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PostPosted: 26 Jul 2018 15:41 

Joined: 26 Jul 2018 15:18
Posts: 2
Country: AU
Hi all,

I recently completed a 4g93 build, DOHC, E85 fuel for a race car. Lots of $'s spent.
Advice at the time was to run in, on Penrite running in oil 15w40. (mineral)
Engine was initially started, run 5 times and run up to temperature with no load, and allowed to cool each time. No leaks, always started fine on the running in oil.
The tuner has then done 3 initial runs on the dyno and shut down the engine after noticing power loss on successive runs all with the running in oil still in.
On strip down, the engine is full of bearing material. All crank bearings and bottom end conrod bearings are shot to pieces.
The head is also a mess and will require a lot of work.

Whats is the general opinion on running in oil ?

Again the tuner said that they always fully tune a new engine on running in oil and oil and filter changed out after the tune with the oil you will run the engine on for its life.

Others have said this is crazy, the engine should have had its correct oil in for the tune.

Opinions or advice please?

PostPosted: 29 Jul 2018 00:43 

Joined: 15 Feb 2011 08:51
Posts: 911
Country: Australia
I am not sure by your post, but are you suggesting that the oil caused this failure?

I can assure you that the oil had nothing to do with it.
There may be some advantages and/or disadvantages of using certain types of oil for run in but surely any decent engine oil will not cause catastrophic failure within a handful of starts.

The engine would've been built incorrectly I'd say.
Wrong bearings? Oil starvation?

What car is it in btw?
And where will you be racing it?

PostPosted: 30 Jul 2018 18:10 

Joined: 26 Jul 2018 15:18
Posts: 2
Country: AU
yes, i feel like the oil was the failure here but again i don't know enough to be certain..... thus why i shared to post to get some insight from others.

There is such a varied opinion through the motor building industry on oil and running in which is confusing.
The running in oil is extremely thin mineral oil and most recommend only low to moderate revs and load whilst this is lubricating the engine.

The engine was exposed to high load and high revs during dyno tuning, and this oil has not provided enough protection to the bearings in my opinion.

Pot no.1 has suffered the most as it is last on the crank to receive its feed. Also signs that the oil has separated.

Unfortunately, the metal fragments have gone through the head and destroyed all the cam journals as well.

The builder of the bottom end has done oil flow tests, and nothing there out of the ordinary so I'm told.

This engine is in a mirage cup car, has been racing last few years in Perth. State championship winner in 2016 U2l IP.

Reason for asking is i dont want to make the same mistake again.

PostPosted: 30 Jul 2018 21:43 

Joined: 15 Feb 2011 08:51
Posts: 911
Country: Australia
I don't like to use overly definitive terms, but I can tell you that the choice of oil 100% did not have anything to do with the failure.

The engine failed within hours of being built? No oil in the world would have given this engine a long life especially under race conditions.
In fact in my opinion no oil in the world would have extended the life of this engine even by minutes.

There is a different underlying cause to this catastrophic failure.

My advice is never go back to that engine builder.

There is a forum you should sign up to:

Lots of very experience and knowledgeable people who know a lot about engine build and engine oils. They may give you more ideas of what went wrong but I am sure they will all tell you that the Penrite oil that you used was not at fault.

What spring rates do you use btw and what swaybars?
I have a Lancer coupe CE with a 6A12 MIVEC engine from the FTO that I use for track use at Winton Raceway so would be interested in your setup

PostPosted: 01 Aug 2018 13:29 
Mivec Guru

Joined: 04 Jul 2005 13:25
Posts: 1216
Location: Lower Hutt
Country: NZ
Sounds like a combination of engine built wrong and engine tuned wrong.

If you throw lots of $$$$$ at it.......well .....there's no need to.
Not if you know what you're doing.

Post mortem required.
A proper post mortem is the opposite of a proper build.

You pull it apart carefully noting torque specs on bolts (Part of the learning process).
Then you measure everything.

To have bearing fragments usually means a spun big end bearing.
That might be the wrong bearing clearance.
Wrong piston to bore clearance.
Not cleaned when built.
Failure to change filter after first startup.

But NOT the fault of the oil grade.

Then there's the tuning part.
Most common is a knock detector which doesn't detect knock.
Common with aftermarket computers which never work right with stock knock sensors.

Lots of pics needed.....everyone like pics of broken engines.

Actually, just spotted the E85 bit.
That's the usual cause.......it's tuners that can't tune.
E85 doesn't detonate but suffers from pre ignition when too lean.
Inexperienced tooners usually toon with too much timing advance which makes the peak pressures go sky high and ends up making the headagaskets leak, bends the rods and flattens the bearings.

Inexperienced tooners don't know that injectors flow a different volume of fuel comparing petrol with E85.
E85 contains 30% less calorific value that petrol (by weight) so you don't need 30% more (that's what you've been told by google) you need between 40 and 50% more by weight, the SG is different so that offsets the difference in volume flow rate.
Wideband AFR meters never work as well as you think they do......not when you change the fuel.

That gives you lots to think about.

You'd really want to know how much total timing advance has been put into it and at what load.

You didn't mention any boost so it's N/A ?
Is it a mivec or just a normal DOHC?
What sort of power was it making?


Pot no.1 has suffered the most as it is last on the crank to receive its feed. Also signs that the oil has separated.

No 1 gets the oil first as the pump is on the nose of the crank.

Maybe you mean no 4?
No 4 always runs the leanest.

6G72 mivec Twin TDO5 20Gs up and running.
6G72 mivec bored and stroked to 3.4 litres...Frankenmitsi build
6G74 mivec bored and stroked to 3.9 litres....Frankenmitsi build.
6G75 under construction....4.2 litres bored and stroked.Another Frankenmitsi.

PostPosted: 30 Oct 2018 16:22 
User avatar

Joined: 20 Oct 2004 16:05
Posts: 2128
Location: Wellington
Country: New Zealand
Ive had this before with my current engine, cooked oil would be my guess, sorry to hear about this, hope you have it sorted


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