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Low Octane Fules and Octane Booster

3 March 2002
Oceanside, CA, USA
Here in So California, the highest octane fuel we can buy is 91 Octane

Is 91 too low for 10:1+ engines like the NSX? Does anyone use octane booster products, do those work at all?

I don't have an NSX yet, but my Mr2 Turbo is in dire need of higher than 91 fuel. It's an unhappy pinging baby at full 10-12 psi boost. Are there any brands of octane booster that you all recomend. I bet it's important to you guys with superchargers or turbos. Thanks

-Eric C.

(wish me luck on my first NSX purchase..)
According to the owner's manual, 91 octane or higher is specified for the NSX. You can use less than 91 octane but performance will be lower. IOW, 91 should be fine - at least, for a stock NSX.
Originally posted by EricC:
It's an unhappy pinging baby at full 10-12 psi boost.

It didn't help me with my 1965 327 365HP vette engine. I had to retard the timing and give up some performance.

I'm not sure if octane boost will help you, but if you let it ping at full boost, you won't have to worry about gas much longer. YMMV

keep the shiny side up
MikeC 01 #46
You don't need any octane boost for your stock NSX, even here in Cali with the crappy 91 oxygenated gas we are forced to buy for close to $2 per gallon these days.

Sounds however like you may want to consider it for your MR2 however.

The octane boost you buy in the little bottles for $4-8 each is a total waste of money.

A better solution may be Toluene. A Porsche club freind of mine turned me on to it last year. Sounds crazy, but he swears by it. Take a look at this article:
I recently read an extensive breakdown on fuel and octane in our market today.

The basic summary is very familiar with the article posted. The report stated that one of octanes primary functions is to prevent pinging. It does this by increasing the resistance to ping under combustion.

Octane in gas is mixed via the 50/50 ratio. What this basically means is that if you were to take 10 gallons of 108 octane race gas, and mix it with 10 gallons of 91 octane pump gas you will get the average of both octanes in your tank, yielding a net gain of roughly 8.5 octane and giving you a full 20 gallon tank of roughly 99.5 octane gas to drive on.

The octane booster you buy in bottles are designed usually around a "full tank" of gas, which on todays cars is between 12-18 gallons. The actual net gain of octane is usually LESS than 3 total octane, and the ratio at which it is mixed is very poor. In other words if you have a 12oz bottle of octane boost dumped into an 18 gallon tank, think about the true likely hood that every blast of fuel into your engine will benefit from that bottle of octane boost.

The reality is that isn't the case and that the 12oz bottle will mix-unevenly and in turn you are not really gaining the benefits of having "truely" higher octane, but moreso a chance of having higher octane on one revolution of an engines combustion.

Again remember that octanes primary function is to increase the resistance to ping under combustion. If your engine isn't pinging, there is no need to buy higher octane gas.

How octane is often mis-understood and myth'd to "create more power" is false.

What octane allows you to do is increase the compression ratio (which is where your power comes from). Under higher compression ratios you are more likely to have pinging. To reduce this, you run higher octane gas and hence the myth of octane = power is false.

Increased compression = more power = more chance of ping. Octane increases your resistance to ping, and helps you towards the goal of happy engine life :P

"...How octane is often mis-understood and myth'd to "create more power" is false..."

Well, yes and no.

Modern cars, like the NSX, can adjust timing and engine functions to take advantage of higher octane fuels.

When I was running on the track at NSXPO 2001 - Road America, I needed gas. Rather than leave the track and find a gas station in town I splurged and filled my tank with race gas.


The car ran smoother and had a noticeable increase in power.


1992 NSX Red/Blk 5 spd #0330
1991 NSX Blk/Blk Auto #3070 (Sold)
1974 Vette 454 4 spd Wht/Blk
Looking for 76-79 Honda Accords
Originally posted by Jimbo:

The car ran smoother and had a noticeable increase in power.

I've tried race gas (100 and 105 octane unleaded) in my NSX on numerous occasions and tracks, and never noticed any difference in power from the conventional premium (92 to 93).
Here we have low-octane fuel (95 octanes) and high octane fuel (98 octanes)...

No jokes, we really have hi-octane gas as standard gas but one liter gas costs about 90ct of US$