Honda CBR600RR Discussion Forum

Pics - Videos - Intro's - Misc => Stupid Questions => Topic started by: Zagan on April 18, 2005, 04:28:30 AM

Title: Safe Piston speed
Post by: Zagan on April 18, 2005, 04:28:30 AM
Does anyone know what the safe piston speed is for a CBR 600 RR 04 model is, or all of them I guess as it's the same engine in all of them.

it wouldn't be max rpm on the dial would it?

I've read 4500 feet per minute is safe in racing but that was around 98 or so.
Title: Re: Safe Piston speed
Post by: Jeff on April 18, 2005, 08:55:50 AM
wow... so early in the game and already another candidate for stupid questions!!  Don't take that bad, it's an honor, really!

~160mph... 
Title: Re: Safe Piston speed
Post by: NewRedRider on April 18, 2005, 10:00:55 AM
Does anyone know what the safe piston speed is for a CBR 600 RR 04 model is, or all of them I guess as it's the same engine in all of them.

it wouldn't be max rpm on the dial would it?

I've read 4500 feet per minute is safe in racing but that was around 98 or so.

:-X Piston is connected to the rod and the rod to the crank. The crank is measured in RPM. Therefore, the piston should be rated in RPM?  I've never heard of a piston speed rating. ???
Title: Re: Safe Piston speed
Post by: Jeff on April 18, 2005, 11:20:51 AM
Take the stroke (43.5mm), multiply it by 2 (as it's going up AND down), times that by RPM and continue calculations.

e.g., at 10,000 RPM, the piston is moving 870,000 mm/min or 2854.33 FPM (feet per min).
at 15,000 RPM, the piston is moving at 1,305,000 mm/min or 4281.5 FPM.

The big question is WHAT EFFEN DIFFERENCE DOES IT MAKE?!?!?!  The  bike is designed around a specific redline max RPM.  It's not going to exceed tolerance before that point.
Title: Re: Safe Piston speed
Post by: TopgunRR on April 18, 2005, 02:59:19 PM
Take the stroke (43.5mm), multiply it by 2 (as it's going up AND down), times that by RPM and continue calculations.

e.g., at 10,000 RPM, the piston is moving 870,000 mm/min or 2854.33 FPM (feet per min).
at 15,000 RPM, the piston is moving at 1,305,000 mm/min or 4281.5 FPM.

The big question is WHAT EFFEN DIFFERENCE DOES IT MAKE?!?!?!  The  bike is designed around a specific redline max RPM.  It's not going to exceed tolerance before that point.
:P yay for math. combine these calculations with my rpm to mph breakdown ( http://www.cbr600rr.com/forum/index.php/topic,9435.msg167784.html#msg167784 ) and you can go from piston speed to bike speed! who knows why you would want to....
Title: Re: Safe Piston speed
Post by: 600RRpilot on April 18, 2005, 05:19:09 PM
where did you hear that that was correct for "racing"?  ive never heard of piston speed in relation to anything.
Title: Re: Safe Piston speed
Post by: Jeff on April 18, 2005, 05:23:36 PM
gunRR, that way while going down the track, you can break out your palm pilot and slide-rule to figure out how fast you're going!

My pistons are special.  They go up & down really fast while moving forward really fast too...
Title: Re: Safe Piston speed
Post by: Audiofyl on April 19, 2005, 01:02:33 AM
maybe you should pull your tach and replace it with a piston speedometer.  better yet get 4 of them, one for each piston, just incase one of them is going faster than the others. :P
Title: Re: Safe Piston speed
Post by: frankie on April 19, 2005, 01:12:14 AM
pretty sure he is not coming back.
Title: Re: Safe Piston speed
Post by: Meddiepie954rr on April 19, 2005, 06:21:05 AM
DOOD! HAHAHAHAHAHAHAHAHAHA  :P  This thread is fucking HILARIOUS!!
Title: Re: Safe Piston speed
Post by: Zagan on April 19, 2005, 09:22:16 AM
I'm back just can't look on here everyday.

Safe Piston speed, is the real speed of the pistons that should be safe before they start to break up or detroy your engine.

MAX RPM on the tacho can be higher than the safe Piston speed.

