brendasue555
Expert Class
Posts: 436
|
posted November 29, 2008 10:29 AM
Detonation and pre-ignition from a girls understanding.
This is what I have learned about what hurt my bike and made me cry! In the cumbustion chamber it is ideal to have the location of peak pressure at 14 degrees after top dead center. I think this is true for practically every combustion engine. This is the place where the piston should be to get the maximum work out of the combustion process. So depending on the design of chamber and the burn rate of the fuel you would want to start this process with the spark at whatever degree before top dead center it would take to cause the controlled burn's peak pressure to be at 14 degrees after top dead center. Now detonation is caused by left over fuel being ignited by hot spots in the chamber(for example an exaust valve) at a point after the normal combustion process. Pre-ignition is caused when the fuel in the chamber is ignited prior to the spark in the normal combustion process. Each of these things is able to cause the other to happen. Pre-ignition can lead to detonation and vice versa. Pre -ignition is the most damaging of the two because it happens when the piston is still on its way up and last a long time detonation is a spike that happens when the piston is on its way down. Detonation causes a snowball effect on the engine becasue of the spike of pressure causing a shockwave effect in the chamber that disrupts the thin layer of gas that protects the piston head and the cylinder causeing it to over heat causing more detonation causing it to over heat and so on. Pre-igniton usually causes failure in high compression engines within seconds. There is a lot more to it but this is my basic understanding. So do I have it right?
____________
Brenda
  
|
flite leader
Zone Head
Posts: 651
|
posted December 05, 2008 09:47 AM
some engines have run as much as 50 degrees advance ignition timing
many engines today rarely get beyond the mid to hi 30 degrees ignition advance
almost all engine maunfacturers realize that the optimun cylinder size is around 100mm
thats because even after you ignite the proper mixture
it take time for it to travel across the cylinder
at 14 degress after top dead center..........................maybe a diesel
but a gasoline engine altho it would run will show very BAD perfiormance figures
there is a factor called "blow down" as a result of speed of the piston moving
in most performance engines at 30 to 35 degrees after top dead center
aint nuthin happn !!!!!!!!!!
peak power inside the combustion chamber should occur in the first 5 degrees
____________
bend your mind.....
or break your ass...!!
|
aliveagain
Needs a life
Posts: 5033
|
posted December 06, 2008 08:24 AM
quote:
some engines have run as much as 50 degrees advance ignition timing
many engines today rarely get beyond the mid to hi 30 degrees ignition advance
almost all engine maunfacturers realize that the optimun cylinder size is around 100mm
thats because even after you ignite the proper mixture
it take time for it to travel across the cylinder
at 14 degress after top dead center..........................maybe a diesel
but a gasoline engine altho it would run will show very BAD perfiormance figures
there is a factor called "blow down" as a result of speed of the piston moving
in most performance engines at 30 to 35 degrees after top dead center
aint nuthin happn !!!!!!!!!!
peak power inside the combustion chamber should occur in the first 5 degrees
Never thought about that but makes sense.As far as optimum cylinder size,would that be why the big bore harleys and old big bore dragbikes went to two spark plugs?
____________
I wondered why the baseball kept getting bigger. Then it hit me.
|
flite leader
Zone Head
Posts: 651
|
posted December 06, 2008 09:21 AM
2 spark plugs help
ducati.......ferrari .....porsche & chevy found the optimun size [also very RPM related]
the speed at 10k rpm is a totally different factor than at 15k rpm or 5k rpm
in F1 & motoGP engines that rev from 10k to 20k the piston moves past optimum on the
down stroke very quick
on the preigniton detonation factor...... the diametre of the piston at that speed is the next
huge factor
gas will only burn so fast...........will only cover a definite distance !!
if blow down occurs b4 that distance is cover ......wasted cylinder diameter
even if you could turn a harley type engine 15k [it is possible !]
the cylinders are toooooooooo wide !!!
still all the cylinder configurations hovering around 100mm actually do more to shape
the torque than HP
no less valve area to cylinder diameter ratio etc
no doubt in ALL of them you NEVER want preignition or detonation
thats why everyone has been waiting for DIRECT INJECTION in mass production
long since a staple of diesels........................im thinkin porsche 1st at bat with gasoline
putting a finite spray of Gas into the cylinder at the optimum spot
there are places that literally get NONE
a gasoline engine operates at about 30-40% inefficiency
direct injection could lower that considerably
many hold onto the misconception that injection MAKES power...............................
depends on HOW you look at it....the perspective
by decreasing the negatives.......................maybe increasing a few positives
YES one has more power
you could still slap a pair of KEIHIN flatslide CRs on a 12 & make the same or more HP
its been done b4
in some places there would be glaring disadvantages except at the one place
we all like
WFO ! ! ! ! ! ! ! ! !
____________
bend your mind.....
or break your ass...!!
|
brendasue555
Expert Class
Posts: 436
|
posted December 06, 2008 09:29 AM
one step forward two steps back,.......... so with keihin 41mm flatslides on a zx11 what size pistons would you think optimum?
____________
Brenda
|
flite leader
Zone Head
Posts: 651
|
posted December 06, 2008 09:55 AM
 Edited By: flite leader on 6 Dec 2008 18:30
this is how i would approach that situ....... i assume its drag racing or street racing
[im a road racer.......altogether different tuning.......it wouldnt be an 11]
i would install the lightest ...strongest pistons & rods available
free up the revc limiter at least 1000 to 1500 rpm
port the head lite to medium.............install a crank wiper & watch out for the #3 cylinder big end that is prone to go........usually oil starvation
MTC.......APE ........or Falicon can hhelp you with the crank
run the best gas available & increase ignition 3-5 degrees
i wouldnt put bigger cams.............reason being if you increse flow& REVS......
thats about all you can do without grenading
____________
bend your mind.....
or break your ass...!!
|
brendasue555
Expert Class
Posts: 436
|
posted December 06, 2008 01:02 PM
HMMMM, well I think it has a muzzy 3x something and falicon knifer rods and lightened somethings and a stroked cranker magiggy, or something like that.
