Bluebyyou
Expert Class
Gettin My Curve On
Posts: 276
|
posted November 23, 2008 04:20 AM
Running lower octanes explanation
I've read many posts about using 89 or even 87 octane and making more power. I'm not sure I understand this logic since 92 is clearly recommended with our 12/1 compression ratio engines. If you use lower octane do you have to change the timing to compensate for it and not constantly detonate?
____________
2007 Bad to the Bone ZX-14 flies out, full Muzzy exhaust system, PC III, BMC race
  
|
pazx14rider
Zone Head
Posts: 953
|
posted November 23, 2008 06:15 AM
Higher octane fuels have more additives in them. A higher octane fuel will give you better fuel milage where as a low octane will give more hp.I dont know what your set-up is, i wouldnt run low octane with a stock set-up. all of us that run low octane have exhaust, pc111, and a different map, and no secondaries. and no need for timing changes either
|
Mark524
Expert Class
Posts: 297
|
posted November 23, 2008 06:27 AM
The higher the octane rating, the more resistant the fuel is to combust. This helps to resist detonation. Detonation occurs when cylinder pressures are high enough to combust the fuel before the spark plug fires. Running high octane gas kills power because it's harder to ignite. You only need it when compression or a power adder increases cylinder pressure to the point you need to raise the octane. My motor is 13:1 and 94 pump gas works and I use C16 with nitrous.
87 seems to work in most stock bike motors. I don't know why it works on bikes. I know I wouldn't put 87 in a 12:1 car motor.
|
bigdtd
Needs a job
Interceptors
Posts: 4209
|
posted November 23, 2008 06:37 AM
 Edited By: bigdtd on 23 Nov 2008 14:39
lower octane is quicker burning and can cause detonation, if you can run it without any detonation it won't hurt. most folks that race run wide open so there is no lugging at low rpms and less chance of detonation. if you ride primarily street the octane is an insurance policy against heat and lugging it, both which will cause detonation. for the street most have had no problem with 89. i use 93 most of the time but use 89 when i know i am going blasting in limited traffic situations like out in the country. folks that i know that race have proven the lower octane makes more power and the bikes run lower times.
____________
2006 Black ZX-14,6 inches over,16/42, flies out,BMC Street Filter,Brock's Street Meg,Brock's Radial Mount Strap,PClll with Race map,Dynojet LCD w/Techmount, ZX-14 fender eliminator,Pilot Power2CTs,Speedohealer,Pazzo Levers,Cox Radiator Guard, Garmin Nuvi 265WT
|
Shane661
Needs a life
Posts: 11494
|
posted November 23, 2008 06:42 AM
Since the lower octane fuel burns more quickly, it is somewhat like advancing the timing. This can increase power. For example, you may see someone running 93 octane, but advancing the timing a few degrees to increase hp. What they are actually doing is igniting the fuel sooner since it takes longer to burn.
When riding on the street you have to look at the kind of load you are putting on the engine. If you lug the engine at low rpm and run it hot in traffic all of the time, I would run the higher octane fuel. The demands of the dragstrip and the street are very different.
Anyway, that is just my basic understanding of things. I'm sure that someone else can explain it better.
Shane
|
Bluebyyou
Expert Class
Gettin My Curve On
Posts: 276
|
posted November 23, 2008 09:23 AM
Edited By: Bluebyyou on 23 Nov 2008 17:24
Ok, here are my mods so far: PC III USB, BMC Race filter, Secondary Flies removed, Fully Muzzy 4 into 1 exhaust with a M10 meg, air injection system plugged and disabled. I ran 89 once because I had to, and had no issues. Also I never ever lug this bike, I bought it to ride hard and fast and thats basically all I do. Now what say ye ole wise ones??
____________
2007 Bad to the Bone ZX-14 flies out, full Muzzy exhaust system, PC III, BMC race
|
rACeRs
Expert Class
Posts: 413
|
posted November 23, 2008 09:39 AM
very good replies, and on a side note I tried 89 and 87 pump gas at the track yesterday and I ran the same exact mph on both of them.
____________
tiwinder, lowered and strapped, pc5 w/ brocks pump map, 40t rear
9.1 @ 149 w/ 1.57 60' SWB
|
kaw now
Expert Class
Posts: 446
|
posted November 23, 2008 01:32 PM
I believe the reason these bikes get away with high compression and lower octane gas has something to do with the combustion chamber design. The chambers are flat and smooth this is as a result of the valve angles in relation to the pistons. I remember reading that hemi head engines required more ignition advance than other engines because the cylinder shape caused a slow burn of the fuel and slower rise in peak cylinder pressure. Old automobile chamber designs had shrouded areas around the valves creating hot spots in the combustion chamber which would result in detonation. In relation to cars it may also be the total volume of gas and the size of explosion in the combustion chamber creating a lot more total heat in one area as well as the weight of the car itself.
|
smokinzx14
Needs a life
Posts: 10197
|
posted November 23, 2008 02:47 PM
quote:
I believe the reason these bikes get away with high compression and lower octane gas has something to do with the combustion chamber design. The chambers are flat and smooth this is as a result of the valve angles in relation to the pistons. I remember reading that hemi head engines required more ignition advance than other engines because the cylinder shape caused a slow burn of the fuel and slower rise in peak cylinder pressure. Old automobile chamber designs had shrouded areas around the valves creating hot spots in the combustion chamber which would result in detonation. In relation to cars it may also be the total volume of gas and the size of explosion in the combustion chamber creating a lot more total heat in one area as well as the weight of the car itself.
