What octane to use

[Willtill]

Hi all,

I am a little confuse with the required octane for my new Rocket 3. The salesman told me to use premium (92), the book says 89 or higher. This is not a high compression engine, is it?

Can I get by with regular unleaded?



Kindest regards,


-Will

 

[Blastedbones]

In Aus, we have 91,95 & 98 octane rated fuels; rated as regular, premium & ultimate( although i'm not sure if those ratings corrispond directly with U.S. fuels). The rocket doesnt like 91 if youve piped & tuned it.. runs rough. 95 works fine however, as does 98, which is supposed to be the cleanest fuel.I doubt you will notice any OTR performance difference between 95& 98 in an unmodified engine, mebbe a couple more MPG is all.

 

[Willtill]

Ha! Ok, sounds like Premium (or 89) is the stuff! Thanks!


Kindest regards,


-Will

 

[xhdskip]

I've used 87 in mine for over 20,000 miles now with no problems,
and it runs fine.
Have the 5 K&n's on it and a custom exhaust.
Why pay more, its not a high compression motor and with 87 octane,
it'll still do just fine..

 

[tdragger]

WillTill, I'm not sure what country you are in but the numbers are different depending on whether you are in a RON country (most of world) or an (R+M)/2 country like the USA. These are the octane measurement standards

For the USA and the (R+M)/2 method, you want to use 89. It is a waste of money to use premium and a lot of us that have tried it found that it actual led to decreased performance.

The RON method is generally 3 points higher so the rest of the world is using 92 octane.

 

[Willtill]

OK, 89 it will be. Thanks ya'll!

:wink:


Kindest regards,

-Will

 

[tdragger]

After reading your intro thread regarding the poor assembly of your new Roc and the inaccurate info about fueling, I would feel good about going back to your dealer.

Clinton Cycles near Andrews AFB is fairly close for you and of course the one out in Frederick would be convenient to you as well. I hear good things about them. I go out to Winchester for my work but that would be a bit far for you. It is for me but its been worth it.

 

[Bc fisherman]

I have always run prem gas 92 or better and I have tors and cat bypas . I will try the 89 and see if it doe change the decel poping and its cheaper

 

[Willtill]

Clinton Cycles near Andrews AFB is fairly close for you and of course the one out in Frederick would be convenient to you as well.

I think I'll visit Clinton cycles soon. Thanks for the advice. I have been at the Frederick dealer several times; the owner seems to be miffed at his mechanics about something

I had waited on them (at the Frederick dealer) to pull a Rocket 3 out of the crate but gave up. So Pete's Cycle up in Baltimore got my business.

Kindest Regards,

-Will

 

[tdragger]

A parameter of octane rating is resistance to ignition and the rate of combustion.
Higher octane; higher resistance to ignition and a more controlled combustion rate.
Higher octane is for compression ratios of 10:1 or higher and or hotter (temperature) engines to eliminate pre-detonation.
A quality 89 octane (US, RM/2) is perfect for the Rocket that still retains OEM compression ratio and timing advance.
I have a Rocket buddy with TORs and cat-bypass that I would hate to ride behind because of all the popping and farting on decel.
One day we are riding and pull in for gas.
I see him putting 93 octane in.........WTF!!!!
I tell him NO!!!...use the 89!!!!....this is why your Rocket sounds like the 4th of July on decel.
He is now convinced and only uses 89...most if not all of the decel popping is gone.
The 93 octane WILL NOT completely ignite in a stock Rocket engine with 8.9 CR and simply collects in exhaust.
During decel when your Rocket engine turns into a 2300cc air pump you get the ingredients for pop-boom-bang!!!
Un-burned fuel, fresh air and a hot exhaust providing a secondary ignition source.
This is all I would like to say.
Hope this helps someone, somewhere....somehow...

Gary

Thanks, Gary. This is what my college professor had described many years ago about the burn and flame-front propagation rates based on octane rating. For a relatively low-compression dump truck (affectionately said) engine like the Roc's, running Premium is a waste.