Simple V4 engine is here.

karl_1052 · 02-01-2010, 09:53 AM

Quote:

Originally Posted by goof2

Those are weak examples. I'll bet the Mercedes/Ilmor pushrod engine from the 1994 Indy 500 redlined north of 10k rpms. That also has about as much to do with a production engine for the street as what you posted.

Well, those are all big V8s with heavy pistons and valvetrain. Did you expect this 1650cc motor to use the same size valvetrain as a 5000cc V8?
I posted those vids to show with a lightweight valvetrain(which this motorcycle engine could have) can rev to high RPM limits.
It all comes down to the ability to control the valves, and with light valves and good springs, there is no reason that a pushrod engine won't rev past 10K.

goof2 · 02-01-2010, 10:40 AM

Quote:

Originally Posted by karl_1052

Well, those are all big V8s with heavy pistons and valvetrain. Did you expect this 1650cc motor to use the same size valvetrain as a 5000cc V8?
I posted those vids to show with a lightweight valvetrain(which this motorcycle engine could have) can rev to high RPM limits.
It all comes down to the ability to control the valves, and with light valves and good springs, there is no reason that a pushrod engine won't rev past 10K.

While there is no reason it can't be done there are 3 reasons it isn't commonly done. 1) It costs money to make that lightweight drivetrain, 2) the lighter they make the valvetrain the more issues they may run in to with reliability, and 3) with only 2 valves per cylinder it is more difficult to fill the cylinders with air, the benefit of higher revs.

According to the Cycle World article below the engine makes peak power at 7800 rpm. I doubt it redlines much above 8,500 rpm.

http://www.cycleworld.com/article.as...&page_number=2

marko138 · 02-01-2010, 10:43 AM

Where are we gonna see this thing?

goof2 · 02-01-2010, 11:00 AM

Quote:

Originally Posted by marko138

Where are we gonna see this thing?

The internet. Maybe the magazines will get a prototype to test. I doubt it will get much further than that.

marko138 · 02-01-2010, 11:01 AM

Quote:

Originally Posted by goof2

The internet. Maybe the magazines will get a prototype to test. I doubt it will get much further than that.

Shitty.

Dave · 02-01-2010, 11:06 AM

Quote:

Originally Posted by karl_1052

Well, those are all big V8s with heavy pistons and valvetrain. Did you expect this 1650cc motor to use the same size valvetrain as a 5000cc V8?
I posted those vids to show with a lightweight valvetrain(which this motorcycle engine could have) can rev to high RPM limits.
It all comes down to the ability to control the valves, and with light valves and good springs, there is no reason that a pushrod engine won't rev past 10K.

valvetrain and cam profile are important, but the real question here is geometry. If the strokes too long the piston speed can be a very limiting factor

karl_1052 · 02-01-2010, 11:43 AM

Quote:

Originally Posted by goof2

While there is no reason it can't be done there are 3 reasons it isn't commonly done. 1) It costs money to make that lightweight drivetrain, 2) the lighter they make the valvetrain the more issues they may run in to with reliability, and 3) with only 2 valves per cylinder it is more difficult to fill the cylinders with air, the benefit of higher revs.

According to the Cycle World article below the engine makes peak power at 7800 rpm. I doubt it redlines much above 8,500 rpm.

http://www.cycleworld.com/article.as...&page_number=2

I never said this engine had a high redline. You said pushrod motors cannot rev, and I proved you wrong.

Quote:

Originally Posted by Dave

valvetrain and cam profile are important, but the real question here is geometry. If the strokes too long the piston speed can be a very limiting factor

Once again, my comments have nothing to do with this motor, I was just pointing out that pushrod engines can have high redlines.

marko138 · 02-01-2010, 11:43 AM

Quote:

Originally Posted by karl_1052

I never said this engine had a high redline. You said pushrod motors cannot rev, and I proved you wrong.

Once again, my comments have nothing to do with this motor, I was just pointing out that pushrod engines can have high redlines.

Get 'em, Tiger.