Engine Location

[Cobra EESC-USP]

Anyone thought rotating a CBR 600 F4i engine 180 degrees on the frame?
Main problem is the transmission but this configuration seems to provide a better packaging against the usual one.
What do you think?

[Cobra EESC-USP]

Anyone thought rotating a CBR 600 F4i engine 180 degrees on the frame?
Main problem is the transmission but this configuration seems to provide a better packaging against the usual one.
What do you think?

[Conor]

I've put some thought into that as well. The truth is, are you willing to spend the time, money, research, and effort to make that tansmission work for maybe an extra cubic foot of packaging space? I'd like to see it done, but I honestly don't think it's worth it.

[Travis Garrison]

Been done...by Kettering I believe...maybe others as well.

[Storbeck]

Michigan Technological University did it for a few years from something like 00-02, I believe 99 was a sidewinder. They had the motor actually running backwards. If I were going to do it again I'd have the motor run normal and have a gearbox to reverse direction of rotation. We might do it in 07.

It lets you put the motor WAY further forward, maybe 8 or 10 inches, which in my opinion is pretty substantial. Shorter overall package and lower moment of inertia. It also gets the exhaust away from the driver's back, and allows the driver to be more reclined for a lower cg. Creates big packaging problems for chain though, and obviously there's the problem that it's rotating the wrong way.

[Travis Garrison]

You sure you WANT your engine 8-10 forward? You might have trouble with acceleration...

-Travis

[absolutepressure]

Hey cobra, I can't find it, but someone had a post about mounting the engine perpendicular to the axles. They were thinking of connecting a shaft directly to the tranny output (w/out the sprocket) and run that straight to the diff. Look around, it's here somewhere. It won't save you space, but I heard it's a simpler setup that a few teams have used.

[Kamil S]

hmm, I think I saw CSU run a sideways engine... i think the "spatial" setup was engine, differential, then gearbox.

with a 180 degree rotated engine setup, that would be REALLY helpful with packaging a turbo. you could keep things close to the car's centerline, and not have to sacrifice things going to the sidepods.

cool post.

[jonno]

we did it this year, but with a single cylinder where it made the car shorter. The benefits of doing it with a 4 cylinder are obviously that the exhaust is in a much more convenient place (i think guelph do it with a 4 cylinder to get a 4wd system...)
http://www.brunelracing.co.uk/images/cars/br6/top-750.jpg

we can lose an additional 5in or so, we're running a short prop shaft with flexible coupling to compensate for misalignment.

[Storbeck]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">You sure you WANT your engine 8-10 forward? You might have trouble with acceleration... </div></BLOCKQUOTE>

You have to move he wheels as well to get your desired weight distribution. With the motor further forward, and way more room for the sprocket, you can move the rear axle as far forward as you want, to get whatever weight distribution you want. It is possible to get way more rear weight with this settup.

[Z]

Cobra,

IMO a good idea. I posted on this in a thread to do with Acceleration event. As Storbeck says you can get more rear weight which is good for acceleration. Shorter car and lower yaw MoI is also good for Autocross events.

One way to do it would be to have a short shaft (4" - 6") from the engine output to a chassis mounted sprocket, a chain going back to a similar sized sprocket, then a gear pair driving the diff. This gear pair might come from the final drive of a small front-drive car (ie. complete with the diff).

There is a small added complexity (the extra gearset), but big advantages in overall packaging.

Z

[CMURacing - Prometheus]

i could see it being an advantage in packaging, but z, your big geartrain setup: needs some big 0.120" steel plate as a chainguard. and quite a bit of it too. not exactly the sort of thing that's advantageous, though it WOULD give you even more weight on the rear wheels...

[Z]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by CMURacing - Prometheus:
but z, your big geartrain setup: needs some big 0.120" steel plate as a chainguard... </div></BLOCKQUOTE>
Mike,

Probably less "chainguard" than the standard setup, because smaller rear sprocket and the centre distance is only ~12".

But yes, extra weight from the gear pair (and their housing) driving the diff.

But then again, about 12" shorter chassis and bodywork...

(Edit: The chassis would be shortened at the front of the car, giving lower yaw inertia for better corner turn-in.

So, starting at rear-axle and going forward: Diff and its gear pair and housing. Engine cylinders pressed up against diff (exhausts directly above diff). Seat-back pressed up against engine gearbox and intake/plenum (driver's headrest above and just forward of rear-axle line). Driver's feet on front-axle line. And all this inside the minimum distance 60" (1.52m) wheelbase!http://fsae.com/groupee_common/emoticons/icon_wink.gif)

Z

[GTmule]

My thought was just to have three spur gears (one on the tthe diff, and idler, and one on the output of the engine. It'd be noisy, but I think, in theory, you'd avoid the chain guard. Gear alignment might be tricky.

[Z]

GTmule,

Err, with conventional engine rotation and 180 degree reversed engine... that would give you 6 gears in reverse... and none forward http://fsae.com/groupee_common/emoticons/icon_confused.gif?

With 4 gears (2 idlers) it would work ok. My idea to include a chain drive is mainly to make for easy overall ratio changes - it being easier to swap a sprocket and readjust chain tension, than to swap gears in some kind of rigid gear carrier.

BTW, for those interested in taking a shaft drive off the output sprocket of a bike engine, a simple "misalignment" coupling is to have two equal sized sprockets next to each other (one on the engine output, the other on the input to the drive shaft), then wrap a double row chain around the pair of sprockets. This is a standard industrial coupling that allows for a small amount of misalignment in all directions/angles.

Z