Stroking the 954! - Honda Motorcycles - FireBlades.org
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post #1 of 24 Old 09-12-2003, 9:16 AM Thread Starter
 
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Re: Stroking the 954!

Some of u may well remember a thread I posted on the old forums about stroking the 954, with one of the suggested bore x stroke combinations being 75 x 56.5 for 998cc's with a hand full of 'know it alls' saying that it wasnt a good idea and that piston speed would be too high with that combination! well somebody better tell honda because look what theyve gone and done!

Sorry couldnt help myself! * * *




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post #2 of 24 Old 09-12-2003, 10:00 AM
 
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Re: Stroking the 954!

They also lowered the rev limiter . . .
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post #3 of 24 Old 09-12-2003, 10:10 AM
 
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Re: Stroking the 954!

Yep,

They just stroked it, lets hope they gained some serious torque, because they lost some revs...

Its all about piston speed...
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post #4 of 24 Old 09-12-2003, 10:18 AM
 
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Re: Stroking the 954!

So the new 1000 is a stroked 954 motor? Didn't Honda give us some line in 02 about 'rather than make it bigger we wanted to keep it reliable' or something like that?
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post #5 of 24 Old 09-12-2003, 10:38 AM
 
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Re: Stroking the 954!

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Serial Thriller : So the new 1000 is a stroked 954 motor? Didn't Honda give us some line in 02 about 'rather than make it bigger we wanted to keep it reliable' or something like that?
not really 'just a stroked' engine... Its all new supposedly, but the bore was kept the same...
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post #6 of 24 Old 09-12-2003, 11:10 AM
 
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Re: Stroking the 954!

Sorry couldnt help myself!

Maybe you should have looked at the rest of the specs before you decided that Honda has somehow changed the laws of physics. For a production machine that must be reliable enough for daily street use, most manufacturers follow the SAE and DIN guidelines for maximum piston speed by either limiting the stroke or limiting the revs. Race bikes regularly exceed these guidelines, but they also use hardened TI rods, micro balanced/knife edged crankshafts, TI valve retainers, hardened valve springs, larger sump oil pans with guide baffles etc., etc.
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post #7 of 24 Old 09-12-2003, 11:20 AM
 
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Re: Stroking the 954!

Abtech...

Do you know by chance what that piston speed value is??
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post #8 of 24 Old 09-12-2003, 11:28 AM
 
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Re: Stroking the 954!

5000 feet per second is the maximum safe piston speed generally accepted for production engines.

correction: 5000 feet per minute . . .



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post #9 of 24 Old 09-12-2003, 11:32 AM
 
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Re: Stroking the 954!

Yeah, the engine is all new. It is setup in the frame different.
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post #10 of 24 Old 09-12-2003, 11:42 AM
 
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Re: Stroking the 954!

Sorry this is a bit off topic but I am curious

5000 ft/sec is fast, Abtech do you the tempeture in the cylinder, I know that temp and pressure affect the speed of sound ins the temp was 600 deg F the speed of sound is 1718 ft/sec I am not sure about how pressure affects the formula but is the speed of sound the limiting factor?

Thanks
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post #11 of 24 Old 09-12-2003, 11:49 AM
 
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Re: Stroking the 954!

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Purpdust : I know that temp and pressure affect the speed of sound ins the temp was 600 deg F the speed of sound is 1718 ft/sec I am not sure about how pressure affects the formula but is the speed of sound the limiting factor?
Either the question or the answer have something to do with Molson................
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post #12 of 24 Old 09-12-2003, 11:59 AM
 
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Re: Stroking the 954!

I think the limiting factor is stress fatigue of the rod/rod bearing material due to stretching as the piston crests TDC. *Even hardened TI rods stretch quite a bit at full chat. *I realize the speed of sound changes due to temp, pressure, RAD etc, but at 5K FPS, it's already well beyond the SOS.

BTW, Molson is the preferred beverage used for discussing the finer points of engine design . . .



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post #13 of 24 Old 09-12-2003, 8:12 PM Thread Starter
 
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Re: Stroking the 954!

