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Oil Consumption In Forged Engine

Gareth87

By Gareth87,
in Engines & Forced Induction

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Gareth87 Community Regular

Gareth87

Posted
Posted

I understand that when using forged pistons, oil consumption tends to be increased. I'm just wondering by how much and what is considered normal?

Also, what other factors will increase oil use? ie. Will thrashing it increase it drastically or not?

G

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STATUS Grand Master

STATUS

Posted
Posted

No it shouldnt unless your making stupid horsepower or big boost 25psi up (as clearances are generally increased @ these power levels).

It should use no more than a new std rebuild.... ie nearly nothing.

Poor piston choice could also be a factor but most decent brands run nice tight tolerances if put together right

TiTAN Grand Master

TiTAN

Posted
Posted

over the past month my engine has used a couple of litres of oil (forged built engine, no visible leaks). i have been told that i get pufs of oil smoke when i back off at mid to high revs and the catch can was putting out a fair bit of vapour, but is not filling up with oil and deffinately not a couple litres of it (could this be caused by E85 or is it likely other issues?). it was setup with the PCV blocked off but that has been connected again and i have noticed a significant reduction in vapour from the catch can though the oil usage is still there.

The engine is fairly noisy when cold but once up to operating temp doesnt seem any louder than the old engine was. it idles smoothly and doesnt feel like its lost any power its just started drinking oil.

STATUS Grand Master

STATUS

Posted
Posted

over the past month my engine has used a couple of litres of oil (forged built engine, no visible leaks). i have been told that i get pufs of oil smoke when i back off at mid to high revs and the catch can was putting out a fair bit of vapour, but is not filling up with oil and deffinately not a couple litres of it (could this be caused by E85 or is it likely other issues?). it was setup with the PCV blocked off but that has been connected again and i have noticed a significant reduction in vapour from the catch can though the oil usage is still there.

The engine is fairly noisy when cold but once up to operating temp doesnt seem any louder than the old engine was. it idles smoothly and doesnt feel like its lost any power its just started drinking oil.

do a fairly agressive leak down test on it (@ operating temp), it will tell you whats going on.

Here's one we did not long ago.

CYL COMP LEAK DOWN

1 155 10-16% @100-110psi

2 155 10-16% @100-110psi

3 155 10-16% @100-110psi

4 155 10-16% @100-110psi

5 155 10-16% @100-110psi

6 155 10-16% @100-110psi

http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/index.html

TiTAN Grand Master

TiTAN

Posted
Posted

do a fairly agressive leak down test on it (@ operating temp), it will tell you whats going on.

Here's one we did not long ago.

CYL COMP LEAK DOWN

1 155 10-16% @100-110psi

2 155 10-16% @100-110psi

3 155 10-16% @100-110psi

4 155 10-16% @100-110psi

5 155 10-16% @100-110psi

6 155 10-16% @100-110psi

http://www.carcraft....ster/index.html

did a basic compression test this afternoon/evening 150-160 across the board. took the throttle body off and the intake plenum is clean with only a tiny bit of oil residue just after the throttle but thats it.

will give the leak down test a go assuming we have a tester that will do it.

it was all working fine with no real oil usage to speak of, sat in the garage defected for 9 months and now it uses heaps :/

TiTAN Grand Master

TiTAN

Posted
Posted

^^ i have a customer with a mx5 that had a 1cm raduis chunk missing off the crown of a piston and it comp tested fine... comp test can be misleading.

stuck a camera down the sparkplug holes. bores still have hone marks visible, cant see any signs of damage to the piston heads.

we dont have a leak down tester that gives measurements, though we lined them all up a TDC and put ~100psi into each cyl. all cyls had a little leakage on intake and exhaust (very small amount could be heard leaking out), none of the cyls gave any bubbles in the coolant however with the oil filler cap off there was a fairly audible amount of air coming out though i am not sure how much should be leaking out from there if everything is fine.

as far as the valve guides go, i am not sure though the valve stem seals were replaced in 2008

r33_racer Grand Master

r33_racer

Posted
Posted

I was going to suggest valve guide clearance and condition of stem seals also... on lift off the high vacuum can pull oil down through the seal around the valve guides.

Maybe after sitting around for so long the seals went dry and got damaged when you first started it up again???

  • 4 weeks later...
TiTAN Grand Master

TiTAN

Posted
Posted

i have noticed recently with this that it only seems to use oil when running on the caltex E-Flex ethanol fuel, while running on this fuel there is a significant increase in the length of time i can hear piston slap as well. i have been switching between the two fuels recently, however i will give it a few tanks worth on just 98 and see if the oil usage continues or not.

3BEPKA Enthusiast

3BEPKA

Posted
Posted (edited)

Hmmm got same problem here,forged engine (482whp @ 24psi) 30,000km old uses 1L per 5000km serice, I was told that it's normal with forged engines and just to keep an eye on it :unsure:

P.S Also once oil reaches operating temp.(80 -90 C) oil pressure drops to 2bar when on idle( eg. waiting at the lights or cruising 2500rpm in 5th) but when I start to accelerate it goes back to 4 bar or above, should I be worried because of pressure drop and get it checked ?

Edited by 3BEPKA
Simon-S14 Grand Master

Simon-S14

Posted
Posted

P.S Also once oil reaches operating temp.(80 -90 C) oil pressure drops to 2bar when on idle( eg. waiting at the lights or cruising 2500rpm in 5th) but when I start to accelerate it goes back to 4 bar or above, should I be worried because of pressure drop and get it checked ?

that seems pretty normal to me... as oil gets hot it thins a bit and the pressures drop compared to cold start pressures

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