I was looking around on Kawasaki.com and for the ZX10R they have a piston/rod kit that is lighter and raises the CR to 14.3:1 Now i know nothing about the ZX10R's engine but what do you think the highest CR that could be run on 91 & the highest for 93? i know this is different from engine to engine but just for the sake on conversation.http://www.kawasaki.com/defaul...d=565

 

All I can say is "wow"!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Khmai_guy &raquo;</TD></TR><TR><TD CLASS="quote">All I can say is "wow"! </TD></TR></TABLE>

yeah thats what i thought! just looking at that piston... it looks like it came out of a F1 car

 

i was told piston / cr's act differnetly in a bike than from a car in reference to ocatane rating...maybe i'll try to dig up that post.

think about it.. my bike stock has 12.0 c/r yet recommends 87, think a 12.0 gsr would last more than 5 minutes on 87? haha

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RedStarGsr &raquo;</TD></TR><TR><TD CLASS="quote">i was told piston / cr's act differnetly in a bike than from a car in reference to ocatane rating...maybe i'll try to dig up that post.

think about it.. my bike stock has 12.0 c/r yet recommends 87, think a 12.0 gsr would last more than 5 minutes on 87? haha</TD></TR></TABLE>

I'd venture a guess that's because of temperature control issues, which, again, are going to vary significantly from bike to bike.

Octane rating is all about stopping pre-ignition. This, of course, is a function of temperature. Cars don't exactly get ideal engine airflow, thus they run hotter and require higher octane fuels for similar compression ratings than their two wheeled counter parts. Stick a one liter (or smaller) power plant right in the middle of 70mph airspeeds and you'll find that it:

a) generates less initial heat (thanks for lower overall mass [I'd guess that this is only true to a point. Conventional auto gasonline engines have higher rotating masses than motorcycles; they spin more slowly than a bike engine will, but a conventional 7,000rpm redline is nothing to balk at and they generate a good amount of heat... however, very large, 1,000 rpm redline engine [[which reaches peak efficiency around 350 rpms]] generates very little heat. Showing that the thermal efficiency of [gasoline] engines is a *roughly* parabolic curve when related to displacement.]

and

b) is able to shed that heat much more quickly than a car.

Cooler running temperatures translate to, as in the begining, a lower likelyhood of pre-ignitiion (detonation) and lower octane ratings.

I think what I just said translates to "motorcycles are very efficient."

 

ok well 14.3 vs 12 is a 16.1% higher CR. so in theory from CR alone thats 16.1 higher temp. i know their are 1,000,000 other factors but do you think a 14.3 could run on 91?

 

Can somebody supply average operating temperatures and octane requirements for a couple daily drivers and a couple bikes? Offhand, I don't know any. None of my vehicles have digital gauges.

 

my buddys r1 has that option i think..maybe its intake temp, i'll ask

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ASteele2 &raquo;</TD></TR><TR><TD CLASS="quote">Can somebody supply average operating temperatures and octane requirements for a couple daily drivers and a couple bikes? Offhand, I don't know any. None of my vehicles have digital gauges.</TD></TR></TABLE>

03 ZX-6R and I average around 170-190 operating temps with a octane requirement of 91 or above.

and yes, my manual states that 87 should be ok, but it recommends that it should be replaced at the next fill up with 91 or above.

 

It has to do with the fact that car engines are designed for fuel economy,
while sportbike engines are designed to extract the most power from the fuel.
There is a reason why a .6l sportbike gets worse fuel economy than a car thats
7 times the weight, and has a motor three times the size. Strain on the engine
has a lot to do with it also.

Motorcycle and car engines are very different animals...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rioninja &raquo;</TD></TR><TR><TD CLASS="quote">There is a reason why a .6l sportbike gets worse fuel economy than a car thats 7 times the weight, and has a motor three times the size. Strain on the engine
has a lot to do with it also...</TD></TR></TABLE>

I get over 50mpg on my R6 while beating the **** out of it...what do you drive, a prius?

You have no idea what you're talking about.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nims &raquo;</TD></TR><TR><TD CLASS="quote">
I get over 50mpg on my R6 while beating the **** out of it...what do you drive, a prius?
You have no idea what you're talking about.</TD></TR></TABLE>

Dont I?
http://www.sportrider.com/bike...amaha
Just some average fuel economy figures for a few modern motorcycles.

