hello all,

i'm runnning a jdm b16 i always run premium gas but with prices hitting $4.19 a gal its getting pretty costly to fill it up. has anybody ran theirs on regular or mid gradeand not have anything bad happen? or regular gas with maybe a bottle of octane booter?

 

I don't know what octain your engine requires. Unless it's a high compression engine, you can use regular 87 octaine. Knock sensors can compensate for low octaine, but you lose performance and fuel economy.

As for octaine booster, add up the cost of the product and compare it to the cost of using mid or premium grade fuel. I think it's a wash.

 

From what I understand, using the lowest grade of fuel you can without your engine knocking produces the most power because your engine doesn't have to work as hard to combust it. Of course if your running higher compression then stock or boosting then use the higher octane.

Also if you think putting higher octane in say a geo metro for example will make it faster, your wrong. Try it out and the car won't even start cuz it doesn't have enough compression.

 

this is actually the source of much argument around here.

the jdm cars are rumored to be tuned for higher octane, but run just fine on 87 in my experience.

another argument stems from the idea that lower octane burns more easily, so you may get better performance than the higher octane stuff, even in a higher compression engine. I have yet to see dyno numbers to substatiate this, and it really only matters what your tune (factory or otherwise) can handle as far as knock is concerned.

the issue comes really from knock and whether you experience it running lower octane. I run my fiance's '91 DX on 85 octane, and my '91 SI (equipped with fuel cut launch control) only on 91 octane (which is the highest octane I can buy in CO). neither of the cars knock on their respective octanes, but my SI will knock with anything lower than 91, but it was tuned that way, and fuel cut launch control only causes more issues with lower octane.

 

i'm about 99% sure that the b16 requires premium fuel. i'm not looking for my car to go faster. Higher octane actually burns slower than lower octane fuel. i'm just trying to look for a less costly alternative.

 

the shop manual i have that covers the SIR says 95 RON or higher.. so it sounds like premium is what you should be using, if you are using a factory ecu and engine build.

 

you can get away with mid grade, It should not knock

 

i don't care how much gas is...premium will probably be 20 cents more regardless. 20 cents on $4 is really nothing. in a crx that's $2 more for a tankful. that's a coke and small bag of doritos. my b16 is always getting the premium fuel honda recommends.
heck the peace of mind is worth $2 a tank