33)

Turbo Blue or Cam 2 cost me $4.20 here at a local station that sells it.

askulte

Higher octane has nothing to do with running rich or lean.

anesthes

iTrader: (12)

Your kidding right? You need to look at BLM and o2 changes with various octanes at the same spark advance.

edit: http://www.westechperformance.com/pa...ng/octane.html



-- Joe

Rembrandt

You are confusing octane number for specific gravity and its relation to carb characteristics and therefore rich/leanness.

You can have the same octane number and 5 different specific gravities, each which would like their own air:fuel ratio.

Rich/Lean is the relative standing compared to what the motor likes. The average ratio of one engine might be 12.3:1, which numerically might be rich compared to an engine that likes 13.8:1, but perfect for the first engine. Rich or lean either way it would run less well.

Rembrandt

you don't have to buy expensive racing fuel although it is more suited to the purpose than my suggestion:

just go to a paint store and buy some toluene, add it to your normal high octane pump gas.

Toluene is one of the most potent anti-knock additives/components there are. You may have heard about the Formula One turbo era where cars were running 40-50+ pounds of boost and making insane horsepower per liter. Well their boost level was almost directly proportional to the percentage of toluene in the fuel, the more the better.

anesthes

iTrader: (12)

First of all, I am not confusing anything. I've experimented extensively with various fuels from various suppliers in my logging. I've record atmospheric conditions, ambiant temperature, etc.

The higher octane fuel (93, 101, 103) produces way richer O2 results than lower octane fuel (89, 87).

The Rich/Lean is relitive to whats "left over" after the combustion process.

Since injector firing is based on time, and not the size of the pipe, the VE/load tables will keep the injector open the same amount of time regardless of octane or SG. The end result is more fuel, or less fuel, hence the blm and o2 change.

-- Joe

88 350 tpi formula

iTrader: (9)

I would think that since higher oct. fuel burns slower than lower oct. (under same pressures and heat...... I must add. I don't want to get flamed)


so as stated if you keep the same spark timming it would only seem correct that the mixture could not possiably burn completely before the exaust stoke is well in effect

Rembrandt

so like I said, it is the higher specific gravity and not the octane number that makes it run richer.

same pulsewidth/jet delivers more fuel by weight, no kidding.

I thought that air:fuel ratio was pre-combustion estimation. Pounds of fuel per pounds of air. Granted, it is recovered from the exhaust o2 sensor and I'm not sure how they do that.

what is BLM?

Rembrandt

I'm trying to find some article that relates octane number to burn rate, I can't remember what it was saying.

How directly is octane rating and burn rate related?

anesthes

iTrader: (12)

The higher the octane the higher the specific gravity. You can't chemically change the mixture, and end up with the same weight of substance - unless all the parts are equal weight to begin with.


-- Joe

Apeiron

No, but you could add a small amount of something like tetraethyl lead which will have an insignificant effect on the specific gravity (we call that density these days) of the fuel, but a drastic change on the octane rating.

MrDude_1

anyhooo.... Jet fuel is basicly kerosene.

thats why anyone who puts "jet fuel" in their car is a idiot.
that also why i laugh my *** off at these "jet fuel" additives. hell, lets just pour some lamp oil in while we're at it..



some AV gas still contains lead... so be careful about what you're putting in your tank.

specific gravity (aka density) has nothing to do with octane.

Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines.
of course, if you leave everything the same, take a engine that runs fine on 85 and put 118 AV gas in... it'll burn so slow that the O2s will appear rich, since you have incomplete combustion.

higher octane means it burns slower. so you need to either jack the timing up sooner to keep the cyl pressure up, or just run a lower octane gas.
boosted cars love it because they can keep their timing, and run insane dynamic compression ratios (aka run alot of boost) without detonation (fuel exploding before its suppost to, or burning irregularly).

also, while two diffrent things, the burn rate of most STREET higher octane fuels is slower then that of lower ones... its not the octane doing it, its just the mix they have has that effect. it'll vary from location to location, even season to season, depending on the chemicals they added. im not going to pretend im a chemist and tell you what they are or how they do it... i donno.

hot rod magazine (i think it was them) did a dyno test with diffrent fuels awhile back... they found that cali gas sucked *** and by using pump gas of the same rating from NV, they got 10 hp or so...

