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BEC Oil Consumption?
Guinness - 19/8/06 at 02:39 PM

I'm confused? No change there then, but I am getting quite a variance in the amount of oil my engine uses.

I know in an ideal world it shouldn't use any, but I'm running an engine bought from a scrappy which is at least 10 years old.

On the trackday at Teesside I drove down to boro (40 miles), drove hard all day (say 6 sessions of 10 laps) and then back home (40 miles) and didn't have to top it up once.

But on the round trip to Harrogate (160 miles) it used nearly 500ml of oil. Same story on the trip to Stoneleigh earlier in the year, had to top up twice on that trip (420 miles).

Trackday driving was mainly 8k to 11k and mostly full throttle. The trip to Harrogate was nearly all done at 6k and part throttle. (So much part throttle that my 5 year old son fell asleep in the passenger seat!).

What's it all aboot? Does this mean I have to drive harder? It's running Halfords Semi Synth cause all the bike shops were shut on the last Sunday I went shopping for the car.

I'm guessing changing oil type to fully synth on a 10 yr old engine aint going to make much difference?

No visible smoke on start up, down changes or upshifts.

Mike

stevec - 19/8/06 at 04:16 PM

On full throttle there is very little inlet manfold depression, on part throttle there is reletivly high inlet manifold depression, mabee the valve stem seals are letting oil down on the inlet side.
Steve.

G.Man - 19/8/06 at 05:11 PM

Does the engine have a kleen air system?

If it does and the reed valves are bocked off, the engine can draw oil in to the exhaust thru the rocker cover gasket..

froggy - 19/8/06 at 06:18 PM

also worth remembering that a bike engine in a car gets a much harder life than its original home so each road mile in a car is prehaps ten or twenty in terms of wear

JoelP - 19/8/06 at 07:09 PM

i personally would equate one steady motorway mile in a kit car to maybe 1.5 in a bike, nowhere near 20 times more wear. Maybe a trackday with oil surge issues would be different though.

smart51 - 19/8/06 at 07:10 PM

quote:
Originally posted by froggy
also worth remembering that a bike engine in a car gets a much harder life than its original home so each road mile in a car is prehaps ten or twenty in terms of wear


10 or 20? The load on the engine is perhaps 1.5 x greater in terms of weight, if you take account of the final drive and wheel differences.

JoelP - 19/8/06 at 09:55 PM

gee-whizz how freaky is that?! within a minute of each other we precisely calculated the same answer!

froggy - 19/8/06 at 09:58 PM

ok im not a scientist , but no bike engine has been designed to cope with the engine and gearbox loads that they have suffer in a bec. ive yet to see a bec with 20- 30k on it with the same engine.

ChrisGamlin - 20/8/06 at 04:25 PM

Thats only because the vast majority of BECs are only driven a few thousand miles per year, so even BECs built in the early days 5-6 years ago aren't going to be hitting those kind of figures yet. I agree with the other estimates of maybe 1.5x the wear rate for equivalent road /track use, if it was 20x then an engine wouildnt last more than 3-4k miles of road use, let alone track use.

[Edited on 20/8/06 by ChrisGamlin]

smart51 - 20/8/06 at 04:55 PM

quote:
Originally posted by froggy
ok im not a scientist , but no bike engine has been designed to cope with the engine and gearbox loads that they have suffer in a bec. ive yet to see a bec with 20- 30k on it with the same engine.


The load on the engine and gearbox is only what the engine produces. 110 Nm of torque and 150 BHP in my case. The wheels, the weight and aerodynamics only react the force that the engine produces. Sure, a 0-60 sprint in my car will take almost twice as long as it does on the bike but the crank and gears are not taking any MORE load than they would, they just take full load for twice as long per sprint. At a steady speed, you're only running at part load both on a bike and in the car. Aerodynamics mean that my car only has enough power for 70% of the top speed of the bike but at 70 MPH I'm only using 20% of the enigne's ultimate power.

Engine wear on a BEC is only 2x that of the bike at full throttle and only about 1.1x at a steady speed. As stated before, perhaps about 1.5x overall. No way is it 10 times.

I've done about 4000 miles in 9 months with my 7 year old bike engine. We'll see in 3 or 4 years whether your estimates are right.

[Edited on 20-8-2006 by smart51]

froggy - 20/8/06 at 06:51 PM

i did say perhaps so if its agreed that engine wear is 1.5 times that in a bike what is the lifespan of a sports bike engine 30-40k? if most donor engines have 8-12k on them before being used in a bec then surely the engine might only last for 15k ?

smart51 - 20/8/06 at 06:57 PM

quote:
Originally posted by froggy
what is the lifespan of a sports bike engine 30-40k?


Sounds like another assumption to me.

JoelP - 20/8/06 at 07:04 PM

i bet the single biggest killer of bike engines in cars is oil related. Either surge that is enough to starve but not enough to light the oil light, or simply not enough oil cos its impossible (in mine at least) to see through the sight glass. Hence i change it often, maybe every 1000 miles. Probably more often in fact Ive changed it 4 times in about 6 months!

froggy - 20/8/06 at 08:12 PM

a semi- assumption but i know a couple of salesmen at the biggest bike importer in europe which is a mile from my garage and they wont sell any big bike with a warranty of any kind with over 20k on the clock .

Guinness - 20/8/06 at 09:05 PM

quote:

the single biggest killer of bike engines in cars is oil related


I can vouch for this having had the following oil related mishaps, and killing two engines so far:-

On a blat in January an oil hose from the engine to the cooler split (it was an original from the donor bike) and pissed all my oil out. Once the hoses were re-made the engine still ran but I'd lost 2nd and 3rd gears somewhere.

Replaced engine.

On a blat in June, had the big ends go on engine no2. Blocked oilway was the cause.

Replaced engine.

On a blat in July, had the oil pressure sender adaptor split, pissing oil out. Luckily I spotted the pressure dropping, and caught it in time.

Hope you can see where my concern comes from!

Cheers

Mike

froggy - 20/8/06 at 09:56 PM

im not knocking bec,s as ive just done one myself but i still think that the trade off is short life for the performance you get from a bike engine

Coose - 21/8/06 at 02:21 PM

quote:
Originally posted by froggy
ok im not a scientist , but no bike engine has been designed to cope with the engine and gearbox loads that they have suffer in a bec. ive yet to see a bec with 20- 30k on it with the same engine.


I know a chap who races a GSXR1000 OMS type of thing in the Scottish hillclimb championship. He also has a prehistoric Westie with a wet sumped Blackbird, which he built a fair few years ago as a road car. That now has several tens of thousands of miles on it, with the only failures being reverse boxes! He now carries a spare box on the spare wheel rack....