I have no complaints about my low-comp Supertechs, but I haven't torn down the bottom end. I like 8.6:1 compression ratio more though. It typically makes significantly more output with a small compromise in throttle response that can be further minimized with spark angle.

 

alrighty, finally got another digital scale (thank you harbor freight) that measures in .1 g.

piston weights are: 296.4g 297.1g 297.7g 298.2g

wrist pin weights are: 97.2g 97.6g 98.2g 99.2g

wirelocks each weigh exactly .8 grams

 

Idea for funsies: weight the stock cast slugs and pins when you get them out of the old motor

 

Happy with my 8.6:1 supertechs as well.

 

I kind of wonder whether they "balance" like this before they box up the pistons. If you put the heaviest pin with the lightest piston and vice versa, you end at 395.6/395.3/395.3/395.4.

 

yeah, I was wondering that too. Works out pretty nice

 

Did you get the total weight out of the box with poston and wrist pin?

I had to swap around the wrist pins to get things closer in the bix I had.

https://www.miataturbo.net/engine-performance-56/first-look-supertech-pistons-1-8l-dohc-65235/

Seems the right wrist pins were in the box, but they mixed up the wrist pins during packaging.

 

oops, should have responded to this thread earlier, but they didn't have the wrist pins matched to the pistons in the box, but I weighed them and after switching wrist pins around, they were matched almost perfectly.

Had everything machined and balanced, including the crankshaft and flywheel and pressure plate. Finally got the pistons in the block today

Some pics for your viewing pleasure. This is my very first engine build. First time putting pistons in, etc. taking it as slow as possible and having a great time

 

With a beam torque wrench, see how much force it takes to get it rotating. I like to see less than 20ft/lbs

 

I don't have a beam torque wrench, however it's quite a bit easier to turn than when I first tore down the motor. I'm sure it's less than 20 ft/lbs

 

Set your clicker style to 20 then and give it a spin!!

Looks good so far!!

 

with the clicker torque wrench, it won't click unless it's at 4 lbs or below

 

Sounds like everything is going together slick as teflon owl ---- then!

 

Got the motor in and she's back on the road So much smoother than before, and she keeps asking me to step on her more and more (can't as I've only just broken her in). Trying to avoid boost, but have done my 100 kpa runs to set the rings. So this is what it feels like to have a motor that's half built and balanced right :P Thanks again guys! especially BogusSVO, your threads are priceless

 

Get boost on the rings for break in!!

http://www.mototuneusa.com/break_in_secrets.htm

 

I've been trying to get it to full load for a good 2 or 3 gears up to 5500-6000 rpms, but avoiding too much boost. I think the most I've boosted is 5 psi. It's run it hard, but then other people have said to run it hard in respect to an N/A engine. I haven't had enough time in autotune to go into boost for extended periods and feel safe (connection issues with my laptop)

 

I'm finishing up a rebuild on a 1.6 motor with a JRSC kit on it. In the process I am also switching to a MS ECU. When I get the motor up and running, it probably won't be in a state of tune to handle boost. I'm not good at all at tuning.

The plan was to get the engine running, take it over to my tuner and get it setup from there. Only issue with this is how to I break in the rings if I can't really get the car into boost. From readying the Flyin' Miata how-to, seems as though I just need to get to 0 psi of boost with some accel/decel runs. But this Mototune link contradicts that.

Any words of advice to this issue? I would like to avoid doing a bunch of work self tuning if possible. Thanks.

 

Do Three 1/2 Throttle runs from
40% - 60% of your engine's max rpm

Do Three 3/4 Throttle runs from
40% - 80% of your engine's max rpm

Do Three Full Throttle runs from
30% - 100% of your engine's max rpm

Interesting.

 

I had that issue too of when I first started up the car to break in the engine. My tuning laptop was having connection issues as I was connected through bluetooth. I had to go back to my cable and then I think I raised all of my VE table cells by 5 just in case as it was running a tiny bit lean.

I also put in a new FM stage 1 clutch, so I didn't want to beat on it in the beginning (always a dilemma), but I was able to get the engine to 100 kpa (full N/A load) and then as my VEanalyze did its thing, I did some boost runs with probably about 3/4 throttle up to 5500-6000 rpms. Engine seems super strong, without any smoke. It had a bit of smoke on initial start up, but I'm attributing that to assembly lube burning off and the rings not seated yet. I've been varying the rpms constantly as I drive around, pissing more than a few people off on the hwy, lol. So far I think I've gotten my car up to 10 psi, from what my log shows