Engine Tilt Angle...

[DoItDoug]

We're considering tilting our engine a bit more this year for a better diff placement. What are the angles that other teams are tilting their engines forward and what problems does it create for you? We're at 16 degrees forward now with nearly vertical intake.

'02 VT FSAE

[Lyn Labahn UW-Madison]

There are two issues that need to be addressed.

1. Make sure that your engine can run reliably at that angle for your sake: oil pressure, cooling etc..

2. Make sure that you can explain to the judges how you determined this (testing methodology), because they will want concrete evidence, not Joe Schmoe on the forums said it would work great.

Let me know what you find out,

2002/2003 Team Leader

[Jade]

We're using a CBR F4i engine. The engine is tilted because of packaging issues. It's tilted at an angle of approximately 22 degrees, the oil filter going up.

I have no idea if the lubrication system will work in such an orientation. I have opened up the sump, and the oil strainer pickup seems to be OK. I do not know if there are other oil pickup points in the engine which will cause issues. I do not have the confidence to open up the engine. Engines are VERY difficult to come by here.

If you've opened up an F4i, can you tell me if this is OK? I really need to know this as I will have to redesign my chassis if it will cause a problem.

Thank you.

Shyam Jade

[Pete M]

There are no other oil pickups. The main thing you have to be sure of is that the oil pickup is never uncovered as oil sloshes around from the acceleration in all four directions. In your case, i'd be concerned with what would happen under forward acceleration. The oil will already be sitting mostly in the gearbox area due to the tilt.

If you're not confident that it will be ok, then why are you doing it? The large majority of teams don't tilt their engine.

[Brian Barnhill]

I've got the numbers from Honda somewhere. I'll search and see if I can find the exact numbers.

[Ecks]

Keep in mind that longitudinal accelerations will have the same effect as tilting the engine. (No-one seems to worry about losing oil pressure on accel runs, though)

The big idea here is that this is a dynamic problem.

[Grant Mahler]

Originally posted by Ecks:
Keep in mind that longitudinal accelerations will have the same effect as tilting the engine. (No-one seems to worry about losing oil pressure on accel runs, though)

The big idea here is that this is a dynamic problem.

The bikes from which these motors came will accelerate much faster than any of these cars will go. The problem lies in cornering. Where a bike will lean, leaving the oil in the bottom of the windage tray, the cars will not, necessitating some modifications.

It becomes a static problem if you tilt the motor enough that the oil pickup(s) is (are) not in the low point(s) anymore.

[Jade]

@Pete:

My main oil pickup seems to be OK. I'm more concerned about things like this:

I'm quoting Tony K from another thread:
"Well, I can tell you from experience that +/- 15 degrees is a horrible answer. In '04 we experimented with tilting the R6 engine 15 degrees to try and lower the CG of the engine but ended up burning up the camshafts instead. The buckets that hold the oil for the tappets don't like to be tilted downward as all the oil runs out and starves the tappet surface, hence trashing the camshaft lobes."

Now the obvious thing for me to do is to open up my engine and check for such things. But I can't. Can you? http://fsae.com/groupee_common/emoticons/icon_smile.gif

@Brian:

Any and all info would be really useful!

@Grant:

Some back of the envelope calculations -- an acceleration run of 4 seconds would mean a longitudinal acceleration of g. A CBR F4i bike is said to have a 0-60mph time of 3 seconds, which gives an acceleration of roughly g again.

So there really isn't much of a difference in longitudinal accelerations ...

[Wesley]

At 22 degrees, you'll probably have significant windage losses. I've noticed on our cars that the majority of oil starvation issues occur under braking - something a bike doesn't really do very well.

Even with our flat mounted F4i's we regularly turn the oil pressure light on with no baffle system. In a tilted one, that will be amplified a lot.

You might consider a custom sump that will at least help with some of the braking issues (deeper at the front than back maybe?)

[fart can]

Wesley-

Do you notice starvation because of oil light blips or do you have another method?

Does anyone think this problem is significant enough to warrant designing baffles?

We don't run a tilt or modified sump on our F4i. So far we haven't had any noticeable problems.

Shyam-
You should download the service manual from a recent post and gather the courage to open up some engine cases. Taking off cases isn't rebuilding a motor. If you follow the instructions in the manual you should be fine. We all had to do it at one point, and you'll have to do it as well. If you guys test and have novice drivers you're probably going to fry a clutch. I'm sure you can handle it.