F1technical.net

xpensive wrote:And what bore would that mean then?

Bore is rules limited to 98mm

http://www.f1technical.net/f1db/cars/949

xpensive wrote:And what bore would that mean then?

It's 98mm max I think...

How things chage Scot, I seem to recall the 1975 Ferrari Flat-12 having a bore/stroke of 80/47?

A 38 mm stroke on a 2.4 V-8, would mean a bore of 100 mm.

Well the change is brought through committee, not development. Imagine setting specific bore size and bore centres. Enzo and Colin would be cursing it all.

Scotracer wrote:

xpensive wrote:I don't know the stroke of an F1 engine of today, but 45 mm shouldn't be that far away, which means 30 m/s a 20kRpm?

35-39mm IIRC...

If you wish to stay within a 98 mm bore limit for a 2.4 V8, stroke cannot be any less that 40 mm.

A 40 mm stroke at 18k, means an average piston-speed of 24 m/s.

Given all that, Con rod length would determine the Peak piston speed. Any ideas?

countersteer wrote:Given all that, Con rod length would determine the Peak piston speed. Any ideas?

Peak piston speed is related rpm and conrod length/stroke length.

I found this spreadsheet that'll be useful to anyone wanting to get some values...

countersteer wrote:Given all that, Con rod length would determine the Peak piston speed. Any ideas?

Well I don't know the actual length of the con rod. But I have read that peak piston speeds are in the neighborhood of ~40 m/s. So you could back out the con rod lenght using the formulas posted on this page

http://www.camotruck.net/rollins/piston.html

Krispy wrote:

countersteer wrote:Given all that, Con rod length would determine the Peak piston speed. Any ideas?

Well I don't know the actual length of the con rod. But I have read that peak piston speeds are in the neighborhood of ~40 m/s. So you could back out the con rod lenght using the formulas posted on this page

http://www.camotruck.net/rollins/piston.html

Actually you would need the crankshaft radius as well. I think we are out of luck unless someone wants to share some data they have.

Krispy wrote:

Krispy wrote:

countersteer wrote:Given all that, Con rod length would determine the Peak piston speed. Any ideas?

Well I don't know the actual length of the con rod. But I have read that peak piston speeds are in the neighborhood of ~40 m/s. So you could back out the con rod lenght using the formulas posted on this page

http://www.camotruck.net/rollins/piston.html

Actually you would need the crankshaft radius as well. I think we are out of luck unless someone wants to share some data they have.

Crankshaft radius is half the stroke.

EDIT: I haven't read all the thread, so I dont know if the stoke is a known. So I dont kow how relevent the above is.

xxChrisxx wrote:Crankshaft radius is half the stroke.

EDIT: I haven't read all the thread, so I dont know if the stoke is a known. So I dont kow how relevent the above is.

We know stroke-ish....35-39 mm's Good point on the crankshaft radius...I forgot about that

The peak piston speed will obviously be a geometric relation between half the stroke, con rod length, angular position and angular velocity of the crank. There should be a lazy-dog formula for this in some engine litterature?

But considering that piston speed is zero twice per revolution, the peak should be consideraby higher than mean.

Piston speed doesn't mean much.. it is the acceleration that kills it.

When i was doing research on the rotary valve engine.. I came across a pdf on the rotary valve engine made by a company and Toyota. THe link is somewhere on this forum. If i remember correctly, Toyota said a poppet valve Formula1 engine can do about 22 or 23 thousand ? rpm.. (or something like that).. that is when there are no returns no matter what you do. The proposed rotary valve engine was supposed to be able to do 24,000 rpms.

So you can see there that it is most likely the valve train and the combustion aerodynamics inside the cylinder that is limiting them from increasing the rpms..

here it is

http://www.v-eight.com/multimedia/pdf/AutoTechBRV.pdf

=D>
cheers malbeare

xpensive,

Recip mass inertia forces are a function of instantaneous accelerations, not velocities. F=Ma right?

The kinematics of a crank and conrod mechanism will produce zero piston linear acceleration and constant piston linear velocity when the conrod length becomes infinity. Conversely, piston linear accelerations will become infinite when the conrod length is zero.

A longer conrod will produce lower peak linear piston accelerations, and potentially lower inertia loads on the piston, crank and rod structures and bearings. But a longer rod also weighs more, so the "M" variable of the force equation is negatively affected.

What most high RPM race engine designers have concluded, is that a titanium conrod of the shortest length possible, is the best solution with regards to the trade-off between kinematics and inertia loads on the crank bearings. The only limit on how short the conrod can be is the interference between the piston lower skirt edge and the crank throw at piston BDC.

Terry