v12 or v10

[saviour stivala]

While the Cosworth CA was itself a V8, formula 1 engine developments never stops, they were only ever stopped by the rule makers. While the CA was the first to run at 20k RPM, the 3.0L V10’S before it were already very near running at 20k RPM Before the brakes were slammed on their development. Likewise on the V8’S that followed, about which time they were all running at 20k RPM plus. Re-friction losses which will negate the gains benefit of running at higher RPM and higher number of cylinder count at the same capacity, the development quest for ever higher RPM and cylinder number count at same capacity was always able to overcome and gain an advantage. The quest for ever higher RPM:- ‘’Brook Woods Cosworth technical director’’ ‘’To go faster (RPM) you have to keep making the bore bigger, the stroke shorter, and sort-out your valves.’’ Going in that direction of making the bore bigger for a given capacity necessitates overcoming the weight problems of the reciprocating parts (pistons/con-rods and crank-pins) to be able to keep the engine in one piece at the aimed for higher RPM. It follows that the smaller the cylinder number count for a given capacity, the bigger the bore will have to be. And that is why the V12 will be easier to achieve higher RPM then a V10 or V8. This always at same capacity. Although I said that all F1 engines convarged on the V10 design, both Cosworth and Toyota had a V12 in the making when the rule makers capped the cylinder count to 10.

[Bandit1216]

Yes.

There are practical issues. Let's say you have a 3 liter V8 and you strive 25 krpm. At one point the bore - stroke ratio gets ridiculous. At one point you would get a smaller stroke then the size of your main bearings and a relative heavy piston /conrod. More cylinders would give you the opportunity to apply the shortest stoke practical, yet smaller bore, and thus lighter pistons.

[saviour stivala]

Yes.

There are practical issues. Let's say you have a 3 liter V8 and you strive 25 krpm. At one point the bore - stroke ratio gets ridiculous. At one point you would get a smaller stroke then the size of your main bearings and a relative heavy piston /conrod. More cylinders would give you the opportunity to apply the shortest stoke practical, yet smaller bore, and thus lighter pistons.

Exactly.

[Tommy Cookers]

.... you strive 25 krpm. At one point the bore - stroke ratio gets ridiculous. At one point you would get a smaller stroke then the size of your main bearings and a relative heavy piston /conrod. More cylinders would give you the opportunity to apply the shortest stoke practical, yet smaller bore, and thus lighter pistons.

yes
Honda used such (shorter strokes and more rpm than ever F1 did) ..... in the ....
unsuccessful NR500 (4 non-cylindrical 'cylinders) and ....
the successful CR??? 5x25cc cylinder and 2x25cc cylinder
smaller cylinders work via the relatively lower gas speeds helping the breathing
so apparently a narrower power-band - needing more gears

for roughly the first 50 years of GP racing the engine rules changed frequently ... but cylinder count was free
for roughly the next 50 years of GP racing the engine rules hardly changed ... but cylinder count became limited ...
this led to systematic pursuit of increased bore:stroke ratios

[Bandit1216]

So narrow power band you need a 12 to 16 speed gearbox (Suzuki RK66-67 RP68)

[echedey]

The truth is that I am going to take the cosworth ca engine for reference but as far as I know there is not much reference and data on that engine, as I would like to know certain data such as:

Compression ratio.

Diameter of the exhaust and intake valve heads.
and valve angle.

Piston diameter, piston size and piston length.

Connecting rod size.

Diameter of the crankpin and connecting rod.

Crankshaft radius.

Crankshaft counterweight grams.

[Zynerji]

The truth is that I am going to take the cosworth ca engine for reference but as far as I know there is not much reference and data on that engine, as I would like to know certain data such as:

Compression ratio.

Diameter of the exhaust and intake valve heads.
and valve angle.

Piston diameter, piston size and piston length.

Connecting rod size.

Diameter of the crankpin and connecting rod.

Crankshaft radius.

Crankshaft counterweight grams.

Intellectual property that costs millions to develop if quite often kept secret...

[Hoffman900]

For a time, but that is all useless information now.

Check out here: http://indycompetition.com/engines--engine-parts.html

I would just start with a modern Sportbike engine, honestly, and scale that. Way easier and they are awesome pieces.

