Wicked_Warren63

"unleaded only"

is because if you ran anything else 90-93 octane is because it would mess up you catalytic converter......

just somthin i thought was a cool FACT

sv41878

yeah, it's kinda unnecessary now, it mattered back when you could drive up to the pump and choose between regular or unleaded. Now days, since you can't buy leaded gas at the pump, if you put anything else in it, you deserve to mess up your cat.
At the same time, I had a 85 RX7 I ran 1/8 jet fuel (not sure if that's leaded) and 7/8 premium unleaded mix regularly + nitrous and it didn't hurt anything. Had over 10k in mods to be able to do it, but it was worth it and I have to 220 mph plus ticket to prove it (His radar detector topped at 220 is what he said). My honest guess is I was going closer to 240 cuz it was at 10k rpm in 5th.

5-90

Couldn't have been jet fuel - the JP series runs closer to Diesel (it's mostly kerosene) than gasoline.

May have been aviation gasoline. I used to run a couple gallons of that through my old Bug to clean it out (but this was back when the stuff only cost a buck a gallon.) LL AvGas is not only highly detergent, but it's even slower-burning than 100% octane - which has a RON of 100, a MON of 100, and an AKI of 100 (by definition. At the other end is hexane - RON 0 MON 0 AKI 0 by definition.)

AKI ratings above 100 are actually called "performance numbers," since the fuel combusts slower than 100% octane. Some fuels run high AKI numbers naturally - toluene, for instance, has a RON of somewhere around 135, a MON of around 128, and therefore an AKI of 131. It's often used as an "octane improver" additive.) Typical AvGas grades are 100LL, 112LL, and 120LL (but the last is getting rare.) The "LL" stands for "Low Lead" - they're not strictly "unleaded" fuels (there is some tetraethyl lead in them,) but it's lower than the "regular" fuel we used to have available. It will still poison a cat bed over time.

Running a higher-octane fuel than normally called for won't poison the cat bed, but it usually causes it to fail prematurely (because the thing get so damned hot from working overtime.)

"Octane" or AKI numbers are a measure of how slowly the fuel combusts, and how resistant it is to detonation/pre-ignition. This is why high-compression engines need high-octane fuel - if the AKI or MON were too low, the fuel would be pre-ignite due to compression and damage engine parts. Thus, you can get away with running a high-octane (unleaded) fuel in a low-compression engine, but I wouldn't do it for long.

Also, there isn't any real benefit to running a higher-octane fuel than the manual calls for - and there can be a detriment to doing so, if the difference between the AKI required and AKI used is great enough. The problem would come from the fact that not enough fuel gets burned in the cylinder - because the higher-octane fuel burns more slowly.

Short form?
- You can run a high-octane fuel in a low-compression engine (like ours,) but why? If you want more detergent, four ounces of acetone to a 20-gallon tank will get you good results, and cost you less.
- Even high-octane auto fuel is unleaded - TEL isn't used as an AKI improver anymore (in automotive fuels.)
- There's not enough benefit to running high-AKI fuel in a low-compression engine (in proper trim and clean) to justify the additional expense.

Glossary:
AKI - Anti-Knock Index. (RON+MON)/2. Also known as "pump octane."
TEL - TetraEthyl Lead. Formerly used as an octane number improver in "Regular" gasoline. Also used to lubricate valve margins and help prevent recession of valve seats by forming a "sacrificial layer" of metal - valve seats for use with "unleaded" fuel are typically hardened, as are the valves themselves.
MON - Motor Octane Number. Figure derived from running a fuel/air mix through a test engine, while driving the engine from an external prime mover. Involves checking for detonation/pre-ignition without having heated parts.
RON - Research Octane Number. Derived from running stoichiometric FAR into a variable-compression engine until the point of detonation/pre-ignition, and comparing to a chart of varying proportions of octane (MON/RON 100) and hexane (MON/RON 0.) This is the same chart used to derive the MON - just the method differs.
LL - Low Lead. This is a fuel that still contains TEL (used to prevent recession of valve seats and to lubricate valve margins,) but not as much as typical regular fuel.

I think that's everything...

sv41878

Ok, very informative, thank you. LL112 sounds familiar, but my RX7's life was like 15 years ago, so can't be certain. it had a cat on it and in the year and a half I had it, I didn't do any damage to it, at least that I know of. But like I said, I had crazy mods to the engine anyway. I mean it didn't red line until 15k and then I think it could have handled higher. We weren't really sure and 15 was fine for me, she screamed. That's the nice thing about not having pistons and rods, it could actually scream.

ZachsXJ

Well, considering F1 engines can handle at least 21,000rpm that doesn't mean a whole lot. Its just easier and cheaper to build a rotary engine capable of 15k over a piston engine

sv41878

I have never seen a piston engine that handles over 10k, but have never built an F1 either, so I don't know. As for it being cheaper, well yeah I don't have a racing team budget. But I had 10k in mods to the engine alone, so it was worth it. I used it to smoke a Lambo off the line and maintain smoking it for like 10 miles (I5 race between Mt Vernon WA and Stanwood WA exits). Absent a racing team budget to build, I think it's about the best that could be done.

ZachsXJ

Well yeah, thats a given. I've never built an F1 engine either, and I'd rather not know what it costs to build one. There videos all over youtube of them pushing 17k and beyond. I've seen a couple of them pushing 21k.

sv41878

Must be nice to have stupid money like that i had to sell 2 of my other cars to raise the money to build mine. Bet they spend over 100k on them.

ZachsXJ

I was gonna guess somewhere in the market of 60-70k. either way thats an insane amount of money to spend on an engine. All because FIA rules say they can't use Turbo's. They could make double the horsepower out of the same engine at half the cost if they were allowed the usage of Turbos, or they could probably make the same HP at 1/4th the cost. I don't see why FIA didn't just put a power and TQ cap on the F1 teams, since now they are putting a rev limit on them.

PingPong

I wanna see the 220MPH speeding ticket I also what to know what kind of penalties he got

XJ's~For~Life

At 220 I don't see even getting a ticket. They wouldnt have caught ya! At that fast they either take your license or not.

Alex

thats just cool

ZachsXJ

haha, a buddy of mine knows a guy(I know sounds unlikely) who got pulled doing 160 in a TT 300zx, he decided to street race a Skyline on one of our local highways. Anyways he was 19 at the time and his speeding ticket was somewhere in the area of $8000 and he has a suspended license with no possibility of getting it back until he's 21. That was for a first offence speeding ticket too. Needless to say he had to sell the car to pay the ticket. He may have also served some minor jail time too.

sv41878

it's classified as a felony, no jail time and like 5k in fines and I can NEVER have a license in the state of WA again, nor can I drive with my NY license there. It's like catching 10 DWI's at once. I will look and see if I can remember where I put the ticket. It's in all the stuff from my young and dumb days.

98xj_john

rx7 is not a piston motor its rotary an if u Renove rev limiter the motor wwill rev up til it flys apart. Would like to see ticket too
Also I run midgrade gas In mine an mine runs better an I get on Average an xtra 50 miles to a tank .