5000ft/sec * *(Abtec I think u may mean ft/min) Also what exactly is the new rev limit and what is your source?? Modified blades with std crank, rods and pistons have been to 15000rpm with out failure (motopower's 178hp fireblade)
So the even with a 2.5mm stroke increase the new blade could easily handle 12000rpm (and thats being conservative).
The new blade would have a mean piston speed of 74.15 ft/sec @ 12000rpm! (22.6m/sec)
(5000ft/min = 83.33 ft/sec or 25.4m/sec)

56.5 x 2 = 113 x 12000 = 1356000mm/min
1356000mm/min / 1000 = 1356m/min / 60 = 22.6m/sec
(1ft=0.3048m)
Anyway my origional argument was not that they would or would not have to change the rev limit with these mods, it was that that the engine would have better power characteristics with this bore x stroke ratio and it seems honda agrees with me, also if this figure you obtained from SAE is correct ('5000ft/min' not sec) when was it last updated, the japaneses factories have much greater resources than the the british SAE, The japanese companies developments in metallurgy is growing year by year (this figure from the SAE is it updated every year to keep up with metallugry developments or is it 5 years old?) and i doubt very much if honda would design there engines from their guidlines as their reasearch budget would be much higher than the SAE's
Once again i make my point that i was saying the 'blade would have better power characteristics with these dimensions' (and i was right! ) not any other side argument you may try to make just so u can appear to be an expert!




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post #14 of 24 Old 09-13-2003, 8:46 AM
 
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Re: Stroking the 954!

SAE stands for Society of Automotive Engineers and is headquartered in the United States, not Britain. *They have a budget that far exceeds anything the Japanese R&D may have. *They update their database hourly with any new available information, not yearly.

I did incorrectly state the range, it is feet per minute, not second. *Your rather simple calculations do not take rod length into account which has a significant effect on mean and maximum piston speed (due to the underlying piston acceleration). *The standard calculation for piston speed (w/o regard to rod length) is stroke (in inches) times RPM divided by 6. *Using an approximation of 2.21' for a 56.5 mm stroke you get:

2.21 x 12,000 (26,520) / 6 = 4420

With the current rev limiter on the 954 (~12,700) you get

2.21 x 12,700 (28,067) / 6 = 4677.84

With your example of 15,000 RPM you get 5525 fpm which rather exceeds the maximum recommended safe piston speed.

5000 fpm is the MAXIMUM, not the mean. *I seriously doubt that any of the Japanese manufacturers are selling production rods and cranks in their 'off the shelf' offerings that exceed the capabilities of Carillo or Fallicon, yet even these high performance single purpose components are known to fragment under load at much less than 15K in race use. *

Most serious teams replace the crank, rods, pistons and bearings every 20 hours or so because running these components beyond the maximum safe piston speed exceeds their design criteria and drastically shortens their useful life.



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post #15 of 24 Old 09-13-2003, 3:08 PM
 
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Re: Stroking the 954!

Quote:
Jungleboy : 5000ft/sec * *(Abtec I think u may mean ft/min) Also what exactly is the new rev limit and what is your source?? Modified blades with std crank, rods and pistons have been to 15000rpm with out failure (motopower's 178hp fireblade)
So the even with a 2.5mm stroke increase the new blade could easily handle 12000rpm (and thats being conservative).
The new blade would have a mean piston speed of 74.15 ft/sec @ 12000rpm! (22.6m/sec)
(5000ft/min = 83.33 ft/sec or 25.4m/sec)

56.5 x 2 = 113 x 12000 = 1356000mm/min
1356000mm/min / 1000 = 1356m/min / 60 = 22.6m/sec
(1ft=0.3048m)
Anyway my origional argument was not that they would or would not have to change the rev limit with these mods, it was that that the engine would have better power characteristics with this bore x stroke ratio and it seems honda agrees with me, also if this figure you obtained from SAE is correct ('5000ft/min' not sec) when was it last updated, the japaneses factories have much greater resources than the the british SAE, The japanese companies developments in metallurgy is growing year by year (this figure from the SAE is it updated every year to keep up with metallugry developments or is it 5 years old?) and i doubt very much if honda would design there engines from their guidlines as their reasearch budget would be much higher than the SAE's
Once again i make my point that i was saying the 'blade would have better power characteristics with these dimensions' (and i was right! ) not any other side argument you may try to make just so u can appear to be an expert!
For reference purposes only.

Motorpowers motor is running a special crankcase and if I remember correctly they have new rods running tighter clearances on the outer bearings and slightly looser on the inners. The crank is a factory item that is micro polished, knife-edged, and balanced for 15K use. The road motor is only good for like 14.5K redline though for reliablity. Cams are special grinds, Ti retainers etc, so that is for sure not a factory motor.....

Just going on memory here, I do have the artical but not here in front of me... Again, just for reference...
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