'87 IROC VERT

iTrader: (4)

I'm a pilot, I ran some 100LL (low lead) - didn't make much of a difference. I think if I had a chip and advanced my timing to take advantage of the fact that 100LL won't knock as easily, I might see something. It's currently running $.15 more than premium at my airport.

Note on running rich - I bumped up my fuel pressure with an adjustable fuel pressure regulator. I am getting around 30hp from the upgrade when I set it to 53pis - however, an interesting side effect was the engine runs cooler. When I scanned it, it was also running richer (which was the point of running 53psi).

Duh - as a pilot, I should have already realized that of course running rich would give me lower combustion and CHT. Nice side effect - my car never runs above 205/210 F - nice, especially for LA.
(I as say as a pilot, because in almost all piston aircraft, you adjust the mixture by hand to compensate for altitude, etc. And you use the mixture sometimes to keep your cht and egt temps down, and to prevent shock cooling when decending)

B4Ctom1

Considering that we already mentioned that O2 sensors lifespan are diminished by leaded fuel, Im very surprised nobody has mentioned that even a small amount of lead introduced into a catalitic converter begins a process that destroys it. A catalitic converter works through a chemical reaction which converts un burned hydrocarbons and other by products into water vapor and a few other less invasive products. If you have ever smelled a rotten egg smelling cat, that is a dead givaway that lead has been introduced to the substrate in the cat. The lead and the other parts of the cat convert some of the other byproducts in to sufer dioxide or other sulfer based chemicals. These products and the lead itself work to PLUG the cat up. and also shield the remaining chemicals in the cat from being able to be used. The result is a ruined, useless, plugged cat. The worse part is that it takes only the tiniest amount of lead to start this process.

In short, if you have cats, then NO LEAD!

'87 IROC VERT

iTrader: (4)

My apology, I (wrongly) assumed everyone knew that leaded fuel would harm a cat. I seemed like every car I rode in growing up ('70s/early '80s) had something about that on the inside of the driver's side visor...

(I ran it when I knew I would be replacing my cat that week, I just wanted to see if there was a difference. I now have a new cat, which I did before I had my out of state car smogged. The factory one wasn't going to pass, I was sure, and a new one cost around $100 installed).

Free Bird

iTrader: (1)

Ok, this is all great info. But lets put it to use.

Lets say you put in 100, or even 114 or 118. Is there any kind of chart that would tell you how much you could advance your timing? Or is it all hit and miss? Is there even a simple "rule of thumb" to go by?

I'm runing race fuel in my 1gal cell for a 300 shot of N20 but my ign. box only retards the timing 9* if I try to follow the 2* for every 50hp puts me at 12* of retard, what octane would make up for 3*. Or 5* or more? What if I want to jet it for a 600?

anesthes

iTrader: (12)

I never finished my license, but yeah. You learn a lot. Weight of fuel and distance calculation, airfoil designs, etc. Lot of physics.

Maybe next year I'll finish it up.

-- Joe

Dano 00TA

Unless you're ruunning high compression and have detonation problems av-gas aint gonna help ya. Save your money for a 6-pack

anesthes

iTrader: (12)

I made a few passes at the track friday in street trim.

Shifting at 6500, but because of the small tires I ran outta injector in 4th almost at the end. Had to stuff it in neutral about 200ft shy of the end.

Rolled (in neutral) through the end at 12.50 @ 112mph.. heh.

Gonna try my water/alky injection wednesday, and if that doesnt help the 6600rpm detonation, i'll try some type of octane booster.

