Porchapa

A friend of mine who drove an 89 n/a streetport recently told me that he used to run 85octane offroad fuel and saw a reasonable power gain. Any thoughts on that?

raptor22

Its possible, these cars can run on surprisingly low octane fuel (the rotary has natural resistance to detonation). But, I'd be really surprised if he could feel any power difference.

Sure, lower octane fuel requires less heat to burn, so you could argue that lower octane fuel would burn faster and free up a tiny bit of power. But, think of it this way, if you switch from 87 to 93 octane at the pump, do you feel a "decent power loss"? No.

The fact of the matter is that changing the octane doesn't change the amount of energy available from the fuel, so the only way that changing octane would give much more power is if you run high octane and high boost.

--Alex

azdk

correct me if im wrong but doesnt lower octane build up more carbon than higher

raptor22

No, higher octane would be more likely to suffer from carbon buildup.

azdk

oh alright thanks

Evil Aviator

Off-road fuel may have a slightly higher energy content, depending on the formula used by the manufacturer. Unfortunately, it is illegal to use off-road fuel in street cars, and the resulting fines would not be worth the small increase in power, if any.

The octane rating is just measuring the fuel's resistance to knocking, nothing else. It does not necessarily indicate carbon build-up, power, economy, mojo, bling, gravitas, or anything else.
http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

No, the primary reason why people think this is because novices tend to run high octane fuel in their turbocharged engines and richen the mixture to "be safe". The rich mixture is what usually causes the carbon build-up. There are many other documented reasons for carbon build-up, but none of them are attributable to the octane rating of the fuel.

arghx

iTrader: (3)

dude. you have an n/a. you know you are scraping the bottom of the barrel when you think lowering your octane will get you an hp or two... just drive the car, it won't make a damn bit of noticeable difference

btw they sell 85 octane at the pump in high altitude areas

MmSadda

iTrader: (2)

. nevermind. I don't want to argue with evilaviator, because he is probably right.

MmSadda

iTrader: (2)

I have an n/a, and my engine rebuilder (Ken Carswell of Rotary Connection in Ohio) said that there is never a need to put anything other than standard 87 octane in an n/a FC.

That is null, however, if you change your 6-port engine to forced induction.

azdk

[QUOTE=The octane rating is just measuring the fuel's resistance to knocking, nothing else. It does not necessarily indicate carbon build-up, power, economy, mojo, bling, gravitas, or anything else.
[url]http://www.ftc.gov/bcp/edu/pubs/consumer/autos/aut12.shtm[/url]
QUOTE]

thanks thatll save me money at the pump for now

Sideways7

iTrader: (7)

Actually, even the TII was rated for 87 octane from the factory.

well uhhh

^ +1 correct me if i am wrong here, but there isn't really a need to use anything higher than 87 in a TII unless boost is increased, correct?

misterstyx69

iTrader: (142)

Isn't the best Octane Rating for an N/A at 83?..(it's On here somewhere,If you search for it,it will "come"!)..and since that isn't available 87 Octane Pump gas is sufficient.

CyberPitz

Yeah, I used 89-90 when I filled up, since I believed when someone told me it's better to prevent detonation, since there is more air coming in. I can't count how much money I could have saved if I stayed at 87

azdk

i know how you feel its depressing haha and yes if you increase compresstion enough you will need to increase octain

Evil Aviator

Higher octane fuel also helps engines that are worn, have hot spots (deposits/sharp spots), or otherwise NEED the higher octane fuel to keep from knocking.

No, I think that myth is from a misintrepetation of the book, "How to Modify Your RX-7" by Dave Emanuel.

The stock airflow meter measures the air so the computer can compensate and inject more or less fuel as necessary.