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What kind of gas do you use?

3K views 20 replies 14 participants last post by  shorty_boy 
#1 ·
The e85 thread got me thinking....I personally all ways use premium (93 octane) I couldn't tell you if there war any difference between premium gas and regular gas in my car because i have never used regular. I have a b16 with basic i/h/e few other non engine mods
 
#3 ·
I use the cheap stuff, tried using gas without ethanol mixed in but I didn't really see a change in gas mileage. Well, a change that was significant enough for me to care.
 
#4 ·
I am pretty certain that all of the US-spec CRXes were designed to use regular-grade fuel. IIRC, the owner's manual for mine said minimum 85 AKI. Yes, 2 points lower than the regular you get in most areas. I've only seen 85 for sale in Colorado, so it's probably a high-altitude thing.

Note that RON numbers are about 4-5 points higher than AKI (which is what US pumps are rated in) for the exact same gasoline.

--DD
 
#7 ·
Unless you're building a high compression engine, or on a tune that was designed for higher octane, there's no point in running above 87 on our little engines. It's what they were meant to run. You won't experience any different in running a higher octane (performance or MPG), a higher octane just = more knock resistance.
 
#8 ·
Spyke=correct.....running premium in a stock crx engine is a waste of money..

Higher octane fuel is used to help prevent detonation.
 
#11 ·
^^correct
 
#12 ·
ollie said:
Spyke=correct.....running premium in a stock crx engine is a waste of money..

Higher octane fuel is used to help prevent detonation.
Thank you for this... I was half expecting someone to jump in going, "NUH-UH! My best friend's girlfriend's uncle SWEARS ON HIS LIFE that premium adds as much horsepower as 3 stickers" or something ridiculous like that. I see it all the time on other forums, and hear it from people who pretend to know about cars. :rolleyes1:
 
#16 ·
JohnnyBlaze said:
dmudd said:
whats the stock compression for our motors including the b16? i know the 3000gt na is 10.1 and it said premium only.
As mentioned above, the 3000GT is a turbo engine and requires premium to prevent detonation.
Compression numbers= :google:
Not trying to argue but not all 3000gt are turbo only the vr4 are turbo.
 
#17 ·
Lots and lots of things change the propensity of a given engine to ping. The octane of the fuel matters, of course, as does the ignition timing. The pressure of the ambient air the engine is pulling from (high altitude or low), the amount of boost if any, intake air temperature, how wild or mild the cam is, the combustion chamber shape, the presence or absence of hot spots or sharp edges in the chamber, the number and location of spark plugs, the mixture quality, how rich or lean the mixture is, and on and on and on and on. All of those things affect if an engine pings or not.

Most engines today are built with knock-sensors that can tell when pinging starts. They can then pull timing out (and boost if they have computer-controlled boost) or richen the mixture slightly until the pinging goes away. So they can run higher compression and count on the engine management system to make sure the engine doesn't destroy itself.

Our engines are a little older, and do not have a knock sensor. (Not on a stock US-spec CRX, at least.) So they had to be a little more conservative with the compression and timing and such, to leave some margin of error.

Some even older engines (VW Bug ones, for example) are even more primitive. Because of the sub-optimal combustion chamber design, the very primitive engine management system (centrifugal-only spark advance in some cases, and a single carburetor in most cases) and other factors, they have to run premium fuel when they get over about 8.0:1 compression.

--DD
 
#18 ·


This thing works if you take the time to tap a spot for the sensor and you can also make your own voltage monitor for the knock. I dont know yet what voltage would be a bad knock but you get the idea.

I had one on a B16 and never got it to read high with 87 all up through @8500rpm but it is still good to have if something with the motor is going wrong or just bad fuel. Performance mods is where it will help the most.

Why let the computer have the most fun with the knock sensor?
 
#20 ·
Dave_Darling said:
Lots and lots of things change the propensity of a given engine to ping. The octane of the fuel matters, of course, as does the ignition timing. The pressure of the ambient air the engine is pulling from (high altitude or low), the amount of boost if any, intake air temperature, how wild or mild the cam is, the combustion chamber shape, the presence or absence of hot spots or sharp edges in the chamber, the number and location of spark plugs, the mixture quality, how rich or lean the mixture is, and on and on and on and on. All of those things affect if an engine pings or not.

Most engines today are built with knock-sensors that can tell when pinging starts. They can then pull timing out (and boost if they have computer-controlled boost) or richen the mixture slightly until the pinging goes away. So they can run higher compression and count on the engine management system to make sure the engine doesn't destroy itself.

Our engines are a little older, and do not have a knock sensor. (Not on a stock US-spec CRX, at least.) So they had to be a little more conservative with the compression and timing and such, to leave some margin of error.

Some even older engines (VW Bug ones, for example) are even more primitive. Because of the sub-optimal combustion chamber design, the very primitive engine management system (centrifugal-only spark advance in some cases, and a single carburetor in most cases) and other factors, they have to run premium fuel when they get over about 8.0:1 compression.

Nice write up thanks explained alot

--DD
 
#21 ·
I use mid grade to prevent knocks. I notice a difference in my car. This was the obld and tired d15b6. As of right now, the three stage requires premium. I think that I'll just keeping getting mid and add octane booster to prevent knocking on the crappy California gas. Once I get it back on the road, then I will be able to see a difference.
 
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