died on the dyno. your veiws please

[!kid]

You obviously haven't been around too many engines. Rod bearings fail, pistons start stroking 1 or 2 mm more than normal, piston hits head, compresses ring land, and massive blowby/leakdown occurs.

I think you may be over exaggerating just a little. If this dudes little m20 Is causing a bearing to fail at 2000+/- miles he's got other problems. And 1-2mm? That's about .080 thou. I don't think there would be much of the bearings left after,or much oil pressure left. haha and again he would need to have major issues to be eating away that much bearing in such a short time.

[329jay]

i only just started taking some bits off yesterday. engine isnt even out yet. i lost interest in it.

[LJ851]

Pics of carnage?

[329jay]

ill take it apart saturday and hopefully get some nice pics for y'all

[Kershaw]

10:1 is pretty much standard compression these days...

my rx8 is 10:1. a 2012 honda civic si is 11:1...

[Brandon12V]

Agreed, look for the basics first. specks in the oil and remove that valve cover to check the rockers. a leak down test would be a good way to narrow it from rings or a valve. where is your timing right now? specs on the short block? what cam? remove the head and inspect the valves. Still nothing? remove the oil pan and crank. check the bearings. if none of this helps, you could have torqued your crankshaft out of timing, but I highly doubt it. I've seen this happen, but I don't think i've ever heard a case on the m20 NA.

Edit: it would normally take alot of transverse load for this to happen, even on a 2.5 crankshaft.

[LJ851]

All of this is speculation. You need to inspect the engine damage, and if you don't know exactly what to look at or for ,find or hire someone who does. If the engine was detonating enough to cause engine failure it will leave it's mark on the head and pistons. Are you running a forged crank? A lot of diagnosis can be done with the engine still assembled. Get out to garage, man!

[z31maniac]

they are wrong. 10:1 is basically a standard these days - my M20 reached MBT with 10:1 CR on pump gas *long* before the detonation threshold.

and unless your engine is turbo, a bit of detonation isn't going to kill it that fast.

This.

Hell the turbo engine in my Speed 3 was 9.5:1.

[nando]

i got this from someone....
it sounds to me like your tuner could have advanced your timing forwards in an effort to find MBT (mean best torque). Problem is, being a high CR (even 10:1 is high CR by modern unleaded standards) your engine probably started to detonate long before MBT, resulting in extremely high peak combustion temperatures and pressures, to the point where you quite possibly now have a broken ring and/or ring-land on one or more of your pistons. He may have even thought it was safe to advance the timing because he saw the power falling, but in reality it was dropping because he was pushing your timing into dangerous territory, not because he was still well in advance of MBT. Usually if you hear full blow detonation its too late. Detonation starts long before we can actually hear it,

they are wrong. 10:1 is basically a standard these days - my M20 reached MBT with 10:1 CR on pump gas *long* before the detonation threshold.

and unless your engine is turbo, a bit of detonation isn't going to kill it that fast.

[psyber_0ptix]

there is a 99.9 percent chance it wasn't your tuners fault. hanging out at shops enough i have seen way too many people try to blame a tuner for an issue their car already had when their car was put on a dyno.



not sayng you are of course. but i'd bet money it was an issue that isn't the tuners fault.

tuners work with what they have, and when starting from scratch on a non-standard motor, it can be a bit tricky to get right. As stated above, if there was a problem to begin with, tuning it might further exploit weaknesses in a motor until failure.

...but how many runs was he pulling? and did you ask him any questions during the tuning process? (as to why he looked puzzled) That in of itself would raise alarms for me. I'd be the curious bystander, while trusting the tuner to do what he does, I'd want to be kept in the loop at all times especially regarding a labor project of love/hate.

[dkbmxer002]

there is a 99.9 percent chance it wasn't your tuners fault. hanging out at shops enough i have seen way too many people try to blame a tuner for an issue their car already had when their car was put on a dyno.



not sayng you are of course. but i'd bet money it was an issue that isn't the tuners fault.

[329jay]

i just re read my first post. i didnt mention that while he was doing the timing the power was going down. he kept stopping, getting out the car and looking at the power graphs on the screen. he did look a bit puzzled.

[329jay]

i got this from someone....
it sounds to me like your tuner could have advanced your timing forwards in an effort to find MBT (mean best torque). Problem is, being a high CR (even 10:1 is high CR by modern unleaded standards) your engine probably started to detonate long before MBT, resulting in extremely high peak combustion temperatures and pressures, to the point where you quite possibly now have a broken ring and/or ring-land on one or more of your pistons. He may have even thought it was safe to advance the timing because he saw the power falling, but in reality it was dropping because he was pushing your timing into dangerous territory, not because he was still well in advance of MBT. Usually if you hear full blow detonation its too late. Detonation starts long before we can actually hear it,

[LJ851]

Sounds like a bent valve to me. Not sure what would have caused it, assuming all your clearances were good to begin with. Rod/main bearings failing wouldn't cause low compression

You obviously haven't been around too many engines. Rod bearings fail, pistons start stroking 1 or 2 mm more than normal, piston hits head, compresses ring land, and massive blowby/leakdown occurs.

[AndrewBird]

Sounds like a bent valve to me. Not sure what would have caused it, assuming all your clearances were good to begin with. Rod/main bearings failing wouldn't cause low compression. Could also be a blown head gasket.