Here's what I'm dealing with. Built BPW4 with ~1500 miles on the build. Broken in per flyin miatas break in procedure and I'm burning a good amount of oil. About a quart every 500 miles. No smoke under any conditions that I've been able to tell. Just did a track day at Watkins Glen and put about 120 hard track miles on the car with no issues. Went through ~.5 qt of oil with no smoke and only a few tablespoons in the catch can.

Weisco 84mm pistons & rings (.017" top ring gap, .019" second ring gap)
Boundary pump
Manley rods
Kraken turbo kit with GT2560R running 16psi
Catch can on the intake side with upgraded PCV valve

Cold compression numbers
180psi
175psi
185psi
185psi

Cold compression with a few tsp of oil in the cylinders
235psi
230psi
220psi
235psi

Could it be anything other than the rings? Trying all of my options before I bite the bullet and do a rebuild.

 

The NPR ring is very popular and many have had good results with it, so not the ring option. Maybe the bore finish, PTW clearance and ring butting from the tight end gap. High oil usage on a new engine could be the rings were damaged on install or were installed upside down. Also could be it is pulling oil through the intake or bad valve stem seals.

 

Hmm yeah those are pretty tight ring gaps for that much boost. Are you sure the turbo seals aren’t leaking? Are you getting soot on the bumper around the tailpipe?

 

I'd be boroscoping trying to find the source. Or pull off the turbo and downpipe and look there, pretty easy to tell when the turbo is eating oil that way. Boroscope will also be able to see if stem seals are the cause, that would be pretty obvious too.

Ring gaps don't matter for oil consumption tbh since it's the oil control rings doing the work. NPR rings here and no problems on my build.

 

Update: I should have mentioned that this turbo and the rest of the setup (minus exhaust manifold) was on the 1.6 engine that came with the car. I had 0 oil consumption issues with this setup over ~5000 miles.

The rings I'm using are the rings that come with the Wesico piston set from Fab9: https://fab9tuning.com/wiseco-forged...ncludes-rings/

Last night I borescoped the cylinders. There is some visible scoring on each cylinder. They all look about the same. The photos of the tops of the pistons are after around 750mi on the break in.

 

There are only one set of rings for these engines and they are made by NPR. The different piston manufacturers just relabel them or supply them with the kit.

The tight ring end gap causes ring butting at higher temps and loads. The initial result can be damage to the cylinders which reduces the effectiveness of the scraper ring. The cylinders show signs of this. This vertical lines can also be caused by contamination from excessive wear or poor cleaning before assembly.

 

I should say that this scoring was present before the motor had seen any boost or hard driving. I also would expect if the ring ends meet to get more of a catastrophic failure. Compressions loss, running horribly, or smoking. The car after the track day is still running well after almost 2 hours of very hard driving.

I am now wondering about the cleanliness of the intake manifold during break in as it was a junkyard motor that I had cleaned as well as I could, but there could have been some debris I missed in the VICS system.

My thought for the rebuild would be a 400 grit ball hone and new rings. 400 grit based on this recommendation from weisco: https://www.wiseco.com/wp-content/up...z1aSHjDCqntKLo

Any thoughts? Not sure if needs a machine shop since the block was just bored and cylinders should still be cylindrical. Don’t want to have to go up to 84.5mm pistons…

 

It is hard to tell how significant the scoring is from the pictures. The second ring reacts differently than the top and there can be acceptable compression measurements with oil consumption. A good example would be when the second ring is installed upside down. A ball hone is not the correct tool for job. They can make a bad cylinder look good without improving any of the discontinuities. A touch up for new rings should be done with a correction hone. It's always best to just take it to a shop and have them give it a few passes.

 

I've honed many cylinders myself on BPs. I highly recommend having a machine shop do it. I'll do many things myself, but I can't argue with results. The machine shop bored/honed cylinders have outperformed and outlasted everything I've ever done.

 

I'll ball hone a good block for fresh rings, but if there's damage, it needs to be professionally honed, if not bored. I'd be very hesitant to run that motor with the scoring. It's not terrible for a used motor, but this is a 1500 mile build.

 

That scratching looks deeper/worse than my 30k built motor (oil is from valve stem seals after sitting).



Or even the 140k block when I tore it apart before rebuilding. I definitely think that's related to your issues.