Honda Power Unit Hardware & Software

[DiogoBrand]

I found in 2018 FIA Technical regulations that F1 engine must have cylinder diameter of 80 mm, but I didn't find anything about stroke.

Renault and Ferrari state that their stroke is 53 mm while I didn't found data for Mercedes and Honda. Is this 53 mm stroke also regulated or is it just a coincidence that Ferrari and Renault engines have same stroke?

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

[CLKGTR]

Thanks, now it sounds logical

[Sieper]

It almost gave me a stroke.

[godlameroso]

I found in 2018 FIA Technical regulations that F1 engine must have cylinder diameter of 80 mm, but I didn't find anything about stroke.

Renault and Ferrari state that their stroke is 53 mm while I didn't found data for Mercedes and Honda. Is this 53 mm stroke also regulated or is it just a coincidence that Ferrari and Renault engines have same stroke?

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

How you achieve that stroke is where the fun starts, as the rod ratio has a huge influence in a lot of the mechanical properties of the stroke. Increasing the crank throws shortens the rods, reducing the throws lengthens the rods, longer rods have longer dwell times at TDC and BDC, and lower acceleration from TDC and BDC. However with the rapid combustion these engines use maybe super long rod ratios aren't beneficial.

[Big Tea]

I found in 2018 FIA Technical regulations that F1 engine must have cylinder diameter of 80 mm, but I didn't find anything about stroke.

Renault and Ferrari state that their stroke is 53 mm while I didn't found data for Mercedes and Honda. Is this 53 mm stroke also regulated or is it just a coincidence that Ferrari and Renault engines have same stroke?

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

How you achieve that stroke is where the fun starts, as the rod ratio has a huge influence in a lot of the mechanical properties of the stroke. Increasing the crank throws shortens the rods, reducing the throws lengthens the rods, longer rods have longer dwell times at TDC and BDC, and lower acceleration from TDC and BDC. However with the rapid combustion these engines use maybe super long rod ratios aren't beneficial.

Can't get my head around this. If the throw of the crank is set, is the stroke not also set independently of the length?
Does length not just decide the start point of travel (TDC?)

I am usually wrong mind

[63l8qrrfy6]

I found in 2018 FIA Technical regulations that F1 engine must have cylinder diameter of 80 mm, but I didn't find anything about stroke.

Renault and Ferrari state that their stroke is 53 mm while I didn't found data for Mercedes and Honda. Is this 53 mm stroke also regulated or is it just a coincidence that Ferrari and Renault engines have same stroke?

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

How you achieve that stroke is where the fun starts, as the rod ratio has a huge influence in a lot of the mechanical properties of the stroke. Increasing the crank throws shortens the rods, reducing the throws lengthens the rods, longer rods have longer dwell times at TDC and BDC, and lower acceleration from TDC and BDC. However with the rapid combustion these engines use maybe super long rod ratios aren't beneficial.

Stroke is independent of rod length. It is 2 times the distance from the main journal centreline to the pin journal centreline. You can put in 10 meter long rods, the stroke is the same.

[PhillipM]

And you can't change the throw lengths because your stroke is fixed.

[etusch]

I think this was shared here. There was an article talks about rod lengt but I couldn't find it.

http://rehermorrison.com/tech-talk-93-a ... ting-rods/

[godlameroso]

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

How you achieve that stroke is where the fun starts, as the rod ratio has a huge influence in a lot of the mechanical properties of the stroke. Increasing the crank throws shortens the rods, reducing the throws lengthens the rods, longer rods have longer dwell times at TDC and BDC, and lower acceleration from TDC and BDC. However with the rapid combustion these engines use maybe super long rod ratios aren't beneficial.

Stroke is independent of rod length. It is 2 times the distance from the main journal centreline to the pin journal centreline. You can put in 10 meter long rods, the stroke is the same.

You're right, I feel silly.

Would it be worth using short rods to shorten the deck height? Would it be worth using longer rods to reduce thrust loads, but a taller engine? Somewhere in the middle? Would combustion process influence this? Shorter rods are also less prone to detonation, but longer rods favor mid and high speed operation. I guess playing around with this wouldn't be worth it cost wise as the gains would be marginal if any one way or the other.

[PlatinumZealot]

Gonna take a swing: long rods means more rod and more engine block and more weight. Shorter rods means slower velocity as the piston rises up and down. Slower piston motion can mean more power if combustion is relatively slow, but with TJI it is very fast.. So shorter rods are a disadvantage for this. So overall it is an optimization between rod
weight, engine weight, reliability and response (side loads), and the cylinder pressure characteristics.

[gruntguru]

Gonna take a swing: long rods means more rod and more engine block and more weight. Shorter rods means slower velocity as the piston rises up and down.

Shorter rods mean shorter dwell (higher acceleration) around TDC and longer dwell near BDC. Infinite rod length yields simple harmonic motion (same dwell and acc' at TDC as BDC).

Average piston velocity doesn't change with rod length.

[rscsr]

How you achieve that stroke is where the fun starts, as the rod ratio has a huge influence in a lot of the mechanical properties of the stroke. Increasing the crank throws shortens the rods, reducing the throws lengthens the rods, longer rods have longer dwell times at TDC and BDC, and lower acceleration from TDC and BDC. However with the rapid combustion these engines use maybe super long rod ratios aren't beneficial.

Stroke is independent of rod length. It is 2 times the distance from the main journal centreline to the pin journal centreline. You can put in 10 meter long rods, the stroke is the same.

You're right, I feel silly.

Would it be worth using short rods to shorten the deck height? Would it be worth using longer rods to reduce thrust loads, but a taller engine? Somewhere in the middle? Would combustion process influence this? Shorter rods are also less prone to detonation, but longer rods favor mid and high speed operation. I guess playing around with this wouldn't be worth it cost wise as the gains would be marginal if any one way or the other.

Cosworth stated once in a RET that they used the shortest rod possible, since they found that it had no measurable power penalty to them (back in the V10/V8 days).

[sosic2121]

I found in 2018 FIA Technical regulations that F1 engine must have cylinder diameter of 80 mm, but I didn't find anything about stroke.

Renault and Ferrari state that their stroke is 53 mm while I didn't found data for Mercedes and Honda. Is this 53 mm stroke also regulated or is it just a coincidence that Ferrari and Renault engines have same stroke?

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

Maybe Mercedes downsized their engine and that's why it is so efficient

[Big Tea]

I found in 2018 FIA Technical regulations that F1 engine must have cylinder diameter of 80 mm, but I didn't find anything about stroke.

Renault and Ferrari state that their stroke is 53 mm while I didn't found data for Mercedes and Honda. Is this 53 mm stroke also regulated or is it just a coincidence that Ferrari and Renault engines have same stroke?

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

Maybe Mercedes downsized their engine and that's why it is so efficient

5.1.2 Engine cubic capacity must be 1600cc (+0/-10cc). Someone must have tried it before

[sosic2121]

It's no coincidence. To achieve 1600cm3 with 6 cylinders of 80mm bore you need 53 mm stroke.

Pi*4,0^2*5,3*6~1600

Maybe Mercedes downsized their engine and that's why it is so efficient

5.1.2 Engine cubic capacity must be 1600cc (+0/-10cc). Someone must have tried it before

Such a shame.
Imagine the efficiency if they could downsize these engines...