Hypotetical: F1 Two-stroke engine.

[jbenum]

Lets assume it was allowed to have a two-stroke engine of half the displacement the regular uses, that would be 1.2L. Lets also assume it's allowed to make use of "rare" materials and variable geometry.

I know nothing about engines, but many here seems to know alot. I'm currently "researching" this for a mod for rFactor. How competative do you think it will be? Will the torque-curve be very peaky?

Thanks in advance.

[RH1300S]

Lets assume it was allowed to have a two-stroke engine of half the displacement the regular uses, that would be 1.2L. Lets also assume it's allowed to make use of "rare" materials and variable geometry.

I know nothing about engines, but many here seems to know alot. I'm currently "researching" this for a mod for rFactor. How competative do you think it will be? Will the torque-curve be very peaky?

Thanks in advance.

Sounds like an interesting mod

Could you get data from the last GP500 engines and extrapolate the torque curve for additional displacement? There must be mods for the GP500 games you can look into to access the data.

The bikes were 4 cylinder (in the main) and, although powerful, were tuned with rideability in mind.

Far less engine braking in a stroker (you can model this in rFactor I think).

The engine would probably have considerably less mass than current engines.

Interesting idea............

[joseff]

The 500cc V4 bike engines had 220-ish hp. Scaling this up to a 1.2l V8 that's competitive with a 4-stroke 800hp engine is going to take some work.

Driveability is also a problem. 2-strokers are known for being peaky. Reed valves have done so much, but I'm quite sure 4-stroke motors are still more driveable.

And finally... the deal breaker. The whole appeal of 2-strokers is the idea that you can have a much smaller engine for the same power output. This is true for a 2 cylinder engine, less so for a 4 cyl one, and very likely negated for a V8. The reason is that a 2-stroke engine needs big expansion chambers. Packaging 8 of them into a coke-bottle-shaped F1 car would be a nightmare.

On the up, RH1300 summed it up: a 2-stroker would be lighter and have fewer moving parts than its 4-stroke counterpart.

[jbenum]

But what if any cylinder configuration was allowed? That sould be of some help i guess.

One problem with rFactor is that it is only possible to have 7 gears, and i guess if someone seriously made the engine they would have used more. There sould be room for a bigger gearbox at least.

[DaveKillens]

The biggest difference bwtween 2 and 4 strokes is that 2 strokes don't need valves and the associated valvetrain. That means you don't have the RPM limits that valves place on engines, and the lesser mass and parts. Because most racing 2 strokes are tuned for peak power at a specific RPM, they do have a very abrupt powerband. But it's very possible to design a 2 stroke with a flatter, more gradual powerband.
Because each cylinder requires pumping from the crankshaft/crankase (unless you use forced induction), the crankshaft is usually longer than a comparable 4 stroke. Then unles packaging requires a compact V configuration, an inline engine cannot be ruled out. And if your final displacement is 1.2 liters, a four would have 300 cc cylinders, and a five 240cc. Eight cylinders would have 150cc.
Each cylinder does require it's own expansion chamber, but they just take up room, their mass is negligable.

[RH1300S]

I thought the biggest difference was the fact that every down stroke is a power stroke

I hadn't thought about the expansion chambers. Typically, high revving two strokes tend towards shorter/fatter spannies; so packaging could be a challenge (although there is nothing to say they need to have a round section )

I think strokers only get the peaky tag because they are knocking out very high bhp/litre. A 4-stroke with the same type of output would be pretty peaky too. IMHO a 2-stroke can have a pretty useful spread of power - it's just that they are utterly crap when the are "off pipe", so the difference is very noticeable.

I know it's only theoretical, but you would have to get fuel injection working properly (I think Bimota got close) - just imagine what would happen to the fuel inside a carb at 5g!

One thing - I would love to listen to one of these things running - it would be nuts. I have always loved strokers (ex MXer & previous owner of RGV250).

[RH1300S]

Hells teeth - a thought has just occured

Gamers out there will understand - the rest will think I need a lie down........

Chain of thought..........two strokes, each down stroke is power stroke, traction problems, big bang engines.............and I made a JUMP to:

When a computer game simulates the power output of a fourstroke engine; that's all it does - it delivers constant thrust to the driven wheel, the amount of thrust being affected by the instantaneous torque and final gearing. There is no small pause between the power pulses that you get in a 4-stroke (or a multi cylinder 2-stroke with the right firing order). These pulses help with traction in real life.

So........every computer game should have a minimum amount of traction control to suit the engine being modelled (over and above any traction control that may be part of the vehicle being reproduced).