Engine Position?

[Infinity]

Hi
We were trying out our engine(Motorbike engine) in different position and analysing its outcome. We figured out that placing the engine with the cylinder head towards the rear has some benefits over its current position. I searched for the similiar car to figure out how to modify the transmission but could find any.

I could make out how to implement it or why havent any university used it before? Does it have any disadvantages?

[Infinity]

Originally posted by Infinity:
Hi
We were trying out our engine(Motorbike engine) in different position and analysing its outcome. We figured out that placing the engine with the cylinder head towards the rear has some benefits over its current position. I searched for the similiar car to figure out how to modify the transmission but could find any.

I could make out how to implement it or why havent any university used it before? Does it have any disadvantages?

I meant I couldnt figure out how to implement it. Sry

[Pete M]

The simple answer is that figuring out how to get drive to the rear wheels is hard without ending up with something awkward and heavy.

[Infinity]

Originally posted by Pete M:
The simple answer is that figuring out how to get drive to the rear wheels is hard without ending up with something awkward and heavy.
Sry If I am not clear. Thats quite obvious. Thats what i need to figure out... but any suggestion how to implement it?

[Greg 08]

I have never really researched this topic, however Michigan Tech used to have the engine mounted in the manner you are suggesting. The engine was run backwards, turning the other direction. I have no idea what they did about cams, but apparently beyond that the major change was an auxiliary oil pump and dry sump. The MTU car from 2001 and 2002 ran this set up, but I am really not familiar with any of the people who did it.

The short version: it's quite complicated, but it has been done before. This is where you employ all that knowledge you have spent so much money to acquire. I am sure that they used nothing more than some thought, math and elbow grease to get the job done.

[Michael Hart]

Out of curiousity, why would you want to do this? If you're worried about moving more weight to the rear axle, why not just recline the driver more? Most drivers weigh more than the engines, and the driver's COM is right around his/her abdomen, so wouldn't reclining the driver more move that back farther than flipping the engine?

[VFR750R]

Putting the battery, radiator in the back help rear weight bias. So does angling your rear a-arms foward or a bayless rear, and those things are WAY easier then reversing the position of the engine.

I think reclining the driver more will lower the CG but won't move it back. I guess it depends on what part of the body isn't going to move, but usually the limit is the drivers shoulders being directly in front of the engine head itself. That being the case, reclining the driver will move thier arse and feet forward, which not only will move the drivers cg forward but the pedal bay will also be forward the same amount.

[Moke]

We (University of Auckland) did such a thing on our 2005 car and ever since. We run a Yamaha R6, which has a stacked gearbox; some CBR engines would be unsuitable. We did not reverse anything, just ˜pushed' the engine over backwards.

Our reasoning was thus:

1) Lower COG for engine, I think it lowered by about 40mm.

2) Better packaging, as the angle of the engine now matches the seat back angle. The engine sits more under the driver not behind them.

3) No big space behind the seat, with the headers in it. Headers are now above the engine, in air flow, not heating the drivers back and anything in that hole.

4) Lower COG of driver as we can lay them back further. Our '05 car (without wings) is less than 1m, to the roll hoop.

5) Less front overhang. Since the engine is under the driver we can slide their position back reducing the overhang.

6) Greater rear weight bias. As the driver is further back their weight is also further back. We got about a 40/60 rear weight bias.

But this was not without problems. We had to develop a dry sump system, as the stock sump was now vertical. This proved harder than dry sumping an engine in std orientation as oil now pools in new places and doesn't get to others. We had to develop peel plates and scavenge points.

We got new cams ground but that was more to do with the supercharger.

Now for the warning: It took heaps of time. From memory a month just staring at the block pretending to be oil to see where it will go. Also you could be sacrificing an engine, we have had to chop and change ours, and it has new holes and old ones covered over.

