Fantasy engine

[Bus_Lengths]

Well,if we are going the $$$$ and time route of custom building a 600cc V10 or equivalent, I'd just ditch the restrictor and silly 610cc limit altogether. Why spend years of manpower and $$$$ for something you get less than 1 weekend out of?

Instead, I'd get a higher mileage LS7 out of a totalled vette. Throw in the cam and valvetrain required for 8500 RPM's along with the necessary portwork. I'd just run one gear because a full transmission wouldn't really be necessary. It would weigh about 320 lbs for the engine (as opposed to 100 for your typical 4 cyl) and your driveline would be heavier, BUT it'd also make about 740 bhp. With no transmission at all, gear changes will be infinitely quicker than an F1 car too.

I'd run a 3.42:1 total gear reduction, giving its single gear a 150mph top speed (about as fast as I'd feel safe in a 700 hp student built open wheel car). This would also give it about 2700 lb of thrust at the tire at peak torque. Taking a 400 lb FSAE car, adding 220 lbs for the engine, and 150 lbs for the driveline, and 50 lbs more to the chassis, this car could weigh just under 1000 lbs with driver. This would give it a much better power to weight ratio than a measly F1 car.

Such a car should be able to pull 2.0g of launch accel off idle, upwards of 2.7g at peak torque, and back to down to 2.2g at redline. Might need a little assistance from some VHT for these numbers, but the point stands. If you can get the car to hook, top speed (150 mph) should be reached in approximately 3.1 seconds according to my tractive effort spreadsheet.

You could roll people up at the drag strip on Friday nights and destroy the autocross courses on Sunday. That's what I'd do.

[JT A.]

8 or 10 cylinders just seem like too much of a hassle to make an intake & exhaust for.

I would go with a parallel twin around 500cc, if they could get it to weigh somewhere around 60-70 pounds like the aprilia instead of 90-100 pounds like the current snowmobile motors. A dry sump so it could be laid down horizontal, and direct injection cuz why not. Ideally I'd want a well set up CVT for a transmission.

[Jan_Dressler]

300cc W-3 (30°+90°, gearbox in the 90°-angle), main bearings on the webs, Bishop-type rotary valves, supercharged, turbocompound for fuel efficiency, 3-speed epicyclic gearbox (a la Wilson preselector), one clutch for each wheel both for starting and torque vectoring (no diff).

[mech5496]

Jan, wow mate! Rotary valves might be a good idea, but I do not know if they worth the hassle. I prefer to be a bit more realistic (possibly wrong for a "fantasy" topic, but, hey, I would love someone to get a bit nuts and actually build something inspired from that very thread). So, onto my "perfect IC FSAE engine"!

As RenM mentioned, more cylinders means more losses. Thus I would go for a single (or inline twin for smoother operation), laid down with the cylinder heads facing rearwards and about 10-20deg from horizontal to make space for the intake port (and a nice big diffuser except for around the intake ports), thus bringing the relatively heavy cranckshaft/flywheel near the CoG (minimize yaw inertia) and as low as possible. Twin (electronically controlled) CVTs, one on each side of the engine for torque vectoring. Turbocharger in the middle of the CVTs, directly above the exhaust port (which would be placed facing upwards), E85 and as many CCs as possible, redline at about 10000RPM, tuned for peak power. Machined/cast motor and CVT casings, backing up as suspension/damper/jacking point mounts and designed to withstand all frame forces. Possibly hollow, so it could also be used as oil tank. Neat small package to bolt directly after the main hoop on a monocoque, with no need for any additional subframe. To aid efficiecy add some Honda tricks, like roller-bearing camshaft(s?), two (instead of three) piston rings and low friction coating (DLC?). I would love to see a team doing it, as mine won't do for sure!

EDIT: To get a bit crazier, maybe direct injection, electric water/oil pump and no alternator. Two really small motors on the front hubs would charge the battery during braking, improving overall efficiency. Thoughts?

[Markus]

3-cylinder with a simple two-speed or three-speed planetary (epicyclic) transmission. Both longitudinal or transverse mounting possible options, can't decide.

Almost constant inertial torque, simple packaging, super fast shifting especially with the two-speed. No forced induction because of restrictor, packaging and weight.

If anything with a "normal" gearbox then zero-shift technology.

I also liked Owens boxer engine idea.

[DougMilliken]

One of the key features of the FSAE rules is no minimum weight. Whatever engine configuration (& unitized frame and suspension mountings as already noted) came out of the packaging study, I'd go for a really light engine. One way to do this is minimize parts count and joints. For example unitize the cylinders and head like an Offy (inline-4 DOHC). A bit of a pain to fit the valves up through the cylinder...

More extreme is Tony Rudd's Lotus Microlight small aircraft engine. This was a pushrod boxer with a split at the crank and one casting for each half-crankcase + cylinder + head. Light rocker covers were the only other gasketed joints. This also had the propeller reduction drive unitized with the 2:1 cam shaft drive (cam above crank to raise the prop center above the engine).

[Ash47]

500cc V-Twin with a 1 or 2 speed transaxle gearbox

[mech5496]

Doug,
being a weight weenie myself, I couldn't agree more; however, unifying the head,cylinders (and crankcase) would only save a few grams in the cost of much increased complexity. So, does it worth the hassle? IMO, no... Weight (and efficiency) is my worry on a twin CVT setup like the one I proposed, and it is true that I really like those epicyclic gearboxes, so maybe using them in a similar twin-clutch setup (like already proposed) looks promising and maybe lighter. BTW does anyone know why those gearboxes are not seen very often? Combined with electronic clutch control and shifting they should kick ass!
On a side note, tilting the cylinder by a bit higher (say 30deg) and swapping intake/exhaust sides, gets the heavy turbo as close to the ground as possible, so this might have a slighter lower CG. (A look on Swanseas S12, note the neat turbo/plenum/intercooler package)

Ash12, I think you have something like the one you describe lying around there...

[Markus]

Harry, epicyclic transmissions are one of the oldest automotive gearboxes ever used and even still are employed inside multi-speed automatic transmissions. What you suggested (epicyclic transmission + electric clutches) is a basic part of a modern auto trans.

FSAE is special in the way that it would not require such a high gear-count as "real-life" conditions so it could really make use of this "ancient technology".

We're already repeating history by re-employing electric motors to produce traction and epicyclic transmissions followed shortly after... So who knows how soon we'll see them.

[theTTshark]

500cc 120 degree V4, twin scroll turbo sitting in the V with a small intercooler for each bank. Mounted to the engine would be a CVT/differential transaxle. It would be dry sumped, oil to water cooler, and a charging system capable of 45 amps. There would be mounting points for all of the rear suspension and rear aerodynamics, and of course they would be stressed chassis members. Whole thing would weight 120 lbs. The engine would utilize an electronic throttle only to be able to idle. Once running on track the gas pedal would be a torque pedal (ala Formula 1 blown exhaust) so that the engine could utilize hot blowing (effectively anti-lag) on the rear wing. Hot blowing instead of cold blowing because flames are cool, and everybody knows that a racecar is instantly cooler if it spits some fire! Plus hot blowing produces higher exhaust gas velocities.