fail
 

my list of engine failures for others to learn from

high mileage + poor luck + boost + oil pump = fail

building motors on the beach + rod cap on backwords + "help" from a friend = spun bearings and devoured crank journals.... fail

crank "kit" = fail ...I don't care what your "book" says the miata does not have a cast, half counter-weighted crank

eagle rods don't like supertech wrist pins.... Don't force them, then take them to your machinist and shrug your shoulders :dunno: your machinist will hone the rod a tiny amount and you will put it all together then find out in a few weeks that your rods are bent by a few thousandths because you will hear loud clanking from "localized, diametrically, worn bearings. see pic below.... fail

on a side note is it just me or do these pistons have a little too much build up for 3k miles

This is one of the reasons I'm debating in my head whether it's worth it to do rods or not. It's not so much the $300, but the install adds another point of potential failure. It's a typical don't fix it if it ain't broken kinda thing.

Don't post this shit up as I get ready to assemble my motor in the gayrage...


I know it's worth it to pay someone to check pin fit...but how exactly did that kill your big end bearings?

Was the hone not straight?

Holy shit man, thats some FML material.

Guys guys guys. Don't sweat putting together a bottom end.
1. Before you disassemble anything, use a sharpie/scribe to mark orientation on the pistons/rods/crank journals if they aren't already marked.
2. Have a machinist check the important bits like rod ends.
3. Liberally use plastigauge and a good set of calipers/feelers. If you aren't sure, check it twice.
4. If everything checks out...Profit. Just be thorough with the torque wrench.

oh yeah and i forgot to mention that your water temperature gauge wont tell you that something put a hole the size of a golf ball in the bottom of your radiator while traveling 80mph down the interstate.... well fast enough to keep your head gasket from going kaboom anyway... yeah deff FML stuff since I am yet to use my boost controller see more than 6psi(aside from boost creep)

well I dont know if it was a crooked hone or me trying to force the the pins in :vash: or a mixture of both but either way it causes the big end to sit crooked on the crank journal and wear out opposite edges of the bearings and the need for new rod(s). I'm going with the M-tuned set this time they have more clearance for the wrist pin .788" instead of eagles .787" and they are cheaper and weigh about 65 grams less per rod... epmiata.com says that eagle claims 900hp capability but I'm willing to bet my engine that I'll never need more than the 600hp m-tuned claims.

don't be discouraged from DIY there is no better way to learn(I pulled and disassembled my engine without an engine hoist or air tools in about 6 hours and that was taking my time) and no better feeling than saying "I built it" but I would say at least take month or 2 to read read read and go and talk to your machine shops and "professional" engine builders (I have literally spent hours doing this and even some of them have learned stuff from debating answers to questions I asked)

I am most amazed by that crankshaft comparison. Did you ever find out what the "half weighted" crank was really originally designed for?

IF you're going to assemble you're own engine, then approach it as if you were going to operate on yourself.

Wasted on nitrous and gin?

^Or with a rusty pocket knife on a boat in the South Pacific while listening to B.O.C.?

Word.

Those look just like the 80K mile pistons in the motor I'm currently tearing down. Damn that's a lot of crap on them for 3k!


Really curious about the rod honing and the problems there. It's been discussed recently that pretty much all the rods need to be honed to fit the pins. Wonder who's mistake made it eat the bearing and what to look out for.

This is why you are supposed to measure wrist pin clearances for ANY build.

I believe the crank is from a 91-93 protege... It fits but it's not what I ordered... I may use it someday for an all motor build with some ITBs and an electric supercharger for the extra cool kid effect... :td:

Although idk if it was just honed wrong or whatever. I was talking to an engine builder and he told me to always lay the rods on a piece of glass to make sure they are perfectly straight... If they aren't find some new ones

The fsm for the B6 says 0.0004-0.0011 clearance between small end and pin, I would assume the same for BP (check, though). Guys smarter than me can chime in, but even with this little amount of clearance, there should be no appreciable bind or tightness when inserting the pin in the rod. This is going to sound like a broken record to some guys, but my local NAPA only charges $60 to fit the set, and they will turn them around within 24 hrs. You should be able to measure them in your home shop well enough.

i wish i had a picture of my dsm eagle crank one day i pressed the clutch in it shudderd like a sonabitch. first thought flywheel bolts backed out "the stroker motors" tend to do this. i pulled the tranny the crank was snapped in two she made it like that 4 miles home. it is now a paper weight at a buddies performance shop

Yup.. Very very clean area..

Always check your clearances and NEVER force anything. If the Piston Wrist Pin is tight is will take only a few $$s from a machinist to make it fit proper.

We could claim 900hp but there has never been a Miata who has made 900hp. We have had our rod used in a 600hp with our ARP 2000 Bolts.

I used to own a 500hp Miata. It was nuts! 4th Gear Burnouts on the Highway when I got on the loud pedal!! 900hp would be retarded = CRASH!

"900 HP Miata" im gonna be the one to do it!:giggle: