b20beast83

So my Built B16a Engine [Srp STD Size Pistons] began to missfire[Subaru sound]
Pulled Head, Valves good.


So i took out the piston in the cylinder with low compression.

So turned out i had a BROKEN TOP Compression Ring.
What could cause it to break?

I went from 4th gear at 8200rpm, Missing 5Th gear, into 3Rd gear
So
4th Gear 8200rpm -> 3Rd Gear XX000RPM.


Any insight would be useful

90blackcrx

Was it just the ring, or was the ring land also cracked ?

Captain Bondo

Hard to imagine a ring failing without killing a land as well... might have had ring flutter I guess...

b20beast83

whats ring flutter?


ringlands are perfect.

no one can give me a clear indication why the ring failed ;(

jdm602

flutter is oscillation of the ring. usually detonation cracks ring lands or rings themselves. but flutter can too. along with improper end gaps or placement.

i would say it failed cause you did a 4-3 shift, overrevved it and it made one of the rings flutter.

JDogg

ring gap too tight? what do the cylinder walls look like

blaze the chemi

Interested in which pistons you ran, compression wise, and what power you were putting down. I have SRP's in my B16a, 9.9:1 with the provided rings too.

Do you have different rings other than the JE/SRP?

b20beast83

Im not 100% certain of the compression of the pistons
I got them used.
I think there around 8:1 Cr. [-std size pistons]

My Compression was about 140-150psi across the board.
Except for #3, which was 80.

I made 246whp @12psi With a B16a, Type R cams, conservative timing and street tuned.
Garrett 60Trim / .63 Backend.
2.5"Dp and Exhaust.
I have 20 thou over je piston rings.
Im gonna file it down and just change top compression ring and go again.


I took them all out, and all look perfect, just the way i bought them used.
I think they hold up to the abuse.

Im going to shoot for 20-24psi or 400whp or closest / pump gas, 91oct.

I am using JE Rings.

Honestly, i dont really feel the lower compression out of boost.
It is almost not noticeable.


Hope this helps you out.

b20beast83

Cylinders are perfect.

Captain Bondo

make sure the 2nd ring gap is larger than the 1st ring gap. Gap em on the loose side.