bluedevil

Interesting read, on a side note I heard that putting premium in helps with mpg but I don't know if that is true, has anyone else heard this or know it to be true or false?

With gas prices where they are I am not in the mood to test this right now, it is cheaper to ask.

Giantviper

From what I undertand what Bluedevil says is true. But I am not sure if the MPG change justifies the Price difference. I have never done th math.

But I baby my 88 N/A and use Premium in her.

whalebird

Premium will help. We should be running the good stuff anyway. There are a lot of people here who will disagree that premium will improve milage. There are, however, regional differences in fuel formulation that has an effect. Do your own tests. The motronic injection on our cars is not smart enough to adjust for fuel quality so we may not realize appreciable gains.

Relaxed90

My 90 S2 gets 24-25city and 28+ highway. Bone stock for the most part. I also use premium because it's required for the most part. I can hear slight pinging at WOT using 87 or 89.

Tom R.

91 octane is required per the owners manual for the S2, 87 is required for the NA. guess that is the price we pay for 50hp. go figya.

supposedly there is no performance gain if you use premium in a NA.

Ben951S

Use the fuel your car was designed for.

Higher Octane = High Resistance to Detonation.

If you have high compression engine design (turbo, or just designed that way), you need higher octane to prevent pinging (pre-detonation).

Running premium fuel in your NA that is regular (not high compressoin), all you are doing is wasting money. All the fuel is filtered and clean, it has nothing to do with the quality of the fuel, but the addatives to make it resist detonation.

I used to run premium too until I looked into it.

Run what the manual says to run.

Mamooguy

Exactly. Most people seem to think that "premium" means "better" somehow.

Luckily I'm a member of Club NA, so I can use the cheap stuff.

Ronin951

My Dad's inventor buddy hooked a hydrogen kit he made to his Insight and got 78 MPG from PC to Tally. If you want to find out more PM me and I'll put you in touch. I don't know much about it. All I know is bolt-on, water, and generator.

Tom R.

And ive read that carbon build up on say valves increases the need for higher octane. also every car is a little different. on our 05 rendezvous the book says regular, and we used regular in NY and things were fine. when we got to colorado with the hills i noticed the big V6 (we had the bigger motor) wasnt getting up and going like it should. we put in a few tanks of the middle grade - which is the same octane as the lower grade in ny and not only did pickup improve, but mileage as well. with the say 5% increase in mpg per the cars computer and the 3% increase in price, it was cheaper to run the better stuff AND get better pickup. remember YMMV!

i ran all three grades in my 90 RX7 convertible that i bought new. i got the best throttle response with the middle grade, so i used the middle grade. i wasnt as concerned about mpg on my weekend toy as i was with rowing through the gears as the wankel hummmmmeeeddd

jtsporsche

so im loesing money and performance by using premium in my n/a?

88BlueTSiQuest

I thought there were some people wanting to mandate a change in the 'naming schemes' of gas. They call higher octane fuels "Premium" which makes people think it's better.

I always get a kick out of watching people spend too much on gas, because they think that Premium fuel will make their eco car better/faster.

The only way that higher octane fuel will make a difference on a non-S N/A would be if you adjusted the timing to take advantage of the higher octane.

Campeck

basically....yes. use 87.

yellowline

On pistons, it marginally reduces the volume in the compressed combustion chamber. Marginally. 1/32" of an inch of carbon is about 0.75 mm, and that buildup is likely a stretch. On an engine that was about as high compression as you could get with regular gas (an 8v 944), this buildup will throw it off.

High-test gas=knock resistance. That's all. In an engine where it is not required, it creates a situation where the engine burns cooler because of more incomplete combustion...larger molecules that won't properly combust. Efficiency goes UP with more complete combustion.

Tom R.

then why did older cars need higher octane as they got older?

apen749

Has anyone tried to make their own octane booster to add to regular gas? I've sent a lot of pages on the we but the data is old.

http://www.clubwrx.net/forums/engine...-formulas.html
http://www.gnttype.org/techarea/misc/octanebooster.html
gas facts- http://www.faqs.org/faqs/autos/gasoline-faq/