And just so you know, "beating the ****" out of a motorcycle, usually means
you take it over 4k on the tach once or twice a tankful.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rioninja &raquo;</TD></TR><TR><TD CLASS="quote">Dont I?
http://www.sportrider.com/bike...amaha
Just some average fuel economy figures for a few modern motorcycles. </TD></TR></TABLE>
While the mileage for my bike listed there is much lower than I've actually measured on multiple tanks, it's still higher than average for a car.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rioninja &raquo;</TD></TR><TR><TD CLASS="quote">
And just so you know, "beating the ****" out of a motorcycle, usually means
you take it over 4k on the tach once or twice a tankful. </TD></TR></TABLE>
According to whom? In terms of rpm vs. throttle, load has almost everything to do with duty cycle, rpm has very little if you look at some fuel maps.

Fuel Usage is just going to be equal to (Horsepower / (HP per lb/min airflow*AFR))*60

What is really comes down to is power, assuming the motors have similar technologies, styles, etc. It doesn't matter at all how much it weighs, it matters how much power is being output by the motor. I'd really rather not have this conversation anyway, I just finished 4 years of arguing with engineering students and I don't have the energy anymore. Lets just end it with...

Bikes &gt; Cars.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nims &raquo;</TD></TR><TR><TD CLASS="quote">(Horsepower / (HP per lb/min airflow*AFR))*60
</TD></TR></TABLE>

thats exactly what i was thinking

jk
i'm going to go back to my finance homework

 

I was using generalizations to make a point.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nims &raquo;</TD></TR><TR><TD CLASS="quote"> assuming the motors have similar technologies</TD></TR></TABLE>
That was my point. They dont.
But i'd rather not argue with you.

/discussion

 

i think due to their being smaller combustion chambers less heat is stuck in the cylinders. I agree with the post above. Fuel doesn't just burn and not go anywhere. Energy cannot come from nothing and it cannot disappear into nothing. The energy from that fuel is going somewhere. A/F ratios being richer on a bike (stock) cant be because you do half to keep in mind we do have an EPA. the EPA isn't going to be letting us DUMP massive amounts of unburned fuel out of the exhaust. the energy that comes from the fuel is Heat which the engine "tries" to convert to reciprocating motion. the problem is that a very small amount of that energy is actually converted. 10% is lost and 70% lost through the exhaust only 20 to 25% actually gets used. so you could argue and say that the higher revs is loosing more power due to friction which exhaust aside, that 1/3 of the power. but yeah its almost 3 im tired im going to go more into this after i get some sleep

 

that didn't make ANY sense... you should start over when you aren't tired.

 

Peak combustion chamber pressure is a function of the piston and cam design. Its not just the piston that matters here. High rpm engines like lots of overlap, open valves bleed off pressure. 14.3:1 does sound really really high thoz. Like methanol high.

 

smaller combustion chambers resist detination better(sp?), like the gsr 1.8 litre vs. a .6 litre sport bike , gsr is 3 times the size !

 

Oy! What the hell happened?

Don't you guys understand how fuel is used?

 

ok first off, engine physics are like the butterfly effect. The "Butterfly Effect", or more technically the "sensitive dependence on initial conditions", is the essence of chaos. A tiny difference in the initial conditions becomes amplified by the evolution. of course engines are quite a bit more predictable then long term weather but you get the idea. there are millions of variables that we cant possibly calculate so in turn we estimate. all engine technology is theory, trial and error.

smaller engine = high % heat dispersed
If you have 2 cylinders, 1 is 50mm in diameter and 50mm tall (98cc) and the other 100mm X 100mm (785) not including head area or piston area, only only cylinder wall the smaller piston has 157^2mm to let off heat wail the larger piston has 314^2mm. that means that the larger piston is 801% bigger but only lets out 2 times as much heat more heat. (in theory)



Modified by hks85 at 1:19 PM 6/24/2005

 

I now remember why I left this forum the last time

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nims &raquo;</TD></TR><TR><TD CLASS="quote">I now remember why I left this forum the last time</TD></TR></TABLE>

lol

 

I didn't mean that in a good way

 

You left the forum because of people like hks giving you headaches?