(and if that dont work, 42# injectors here I come)

-- Joe

B4Ctom1

well put

Free Bird

iTrader: (1)

So the only possible way to tell if you need higher octane is to wait for detonation? That doesn't sound like a good idea. There isn't a chart similar to the Boost:compression chart that always pops up on this board?

'87 IROC VERT

iTrader: (4)

anesthes,

I have a friend who is a CFI, I think the airport is called Hanscom.

You ever go to a place called Forte's Parts Connection? It used to be on Moody Street in Waltham, now it's in Burlington...

Just wondering.

- TransAm90210

'87 IROC VERT

iTrader: (4)

Jet fuel, or 'Jet A' which is the most common blend used by civilian airplanes, is basically kerosene.

100 octane low lead, or 100LL, is close to auto gas, but with some lead and a blue tint so you can tell is apart from other blends (you always drain an ounce or two into a clear strainer and check the color, and look for contaminants before you fly a plane using 100LL or similar fuels).

Here's the funny part - a piston engine airplane can run on 100LL, or in some cases, auto gas with an STC (supplemental type certificate) or even 80 octane (usually MUCH older planes - it's not widely available anymore). But it CANNOT run on Jet A.

However, a small business jet (probably any jet, but I can only speak for the ones I've flown), will run on not only Jet A, but you CAN also run 100LL in an emergency (for instance, you landed somewhere that stopped selling Jet A, even though your flight guide says they still do) and you had no choice but to run something else to at least get to to a nearby airport to get Jet A.

I know you can only go partial throttle, and you can't fly too high (even the small 8 seat jets can go high - the last time I flew a Cessna Citation, pretty much the low end of business jets, I flew from Houston, TX to Burbank, CA at 41,000 feet... not bad!).

I know a guy whose engine stared vibrating a bit during flight - an indication that the engine was getting out of tolerence. He had it pulled and leased a 'loaner' from Pratt & Whitney while his is rebuilt. The cost to rebuld an engine that came off the small Citation jet in running condition? $250,000 if nothing is broken. I'm not kidding, I actually saw the estimate from P&W. I was shocked, I was sure the numbers I heard from people was total BS. I was dead wrong. And this isn't a jumbo jet engine, mind you - I could probably stick it in the back of my T/A with the seats down and the hatch open...

Even time I wish for a jet, I remind myself that one hot start (starting the engine the wrong way, usually a result of a low battery) can ruin the compressor blades....

ooops - I think I got off topic. Well, it WAS about Jet fuel, right?

88 350 tpi formula

iTrader: (9)

you know the funny par about high oct. fuel is every idiot I run into runs it in there car. and if you tell them it will do nothing for there 100% stock eng. but, slow it down they just give you a look.

B4Ctom1

yeah kind of like telling people dropping the exhaust 95% of the time slows down thier car.

'87 IROC VERT

iTrader: (4)

I have had a few cars, such as Ford Crown Victoria Police Interceptors that knock and ping with anything less than 91 octane. There are several warning, including one right on the dash panel that specifically call for use of premium 91 octane or higher fuel. When I did run 87 in it once, the check engine light stayed on until I used it up and refilled it with 91 octane.

As for my Trans Am, I found it runs a little better (but not a lot) on 91 octane. It might be okay on 89, I haven't bothered to try. The few cents a gallon isn't going to kill me.

That being said, I would NEVER pay for race gas and the like for my mostly stock fuel system and timing.

anesthes

iTrader: (12)

All the department cars i've driven we ran on 87 with no probs.. Infact, the dept wouldnt allow us to fill up with anything other than 87..

-- Joe

'87 IROC VERT

iTrader: (4)

Could be that I was raised in Wellesley

haha

83 Crossfire TA

iTrader: (2)

You’ve managed to record some combination of weirdness in your tuning and differences in specific gravity of the fuel you’re using.



