| Author | Message | ||
     Ochoa0042 |
titanium parts in a XB like the connecting rods and valves and springs and whatever else was needed.. would it increase the RPM range to the 5digit range?  | ||
| Greg_e |
Valve springs and the rest of the valve train are the real weak spots for high revs. | ||
| Ferocity02 |
With a pushrod engine you aren't going to be be able to spin those RPMS. | ||
| Lighting |
Why?, you can make a ton of HP by blueprinting & balancing your engine and going with a stroker kit. Are you looking for higher horsepower or a high revving engine?. Nothing wrong with spinning high, it's just with a pushrod engine you would like the band of you HP & torque down low so you don't sacrifice longevity. | ||
| Froggy |
You could buy a pod laden bike that has a 5 digit redline with all the money that you spend titainumizing everything | ||
| Skully |
What do the NASCAR engines rev to? | ||
| Iamarchangel |
My thought is that this engine has been around for a long time in various formats. If the HD race team couldn't do it, I have my doubts anybody can. Isn't that the reason why Eric went to Rotax? | ||
| Boltrider |
Yeah what Arch said. I think the XBRR motor revs to 9000 and that thing is built to the hilt. (Message edited by boltrider on October 04, 2009) | ||
| Starter |
Max piston speed is your enemy, not the top end. | ||
| Fast1075 |
+1 Starter on the piston speed...the 2nd weakest point is the valvetrain and the crank is #3 ....you can build a high(er) revving XB motor...but reliability for street use is out the window. Anything over about 120 hp will not be long term reliable of you USE it a lot. | ||
| Slaughter |
Yep... a whole bunch of trade-offs in the question. These motors seem "happiest" when built for about 100-105 HP... and with a big bottom (2008 or newer) end and RPM kept to 8K or less. RPMs at 7800 or less - unless you have a staff on salary to do the rebuilding. The top end seems to "like" as light a spring as you can use and still close the valves at high RPM. Problem is that heavier springs actually rob power... so that's a trade. I think that lighter pistons and balancing the flywheels/C-rods/Pistons is a really good thing. Lightening the mass of the flywheels can do a lot for throttle response (a bit more than 2 pounds out of the whirling bits inside your motor) - but it's not going to really ADD to your HP, just improves throttle response. My little experiment is to see if I can go the year on this rebuild without tearing the motor down until the very last race. That'll be 9 race weekends, 36 races and a couple track days. So far, so good. Realize that you can build a street motor that "has more power" - but you cannot possibly spend as much time actually IN the powerband as you can when the only traffic you have is at speed and going in the same direction. -and while I can legitimately call myself a "racer" - I'm not all that fast... I just do this racing thing at least one weekend a month (except December or when the finances dictate otherwise) - so I'm not quite as hard on a motor as a "real racer." (Shouldn't try posting when trying to eat cereal and get outta here on a working morning!!!) |
