Add me to the list of blown motors ...
 

Ya so i was leaving the autocross event today and well, the engine knocked with the slightest load. It made it the 15 miles home with careful driving, but it got a bit worse during that time. Basically, it sounds like rod knock and gets much louder under load (I.e 20" vacuum is quite, but 10" was pretty noisy).

I suspect either a bearing failure or a bent rod and the failure to be caused by oil starvation as when I checked the oil after noticing the knock, it was not even hitting the dipstick. The tune on Megasquirt could be another possible explanation, as I have had a few audible detonation events during tuning, but I even added a few gallons of 100 octane to be on the safe side for the race, so i really doubt that was the problem.

Anyway, so my motor is fuxxord and needs to be fixed. My options are:
1)to rebuild the existing short block, or the one from my (240k miles) spare engine.
2)buy a low mileage short block
3)buy a low mileage long block
4)something else?

Anyway, i have a bit of DIY headwork that seemed to pay slight dividends in the power department, but on the other hand it would be nice to not pay for a new headgasket. What would you do?

Oh, and for those interested, If i have a bend rod, ill sell the good ones (carillo A beam) and can even have them checked out by a machine shop before finalizing (thinking a few weeks ahead)

well i would build the motor out of the car and then swap this would minimize your downtime and assure that you have covered all your bases. + if you spun a bearing you coulda chewed up a crank so use the known good motor as a basis for rebuild and sell the other once it is removed for parts. and replace the frigin oil seals this time. Also i used a sawed of 3/8 drive extension and a 21mm socket on a heavy duty drill to prime my oil system. worked like a charm. :D

I swear we have more blown motors lately on this board. We need to get a group engine buy going haha.

Well, the other block has the short nose crank, but i guess as long as it is carefully assembled and monitored, that should not be a problem. Another option would be to get the existing crank offset ground to stroke it out slightly and lower compression. Im thinking that If the bores are able to be honed, to rebuild the 90 and keep all the componants matched to the cylinder they belong to so I dont need to balance it and just be done with it.

oh ya, and i did replace all the seals when i put that thing together, thats what gets me ...

i would offer up my extra engine but i'm in texas and its quite a way to cali...
but reading this makes me feel like spending more cash on oil gauges. Temp, pressure, and is there one for level? hahaa, a digimattell dip stick, you push the button and it comes up with a thumbs up or down, LMAO...

NOOOOOOOOO.
Man that sucks. Makes me want to get my EGT, Oil Temp, and knock sensor installed.
Wish i could help.

The cranks are nitrided from the factory, so if you do cut the crank, be sure to renitride. Personally I'd go with the short crank- since the only problem I've ever had with one was when somebody else worked on my car (tbelt change). I've had four short nose race motors and they're all still intact AFAIK. Curious to hear what caused the oil loss. :dunno:
I love my EGT, Oil Temp and knock sensor. :D
Oil Level? - oil temp will go cold and the oil pressure will go 0 when it's too low ;)

Its no big deal, there is a guy in Fresno who I met at the Autox, and he is going to pick up a japanese 1.6 for me and im just gonna straight swap that thing in. I think a knock lite is going to be installed soon as well.

Knock lite? Is that like the knocksense i was referring to?

EDIT: If you mean knock light then i'm an idiot and wasn't thinking. Sorry.

Man, that sucks. I thought I had a bad day today at autocross when I ran over the time light at the finish line. Sorry to hear it.

if I were you I'd do the straight swap too- you've come too far to have to wait/work through an engine build!

You are running MS aren't you? Get the knock filter/amp and then run knock detection/protection within MS.

I bet the rods are ok. just spun a bearing.

I think ill do that, but i am almost positive that the failure was not caused by the tune. I took it out on an autocross course with low oil, and when going around turns at high rpm, the oil goes to the side of the pan and the pickup probably got air a few times and messed the bearings.

im thinking the same thing.

Sorry to hear that man. I blew mine on a road trip to Vegas.

"Do I need to change the oil? Nah, I'll just wait til I get back."

Wah wah.

Well, i changed my mind after I was told the motor would be $625 +50 for shipping and tax on top ... hellz no. I figure if its a spun bearing, ill just get the crank reground to an oversize and get some new bearings up in there.

somewhere there is a link on here for reman cranks for like ~$150 with matched bearings.

its rpmmachine or some equivalent. I posted it :) It is 150 with a core swap. So assuming your crank is salvagable by regrinding they will give you the core charge back. You need to consider that some of your rods might be bad though. When a bearing spins often it create tremendous heat that can damage the strength of a rod. So if any of your rods a discolored from heat damage get them checked out by a machinist.

thanks for the insight, i was going to look for anything out of shape. So for the color, im assuming the damage will be right around the bearing area itself and not the shaft right? Im really hoping that the rods are alright ... those were a pretty penny and methinks an unwise decision as I should have used stock componants for a first time engine build.

welcome to the dead miata club.