You may think it's a stupid question but back in 1998 4500 in MotoGP was the max limit for Safe Piston speed, in Drag racing it was 5000 feet per second.

Just wondeing if anyone has come across these figures anywhere, I guess you guys arn't in the know.

Title: Re: Safe Piston speed
Post by: 600DubRizzle on April 19, 2005, 10:14:04 AM
I'm back just can't look on here everyday.

Safe Piston speed, is the real speed of the pistons that should be safe before they start to break up or detroy your engine.

MAX RPM on the tacho can be higher than the safe Piston speed.

You may think it's a stupid question but back in 1998 4500 in MotoGP was the max limit for Safe Piston speed, in Drag racing it was 5000 feet per second.

Just wondeing if anyone has come across these figures anywhere, I guess you guys arn't in the know.



Dude, please stop because you're making it worse on yourself.

1.  Racing organizations don't set max RPM or feet per whatever period of time.  The engine builder does that.  Even if the racing organization did......
2.  .......You didn't mention which cc class was under the "4500" rule in MotoGP, or which drag racing organization.
3.  Lastly, bullets don't even travel @ 4500-5000 feet per second.  The engine would blow up as soon as one cylinder got spark.  Sucks too, because that engine would have a ton of power. 
Title: Re: Safe Piston speed
Post by: Jeff on April 19, 2005, 10:33:18 AM
Don't get bent out of shape because we tagged it a stupid question, it's just something that people don't ask every day and it's a fairly unique question you must admit.

As for your last tag about drag racing being 5000 FPS, I'm assuming that was a typo.  In perspective, 5000 FPS on a 600RR would be better than 150,000 RPM's.  At that point you're splitting atoms...
Title: Re: Safe Piston speed
Post by: 600RRpilot on April 19, 2005, 10:48:46 AM
Don't get bent out of shape because we tagged it a stupid question, it's just something that people don't ask every day and it's a fairly unique question you must admit.

As for your last tag about drag racing being 5000 FPS, I'm assuming that was a typo.  In perspective, 5000 FPS on a 600RR would be better than 150,000 RPM's.  At that point you're splitting atoms...

i heard something about a nuclear powered 600rr coming out sometime in 2018. ???
Title: Re: Safe Piston speed
Post by: NewRedRider on April 19, 2005, 10:55:22 AM
:P :P :P Please make it stop!!!!!!
Title: Re: Safe Piston speed
Post by: JQrr on April 19, 2005, 11:10:08 AM
i heard something about a nuclear powered 600rr coming out sometime in 2018. ???

 :P :P 
Title: Re: Safe Piston speed
Post by: Crash on April 19, 2005, 11:26:45 AM
i heard something about a nuclear powered 600rr coming out sometime in 2018. ???

I dont know if they are going to have it ready by then but you can bet by 2009 we will be seeing hydrogin (sp) sportbikes. :spank:
Title: Re: Safe Piston speed
Post by: JQrr on April 19, 2005, 11:35:01 AM
I dont know if they are going to have it ready by then but you can bet by 2009 we will be seeing hydrogin (sp) sportbikes. :spank:

HYDROGEN.  Hydrogin is something you might find at a bar...
Title: Re: Safe Piston speed
Post by: Crash on April 19, 2005, 12:50:45 PM
HYDROGEN.  Hydrogin is something you might find at a bar...

Did you notice the (sp) after that?  God damn dude, I said it was misspelled and you still went spelling Nazi on me. :-X ::)
Title: Re: Safe Piston speed
Post by: some_guy79 on April 19, 2005, 02:35:11 PM
stop flaming the guy, he asked a valid, if uninformed question. Maximum piston speed is an important factor in engine wear and catastrophic failure. The problem is, no one outside the walls of the  Honda engineering department is going to know about that. Okay, maybe some people on top level race teams, but still very few.
Title: Re: Safe Piston speed
Post by: JQrr on April 19, 2005, 02:48:53 PM
Did you notice the (sp) after that?  God damn dude, I said it was misspelled and you still went spelling Nazi on me. :-X ::)

I saw the (sp).  You weren't sure, so I corrected you.  Spelling Nazi?  Haha.  Shut up and get back on your knees, beeotch. :spank:
Title: Re: Safe Piston speed
Post by: NewRedRider on April 19, 2005, 04:02:12 PM
stop flaming the guy, he asked a valid, if uninformed question. Maximum piston speed is an important factor in engine wear and catastrophic failure. The problem is, no one outside the walls of the Honda engineering department is going to know about that. Okay, maybe some people on top level race teams, but still very few.
So why would one ask such a question? Does he want to reset the rev limiter? If it's a stock engine it wouldn't make any sense as the peak HP is around 13,800rpm. Is he building an engine with a cam, valve and head work? I just don't see the point of knowing that information. ??? Please explain.

