Synthetics and proper motor break-in

[Savington]

I'm having some blowby issues in a fresh race motor. It's an 1862cc Mazda BP block in a Miata, currently fed 12psi via a Garrett GT2871R. The motor is putting out 2-3oz of oil through the crankcase breather every 8 laps or so. The motor in the car before this was very similar and had no blowby issues. I did 25 miles of deliberate break-in, followed by dyno time, all on Rotella dino 15w40. Switched over to Redline 15w50 for my first track day with the motor and started having blowby issues. Motor is built pretty loose, .004 wall clearances. I intend to turn it up to ~400whp this year.

Could the early switch to synthetic be preventing the rings from fully seating? Any recommendations for a standard oil that can hold up to high oil temps?

Feel free to link me to reading material, etc. Thanks all!

 

[SteveSRT8]

Depends on how it was honed, ring setup, etc.

Most machinists use mineral oil for a while first. Might just need more time.

 

[brandini]

This is a good read on break in, with pictures and examples to boot.

http://www.mototuneusa.com/break_in_secrets.htm

Quote:
3 more words on break- in:
NO SYNTHETIC OIL !!

Use Valvoline, Halvoline, or similar 10 w 40 Petroleum Car Oil for at least
2 full days of hard racing or 1,500 miles of street riding / driving.
After that use your favorite brand of oil.

 

[d00df00d]

A friend of mine did an easy break-in on his 2005 BMW M3, which takes nothing but 10w-60 synthetic from the day it leaves the factory. He followed the manufacturer's instructions about throttle and revs to the letter, but doubled the duration. Normal oil consumption for his car is supposed to be up to 1 qt/1000 miles, and his car doesn't burn a drop in 7,000 miles.

 

[Steve S]

Originally Posted By: brandini
This is a good read on break in, with pictures and examples to boot.

http://www.mototuneusa.com/break_in_secrets.htm

Quote:
3 more words on break- in:
NO SYNTHETIC OIL !!

Use Valvoline, Halvoline, or similar 10 w 40 Petroleum Car Oil for at least
2 full days of hard racing or 1,500 miles of street riding / driving.
After that use your favorite brand of oil.
sounds like B.S. to me

 

[Steve S]

It is a race motor and how was it built?

 

[Steve S]

I'll use Patmans Vette as an example.If you search his uoas they are all outstanding with the several oils he used. Why? it is not the oil it is the engine and how he operates it .There are some like engines that do not have as good uoas. Some times it is just the luck of the draw. Years ago 4 of my motorcycle riding buddies and I had all the same motorcycles. Mine was by far the fastest by a wheel length at least and we proved over and over .Don't know why but it was the fastest.

 

[Savington]

Originally Posted By: Steve S
It is a race motor and how was it built?


Loose. Largest recommended ring gaps, .004" wall clearances, max allowable bearing clearances everywhere.

If it's any indication of what kind of life the motor will live, the last one blew up at California Speedway after a 25+ second 5th and 6th gear 23psi pull. I don't need it to be quiet, or not burn a little oil, or last me more than 10,000 miles, but what I do need it to do is stand up to some godawful wanton abuse.

 

[Smoky14]

MHO that the engine was built too loose, depending on the pistons used. A quick tear down to check for flame touch on the skirts will tell you a bunch.
Tight motors can be made to run well and last in my experience.
About 2cents worth.
Smoky

 

[Steve S]

Originally Posted By: Savington
Originally Posted By: Steve S
It is a race motor and how was it built?


Loose. Largest recommended ring gaps, .004" wall clearances, max allowable bearing clearances everywhere.

If it's any indication of what kind of life the motor will live, the last one blew up at California Speedway after a 25+ second 5th and 6th gear 23psi pull. I don't need it to be quiet, or not burn a little oil, or last me more than 10,000 miles, but what I do need it to do is stand up to some godawful wanton abuse.
Loose will allow more blowby think about it. Standing up to the abuse is what will cost you.The faster you want to go the more it will cost you exponentially.

 

[hustler]

Savington,
I love you, the way only a man can love another man.

I spoke with John Day who built my motor and he said mine is at .004 also, and I have very minimal blow-by. I think you need to pull the head and look for sign of "unique" flame propagation or possibly cylinder-wall irregularities because this symptom is exactly what John and I saw in Matt's car at Big Willow when the ring-land broke, but his was a much larger scale of course.

Have you checked your 1-way PCV valve at 25-psi?

Although I'm empathetic, its somewhat refreshing to see someone with worse luck than mine. Who built this motor? Time to ship something to John Day?

 

[KA426]

I swithed the 4.7 V8 in my 2000 Dakota over to synthetic at 500 miles and she now has 130,000 miles with no engine issues ever along the way. Look how many cars come off the assembly line with Mobil 1 in the crankcase.

 

[gtx510]

what pistons and rings?
stock pistons with 1.5mm compression rings and 3mm oil control rings?
forged pistons with 1mm comp rings and 2.8mm (low-tension) oil rings? napier 2nd rings???
cylinder honed to piston/ring manufacturer's specs?

fwiw, i think 400whp will need more turbine flow (GT3071 w/ 56mm turbine wheel) or less overlap (measure exhaust backpressure in manifold and compare to boost pressure to check for reversion)