Jets/injectors meter fuel by volume… differences in density will result in a different volume delivered.



They don’t. The relative O2 content on either side of the sensor (outside air vs what is in the exhaust) induces a voltage in the sensor which the ECM reads and then looks up. It knows that a specific value translates to a specific A/F ratio. It’s not perfect, something like a lean miss will show up as running rich and there are conditions that will show up lean that are not.

Simple, it’s not. Burn rate is dependant on the a/f ratio, conditions in the chamber, fuel used… there is no direct connection between burn rate and octane.

What we call it depends on the convention used in the science that we’re talking about… in this case we’re talking specific density.

[/b]

You can run a lot of 100LL through most cars before you kill O2’s and cats…



Wrong. Octane is a fuel’s resistance to igniting spontaneously because of the pressure spike during the ignition delay period after the charge is initially ignited rated on a scale that is relative to the same quality of the same test engine burning a mixture of pure octane and air. It has nothing to do with burn rate.



100LL has a lower heat/energy output when burned then pump gas. If you put it in an engine tuned for pump gas you’ll actually make less power because of it. Some people still run it for either it’s octane or for it’s less objectionable fumes vs gas (I know someone that runs it in his generator and a few other pieced of equipment that might be used around people)



Assuming that combustion finishes in the chamber (it should except maybe during cold start or if you have some pretty big tuning issues), 100LL will cause an engine to run cooler because of it’s lower heat output when burnt.



Even if someone came up with one it would be worthless for anything but exactly the engine that it was generated on under the conditions that it was generated.

An engine will make maximum power with fuel that has a specific burn rate with a specific timing at a specific rpm. Running higher octane fuel will not make more power unless the engine was detonation limited with the lower octane fuel. In other words, you don’t necessarily make the best power running as much advance as you can get away with without detonation.

Real world, give an engine what it wants, not what you think it should want.

That boost:compression chart is next to worthless. Much like trying to do this for octane, this only represents what one engine will do under one set of conditions. I can think of engine designs that on pump gas are prone to detonation with 8:1 compression and no boost, and I can think of one running 14:1 and close to 20psi, again on pump gas, which is fine.

83 Crossfire TA

iTrader: (2)

You’ve managed to record some combination of weirdness in your tuning and differences in specific gravity of the fuel you’re using. It has nothing to do with octane



Jets/injectors meter fuel by volume… differences in density will result in a different volume delivered.



They don’t. The relative O2 content on either side of the sensor (outside air vs what is in the exhaust) induces a voltage in the sensor which the ECM reads and then looks up. It knows that a specific value translates to a specific A/F ratio. It’s not perfect, something like a lean miss will show up as running rich and there are conditions that will show up lean that are not.

Simple, it’s not. Burn rate is dependant on the a/f ratio, conditions in the chamber, fuel used… there is no direct connection between burn rate and octane.

What we call it depends on the convention used in the science that we’re talking about… in this case we’re talking specific density.

[/b]

You can run a lot of 100LL through most cars before you kill O2’s and cats…



Wrong. Octane is a fuel’s resistance to igniting spontaneously because of the pressure spike during the ignition delay period after the charge is initially ignited rated on a scale that is relative to the same quality of the same test engine burning a mixture of pure octane and air. It has nothing to do with burn rate.



100LL has a lower heat/energy output when burned then pump gas. If you put it in an engine tuned for pump gas you’ll actually make less power because of it. Some people still run it for either it’s octane or for it’s less objectionable fumes vs gas (I know someone that runs it in his generator and a few other pieced of equipment that might be used around people)



Assuming that combustion finishes in the chamber (it should except maybe during cold start or if you have some pretty big tuning issues), 100LL will cause an engine to run cooler because of it’s lower heat output when burnt.



Even if someone came up with one it would be worthless for anything but exactly the engine that it was generated on under the conditions that it was generated.

