Bigpower

My tomcat seems to use a lot of oil on trackdays

However it doesn't smoke either on boost or off boost but does smell a bit when driving especially at slow speeds.

Engine compression is not good when cold but when hot are all approx 150 +- 5
(it has forged pistons so would think that's normal)

At last trackday at snett inc driving it to and from the track and around 1 1/2hrs on track it used 1 -1.5 litres of oil

Is this the normal for turbo car?

Someone suggested I should use 10-60 oil on track instead of 5-40 not sure if that might make any differance?


cheers
Scott

Are breathers back into intake or catch tank?
I would have thought 1.5l is a lot my evo alway uses 200mls each time when used from cold unless driven a very long way off boost, everything expands on that first prod and settles down.
Iam guessing no signs off any leakage even in odd areas, into bell housing etc?

5-40 seems low to me

You say it 'smells a bit' at low speeds but is this before or after you've been caning it?

IWANT1 wrote:Are breathers back into intake or catch tank?
I would have thought 1.5l is a lot my evo alway uses 200mls each time when used from cold unless driven a very long way off boost, everything expands on that first prod and settles down.
Iam guessing no signs off any leakage even in odd areas, into bell housing etc?

no obvious leaks
The breather goes to a alloy catch can, but I have got the top catch can connection back into intake, however the can doesn't fill up with oil.

One thing though I did have the pistons out about 1000miles ago for inspection when I did head gasket.
All pistons were good no cracked ring lands, burns or any thing, skirts were a bit marked up though which I think is pretty common for forged.

I am wondering though if the rings are not bedding that well as I didn't change them.

cheers
Scott

Stuart wrote:5-40 seems low to me

You say it 'smells a bit' at low speeds but is this before or after you've been caning it?

Its a bit smelly full stop, it is a bit worse after caning it though, but that might be as it runs no cat or charcoal canister etc

one other thing when engines cold (left over night) oil light takes approx 3-4seconds to go out, any other start when not cold oil light goes out straight away -never comes on again.
( I have always put this down to having larger remote mounted oil cooler).

Scott

Surely putting a thicker oil in just makes the PROBLEM that is actually there ( whatever that is ) less obvious .

Whatever the issue 1.5ltrs of oil is a huge amount in one track day.

Yes, you must have a problem somewhere to use that amount, the oil has to be going somewhere. I would say that 5/40 is too thin for a tuned T series. I would say perhaps a 10/50 fully synthetic would be better. You may be blowing a bit past your turbo seals if the turbo has done a bit of work and a bit down valves guides perhaps. Compressions are not too bad for a turbo lump, but not to say that the oil control rings are doing a good job.
Sure Gary will be along soon to comment

Eddy

the concern for me is you removed pistons,if they werent 100% before you will have made matters worse,

id say get it honed and a new set or better still rebored and new pistons

that oil does sound thin but better oil wont help much.

pull plugs and see what they look like

gary@apt wrote:the concern for me is you removed pistons,if they werent 100% before you will have made matters worse,

id say get it honed and a new set or better still rebored and new pistons

that oil does sound thin but better oil wont help much.

pull plugs and see what they look like

I took the pistons out to check them earlier this year due to the oil consumption before.
The pistons looked absolutely fine no damage no overheating and the rings were nice and free -There were just some marks on lower part of piston skirts -pretty sure absolutely normal due to larger forged clearances not damage.

The plugs all look good no oiling up and all biscuit coloured.


I want to be really sure of the cause before action as it could be a lot of money wasted with rebore and pistons etc.

The car performed really well on last trackday and recent power run on dyno was also really good.

It could be bores but I would have thought it would smoke and have loss of compression?


One thing I am thinking it might be is valve guides wear as when I ported the head I also ground the guides so they are flush with the ports to improve flow -I am now thinking this was a mistake and could be the cause of the high oil consumption as they are a lot shorter and probably run hotter ?

Or main bearings worn and leaking past -doubt this though as just change the gig ends and the old ones were in very good condition as was the crank -I would have thought these would have been well worn if low oil pressure.

I am thinking firstly fit oil pressure gauge been meaning to for a while - if its ok main bearings will be ok?

mechanical or electrical - is mechanical better?


thanks for any help


Scott

valve guides must be fine or you would see smoke on overrun,

do you do many miles on road? if its burning oil will show up on plugs,

turbo probs would show smoke to.

by sounds of it its rings if you cant see it smoke,when you had pistons out was top of pistons oily or dry