Hayabusa Max Rpm???

[Mathewrussell52]

Been on here for a bit and something I'm wondering is when building the motor why don't anyone get more RPM.

A 600 can turn 17,000 rpm. Building a 350 can go from 6,500 to 11,000 rpm.

Why is the busa not the same or is it.

 

[c10]

Short stroke motors can turn more rpms than a long stroke motor . 600 cc usually is a very short stroke 50 something mm while most big 1300 cc engines are 65 mm stroke or more . 15 mm is about 3/4 " x 4 holes

 

[bigoltool]

If I may.
https://www.vcalc.com/wiki/KurtHeckman/Max+Piston+Speed

 

[WuzzaCBXRider]

The 60s Honda 250 track only sixes ran past 20,000 rpm. They wouldn't even idle under 7-8,000. Tiny =less weight and a shorter travel span. Cylinders were the size of bottle caps and their valves, smaller than dimes.

 

[fallenarch]

The Busa can however turn more RPMs. Through an ECU editor I set my redline up to 11,000 and I have heard of people going as high as 12,500 rpms (don't know if there is a limit). Of course the higher the revs the more likely the bike will explode! The real question is why scream a busa? At 11,000 rpm redline you are doing maybe 90 mph in 1st gear and pushing 180+ hp. I would think even on the drag strip you would want to stay in the max torque area (around 9K-10.5K) until you are well down the strip. I know on the track you have to tame the Busa down there's so much power (and no electronics to help you out).

 

[Mathewrussell52]

If I may.
https://www.vcalc.com/wiki/KurtHeckman/Max+Piston+Speed

Great point!! Cool when looking in to other motors what the stroke is and what the mph on the motor is running at.

But with better rods and pistons people are not cranking up rpms. Does the torque curve just die off??

 

[sixpack577]

12,500 is the max in Ecu Editor.
But, you would need internals built to handle that.
For what application you could effectively use 12,500, I do not know. I would assume a low 7 second bike, with whatever power adder to get it there.

 

[sixpack577]

I would *assume* anything over 12,500, and you're just building a very big and expensive grenade.
There is a point where weight/mass vs the speed it's traveling, and parts just can't hold together.

 

[Mathewrussell52]

The Busa can however turn more RPMs. Through an ECU editor I set my redline up to 11,000 and I have heard of people going as high as 12,500 rpms (don't know if there is a limit). Of course the higher the revs the more likely the bike will explode! The real question is why scream a busa? At 11,000 rpm redline you are doing maybe 90 mph in 1st gear and pushing 180+ hp. I would think even on the drag strip you would want to stay in the max torque area (around 9K-10.5K) until you are well down the strip. I know on the track you have to tame the Busa down there's so much power (and no electronics to help you out).

Just curious in car applications people gain serious rpm in the builds. The busa pulls hard all the way to the red line.

Some of the answers are prob why I went turbo instead of building the motor.

 

[Mathewrussell52]

I would *assume* anything over 12,500, and you're just building a very big and expensive grenade.
There is a point where weight/mass vs the speed it's traveling, and parts just can't hold together.

Ya that calculator was neat to see how fast the motor is going compared to other motors twisting a lot more rpm.

 

[bigoltool]

F1 engineers used to live and breathe piston speeds. In the heyday of naturally aspirated v10s they were turning well north of 18k. Pistons accelerating and decelerating at those speeds (25 to 30 M/S)were very special indeed. The slipper pistons we now see with nearly nonexistent skirts came from that development. Now in the Turbo/Hybrid era they arent turning nearly as fast, but they're going faster than ever so...

Here's a good article on wikipedia.
https://en.m.wikipedia.org/wiki/Mean_piston_speed

 

[13013]

I'm good with stock limit.

 

[sixpack577]

I'm good with stock limit.

Liar...yours is up 600rpm in Ecu Editor too, lol.

 

[13013]

Liar...yours is up 600rpm in Ecu Editor too, lol.

 

[Boosted Cycle Perf]

Revving higher doesn't mean you're doing any good. Stock internals can hang out to 12k just fine.

However on both generations their power peaks just before the rev limiter. Revving an engine past its peak HP isn't making you go any faster. It's just puting unesessary strain on the engine.

The f1 cars don't turn 18k rpm just because it's cool. They do it because the engine is still building power.

On turbo bikes, if they have good internals and valve springs we will keep turning them higher until power peaks out. That's usually 11,800-12000 on the big turbo bikes.