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Thanks for the other feedback about the crankcase pressure and sealing it up again. I've used a Wisco piston installer on my MSM, with an 85.5mm bore, so I had to buy a new, 83.5mm one for this NB build. Pushing a ringed piston into a cylinder with just thumb pressure is too rewarding to ever imagine going old school again. I just got the new ring set and put my final 2 rings in place using my fingers instead of the pliers to play it safer.
After the new crank sensor and new trigger wheel, she fired right up!! I only ran it for about 7 seconds because it was too cold to take her out. I gapped the sensor to the wheel down to .012" per Curly's recommendation. The problem with trying 3 things at once is you don't know which part/technique actually solved the issue but I'm happy with the end result regardless.
If you take a look at the Fab9 trigger wheel, you can see the teeth are smaller in stature and the holes never lined up when I got the piece last year so I had to drill them wider. The Flyin Miata piece is just so much better in every way and fit was perfect. I've had some issues with the aforementioned company and will not be using them for any further purchases. Flyin Miata is just by far and away the best miata company out there. Of course theres others for OEM replacement parts that are great too, no disrespect there! FM just puts a lot of effort into R&D and engineering and it shows.
She finally saw the sun this weekend as I took her out on Friday and Saturday. Friday I drove about 1/4mi over to a side street and just went up and down about 10 times for about 3ish miles just doing light load pulls and staying in gear for heavy vacuum. Then yesterday, I went around on town on some more main roads doing heavier pulls, staying in gear longer, varying RPM. Got about 15 miles in so far, no obvious leaks and things look really promising. Pulling 20psi in vacuum according to my gauge.
I have the internal wastegate physically wired open to not generate an ounce of boost on accident until I get a couple hundred miles in. I noticed I was running pretty lean using the same tune as I was before. If my knowledge of engine theory is correct, that would mean my volumetric efficiency is already better as I've had to increase the number in the table, aka more fuel. So I think the rings are seating better already. I pulled the first oil filter off and the oil looked good. Unfortunately, its a brute of a filter so I can't cut it open without getting metal shards all over and then I wouldn't know if it was from the engine or not (I tried lol). Got a cheaper one on there now and will pull it around 100 miles and cut it open.
I was also reflecting on what went wrong the first build and had another thought. I had the Fab9 heads studs on there torqued somewhere around the 85-90ft lb range. I believe this may have distorted the bore and changed the P2W clearance, causing the bad seating and blowby. Just another small piece to the puzzle and only a hunch. This time around, running ARP at 65ftlbs.
Looking forward to my next weekend where I can set base timing, burp the cooling system (she was a lil hot after my drive) and just start getting miles on her! Thanks for reading
Glad to hear you're up and running Matt.... congrats. After my own build experience, I'm now leery of Fab9, and prefer other vendors like FM, for better quality, service and delivery. For your fueling changes, I'm wondering if you also upped your displacement (1.884L?) to account for the overbore, which slightly changes the fueling equation and adds some fuel. There is also that change in compression ratio with the new pistons.
Thanks Mark! Hope once I re-introduce boost it stays this good. I'm currently logging and diagnosing why it likes to die when coming to a stop or when you free rev it and the revs come down too fast. I'm thinking of trying turning on engine states after reading a Braineack post.
All I did was a new hone, its the same displacement as it was the first time around (84mm). I'm going to go to the Castle Rock meet Sunday morning, hope to see you there!
I would have loved to come on here with good news or talk about the nice new shelves I built in the garage, the 240v outlet I wired up with a self-designed and printed outlet. Or my first couple welding projects for the car. Or the countless hours I spent tuning it to run and idle well. Unfortunately, none of it matters.
700 miles on the engine. Did the break in oil change at 500 miles, oil looked fantastic, as did the filters. Bought a borescope and decided to look at it before I plug the turbo back in and start boost tuning. As I feared, the bores look like ****. Same issue as before with tons of scratches all over the thrust and anti thrust side in all cylinders. Haven't done a leakdown test but doesn't matter, the walls are absolutely awful. (date isn't accurate in photos)
It probably needs a new block, I don't think the bores are round and I am blaming the first machine shop for that. But it doesn't matter. I don't have the heart to build this engine for the third time and throw another $2k and 200 hours into it. If anyone wants to make me an offer on the car, shoot me a message. I'll list it locally but will likely just part it out and sell it as a shell to try and get some money back.
