Is my machinist giving me the run around? low comp after 1k miles
 

Hey guys. so I had my engine rebuilt this summer. I went with forged rods and reused my stock 1.8 pistons with new rings. The shop assembled the engine. I used break in oil and followed FM's break in procedure. After 1k miles i switched to rotella t9 5w40. Everything was fine and then i noticed i was getting puffs of smoke after backfires on deceleration (too much fuel in exhaust). today i did a compression test on the engine. My results were (in PSI);

• cylinder 1: Dry -150, Wet-180
• cylinder 2: Dry -150, Wet-180
• cylinder 3: Dry -150, Wet-165
• cylinder 4: Dry -150, Wet 160

After i called and explained this to the builder he told me everything is fine and I should leave it. He said they used chrome molly rings and these can take up to 10k miles to fully seat, I have no experience building engines so i really don't know if this is true. He told me compression should continue to rise up until around 10k.
If you were in my shoes what would yo u do? the plan is to put a TSE kit on this car next year (for a power goal of 250whp) however im not sure that would be wise to do with "unseated" rings.
Thank you guys for your help and experience.

You did the test with throttle at wot? The actual numbers aren't as important as the variance between cylinders (and different testers read differently), in which case dry yours look perfect. I'm kinda surprised to see such difference when wet from dry.

The 10k to seal comment is silly nonsense

Test was done with the butterfly wired open, fuel relay removed, with a harbor freight pressure tester. I also notice if i take a long drive (over 20 miles) if i pull in my driveway and hit the rev limiter it will blow white smoke as it bounces on the rev limiter and for a few seconds (5 seconds or so) after letting off the throttle. I initially noticed white smoke from exhaust while in 5th gear on the highway, after breaking and bringing rpms down to about 2500 and accelerating again in 5th gear i would get a puff. does this sound normal for a freshly built engine? its never a big enough cloud to notice if you're not actively looking for it but its definitely there and does not smell like coolant. The smoke is what prompted the compression test. this being my first build i dont know if im being overcautious or if there really is an issue.

My numbers were very similar after 1k miles. mine does not puff smoke though .

I wouldnt worry about the comp numbers. But the smoke is suspect... but so is bouncing a new motor off the limiter with no load, in the driveway.

the dry is good, the wet on 1 and 2 + smoke is incredibly worrisome.

Yeah. Mechanical empathy, lol.

When you say white smoke... does this puff of smoke dissipate quickly, or linger? If it dissipates quickly then it's just condensation. If it lingers, you've got other problems.

And yeah, if you've been sitting in your driveway bouncing it off the rev limiter within the first 1k miles, um... that's really dumb.

A new motor with 1k miles on it, with low compression and smoking isn't normal. Low compression and smoking is typical of high mileage engines that need a rebuild, not new ones.

Or if the rings didn't seat. I've seen that. Free revving at redline is terrible during break in. But real break in is over in about 20 minutes for the most part.

Piston engine airplanes are broken in by tieing the tail to an immovable object and running it at 80% load or more until the CHTs come down. The temps dropping indicate the cylinder wall to ring cut-in is finished. Running the engine hard is required to seat the rings or they don't cut properly and just polish the bores. If that happens the rings will never seat and it will always use oil.

Chrome rings have a greater need to be loaded heavily during the first 10 minutes of operation, to my recollection. I'm sure you followed the instructions from the ring manufacturer.

No you aren't.

I didn't keep it at redline for long I just reved up to it hit the limiter and let off. I didn't realize that was a bad idea since after 1k miles i thought the engine would be broken in. won't do that again.

As far as ring seating instructions when I asked the builder he told me to just use break in oil and not worry about it he said "just drive it", so I figured doing high vacuum pulls (like FM suggests with their engines) couldn't hurt.

The Shop has a decent reputation but from everything I've read I expected to be given more detailed break in instructions for the new engine. I'm thinking it will likely need to be rebuilt sooner than expected. At which point I'll add some forged pistons and rings I have more information about (wiseco).

but for the time being do you think this engine is worth boosting?

I was planning on getting an ms3 taking the winter to get familiar with it and going turbo in the summer. But now I'm not sure if I should just open the engine up again in the summer, and go fully forged.

Did the shop assemble the motor?

It it might be worth it to bore scope the cylinders to look for a good cross hatch. For peace of mind.
Pressure test the coolant system.

Typically oil in the exhaust is more of a blue/grey color. Coolant or water is white. Mileage may vary.
I once had a head reworked and the brand new exhaust valve seals didn't, seal at all. Just the exhaust side for what ever reason, white-ish smoke.

Exhaust Color Diagnosis | White Smoke Blue Black

Unburned oil gives white smoke, like a smoke machine.
Most extreme example when turbo is completely shot and converts itself to a oil injector.
But white smoke from oil lingers for a loooong time, smoke from water vanishes fast.

What's the shops warranty period 9,999 miles?

Chrome rings can take FOREVER to break in, plasma moly rings break in almost immediately. Chrome rings will outlast most all others in the long run. I would talk to the shop again, find out what cylinder finish they did, check with the ring manufacturer and see what their recommended finish is. If the two correspond, then relax and have some patience.....I would say that 10K is an awful long time to seat rings though, perhaps they are just telling you that to get you not to worry till they do seat..............:2cents: