SR20 major damage on block and head surface? What's the cause?

[KingSpence]

Motor has 15,000kms on it. Hard driving everywhere, took me to Seattle and back two summers in a row though. It's always been reliable.

It's a 1998 SR20 S13 BT. Tomei m7960, BC 264 cams, Apexi MHG, ARP everything. Stock pistons. 355hp/298tq @14psi.

Long story short I had to run out to my storage lot about 10min out of town. Pulled off the highway into the driveway and saw a cloud of blue behind me. Idled clean, blew blue on throttle. Drove it up the 150ft driveway and my temp spiked from 190-210F and I shut it down. Pulled the oil cap to steam blowby and a half empty rad. Clearly, headgasket.

The things that worries me is that I had the head and block decked when I rebuilt it, and it has ARP studs and an Apexi MHG, so a cracked head was on the back of my mind too. Anyways, I torn it down last night to see this, (refer to pictures) I'm devistated and confused. It seems like the coolant was entering the cylinder between the sleeve itself and block.

Possible causes I can think of:

1.) I had a voltage drop issue this summer, My Haltech Sprint 500 was only seeing 12.1v until I figured the issue out. I remember asking around why my car was running odd, and I was told a voltage drop can affect injector opening times, and the overall tune in itself.

2.) Cam timing. I've got BC 264 and oem cam gears. Could this be an issue?

3.) Detonation, either cause from the tune itself, or the affected tune when my voltage was low.

4.) Cavitation. Have I had an unnoticed leak for an amount of time, and when the coolant was entering the combustion chamber under immense heat and pressure it broke down the aluminum.

https://farm4.staticflickr.com/3945/15612129476_507b94745a_b.jpg

https://farm6.staticflickr.com/5605/15635854005_c79cb00a04_b.jpg

https://farm6.staticflickr.com/5600/15636692032_35831d6cd2_b.jpg

[ANDY black s13]

My guess is No 3 detonation

[cotbu]

your gonna have to finish the tear down, unless it just my laptop. I cant see any major damage to the ring lands, sidewalls or rings that would cause the blue smoke. usually there's a piece of piston missing, and or score marks on the sidewalls/sleeve that allow oil into the combustion chamber. Not saying that it isn't something else, but usually there is clearer evidence, of what just happened. I mean i can see those pistons slapping around, during detonation than, maybe some oil made it past the rings. Or you misinterpreted the white smoke for blue, or the white smoke had a blue tint. IDK. just saying i've seen worse. if you get a chance clean around the valves and spark plug area to look for cracks. also look under the oil cap, and remove the pcv valve, and catch can if available. There will be a thick white residue if the head gasket was blown, the water condenses in these places. G\L

[Kingtal0n]

we need better pictures.

Ive never personally blown and sr20det but Ive seen a few that looked somewhat similar, with respect to the way your block appears to have been pitted, especially on the head. Thats a sign of running lean and detonating the poor engine repeatedly for many miles. I saw that on a S15 engine with an all stock setup the guy had turn to 18psi+ and run it for 10,000 miles before we tore it down (because of the HG) and found similar marks. But I cant be sure without a better picture.

I will say that water alone entering the combustion chamber will not cause that. People spray water into the engines all the time, and furthermore, when a HG blows on a single cylinder usually it just cleans everything up real nice and shiny without hurting anything. And if the mass of water is *too much* it would have hydrolock the engine.

The fact you see it in several cylinders points to the tune / fueling, can't be much else than that. If we make a checklist of possibilities you would have to scratch off debris (foreign object), bad gas (you cant do that much damage with one tank), improper assembly (the bottom end is OEM is it not?).

[KingSpence]

I think I've narrowed it down to high egt's.

[Kingtal0n]

I think I've narrowed it down to high egt's.

High EGT is due to running lean.

I've run sr20's lean before- they dont destroy the block like that. what fails is the piston rings, they literally lose tension due to the high heat. And it only take 5-8 runs (ask me how I know -.-) before the engine is spilling oil. You did mention your enine was smoking some oil right?

So I want to say your problem may have been related to high egt (running lean) but was not the primary cause of the block deformation. You have to have been running far too advanced ignition timing, too much boost, or too low of an octane rating, or a combination of all three.

typically, "tuners" will set the ignition timing to 15* BTDC during 12-18psi of boost, which is FAR too much timing for these engines. But nobody knows because the engine will still seem to run normal, and nothing appears to be wrong. Until, like yours, a few months/years later, the problem shows up.

So tell me, what is your timing during 12-18psi of boost? It should have been under 12* BTDC, probably more like 9* if you are using 93 pump.

[cotbu]

So tell me, what is your timing during 12-18psi of boost? It should have been under 12* BTDC, probably more like 9* if you are using 93 pump.

I don't think he knows, that information.
I do agree with it being the tune, but if it lasted 10 years being beaten, and not just sitting in a garage, I'd call it an acceptable loss.

Op, did you finish the tear down? If so, what are the plans? Sleeves, new pistons and rings or go Honda?


Sent from my Slightly Tuned Note 4!!!

[KingSpence]

I don't think he knows, that information.
I do agree with it being the tune, but if it lasted 10 years being beaten, and not just sitting in a garage, I'd call it an acceptable loss.

Op, did you finish the tear down? If so, what are the plans? Sleeves, new pistons and rings or go Honda?


Sent from my Slightly Tuned Note 4!!!

It lasted 15k of driving hard over two summers. It sucks, but I can't be butthurt. Im parting out everything from my SR86 swap, if anyone needs anything check out the Classifieds section.

The new motor is going have x2 displacement, x2 valves, and x2 camshafts.