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Hello everyone,

Sorry if this question has been previously done. I haven't found anything.


So, the question is: "How many degrees can I tilt a bike engine (forwards/rearwards) without risk of failure?" Of course, with respect to its original position in the bike it was designed for.




I think that knowing this could be very helpful in terms of designing a BEC, probably not to lower the cog, but to find more space somewhere near the engine (to locate more easily the exhaust pipes, intake, cooling system...).



Regards!

roller,
welcome to the forum.
Based on the research I've done, not very much. Most people seem to agree that it is best, as close to the original angle as possible. Since the engine is turned 90 degrees, it will be necessary to minimize any oiling issues anyways. So I installed a baffle in my R1, and mounted it as it is in the bike frame.

_________________
Martin


My build log:
viewtopic.php?f=35&t=14520&start=0
My build video:
https://vimeo.com/143524140 password "matovid"

So much of this depend on your engine sump. If you run a dry sump set up, as long as the scavenge pump can pick up the oil you can lay the engine on it's side. Assuming you use a wet sump, I wouldn't go much more than 10 -15 degs tilt forward. Other may disagree, but you also have to look at how the oil want to leave the sump when you are in a fast corner.

Install a windage / pan baffle and an Accusump and you will be golden. I have raced D sport racers for some time and we use 2" deep billet pans with baffles and trap doors, but set the oil level high.
With engine oil warm (and turned off) fill to top of site glass the add 1/2 a quart more of oil.
Our cars are pulling 3G's under braking and close to that lateral. I haven't lost an engine yet.

Any way... hope some of the diatribe helps
Cheers
Linz

Thank you very much for your responses!


Wow, Kiwimanz, 10-15º maintaining the wet sump? That's much more than I've thought!


So... How difficult/expensive would be to modify the sump? Just to have an idea...

I am also interested in reduce the size of the sump, to increase the ground clearance/reduce ride height.

-A slight modification, just to improve the lubrication under high lateral forces?

-All the way down, to have a totally dry sump?


Cheers!

Wow, Kiwimanz, 10-15º maintaining the wet sump? That's much more than I've thought! ***that's running the oil level high bare in mind.


So... How difficult/expensive would be to modify the sump? Just to have an idea... *** actually it's very easy, the bottom of the sump can be cut off and have a flat plate of aluminum Tig welded to the bottom to seal it up. You didn't say what engine you were planning on running. There are Billet pans for sale on ebay for different engine around the $300.00 amount. I bought one for my Hayabusa engine in my car. Works great, then I hooked up an Accusump

I am also interested in reduce the size of the sump, to increase the ground clearance/reduce ride height. **** See Billet pans on ebay
Also see page two of my build and it gives a good shot of the billet pan.

-A slight modification, just to improve the lubrication under high lateral forces? ***Accusump will do that for you, but it's wise to run a pan baffle.

-All the way down, to have a totally dry sump?*** over kill unless you are racing and pulling big G forces. Pretty expensive

What model / type of engine are you planning on running?

Hi kiwimanz,

Thank you again for your answer, full of useful information!


I am planning to use a motorbike engine, probably 1000c.c. But I have no idea what model exactly, (kawa ninja, honda cbr, yamaha yzf, suzuki gsx-r, or even busa).

All of them have almost exactly the same size and power, so probably, it will be my last "engineering" decision, depending on further research about reliability, price, mantainance, aftermarket pieces... and of course the units available in the market during that moment.


Thank you!

Regards

My strong suggestion is a GSXR. These engines are used predominately in DSR racing and providing you don't consistently rev them to the moon and modify them beyond limits, they are an awesome power platform. If you can make it work, the 07 -08 motors are the one's to get. If not that, the prior year is good too.
The 07 - 08 have a slipper clutch standard, and there is a ton of stuff for them, like billet pans etc. The billet pans, will fit 05 - 08 engines and possibly even earlier models. Will not fit 09 and beyond.

Anyway, hope again this helps.
Cheers
Linz

Is this an advantage? I would have thought with the increased mass and traction of a BEC, one would NOT want a slipper clutch.

_________________
-Keith

Well it's nick named a slipper clutch. The proper term is Anti back torqueing.
It slips when you shift down at fast wheel speed that does match the engine speed. This is especially brilliant on a BEC as cars have some much more tire contact patch than bikes. There is no loss of traction under drive unless you back off the clutch spring loading to allow it to slip more on down shifts, problem it will slip under drive. Leave at factory setting and you are golden.Either way... your engine will benefit it.

Any reason why you plan to use a 1000cc engine? I raced my DSR with a 08 GSXR and it ran awesome, but my new car has a Busa power plant and I have to say the difference in torque is astounding! I have a CNC ported head and a 1397cc kit with a custom air box and tweaked engine management it should be up in the 110 ftlbs where a very good GSXR is maybe 82 ftlbs!

kiwimanz
very interesting info (for a guy like me that wants to build a BEC in the near future ) ...
thanks for posting

_________________
- Stephan -

Thank you very much for your advices. They will be very useful in the future!!




Wow, Kiwimanz, you are such an incredible source of information!! Thank you very much

When I said I wanted to use a 1000cc engine, I was thinking "not to use a 600cc". Honestly, I am even a little afraid of using such a powerful plant in the car, because (if i finally build it someday) it will be my very first trackday car.

However, your arguments sound good, and if the engine won't be a 600cc, it probably makes more sense to use a busa unit and take advantage of the extra torque.




Yes!! I will save this post in a .doc file! hahaha




Regards,

oscar

Thanks Guys... been doing this silly stuff for a while.
On the subject of the 600 cc engines. They work well in small chassis, see Formula 600 class in SCCA.
For a car, I'm a bit suspect of them holding up as their transmission is weaker and the clutch pack is smaller than liter bikes. Any way... go ahead and build it chaps

Linz

In some weeks I hope I'll have my layo-out ready, so I can present it in the forum and hear your advices (if you want to haha).

planning something like a funyo 4rc, or a cheap Radical pr6/prosport

Something else to look into is that the stunter motorcycle guys run into this same problem of oil starvation when they do extended wheelies. They make modified oil pickups that reach further and in the right direction, but they also agree that dry sumping is the best solution. You might want to see what those guys do with specific bikes after you pick an engine.

My design on the drawing board lays the pistons/rods horizontal/parallel to ground. But - then again; I'm looking to use a K-Series BMW engine...

bnc