Reading your thread makes my heart hurt for you ... but, I agree with the last comment. Don't give up quite yet, as vertical marks like that can look worse than they are. Compression and leak down needs to be done first, and it may be fine. It seems unlikely the machine shop would have made an oval bore, but I guess its possible.
If compression is even and its not actually doing anything funny, just send it.
Btw, it's pretty simple to check bore roundness. I have a little set of gauges I bought way back for like $25, and they have been nice to have a few times now.
Good morning! The emotions have subsided and I'm not going to throw in the towel just yet. Thanks for the support y'all, it really means a lot.
I will absolutely do a leakdown and compression test before making any further decisions, probably next weekend.
P2W was .004" per the shop that honed the bores the second time around, which I think is actually on the high side? I have also had the thought of just sending it but these marks were there for the first build and it was causing a crap load of blow by and pressurizing the crankcase. I have also thought saying screw it and just driving it like that and treating it like a rotary by adding oil every tank lol.
akaryrye, I don't suppose theres any way to measure roundness without pulling the head off? I'm just at an absolute loss for what these marks are being caused by if its not out of round.
Other thoughts are scrounge what I can out of this by selling it and getting an s2000. Or maybe K swapping this chassis and leaving it N/A for a season so I can actually drive and enjoy it. Or just LS the thing since its probably the price of a K swap and I'd rather put the money towards that before building the B series again. Forced Induction is fun but the simplicity of N/A from a maintenance and tuning perspective sounds so nice right now haha.
They are not deep score marks. There is still remnants of cross hatch across many of them. I have seen these on many engines including many very good running units. Even my current engine has some. Check your tuning and use good oil. If it runs well keep using it. Good luck.
Originally Posted by MillaTyme91
Good morning! The emotions have subsided and I'm not going to throw in the towel just yet. Thanks for the support y'all, it really means a lot.
I will absolutely do a leakdown and compression test before making any further decisions, probably next weekend.
P2W was .004" per the shop that honed the bores the second time around, which I think is actually on the high side? I have also had the thought of just sending it but these marks were there for the first build and it was causing a crap load of blow by and pressurizing the crankcase. I have also thought saying screw it and just driving it like that and treating it like a rotary by adding oil every tank lol.
akaryrye, I don't suppose theres any way to measure roundness without pulling the head off? I'm just at an absolute loss for what these marks are being caused by if its not out of round.
Other thoughts are scrounge what I can out of this by selling it and getting an s2000. Or maybe K swapping this chassis and leaving it N/A for a season so I can actually drive and enjoy it. Or just LS the thing since its probably the price of a K swap and I'd rather put the money towards that before building the B series again. Forced Induction is fun but the simplicity of N/A from a maintenance and tuning perspective sounds so nice right now haha.
They are not deep score marks. There is still remnants of cross hatch across many of them. I have seen these on many engines including many very good running units. Even my current engine has some. Check your tuning and use good oil. If it runs well keep using it. Good luck.
Hey Leo, that does make me feel better. I've had a hard time researching these score marks and their origin or effect on the motor. Where those N/A or forced induction motors? When you say check the tuning, do you have an idea of what would cause that? Only thing I can think would be timing or way too rich but I've gotten it to idle 14.3-15.0 and the auto tune has been doing a bang-up job getting it close to 14.7 under partial throttle and close to WOT. I'm worried the second I plug the wastegate actuator in and hit even 5psi I'm going to see the same problems I saw before.
Both NA & FI. When you run boost make sure you’re safe with the timing and AFR. I doubt over fueling is the root cause. Could be cold seizing. The piston heats up/expands much faster than the coolant filled cast iron block.
Originally Posted by MillaTyme91
Hey Leo, that does make me feel better. I've had a hard time researching these score marks and their origin or effect on the motor. Where those N/A or forced induction motors? When you say check the tuning, do you have an idea of what would cause that? Only thing I can think would be timing or way too rich but I've gotten it to idle 14.3-15.0 and the auto tune has been doing a bang-up job getting it close to 14.7 under partial throttle and close to WOT. I'm worried the second I plug the wastegate actuator in and hit even 5psi I'm going to see the same problems I saw before.
02-25-2024, 12:44 PM
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