Engine bore/stroke calculations

[DannytheRadomski]

I have spent the last few days trying to design an engine I've had in my head for a while. I've tried and retried several times to no avail. What I do know is I want the bore/stroke ratio to be around 1.2:1 and the displacement to be about 2800cc with a V6 configuration. All the engine calculators I tried entering this information into came up short. I've done the math enough to give me several headaches. Any help is appreciated.

[Charles Kaneb]

Danny,

I think you just got crossed up somewhere. It's simple.

Vdisp = Pi * (Bore/2)^2 * Stroke * # of cyls.

Bore = 1.2 * Stroke

Substitute this expression for bore:

Vdisp = Pi * (1.2*Stroke/2)^2 * Stroke * # of cyls

Vdisp = Pi * (.6*stroke)^2 * Stroke * # of cyls

Vdisp = Pi * .36*stroke ^3 * # of cyls

Then find bore by bore = 1.2 * stroke

[DannytheRadomski]

I knew it was just a minor slip-up or something I just wasn't seeing.

Thank you so much for the help.

[PatClarke]

It popped into my head, without any calcs, that such an engine would be about 90mm x75mm

Just what the world needs, another circa 3.0 V6

What on earth are you up to Danny?

Pat

[DannytheRadomski]

My "plan" would be to make a 2.8L 120 degree V6 to be mounted longitudinally in a small mid-engine car.

One of the suspected Honda NSX concepts (there were a bunch) had a 2.8L V6 the revved to something crazy like 12,000RPM or something like that.

I figure similar architecture would be cool, but for some reason I like weird engine angles. So it won't be another 3L 60 degree V6 just like the rest (except the Ferrari Dino V6 which was 65 degrees and there were also a few 90 degree V6s). Besides I think 3L should be reserved to V8s (like Ferraris of old).

[Charles Kaneb]

Look at the trends for brake specific fuel consumption versus cylinder size.

My opinion is that a 2.8 liter engine ought to have either three or four cylinders. If the peak power is inadequate due to low maximum engine speed, then consider increasing displacement still further or turbocharging.

[DannytheRadomski]

I'm not a huge fan of forced induction most of the time. Also in my overall plan for the car the engine needs to be configured this way.