octane ratings

[xjon]

Well that is my question also. At the beginning of this post there is the first post that says Japanese 98 = 91 US rating. Then it is followed by Japanese 100 mon = 112 US.

First of all, what is the recommended Japanese octane rating for the rb? Second, what is the real conversion from mon rating to our rating? I know R+M/2, but what is the "R"?

[Wulfgang]

R is "research" octane number, M is "motor" octane number. Both numbers are determined by measurement on a standardized single-piston engine with variable compression ratio, but the load conditions for the research number are less demanding than those for the motor number. Thus R is always higher than M, and the average of the two (R+M)/2 is used at the pump in the US.

Don't know about the Japanese gas. Someone have any real knowledge on this? Not just hearsay?

[Demonic240]

This is all the info I can provide...

R = RON M = MON

[Wulfgang]

Ok, here's what I was looking for, sort of. From this, it seems that the Japanese use RON, which is the higher number. Thus, Japanese 100 octane gas should be equivalent to about 94 octane USA gasoline.

http://www.iash.net/newsletter/news19/technews.htm

And that seems about right, because if the Japanese were really running the equivalent of 100 octane (or 110!!!), these turbos could easily be running at closer to 20 psi from the factory.

[Wulfgang]

Also found #'s for toluene from API project 45, but I found something that says modern blending #'s are a bit lower. Anyway, here they are.

RON = 124MON = 112

So when you mix it with your pump gas, you should count it as (124+112)/2 = 118 octane in your calculations.

[WDRacing]

Ok...here's how I tuned my RB for high boost, 28 psi on stock internals. I ran a standalone alky kit, best idea ever. I was able to increase my boost 8 lbs by adding alky. Prior to that I used alot of toulene. I have always used a MSD Knock meter. So I could slowly add boost while monitoring for any signs of detonation. When I would reach the limit of my injectors, I would add toulene in proportion to how many gallons of gas I was was using. Just to keep track of where I was and what boost level could be run. I wouldn't ever use this method without some kind of knock meter. I was running 13.7/1 AF ratio's at some points. Only because of the alky and toulene. Normal pump gas will preignite long before you see those kinds of AF ratio's. But believe me, there is a ton of power to be made over 12.5/1.

I also had access to RB's for 200 bucks, so if I blew one up, a quick trip to the junkyard and I had a whole new motor.

As a reference though, Kenne Bell says that for every point of octane you go up, you should be able to add 2 lbs of boost.

Trust me when I say this, the best thing I've ever purchased, aside from a wideband O2 Datalogger, was my MSD Knock Meter. It has saved me so many times, it has literally paid for itself many times over.

WD

[xjon]

wulfgang- toulene is 118 octane instead of 114? Back to the calculator again!

thanks

wdracing- what was the max amount of boost with the stock injectors using both toulene and alky injection? (if you bothered playing with the stock injectors)

[Wulfgang]

Yeah, 118 by API 45, but like I said, they mentioned something about new numbers being lower because refinery streams are higher octane now. Not sure why that matters.... I'll try to find out.

[Tastyratz]

for us something with a better MON rating is better. ron and mon are figured with 2 of the same engines. i dont know exact numbers so consider everything i write bull till you find real numbers, its just examples and misinformation. ron is figured for normal engines, they run the motor at like 500 rpm with an air inlet temperature of 100 deg. and see when it knocks. then MON is for "passing" ability performance. this is when they take that same motor to 1500 rpm, and with an air inlet temp of 300 deg. then see when it knocks. thats why ron #s are always higher, cuz it doesnt knock as easily as a motor getting beat when your driving around town. when you go to the pump, remember the station with the higher mon before averaging is the better beater gas. again those numbers were pulled out of my *** for purely getting the point across, although i think they are just about right i cant confirm it so dont quote me on them.

P.S.btw xjon: thats a little generic a question. how much pressure alky, what size nozzle, how much toluene, whats the base fuel, whats the timing at... etc. etc. etc. generally you have to kinda just play with it yourself and see where it goes.

[S13Sil-line]

This is some pretty amazing stuff. So I take it you can get a lot of hp out of the stock fuel system doing this? And will it mess with emissions if you try to go through emissions doing this or does it help?

[WDRacing]

wulfgang- toulene is 118 octane instead of 114? Back to the calculator again!

thanks

wdracing- what was the max amount of boost with the stock injectors using both toulene and alky injection? (if you bothered playing with the stock injectors)

28psi on stock injectors, but a standalone alcohol injection system.