williams805

iTrader: (2)

^ thanks for that. I read those and am inspired.

I pulled the blower and intercooler today. I haven't opened it up yet but one thing is clear; NA sucks!

SMOG in November. Thinking while she is NA, time to megasquirt and put some real injectors in. At the same time keep eyes peeled for tvs 1900. Give myself to January to find one cheap or decide on alternate method of boost.

kmvguy

How is oil consumption?
Are you still burning/loosing a lot of oil?

Did you retain or remove the OEM oil squirters?

williams805

iTrader: (2)

The catch cans helped a bit, but yes still losing quite a bit. One the intake side catch can has anything in it and not much. I'll add it up when I change my oil in about 200 miles but think I'm at 3 quarts right now.

Yes still have squirters. If I were to do it again, I would pull the squirters and ceramic coat the piston tops. Would run a crank scraper too.

I will be running NA for a while and will keep a close eye on oil consumption. If it still burns that much, I'll be pulling the engine and looking very closely at the oil control rings.

kmvguy

What do you suspect the reason for burning?
Piston to wall clearance or squirters?
This is one of my biggest worry on my future build, seems like it's hard to make forged pistons reliable as cast counterpart :/

williams805

iTrader: (2)

Just not sure at this point. Not enough data.
Compression and leak down are excellent.

Oil temp (and engine temp) are high. Warm engine on 70 degree day is 230 and 220 respectively. Can't help with oil vapor. I do know on longer trips (200 miles) burns more than city miles. I have 4.30 rear end and driving at 80 mph is over 4000 rpm for hours maybe adding to this. I would like to have thrown proper rad and oil cooler on to see what lower temps would do to the oil consumption.

Also, like I said before, in the first 1000k miles with joe Gibbs and no boost = zero quarts burned. I know everyone here preaches rotella t6 but changing to this oil and adding boost resulted in way more oil burn. I had a theory that I damage an oil control ring during assembly but I would have thought this would burn oil from the beginning.

In the next few months I should be able to figure out if the oil is the cause, or some how the boost is the cause. Or possible some other mechanical failure.

The other weird thing is; the cause if me building this engine was rapid oil consumption. Wasn't a problem until I bolted the blower to the stock engine. Then I ran through 2.5 quarts in ~800 miles.

Knowing what I know now, here are the changes I would make to my build:
1) Eliminate oil squirters
2) have piston tops ceramic coated and sides coated with that slick coating
3) run a crank scraper
4) put a shim or 2 in the BE oil pump for higher than 65psi oil pressure
5) shoot for less PTW clearance. Maybe closer to .0033 instead of .0036-.0038. No slap but in interest of less oil consumption.

kmvguy

Isn't supertech recommendation somewhere around 0.00278?

williams805

iTrader: (2)

I believe that is for natural aspiration IIRC.
Give them a call. Pretty sure they told be to run slightly more for FI but, I am a little above that. I think .0033 was the number to hit but that's just going on memory.

williams805

iTrader: (2)

Next step ms3.

psyber_0ptix

iTrader: (4)

I thought it was preached that retaining the oil squirter was more advantageous as the oil draws heat from the piston. Is a hotter piston worth the windage reduction?

Is 0.0003 really going to drastically affect consumption? Others reported running up to .004 without major issues.

I only seek these clarifications as I'm about to send a block off to the machine shop

EO2K

iTrader: (37)

With what pistons?

psyber_0ptix

iTrader: (4)

I thought for supertech

There are several mentions of 0.0040" being okay?

Savington, Hustler, MartinezA92

https://www.miataturbo.net/showthread.php?t=51070


Unless I misread and people are just listing off their non supertech p2w clearances.

Maybe I should stop referencing 4 year old threads. I thought that the minimum for supertechs being about 0.0027 or so meant the being a little lose for turbo application was ok. Being that the OP is running between the recommended minimum, and what others have seemingly run without issue....I didn't know if making the clearances a little tighter by 0.0003" would drastically reduce consumption.


Just asking. I was thinking of shooting for 0.0034 for supertech 8.6:1 pistons in my replacement block.

https://www.miataturbo.net/showthread.php?t=51070

EO2K

iTrader: (37)

No idea, but I'm learning too

Didn't MartinezA92 give up on his motor and part out due to cylinder scuffing and piston slap? I'll see if I can find his thread, but I can't remember if its on here or NCR. Something like "paranoia sets in" in the title. He is semi-local to me and is still around MT, I've seen him post in the Subaru thread. Might be worth shooting him a PM.

Edit: Also, the "paranoia" thread was about ring gaps, not PtW https://www.miataturbo.net/engine-pe...ia-sets-69112/ but might be worth a PM anyway.

psyber_0ptix

iTrader: (4)

CLIFF NOTES:

Minimum piston to wall clearance for Supertech pistons : 0.00276"
Recommended p2w when calling Supertech directly: 0.00316 to 0.00356"



OK. I'm sorry to invade another persons thread, but given that there are tons of numbers being thrown around whenever searching.....


I DID call them just now, they said that these pistons are already considered for turbo application, so as it stands, any additional clearance is at the discretion of the customer. As Savington and countless others pointed out many times, 0.00276" is the minimum. But what I was told over the phone, a "suggestion" would be around 0.00316-0.00356" if one anticipates hotter temps/higher boost.

I'm not certain if that's the extreme end of what they had in mind for a turbo application (if others were indeed using .004 explicitly for Supertechs) or just to get me off the phone so they could go home. I mentioned off the cuff 20psi, but it would also depend on tune.

OP's "number to hit," referenced 6 posts above, is definitely in that ballpark. dafuq?

williams805

iTrader: (2)

If bundy's 350whp, 6 speed raping, track terrorizing car can survive without oil squirters, I'm sure my car would get by okay. I would not remove them without coating the pistons.
Not trying to nudge you one way or another. I was just sharing that once I found out how cheap the coating was, I kind of kicked myself for not doing it that way.

I don't know if that tiny number would do anything or not, but that is the number I'd shoot for if starting over. I would not buy a new block or pistons to get there however.

I still don't have an "official cause" for my oil consumption. My p2w maybe just fine. Oil squirters may have nothing to do with it. There are many other cars on here running squirters and probably similar p2w clearance that don't consume oil. I'm just a little extra peeved because my **** does and cannot find any obvious signs as of yet why.

I'm going to run for at least 3000k miles without the charger. I will be monitoring the oil closely to see if anything changes consumption wise. Then I will decide if I can live with it or I want to pull the the engine and inspect.

Turbo Turtle

did you put valve stem seals on it? just say'n lol

williams805

iTrader: (2)

Yes sir I did. Well machine shop did because that **** sucks without the right tool.

Thinking more and more that an oil control ring may have been damaged on install. Could explain good compression and leak down.

EO2K

iTrader: (37)

I'd like to subscribe to your newsletter. What coating, what surfaces and at what price point?

psyber_0ptix

iTrader: (4)

Hmm I'm just curious which is better though. The supertech pistons support use of the squirters as it has all those little holes to help lubricate the skirts from under the cup. Meh either way, I hope that new rings will sort your build out and it's nothing catastrophic like my motor. My **** ran and I didn't know any better until I cracked it open.

williams805

iTrader: (2)

This guy went Calico. He said $160 for all 4.
https://www.miataturbo.net/engine-pe...pistons-76449/

I can't find what kind of coating bundy is running.

williams805

iTrader: (2)

So this is on ebay right now. Price is right, but looks like way too much fabrication to route the air out of it. I do like the throttle body in front though.
TVS1900 for $610
Cadillac cts V supercharger LSA ZL1 336301 E | eBay