Hey guys, so wondering what your thoughts are as to why I'm burning oil and if there's anything besides rebuilding that I can do about it. I would say I'm burning around 1 litre every 200 miles. It visually puffs blew, weirdly burning less when it's cool, and more when it's hot ( 190 degrees F )

Rebuilt B21a1 with forged pistons/ chrome rings at 83.5mm

It's at about 4000 km's now, 2500 miles, and maybe it's because winter is coming to an end that I'm noticing it, but when it's full warmed up it smokes blue.

I'll be coasting down a hill, and if I touch the gas I see smoke, let it off, no smoke, on and there's smoke, etc.

Yesterday I replaced the valve seals but unfortunately that wasn't my problem. PCV valve is good and by simply eyeing down the hose there's no oil in it, plus I've read PCV valve oil burning doesn't really smoke.

Oil is BLACK.

I followed a break in procedure for my engine, and on the first drive it was burning a tiny bit, and then after about 7 km's it completely stopped, and the engine was great, I thought that the rings had seated perfectly. Now, a recent compression test shows

4 - 152
3 - 165
2 - 165
1 - 172

Pretty all over the place, I know. I've rebuilt 3 engines in the past (mind you, all were stock rebuilds) and those engines are running great compression is even. This was a dry compression test. I've read that for my engine ranges from worst to best 138 psi - 178 psi.

I've also read a lot on compression tests not really saying anything on how your rings have seated.

At this point I feel like like the rings may not have seated, which would be the end of this car unfortunately as I've spent around 7K this summer rebuilding it twice because the first time around I measured my rings to a stock ring end gap (Didn't know wiseco had their own numbers) and tore my cylinder walls apart hence the 0.5mm past 83mm.

This time I made sure all were gapped minimum 0.016 (or 0.16? I forget) so if anything they were barely too big, which maybe explains my weird compression? But still......

Like I said, up till 1600 miles it was great! I was using oil but I didn't notice any smoking. Again, I followed a break in procedure exactly, I never exceeded the recommended rpm, although if the max was 4000, then 6000, I was at the max frequently, it was to much fun. And MANY people also told me to not be a grandma when breaking it in.

So if THAT was fine, the only thing I can think of is the machine shop fucked me over and didn't do the correct piston to wall clearance (They specifically told me I only needed to check ring end gap) and left it too big in assumption I was straight away slapping on a turbo, or they honed the cylinders wrong for my rings, which unfortunately I don't know how I would prove that, as I don't know the CORRECT honing, and that's an area of conflict I'd rather not enter. Being that I was the assembler, I'm sure they'd simply blame me. So basically, if they honed them wrong, I am fucked.

Or somehow they haven't seated and maybe I still have a chance. Lawl.

Thoughts? I can't rebuild it. I no longer have the space, the time, or the money. If it's the rings, has anyone ever tried chucking in some type of additive? (engine restore?) in this case? again, it only has 4000 km's (2500 miles) on it.

 

From what you are saying, I am leaning towards your ring gaps are too loose, giving you blowby and lower erratic compression.

I did the same thing on my last bottom end, as I wanted to keep it safe for nitrous use, but went a bit more open than I wanted to.

If you really have that few miles on it, just replacing the rings again with a quick scuff of the walls might work, but if you don't have the space to do the work, not sure what to say.

That said, the biggest thing to keep in mind when breaking in a new build, is varied rpm, and a TON of engine load/ de-load. Accel and engine breaking for the first 500 miles is a big factor i.m.o. I break in my engines hard, and have never had smoking or issues until parts failure down the road has taken them out.

 

mostly its cause bad piston rings or valve seals

 

Yea, I've narrowed it down to the rings for sure. And yea it sucks, I'm not going to be able to rebuild it. I decided to just throw engine restore and a bunch of lucas Oil into it and it helped quite a bit actually. Plus, it's getting warmer so smoke is way lower since it doesn't take so long to warm up. I've decided I'm just going to suffer the little bit of smoking, since really it starts runs and drives great, untill I can buy something new xD I'll buy another prelude when I do an electric car build.

Thanks for the reply's