Below are a few CAD pics of the setup. Also check out our website www.fsae.co.nz (http://www.fsae.co.nz)
http://www.fsae.co.nz/images/stories/tech_images/2005/engine_layout.JPG
http://www.fsae.co.nz/images/stories/tech_images/2006/engine_small.jpg

Good Luck

[BenB]

Anouther idea I just thought of if you wanted to rotate the engine around (around the vertical axis I guess) would be design a assembly that attaches around the output shaft of the engine that would have 1 set of gears in it. This would reverse the direction the output shaft is spinning.

You could then run the chain and diff the way most of the other FSAE cars are.

The only drawback is you are loosing some efficiency through another gearset. I think gears are around 98-99% efficient typically so if you are making 100HP then you might be loosing a HP through it.

[Infinity]

Originally posted by Michael Hart:
Out of curiousity, why would you want to do this? If you're worried about moving more weight to the rear axle, why not just recline the driver more? Most drivers weigh more than the engines, and the driver's COM is right around his/her abdomen, so wouldn't reclining the driver more move that back farther than flipping the engine?

We were interested in its scope because it would simplify the design and manufacturing of the Intake and Exhaust......

[rjwoods77]

Infinity,

There are all sorts of advantages to doing the engine like Auckland. If anyone asks why you would want to do it then they must not see these advantages. I am suprised more people havent tried it to be honest. However like it has been mention is it a ton of work to get it to work right. The idea BenB mentioned is a good idea except for the fact that the engine would be in the way of the chain getting to the differential and/or you would have to have very offset diff which poses a bunch of problems. You would have to take off a jackshaft like Sherbrook does which adds more problems that you will gain in packaging benefits. Just simplifying an exhaust and intake package really doesnt justify all the work that would go into changing engine config. If you went to a single or v-twin desing you can avoid all of the packaging problems all together. Sometimes the best way to solve/optimizing a packaging problem is to use a different package.

[drivetrainUW-Platt]

I have seen some very nice packaging for longitudional engines with stock atv differential gearcases. Kanagowa, Guelph...etc.

If I wasnt such a chicken about doing something off the wall(out of the box) thats what we would run this year.

[Infinity]

Originally posted by Rob Woods:
Infinity,

There are all sorts of advantages to doing the engine like Auckland. If anyone asks why you would want to do it then they must not see these advantages. I am suprised more people havent tried it to be honest. However like it has been mention is it a ton of work to get it to work right. The idea BenB mentioned is a good idea except for the fact that the engine would be in the way of the chain getting to the differential and/or you would have to have very offset diff which poses a bunch of problems. You would have to take off a jackshaft like Sherbrook does which adds more problems that you will gain in packaging benefits. Just simplifying an exhaust and intake package really doesnt justify all the work that would go into changing engine config. If you went to a single or v-twin desing you can avoid all of the packaging problems all together. Sometimes the best way to solve/optimizing a packaging problem is to use a different package.
Thanks Rob... Actually we have our own problems related to engine (till date we havent got any)...Its great deal of problem to get a superbike engine in India where superbike arent much of success so we rely on importing one... So it has been after a lot of searching and sorting that we found a good engine so cant change it now......
may i ask one more thing....does single cylinder engine perform well? The max we can get is 225cc thats too less a power i guess??

[rjwoods77]

RMIT wins competitions with a single so I would say yes but you have to keep the weight down to really see its advantages.

[Mike Hart]

Originally posted by Michael Hart:
Out of curiousity, why would you want to do this? If you're worried about moving more weight to the rear axle, why not just recline the driver more? Most drivers weigh more than the engines, and the driver's COM is right around his/her abdomen, so wouldn't reclining the driver more move that back farther than flipping the engine?

Well that's incredibly confusing! I thought at first....hang on....I don't remember writing that?! I don't often see 'my' name in many places since it's not exactly the most common surname to start with!

[Nik]

Why don't you try switching your exhaust and intake cams so that the engine breaths in the exhaust ports and out the intake ports?

Ha ha, just kidding, but not really.

[TG]

Originally posted by Nik:
Why don't you try switching your exhaust and intake cams so that the engine breaths in the exhaust ports and out the intake ports?

Ha ha, just kidding, but not really.

I believe UCSD reversed the head on their YZF-600R motor (cam drive is centrally located) so that they did just this.