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Well... goodbye piston.


Fairly confident that the piston is meant to be circular...


I think I know why the crankcase pressurised...

There were also two hairline cracks from the piston crown all the way down to the skirt. I was a few bad knocks away from spitting fragmented bits of piston everywhere. I think I can count my lucky stars.

Engine builder is checking everything over but (fingers crossed) doesn't look like damage to the block. Two minor "polish marks" but I could still see the hone marks in them.

Will also get injectors looked at to make sure injector #1 wasn't a part of the problem. Pistons + cylinders 2-4 all looked healthy.

New pistons on the menu. Looking at mania's Supertechs as they are the right alloy recommended by the builder for this application and he was of the view they were a quality item - and are in stock, which is important! I see on the big forum they are also one of the go-to options. Anyone have other experiences/recommendations (obviously would need to be able to get them locally/within Australia given the state of international travel and shipping at present)?

I see the light!

You’ve had a tough run!

What compression ratio are you planning to use?

Haha yeah look... A smooth run wild have been nice but this is character building, right? Will be fun explaining the bank when I'm going for a mortgage... "What was this?" Car parts... "And this?" More car parts...

I guess the lower-than-stock option (looks like I can go stock, higher, or lower?) But I'll chat to the builder and a (local) tuner first. Thinking chequered who seem to have done a good job with Brendan's car. These will be similar motors, all said and done

StuwieP wrote:Haha yeah look... A smooth run wild have been nice but this is character building, right? Will be fun explaining the bank when I'm going for a mortgage... "What was this?" Car parts... "And this?" More car parts...

This is why I bought the house before building the engine

I guess the lower-than-stock option (looks like I can go stock, higher, or lower?) But I'll chat to the builder and a (local) tuner first. Thinking chequered who seem to have done a good job with Brendan's car. These will be similar motors, all said and done

You're re-bounding quickly, good work! The Supertechs are what I'm planning to use, with the Wiesco XX rings, seems to be the combination recommended by most. You can spend more on pistons, but the Supertechs are more that you'll need on most MX-5 builds unless you're going extreme.

For the turbo setup, you'd probably want 9:1 or maybe 8.6:1, unless you plan on a full time E85 use in which case you could run higher. Apparently the lower the comp the more timing you can run, and the engine responds better to timing than comp.

Thanks Lachy - I've seen the Wiseco NPR rings reocmmended - if I can get my hands on them locally I think that's the way I'll go.

I've pulled the wiring loom now. Ground wire from my COPs had a long split in it - don't ask me how, I've never had a stanley knife back there. Might go some way to explaining my previous ignition issues too...
I have ordered 4 new COPS connectors and and going to re-do the pigtails, grounds and power lines to hopefully reduce any residual inefficiencies there. The existing ones are fairly tired.

Also, one of the wires to the loom side of the crank angle sensor decided to part ways just under gentle movement. Glad it's decided to go now, and not in a few months when I'm back up and running.
I've googled and googled without luck - does anyone know where to get the loom-side crank angle connector? It's easy to find a replacement sensor, not so much the replacement clip...

If not, I have a small box of deutsch connectors, I'll unplug the sensor-side connector and use one of my 3-pin deutch connectors for both instead... downside is it won't have the handy mount to hold it in place against the side of the motor.

What was the AFR and ignition advance when it let go? I've seen a tune from a certain dyno user from Newcastle, it had a LOT of advance in it.

StuwieP wrote:...
I have ordered 4 new COPS connectors and and going to re-do the pigtails, grounds and power lines to hopefully reduce any residual inefficiencies there. The existing ones are fairly tired.

Also, one of the wires to the loom side of the crank angle sensor decided to part ways just under gentle movement. Glad it's decided to go now, and not in a few months when I'm back up and running.
I've googled and googled without luck - does anyone know where to get the loom-side crank angle connector? It's easy to find a replacement sensor, not so much the replacement clip...

If not, I have a small box of deutsch connectors, I'll unplug the sensor-side connector and use one of my 3-pin deutch connectors for both instead... downside is it won't have the handy mount to hold it in place against the side of the motor.

What cops are you using? If it's toyota copies off ebay, I would cancel them and go find some genuine toyota ones.

also - ballenger motorsports has the connector you're looking for - assuming it's the standard crank angle sensor from an NB

https://www.bmotorsports.com/shop/product_info.php/products_id/2077

Thanks for the link! Wary with international shipping currently but will have a look into it.

So I'm not replacing the cops, just the pigtails. The cops were previously from greenmachine - not sure without looking at them what they are. And it's too cold tonight to check!

As for AFR and ignition, I'll have a look and get back to you. It was certainly running the bottom of the table

plohl wrote:
also - ballenger motorsports has the connector you're looking for - assuming it's the standard crank angle sensor from an NB

https://www.bmotorsports.com/shop/product_info.php/products_id/2077

Shipping for the clip was going to set me back the better part of $80.00 for a $10.00 clip

Instead, (since the connector isn't broken) i've sourced some replacement pins locally which is definitely the cheaper options... even with a minimum order of 25, it set me back a grand total of $6.50...

Also expecting to hear from the engine builder next week about the (hopefully minimal) damage to the block.

For those playing along at home, here's the datalog from what I can figure is roughly the moment we went boom. Sorry if it's hard to read.

Ignition timing stable (purple). Boost rising (yellow), AFR stays OK (red), injector DC rises with boost(green) , then boost cut = injectors off. I figure I must have had only a few revs (if that) with detonation or I presume I would be seeing more damage?

New year's update. Short story = hoping for better luck in 2021.

Long story: Got the motor back just before work finished up - good timing with a week and a bit off.


Putting things back together with the help of the local mechanic.


Finished:


Saturday morning:


Saturday night:


Looking like it should:


Had a few rather anxious moments but the car fired up, no "unhappy noises". Checked for leaks then turned it off. Next stop: book in a tune once the shops re-open in the new year.

Fixing the little things, feat. the world's most annoying jigsaw puzzle. Rear garnish was broken and multiple tones of red, so I have some colour-matched paint, fibreglass and filler and working to get it looking half-way decent. It's hardly going to look factory but it will (hopefully) be better than it was before.


Happy new year all