[saviour stivala]

+1

They can't open and close fast enough. Camshafts are REALLLY hard to beat.

5 valve chambers are a mess combustion wise and they struggle with getting good port velocity out of them.



This and they were at the limit of combustion speed with that bore size, and it wasn't the fastest engine of that era.

I'd like to see that Honda auto ignite system on their old V8...

I’d like to see it on a naturally aspirated application as well, assuming it can work that fast.

The recent 'auto ignit' combustion developments by formula 1 engine manufacturers is all about the combustion being superfast, as such a like system will be beneficial to high reveing engines with their big bore and shorter time for combustion, But. It will be very near impossible development on past high reving F1 V10'S and V8'S, for the simple reason that those engines would never be able to obtain the necessaey high compression ratio needed, one of the requisits to impliment the 'auto-ignit/super fast' combustion recently developed in F1.

[Hoffman900]

I'd like to see that Honda auto ignite system on their old V8...

I’d like to see it on a naturally aspirated application as well, assuming it can work that fast.

The recent 'auto ignit' combustion developments by formula 1 engine manufacturers is all about the combustion being superfast, as such a like system will be beneficial to high reveing engines with their big bore and shorter time for combustion, But. It will be very near impossible development on past high reving F1 V10'S and V8'S, for the simple reason that those engines would never be able to obtain the necessaey high compression ratio needed, one of the requisits to impliment the 'auto-ignit/super fast' combustion recently developed in F1.

Fast ignition doesn't mean the hardware can cycle at the speed needed for 20k rpm operation. Compression ratio would be an issue as well.

[Zynerji]

So. Simply raising the compression ratio through piston crown volume couldn't be used?

Aren't current engines like 18:1 already? I figured that was more down to fuel chemistry than anything else...

[rscsr]

So. Simply raising the compression ratio through piston crown volume couldn't be used?

Aren't current engines like 18:1 already? I figured that was more down to fuel chemistry than anything else...

They were running at basically no clearance already. I think the Toyota V8 have been specifically using smaller diameter to increase their achievable compression.

[Zynerji]

So. Simply raising the compression ratio through piston crown volume couldn't be used?

Aren't current engines like 18:1 already? I figured that was more down to fuel chemistry than anything else...

They were running at basically no clearance already. I think the Toyota V8 have been specifically using smaller diameter to increase their achievable compression.

I get that. But isn't the v6 pistons the same size as the v8? It seems like they could adapt the v6 parts onto a v8 block without crazy amounts of rework.

Or, the tolerances are so tight. Any small change just kills all power/efficiency.

[Hoffman900]

So. Simply raising the compression ratio through piston crown volume couldn't be used?

Aren't current engines like 18:1 already? I figured that was more down to fuel chemistry than anything else...

Already tight as can be in the squish areas.

NASCAR runs them tight enough that the piston jusssttt starts to kiss the head with carbon build up. Obviously you need to take rod stretch into account.

Raising the dome hurts combustion efficiency. Everyone is all about high static compression, but there is a trade off and more isn’t always better. Domes / raised crowns always hurt that, just a matter how much juice is worth the squeeze. Valve reliefs as well.

No doubt they have maximized topology for the bore size and combustion speed needed. Honda even showed how they used Bezier curves to build a valve lift curve that bought them slightly less valve relief (gaining .5pt of compression) on the 2008 V8 engine.

[Jolle]

So. Simply raising the compression ratio through piston crown volume couldn't be used?

Aren't current engines like 18:1 already? I figured that was more down to fuel chemistry than anything else...

Already tight as can be in the squish areas.

NASCAR runs them tight enough that the piston jusssttt starts to kiss the head with carbon build up. Obviously you need to take rod stretch into account.

Raising the dome hurts combustion efficiency. Everyone is all about high static compression, but there is a trade off and more isn’t always better. Domes / raised crowns always hurt that, just a matter how much juice is worth the squeeze. Valve reliefs as well.

NASCAR engines can’t have the aggressive cam profiles from DOHC engines, especially on closing. This limits the space available and/or the time the valve is fully open.