True and add tha fact that the head is made of alum and not cast iron .. As a rule you can use one more point of compression with alum Vs cast iron ...The hemi head or pentroof cambers can take a full point of compression over a wedge style chamber..
____________
Smokin Performance Cycles..
Tampa Bay , FL .. Brocks Performance Dealer ..
Gen 2 ZX14R Best ET 8.43 , Best MPH 164.95
|
kaw now
Expert Class
Posts: 446
|
posted November 23, 2008 04:56 PM
Hadn't thought about the aluminum head dissipating heat faster but good point thanks for the info.
|
kawboy81
Expert Class
Busa Eater
Posts: 273
|
posted November 23, 2008 06:22 PM
and to think ive been using 93 since ive had her........ so why use race gas at the track, i use c12, if lower octane makes more power? i mean the logic is there..... higher octane burns slower, so yes advance the timing a few degrees to make some power but running 87 does the same thing?
____________
07 LE bolt on bike
|
ninja12
Needs a job
Posts: 3310
|
posted November 23, 2008 07:34 PM
Starting a slow burn early vs starting a fast burn later.
Which do you think will be the most accurate way to control peak cylinder pressure?
|
kawboy81
Expert Class
Busa Eater
Posts: 273
|
posted November 23, 2008 08:20 PM
i honestly couldnt tell u lol, im not a engineer by no means...... just logic again speaking it depends on when it makes peak power during the stroke? im sure its thousandths of a sec, would it even matter? someone please help lol my head is about to expload.
____________
07 LE bolt on bike
|
kawboy81
Expert Class
Busa Eater
Posts: 273
|
posted November 23, 2008 08:22 PM
thats why i loce this board seriously...... we have some very intelligent people in here.......
____________
07 LE bolt on bike
|
FastestBusaAround
Needs a life
I eat Fish...
Posts: 7889
|
posted November 23, 2008 08:54 PM
I run 87-89 most of the time and have no audible detonation issues I can detect...it runs fine and runs just as cool as 91+
____________
FYYFF!!!
|
KawaBonzai
Zone Head
Leader of the Back.
Posts: 537
|
posted November 23, 2008 09:52 PM
Hey guys!
This is great info. it seems to be a common question and also a subject not well understood.
I want to write a FAQ on this issue and how it relates tot he Zx-14. Anyone object if I use info in your posts for real world facts?
____________
PC-III w/USB, Muzzys M14 + Carbon Oval + M10, BMC Race Filter, Flies Out, Buell Pegs, Heli Risers
www.TucsonSportRiders.com - Tucson's Premier SportRider Community
|
kawboy81
Expert Class
Busa Eater
Posts: 273
|
posted November 23, 2008 11:02 PM
no objection here......as ive not yet to understand
____________
07 LE bolt on bike
|
WindSwordNinja
Expert Class
Posts: 203
|
posted November 24, 2008 09:03 PM
Hey I bet Pissear could explain it!
Somebody send him this thread.
____________
2014 ZX14 Black and Green
2008 ZX14 Black and Red SE
1986 ZX1000R Black
"Faster, faster! Faster would be better!" (Serenity)
|
KawaBonzai
Zone Head
Leader of the Back.
Posts: 537
|
posted November 25, 2008 12:48 PM
quote:
Hey I bet Pissear could explain it!
Somebody send him this thread.
Ok, whats the deal with PissEar? Is that like an inside joke?
I have to concentrate 140% when reading his posts to hunt for and find the meaning.
Clue us in please.
-B
____________
PC-III w/USB, Muzzys M14 + Carbon Oval + M10, BMC Race Filter, Flies Out, Buell Pegs, Heli Risers
www.TucsonSportRiders.com - Tucson's Premier SportRider Community
|
bigdtd
Needs a job
Interceptors
Posts: 4209
|
posted November 25, 2008 06:34 PM
once you get the decoder plugged in it all makes sense with pissear
____________
2006 Black ZX-14,6 inches over,16/42, flies out,BMC Street Filter,Brock's Street Meg,Brock's Radial Mount Strap,PClll with Race map,Dynojet LCD w/Techmount, ZX-14 fender eliminator,Pilot Power2CTs,Speedohealer,Pazzo Levers,Cox Radiator Guard, Garmin Nuvi 265WT
|
KawaBonzai
Zone Head
Leader of the Back.
Posts: 537
|
posted November 28, 2008 11:13 AM
Where can I get this decoder?
____________
PC-III w/USB, Muzzys M14 + Carbon Oval + M10, BMC Race Filter, Flies Out, Buell Pegs, Heli Risers
www.TucsonSportRiders.com - Tucson's Premier SportRider Community
|
Billzx14
Parking Attendant
Posts: 8
|
posted November 28, 2008 06:18 PM
I been running 87 in my 14 best mpg came with it as well 39 mpg most of the time 36 to 37 mpg
|
reward69
Expert Class
Posts: 101
|
posted November 28, 2008 06:36 PM
Remember too that the factory recomendation also takes into consideration the loss of octane from old gas. 91 octane thats old could be as low as 88 or 89. This also holds true for lower grades. The one benefit higher octane gives you is the capability to run more timing if this helps your particular set up. My bike didnt like 87, but runs fine on 89 and cant tell any difference in 93 from 89. A few pennies saved is a penny earned??
|
|
|
HOME
NEW TOPIC