And don't take our flaming personal. We just like to have fun around here. Skin thickens over time so stick around. :thumb:
Title: Re: Safe Piston speed
Post by: honiton on April 19, 2005, 06:22:12 PM
i heard something about a nuclear powered 600rr coming out sometime in 2018. ???

 :P :P :P :P 

wait to be on the thing when it blows up.. Oh wait, might be a good way to die, because you wont feel anything..
Title: Re: Safe Piston speed
Post by: HIROLLER on April 28, 2005, 10:50:08 AM
People on this thread are not aware of the physics of engine builiding. Two engines that are turning the same RPM can have different piston speeds. If the strokes, rod length, or pin hieght are different this will all change piston speed. I have built automotive drag race engines for years and this is an issue that can win or loose a race. This is definitly critical with a small cube engine that is naturally aspirated. This is also the reason that small engines can need massive amounts of air (large throttle bodies) that larger engines do not have. RPM is not the reason! Piston speed determines the V/E of the design!
Title: Re: Safe Piston speed
Post by: HIROLLER on April 28, 2005, 10:57:07 AM
Also, if you wanted to spin the engine less RPM and have the same or more piston speed, knowing these factors can allow you to build the engine to a desired purpose, maybe other forms of racing that does not involve curves...
Title: Re: Safe Piston speed
Post by: Jeff on April 28, 2005, 11:06:48 AM
HIRoller, that's all fine and well, but we're talking about a STOCK cbr600rr which makes the question somewhat pointless...
Title: Re: Safe Piston speed
Post by: 600RRpilot on April 28, 2005, 11:09:52 AM
People on this thread are not aware of the physics of engine builiding.


exactly...these things are takin into consideration and produced during production.  your not going to change piston speed without MAJOR overhaul or BIG money parts. piston speed cannot be changed without changing crankshafts, rods, pistons themselves, etc etc etc.  now if your looking for max reccomended for this engine......to...lets say.....change the rev limiter.......then thats different.  but idk why you would want to anyway.  honda's already done all this research making the engine.  i understand there is such thing as piston speed......but i dont see the practical use for it as a figure unless your building an engine from aluminum stock and up.   if there is in fact something that is relavant to and i can use the numbers....please enlighten me  (no sarcasm...im serious i want to learn about this more)  
Title: Re: Safe Piston speed
Post by: HIROLLER on April 28, 2005, 11:25:48 AM
I couldn't agree more with you both. Only if you are building from the ground up would you concider such factors. As for raising the rev limit to increase piston speed, as you all have stated, peak hp was made 2000 RPM ago why torture it for no reason. Your no going to change that fact no matter it you make it turn 25000!!! :thumb:
Title: Re: Safe Piston speed
Post by: 600RRpilot on April 28, 2005, 11:27:32 AM
I couldn't agree more with you both. Only if you are building from the ground up would you concider such factors. As for raising the rev limit to increase piston speed, as you all have stated, peak hp was made 2000 RPM ago why torture it for no reason. Your no going to change that fact no matter it you make it turn 25000!!! :thumb:

 ;D
Title: Re: Safe Piston speed
Post by: TopgunRR on April 28, 2005, 02:30:01 PM
People on this thread are not aware of the physics of engine builiding.
hey! some of us are. you bring up good points, though.
Title: Re: Safe Piston speed
Post by: nolimits on May 04, 2005, 09:29:48 AM
HIRoller, that's all fine and well, but we're talking about a STOCK cbr600rr which makes the question somewhat pointless...

Did I miss the bit where he said it was going to stay a stock motor?

