Honda Power Unit Hardware & Software

[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...

[Big Tea]

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...

I have not thought it through, but cannot see why it is not allowed. Anyone think of good reasons why not?

[Big Tea]

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.

Would not heavier and longer rods have a negative effect on the rise and fall of engine RPM?
I assume the faster the RPM is able to rise and fall the better for a race engine?

[Revs84]

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...

I have not thought it through, but cannot see why it is not allowed. Anyone think of good reasons why not?

I could not see either. I think that going by same efficiency percentage though, downsizing will generally result in less power as well, so even if it was possible, I think most engine manufacturers would still be playing at the top end of the 1600cc ballpark.

What in my opinion is even more surprising is why they limit the bore. Wouldn't the possibility of playing around with bore and stroke lead to some interesting outcomes? It would allow a bit more freedom to manufacturers, rather than an exact same formula for all. This one-for-all approach is what annoys me the most in modern F1.

[dren]

The PU manufacturers would all likely converge anyway, so they set them in the regulations so money isn't wasted in those areas.

[HPD]

[63l8qrrfy6]

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).

Correct, I have heard that too.
In addition they also had the largest bore (98mm vs Honda's 97mm and Toyota's 96.8mm) so if there was anything to be gained from rod length, they would have found it.

For the same cross section, the shorter rod has less deflection under load (is stiffer in tension). Given that it was not uncommon for pistons to lightly touch valves in V8s, having better control over valve-piston clearance was a nice extra on top of the lower rotating and reciprocating mass, shorter deck, lower CG, etc.

[63l8qrrfy6]

What in my opinion is even more surprising is why they limit the bore. Wouldn't the possibility of playing around with bore and stroke lead to some interesting outcomes? It would allow a bit more freedom to manufacturers, rather than an exact same formula for all. This one-for-all approach is what annoys me the most in modern F1.

It is all for the sake of cost control. By constraining some of the important engine dimensions they are trying to stop manufacturers from splashing out on expensive DOEs.

There's also the off-chance that a manufacturer might get it completely wrong and would need to invest time and money to recover, not unlike Honda.

[godlameroso]

Shorter rods have higher thrust loads on the pistons as well, and lower dwell times, they produce more engine vacuum, so improve low speed response. The shorter the rod the faster the initial acceleration but the lower the mid stroke speed, with longer rods the initial acceleration from TDC or BDC is slowed, but the mid stroke speed increases.

Good ol' Smokey made long rods work, again I'm guessing rod length is dependent on the setup, and the requirements. I doubt they're using crazy low RR nothing less than 1.4:1

[Big Tea]

Shorter rods have higher thrust loads on the pistons as well, and lower dwell times, they produce more engine vacuum, so improve low speed response. The shorter the rod the faster the initial acceleration but the lower the mid stroke speed, with longer rods the initial acceleration from TDC or BDC is slowed, but the mid stroke speed increases.

Good ol' Smokey made long rods work, again I'm guessing rod length is dependent on the setup, and the requirements. I doubt they're using crazy low RR nothing less than 1.4:1

I am guessing that longer rods means a heavier engine as the jornals need to be lower, so more 'wall' and/or sump?

[Revs84]

What in my opinion is even more surprising is why they limit the bore. Wouldn't the possibility of playing around with bore and stroke lead to some interesting outcomes? It would allow a bit more freedom to manufacturers, rather than an exact same formula for all. This one-for-all approach is what annoys me the most in modern F1.

It is all for the sake of cost control. By constraining some of the important engine dimensions they are trying to stop manufacturers from splashing out on expensive DOEs.

There's also the off-chance that a manufacturer might get it completely wrong and would need to invest time and money to recover, not unlike Honda.

Or on the other hand could have given them the opportunity to do better than they did. Honda has historically shown that thinking out of the box is one of their strongest traits.

[63l8qrrfy6]

Or on the other hand could have given them the opportunity to do better than they did. Honda has historically shown that thinking out of the box is one of their strongest traits.

Potentially, I don't really disagree, but I've pointed out a while ago that Honda's most successful engines, the 80's v6 turbo and early 90s v10s have not been considered particularly innovative. They were however very well engineered.

[godlameroso]

I thought only deck height was affected.

[ivanlesk]

What in my opinion is even more surprising is why they limit the bore. Wouldn't the possibility of playing around with bore and stroke lead to some interesting outcomes? It would allow a bit more freedom to manufacturers, rather than an exact same formula for all. This one-for-all approach is what annoys me the most in modern F1.

It is all for the sake of cost control. By constraining some of the important engine dimensions they are trying to stop manufacturers from splashing out on expensive DOEs.

There's also the off-chance that a manufacturer might get it completely wrong and would need to invest time and money to recover, not unlike Honda.

Or on the other hand could have given them the opportunity to do better than they did. Honda has historically shown that thinking out of the box is one of their strongest traits.

Historically, but not necessarily this "generation" of engineers.

[63l8qrrfy6]

Back to the current season:

Honda claimed to have upgraded the turbo/mguh. Considering they had about one week to inspect the failed components, redesign and manufacture new ones (most likely without any form of validation) what are the chances that the new bits turn out to be lemons too ?

Do we know if it is a repeat of the good old bearing issue from last year ?
Does that fact that they have pre-emptively changed Hartley's parts point to a design flaw or a manufacturing issue ?