I think it had/has? 200hp but likes WOT I am in way over my head here so let me just stop and go read some things and try to understand the things you are trying to tell me. oh and it also has a dyna 2000 ignition . Anyway this has givin me something to wrap my brain around then I will try to tell you if I agree and will definately let you know what I end up with. thanks so much for takeing the time to share your knowledge I appreciate you .
thanks again
brenda
\
____________
Brenda
|
flite leader
Zone Head
Posts: 651
|
posted December 06, 2008 01:19 PM
ok i can understand your situ
yet you didnt start with a valid question about setting up a ZX11
how to set up a ZX11 is far from starting at detonation & preignition
2 things you need NOT worry about if your set up is correct to start with
have a basic plan.................then stick to it
tooooooooooo often guys.....or girls get into buying parts
rabid conversation & inverse HP gains as a direct result
put you bike together correctly........set up your suspension correctly
get it running..................ride it .................check it again then worry about making HP
gains are made judiciously & incrementally.............NOT by leaps &bounds
a ZX11 has been set up & raced 100000 times so essentially you are NOT
breaking New ground & you WONT
if you do whats already been done you willhave a fast bike
if you avoid ALL the mistakes ever made
you will save a ton of $$$$$$$$$$$$$ & be happy
check with doug meyer or vincent hill
they can do a ZX11 in their sleep
good luck
____________
bend your mind.....
or break your ass...!!
|
brendasue555
Expert Class
Posts: 436
|
posted December 06, 2008 06:41 PM
oh ok I guess we have not communicated in a way in which we are on the same page. I thought that you knew why I was on the detonation learning extravaganza. lol........... I guess for you to understand where I am coming from you need to go to the dragbike forum and start reading from the post called Doug's old Bonneville bike. I am sorry I took it for granted that you knew. I appreciatte your help but I dont think I am that smart yet. I am having a hard time just understanding the basics and all i really want to know is everything. Hope to hear from you again!
Brenda
____________
Brenda
|
aliveagain
Needs a life
Posts: 5033
|
posted December 07, 2008 09:15 AM
Your having a hard time understanding the basics,I'm learning from you! 
____________
I wondered why the baseball kept getting bigger. Then it hit me.
|
brendasue555
Expert Class
Posts: 436
|
posted December 07, 2008 09:25 PM
what do you mean?
____________
Brenda
|
flite leader
Zone Head
Posts: 651
|
posted December 08, 2008 07:43 AM
quote:
oh ok I guess we have not communicated in a way in which we are on the same page. I thought that you knew why I was on the detonation learning extravaganza. lol........... I guess for you to understand where I am coming from you need to go to the dragbike forum and start reading from the post called Doug's old Bonneville bike. I am sorry I took it for granted that you knew. I appreciatte your help but I dont think I am that smart yet. I am having a hard time just understanding the basics and all i really want to know is everything. Hope to hear from you again!
Brenda
ok i understand the confusion
if you really wantt o KNOW something........ask a specific question
running at bonneville at 200+ mph under "LOAD" + alttitude presents factors
encountered NO where else in the world ! ! ! ! !
if its just a starbux conversation you wish to engage in
that could go on forever
& you still might not learn anythingas a result of TOO MANY VARIABLES
why assume i was answereing on a nother thread on another forum
we should BE on That Thread on THAT Forum
that would eliminate a LOT of confusion
no less from Dougs years of REAL WORLD experience i doubt i could add
anything you what he has already said
but..................................................................[ & theres always a butt !}
detonation is rarely encountered unless
the ignition is advance toooooo hi
crappy fuel
increased compression + the first two
or there is a spike in the LOAD
if you havent skimmed the head
if you are not running more than 12.5 compression
if you are not using pump gas.............if you are competing "VP" offers you approx 2 dozen
if your ignition is set at standard.........& it always should be on skake down runs
if you have adequate fuel supply
& you aint runnin NOS which isa whole nutha witch unto itself
Concern about Detonation or Preignition should be a minimmun or NON Factor !!!!
now out of ALL the above listed factors [& i might have missed a few]
one could do 1 1k word essay on each & still maybe miss an actual
factor or event while actually racing
so a shotgun approach conversational excercise will probablt lead to more
"he said" than actual knowledge being exchanged
____________
bend your mind.....
or break your ass...!!
|
KZScott
Needs a life
high on speed
Posts: 7235
|
posted December 23, 2008 03:35 PM
quote:
Never thought about that but makes sense.As far as optimum cylinder size,would that be why the big bore harleys and old big bore dragbikes went to two spark plugs?
the main reason for old school drag bikes to dual plug the head was because of the design of the combustion chamber and piston. because they were a 2 valve head, there was no room in the middle for a spark plug, so it got shoved over to the side. now introduce super high compression pistons with a huge dome sticking up into the combustion chamber. typical drag bike stuff. the dome of the piston actually gets in the way of the flame front and you dont have a very good burn. the air/gas on the opposite side of the CC as the plug doesnt burn correctly. put another plug on the other side of the CC and you get dual flames travelling correctly, meeting in the middle, making more power with less timing. (i think they usually took out 2 degrees when they dual plugged a head on a KZ)
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
|
|
HOME
NEW TOPIC