If he were tuning the motor to deliver it's power at a higher rpm he may need to raise the rev limiter. Knowing the max piston speed would be useful so you can set your theoretical rpm limit and design your tuning around that.

When I raced a 125 the max power was at 11,300 and the red line around 12,000. We tuned the engine and moved max power up to 12,800 with over rev allowed to go to near 13,500. This allowed the use of lower gearing (to give more acceleration) whilst the extra 1500 rpm allowed us to keep the same top speed. I forget what the max piston speed was but we were just inside the comfort zone. 2 strokes have larger heavier pistons (due to the piston porting) so have a lower max piston speed. Hence the lower rpm limit 12-13,000 for 2 stroke, 15-18,000 for four stroke. 18,000 being those little CBR250rr's with tiny pistons.
Title: Re: Safe Piston speed
Post by: Zagan on May 10, 2005, 12:27:57 PM
Well I was wanting to know so that I could work it out based on the gear ratios, no don't know if the gearing will effect this much or not but at times I end up at 10,000 to 14,000rpm end sometimes going into the redline in 1st or 2nd gears and instead of sitting that high up in the rpm range at such low gears, which to my thinking won't be great for the motor.

I would have liked to work out what the pistion speed would be for the different gears and see what was least damaging at least.

Anyway,  I asked here as a few people here seem to be racing 600RRs rather than simply going fast on open roads and thought they might have a number or and idea about it.
Title: Re: Safe Piston speed
Post by: nolimits on May 10, 2005, 09:22:31 PM
The rev limiter will stop your engine self destructing and I think your more likley to bend valves than break pistons due to excessive rpm.
There is a certain amount of overlap and at high rpm the one valve may not have enough time to withdraw before the other starts its way down. You are relying on spring pressure to close the valve and this can only happen so quick.
Title: Re: Safe Piston speed
Post by: quain159 on February 13, 2009, 06:45:10 AM
where did you hear that that was correct for "racing"?  ive never heard of piston speed in relation to anything.


at the really high engineering level, what jeff points out is crucially important to oil viscosity and thermal reciprocity, and that also play a role in dertermining piston ring attributes...

am i mistaken jeff ???? ;D
Title: Re: Safe Piston speed
Post by: Jeff on February 13, 2009, 05:25:23 PM
Shit, I have no idea...  I just have to laugh at this thread after reading it again from 4 yrs ago...

Good times they were...  good times...

Title: Re: Safe Piston speed
Post by: cejay_2k on February 14, 2009, 07:26:04 PM
Safe piston speed is used to calculate max RPM for a given engine

for example;  Max. RPM = Mean Piston Speed (ft/min) x cylinders / by Stroke in Inches

around 4000ft/min for a motorcycle, Formula 1 is around 7500ft/min

Still a stupid qeustion as the piston speed is used to calculate the max RPM so it will never be less than the redline.

Chris G
Title: Re: Safe Piston speed
Post by: cosmo on February 15, 2009, 04:57:53 AM
dunno where i heard this, but i understood that f1 cilinders have a bigger bore and thus smaller stroke then day-to-day cars, and somehow that would mean the piston speed is actually less then a normal good-performance car, though the rpm is much higher. ??? just what i heard, i don't stand by it since i have no ideea on f1 mechanics. 'sides, it's not that i really have nightmares about f1 piston speeds :P
Title: Re: Safe Piston speed
Post by: Paulred/black on February 15, 2009, 07:06:35 AM
I think that with F1 cars the rpm's are so much higher because of the tolerences in different components in the engine. They are so fine that the engine is actually kinda seized itself when its cold, that is why they need to use special techniques for warming them up. so because of these extra fine tolerences (and parts being so lightin the engine) you can rev it alot higher, its what they were designed to do.

whereas your average car is built iguess for comfort and putting the high miles on  :thumb:
Title: Re: Safe Piston speed
Post by: Paulred/black on February 15, 2009, 07:09:15 AM
i suppose an example of this would be different oils you can use like WATT's that can be used in minus temperatures, compared to oils that are 'designed' <- wrong word i know to be used at higher temperatures.
Title: Re: Safe Piston speed
Post by: CallmeJoe on March 08, 2009, 12:51:10 PM
dunno where i heard this, but i understood that f1 cilinders have a bigger bore and thus smaller stroke then day-to-day cars, and somehow that would mean the piston speed is actually less then a normal good-performance car, though the rpm is much higher. ??? just what i heard, i don't stand by it since i have no ideea on f1 mechanics. 'sides, it's not that i really have nightmares about f1 piston speeds :P

