| Author |
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M1combat
| | Posted on Friday, October 03, 2003 - 03:33 pm: | 
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SP2?? |
Hootowl
| | Posted on Friday, October 03, 2003 - 04:07 pm: |
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Your motor will not live long at that RPM. Also keep in mind that if you raise the final drive ratio, you'll need more power to get to redline. Like I said, changing the gears does not necessarily equate to more speed. I'd also pay close attention to what Aaron has to say on this. Not sure if you know who he is... |
Hootowl
| | Posted on Friday, October 03, 2003 - 04:12 pm: |
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I think I responded to two people in that last one. Sorry for the confusion. |
M1combat
| | Posted on Friday, October 03, 2003 - 05:37 pm: |
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I try to pay close attention to every one and take what they say with a grain of salt after they have proven to me I need to. What Aaron said about the heads is very true, but I think it can be "fixed". Enough to make the power I want?? Don't know, but I'll give it a shot if I can  .
BTW... I don't know who Aaron is... Maybe I should? |
M1combat
| | Posted on Friday, October 03, 2003 - 05:43 pm: |
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Aaron, If the heads aren't what constrains it... What have you run into that does? I am guessing the lack of room in between the heads to make a sufficiently large and straight intake manifold would be a big one?? |
Aesquire
| | Posted on Friday, October 03, 2003 - 11:01 pm: |
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At a certain piston speed, you actually outrace the flame front, and torque drops off. I don't remember ? 4000+ feet per minute? Thats the reason short stroke engines have an advantage in RPM.
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Steveshakeshaft
| | Posted on Saturday, October 04, 2003 - 05:37 am: |
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M1combat, if you have the dollars to throw at it who am I say other wise? But 9.5k is 2.5k rpm over the XB12's red line. So on an XB12 what you want is a more than 30% increase in rpm? Do you know what the maximum piston velocity and acceleration are going to be at 9.5K? Do you know that stress on the lower end components increases as the square of increase in speed? All I'm saying is do some simple math first, decide if you can acheive what you are aiming for. If you can, then go for it. I'd buy the SP2, that already does 130 bhp and 9.5k, oh BTW, its a Honda. Good luck.
Steve
steve_s@ukbeg.com
www.ukbeg.com |
Dynarider
| | Posted on Saturday, October 04, 2003 - 07:37 am: |
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I'd buy the SP2
Psst M1...its also better known as the RC51 |
M1combat
| | Posted on Monday, October 06, 2003 - 11:47 am: |
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he he, thanks dyna...
Steve... It's entirely possible that I'm overly optimistic . I still think though, that 10K RPM's isn't too much to hope for. Granted, I think I would "settle" for 9000 and a six speed... It's really just something to shoot for. As far as doing the math, I will as soon as I need to. When it comes to the money... He he... I don't have it ATM, and probably won't when the time comes so this project will most likely take a while . The way I look at it though, If I can get some discussion going that travels in a direction I like and people don't mind sharing their wisdom and knowledge I'll be better off (as will others) when it comes time to rebuild my XB. I mean, there's no way I'm rebuilding it to stock form and what I'll be going for is RPM's. The more I learn about how to get to 10K the better chance I'll have to get close.
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Aaron
| | Posted on Monday, October 06, 2003 - 12:23 pm: |
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Maybe I'm a little behind the times, but last time I saw an in-car shot with telemetry during a Winston Cup event, I remember peak rpm's in the mid 8000's. Short track motors twist a little higher and the retrictor plate motors somewhat less, right?
Tom Colley participates on this board and he's heavily involved in that stuff, he could tell us.
I'm not intimately familiar with the technology, but I know they're doing Ti valves, beehive springs, and probably the cool oil-spray thing to get their springs to make it through a 500 or 600 mile race.
Those motors have a lighter valvetrain than we've got, too. Small short rockers, shorter pushrods, and probably a "rev kit" (supplemental springs between the underside of the heads and the lifters).
I'm sure they do tall valves and springs so they can run lots of lift with plenty of coil bind clearance, which helps life.
Anyhoo, with respect to HD motors, the only people trying to twist'em 8000 or more are racers, and few people endurance race the things, so getting longevity out of an 8000+ rpm valvetrain isn't really a priority with most folks. I think you'll be breaking some new ground by moving some of that technology over.
I've setup several HD motors for 8000 rpm but the change interval on the valves and springs is not something you'd want in a street bike.
The beehive springs shouldn't be a problem. Getting more than about 1.95" installed height will be a challenge, but there are trick rocker boxes available with movable rocker shafts that could help. Engine height will go up though. A supplemental system to blow cool oil on the springs could probably be rigged up. Ti valves aren't overly durable but hollow-stem stainless are almost as light. I suppose a "rev kit" spring set could be fabricated for a Harley motor.
So far be it from me to say it can't be done. But it's gonna take some creativity and fabrication to build an 8000+rpm HD valvetrain with streetable longevity.
The cam grind has a lot to do with how much spring pressure you need, too. Getting a cylinder fill at those rpms is a HUGE challenge and the cams you'll need will have aggressive ramps and need huge amounts of spring to control the valvetrain at those rpms.
Lots of guys (including me) run 7500 rpm capable street motors. Not that we dwell up there, but it can do occassionally and for short periods of time. That's about where my M2 has it's power peak. |
Phillyblast
| | Posted on Monday, October 06, 2003 - 01:03 pm: |
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btw M1Combat, if you don't know who Aaron is try http://www.nallinracing.com |
M1combat
| | Posted on Monday, October 06, 2003 - 03:30 pm: |
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Already done Philly... Thanks .
Hmm, it just doesn't seem like it's not doable but I'm quite certain you have more experience with it than I do... I certainly agree that the valve train leaves a LOT to be desired in this application though. I look at HD valvetrains and think "What the HELL were they thinking??". I suppose I could settle for 7500... I guess maybe I'm just too used to jap bikes. I have a 21 year old honda that does 11,500...
Maybe I'll just wait and see what people come up with. As far as NASCAR engines (I hate NASCAR BTW, I prefer F1/GT/ALMS) I seem to remember about 9800 at the end of a straight at Daytona/Talledega or something like that. I also seem to remember at least 9500 at Sears Point. Could certainly be wrong though, I've watched a LOT of racing...
Anyway, Thanks for the info and I may indeed look you up in the future when I actually need to rebuild. |
Dynarider
| | Posted on Monday, October 06, 2003 - 03:36 pm: |
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Nascar motors do see 9500rpms on the short tracks. |
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