An engine will make maximum power with fuel that has a specific burn rate with a specific timing at a specific rpm. Running higher octane fuel will not make more power unless the engine was detonation limited with the lower octane fuel. In other words, you don’t necessarily make the best power running as much advance as you can get away with without detonation.

Real world, give an engine what it wants, not what you think it should want.

That boost:compression chart is next to worthless. Much like trying to do this for octane, this only represents what one engine will do under one set of conditions. I can think of engine designs that on pump gas are prone to detonation with 8:1 compression and no boost, and I can think of one running 14:1 and close to 20psi, again on pump gas, which is fine.

slimdawson

[QUOTE][i]what is BLM?

Block Learn Multiplier. It tells you how much the computer is compensating for either a rich or lean condition. 128 being ideal in an LT1. If they are lower than 128, the computer is pulling fuel and vice versa if above 128.

Free Bird

iTrader: (1)

So what would you suggest about a N20 set up that I posted earlier? Can I get away w/ 100LL fuel? Or do I just spray the 300 and cross my fingers that the octane will do it's thing, or drive around on an additional 3* of retard all day long.

Dano 00TA

I used to run 100LL in a 13:1 compression 427 with a 250hp nos cheater kit with no problems.

What compression are you running?

MrDude_1

i suggest you get a small fuel cell. fill it with race gas... and run the nitrous off of it.

slimdawson

If you really are contemplating using 300hp worth of nitrous, I wouldn't be looking for a rule of thumb. First, I would make it possible to retard the timing more than you currently can. I would also run the highest octane(unleaded if you have 02s) you can find. I also would work up to the 300. Start small and make sure the care will take it, then move up. A liitle bit too much and you may luck out and burn some plugs, but if you go too much overboard, you will be burning more than plugs.

Free Bird

iTrader: (1)

That's what I already have. 1 gal. cell. I'm trying to figure out what fuel to put in the cell.

slimdawson, there's is no more contemplating. I've been doing that over the past year. I understand your concern for my motor but adding even MORE electronics to my car is the last thing I want to do. The heater, purge, extra fuel pump, noids, relays, water pump, fans, 2-step, etc. NO MORE WIRES! please.

Dano 00TA ,

I'm running a candy as$ 10.18:1 w/ al. heads, 355.
Thank you for your real world experience.

'87 IROC VERT

iTrader: (4)

The more I read about the work it takes to get a smaller motor to run just right, the more that GM Performance 500 or 600hp ready-to-run motor sounds like a deal.

You know the one, the ad is in or on the back of stuff like GM High Performance, etc.

Maybe I'm nuts, but I bet it would be pretty sweet out of the box...

I wonder, if I had the money, if it would be a relatively simple install in my '87 T/A, or if I woudl have to cut the car up to wedge it in. Anyone ever tried? Just curious. I would probably buy a project airplane before I did that...

Parrydise7

iTrader: (1)

One other thing about running avgas in a car. Although it's been awhile since I checked, it's probably illegal, (at least it used to be and I'm pretty sure it still is) so be careful. I don't think you want to advertise that it's going into a car and not an airplane.

With avgas, there is no road use tax collected.

(Any of you guys with gray hair remember when we could buy gas for 20 cents a gallon? A dollar's worth of gas, and you were good for cruising around on Friday night.)

'87 IROC VERT

iTrader: (4)

You are right, no road taxes, but the FAA related and county taxes MORE than make up the difference!

I was born in 1970, and the only gray hair I have is from my wife. I think the lowest I have even seen was .90 cents a gallon at a cheap AM/PM station here in LA back in the mid 1990's when gas hit an all time low. I was driving an old gas guzzling Mercedes 450SEL at the time, and I was pretty happy for a while...

MrDude_1

umm, its obvious.. (atleast to me)

in the fuel cell, run the high test race gas. you're only buying what the nitrous system uses... its made for it, its usually available there at the track, or even in 55 gal drums for home....

and yea, with any huge shot, id pull a good amount of timing out.