Hi cosmo,

Hopefully I can explain this to you. That is very true indeed and this is why. The max piston speed for any engine out there is 4,400fpm. If you think about it this is pretty crazy, imagine going back and forth at roughly 50mph, no stopping! So with this being said lets say we have two engines, both 1000CC. We will call these engine #1 and engine #2. Let's also say that #1 has a bigger bore than #2, but keep in mind they are still 1000CC. So what is happening is you are decreasing the stroke length of #1, also there is less "ground" for piston #1 to cover when going from bottom dead center to top dead center. Now when you combine the bigger bore with shorter stroke you are actually going to get a higher RPM and not a high piston speed. This because the piston doesn't have the stroke length to reach that magical 4,400 number. Now hopefully you can see why harleys rev out at 9k instead of 15k+ because they have a longer stroke. Hope this information was useful.

Joe
Title: Re: Safe Piston speed
Post by: Paulred/black on March 08, 2009, 01:23:09 PM
Hi cosmo,

Hopefully I can explain this to you. That is very true indeed and this is why. The max piston speed for any engine out there is 4,400fpm. If you think about it this is pretty crazy, imagine going back and forth at roughly 50mph, no stopping! So with this being said lets say we have two engines, both 1000CC. We will call these engine #1 and engine #2. Let's also say that #1 has a bigger bore than #2, but keep in mind they are still 1000CC. So what is happening is you are decreasing the stroke length of #1, also there is less "ground" for piston #1 to cover when going from bottom dead center to top dead center. Now when you combine the bigger bore with shorter stroke you are actually going to get a higher RPM and not a high piston speed. This because the piston doesn't have the stroke length to reach that magical 4,400 number. Now hopefully you can see why harleys rev out at 9k instead of 15k+ because they have a longer stroke. Hope this information was useful.

Joe


+1
Title: Re: Safe Piston speed
Post by: cosmo on March 09, 2009, 09:46:55 AM
yeah, that's something along the lines i remember it being talked about.
tnx for clearing it up ;D
Title: Re: Safe Piston speed
Post by: choose username on January 20, 2010, 09:24:01 AM
Does anyone know what the safe piston speed is for a CBR 600 RR 04 model is, or all of them I guess as it's the same engine in all of them.

it wouldn't be max rpm on the dial would it?

I've read 4500 feet per minute is safe in racing but that was around 98 or so.


Hi zagan,

Don't let these dunderheads fool you into thinking you don't know what you're talking about. Without my notes I believe you are correct with the 4500 fpm, give or take a few. It has to do with a variety of things though such as, bore size, stroke length, and the material the piston is made of. I recommend that all of you take a few tech classes at your local Community College.

PS- Zagan if you have a fax machine I'd be more than willing to fax you my notes pertaining to this subject from class.
Title: Re: Safe Piston speed
Post by: Jeff on January 20, 2010, 12:03:02 PM
Welcome aboard... 

Thanks for clearing up a 5 year old post. 
Title: Re: Safe Piston speed
Post by: Paulred/black on January 20, 2010, 01:21:59 PM
LOL
Title: Re: Safe Piston speed
Post by: choose username on January 20, 2010, 03:38:53 PM
Welcome aboard... 

Thanks for clearing up a 5 year old post. 

I wondered why this place was a ghost town. Maybe you should get a new welcoming committee. I'm out of here.
Title: Re: Safe Piston speed
Post by: cosmo on January 20, 2010, 05:48:30 PM
take care! prehaps on the next forum you'll start with the introductions
Title: Re: Safe Piston speed
Post by: dbrinkley81 on January 21, 2010, 03:02:43 PM
I am so glad he cleared all that up before he left.  Now maybe I will get my first good nights sleep in a year without waking up in a nightmare wondering what the piston speed of my 06 is?  Now if I can just figure it out on my powerstroke.