c.buffm

So, I have found myself in a bit of a predicament and I will give some back story to help set things up. I have had my car (1.8l 94 with ~139K on the clock) turbo charged and running reliably for over a year now and it is my first project and venture into the car world. Important parts list as of now:

MAXG t25 Cast manifold

China 2871

eBay intercooler and piping ducted

FF550cc variant

SpeedyEFI standalone (Arduino based)

MTXL Plus Wideband

Custom downpipe from a shop tied into the stock exhaust

Etc.



You get the idea, done on a budget to have some fun and most importantly for me, learn. I am a college student with a part time job and a fair amount of money saved up, but I don’t have super deep pockets. I read all I could from this forum and was honestly scared to post because I didn’t want to make a fool of myself. All the tuning has been done by me and the car has never been on a dyno, so I have no idea what kind of power it makes.

This past week I noticed a blue smoke and burning oil smell coming out of my exhaust at stop lights and stop signs after driving (occurs after a few seconds of standing still). From reading I’ve done on here, its either the rings or the valve seals (leaning more towards valve seals but need to do a compression test still). I’ve been wanting an excuse to pull the motor and do a mild build with forged rods, and possibly pistons, re seal the motor, and just an over all refresh. The goal then would be to shoot for a reliable power level near 280ish. I don’t plan on tracking the car, just want a fun daily driver (I do have access to another car if this one goes under the knife).

My build would be:

Eagle Forged H-Beam Rods

Supertech Forged Pistons (83.5mm 8.8:1)

Mazda OEM MLS Head Gasket

ARP Hardware all around

ACL bearings

A FM level 1 clutch

Coolant reroute

OEM seals all around

OEM Water and Oil Pumps

And replace the motor mounts while I am there

I have a buddy (who helped me turbo the car) who is a mechanic and has been helping his dad work on and build motors his whole life who could help me with this process but I do not have a engine hoist, or engine stand to do the job. I do not have any ties to any machine shops in the area and I really don’t want to be screwed over.

My main predicament is this: Do I take the leap of pulling the motor and trying to build it with my buddy using forged pistons and rods? If so, are the odds good I can do this without any major machine work? The other option is to keep the OEM pistons and put new rings on them and use forged rods. Or, just try doing just the valve stem seals for now ( the only spooky part about that is shoving rope in the cylinder ).

All advice/criticism is more than welcome. I am a noob after all with no experience in building engines. Thanks for reading through this (if you made it this far LOL) and I apologize for the length

skylinecalvin

iTrader: (2)

in my opinion, if you're not wanting to go above ~250hp, I'd skip the expense of building an engine. Stock engines are cheap and plentiful. If you think it's just the valve seals that needs replacement, pull the head and get it refreshed. Building an engine can get pretty expensive really fast.

DNMakinson

iTrader: (3)

Yes, and a quick search will turn up all the guys that did not get it right the first time, and got to do it again. Additionally, a quick search will show that this very subject (what should go into a build) has already been threaded twice in the last 6 months.

technicalninja

My suggestion is to properly diagnose the oil consumption issue first.
Turbos (especially in-expensive Chinese turbos) can leak oil into both the compressor and turbine housings.
It will **** you off to build a nice motor and it turns out the turbo was the root problem.

Hot compression test, hot leak down test might show indications of trouble with the motor. Check for excessive blow by (remove fill cap- is it puffing like a dragon?)
Removing turbo might show indications of issues with turbo. If the turbine or compressor is drenched with oil you've found your gremlin.
Problems in the compressor housing will put **** tons of oil in the intake track, you may want to remove the intercooler and DRAIN it before before returning to service.
Problems in the turbine housing will drench the exhaust system but the intake side will be normal.
It is normal to have some oil in the intake track but pools of oil are not.
I always look to the turbo first for oil consumption issues...

Both failed oil control rings only(fairly rare) and failed valve stem seals (more common) will NOT be detectable with the compression or leak down test, in fact the excessive oil in the chambers might help the numbers.
All the rings failing or valves not seating properly will show on both comp and leak down.
Oil bypassing at pistons- light smoke all the time.
Oil getting past valve stem seals is more noticeable in high vacuum operation. Getting off throttle, coming to a stop, big burst of smoke leaving stop.
Bad valve stem seals appears to be intermittent smoking to most people.


Diagnosis first, then decide what you want to do.

If the comp and leak down tests are OK and the turbo checks out I might try a set of new valve stem seals before more in-depth surgery.

The motor you specked out is over-kill for your current uses.

If I was building that level of motor one thing I would add to your list is a BP4W head and either a VICS or flat top intake. Better flow and no more HLAs...

c.buffm

This might be the route I end up going. I don't think I have cracked much if any over the 200hp mark so maybe the next step should just be 250. Once I am in a better position maybe then a engine build will be in order. I could do valve seals, head studs, cam seals, and a head gasket and go from there. I will probably do a compression test to ensure it isn't the rings before I pull just the head however.

c.buffm

For sure I want to do it right once. Messing up an attempt an having to redo it would be quite painful.

When searching around for threads I normally just use the google setting for the site, normally I don't scroll the sub categories (I should probably do that more often ). I believe I found the threads you are talking about and I will read through them.

Ideally, I want to get my hands on a second motor and have all the work done on the second motor then just swap it in when the time comes.

c.buffm

Based on the evaluation you gave that pushes me even closer towards valve seals, but my friend has a compression tester I will have to see if I can borrow it to confirm the rings are still a-ok. I haven't been able to have someone behind me look for blue smoke when I am driving but that's on my list of diagnostics. After the smoke dissipates when sitting at a stop, I don't see any more unless I load up the engine.


I checked the compressor side of the turbo and there was a light film on the inside of the coupler leading off of the compressor housing but nothing more throughout the intercooler piping. So I think the compressor side turbo oil seal is fine. Ill have to drop my downpipe and have a look at the exhaust side turbine.

Jumpster74

iTrader: (1)

Aside from the troubleshooting, ill chime in. I was almost in the exact same boat a year back when I disintegrated a rod and piston on my full DIY build I did in college, working a part-time. It was a solid DIY build, just got a bit too "experimental" with NLS on the stock motor. I chose to build a motor with similar goals as yourself instead of throwing in a new 1.8 and staying around the 250 mark, which as you know is already unfairly fun compared to my friends with 5.0s and such.

It's been on jack stands for nearly a year now due to time constraints with school/work and the gradual realization that with each part I purchased, I wanted another as insurance to make the build rock solid. It can easily turn into a money pit. While I'm about to start the car up finally, It is a little disheartening knowing that I could have swapped in a stock motor and had it driving again within a month, and had funds to start my own side business or do other responsible things. I'm by no means saying that you shouldn't go this route, just know exactly what you're getting into, do at minimum a month of reading on here about everything a built motor Miata entails, then establish a set parts list for the full car that you understand and won't deviate from with your set goal in mind.

The choice to go with a built motor is not right or wrong and depends on you and your situation, but I wish Id been a little more aware of what I was getting into when I started a year ago. With that being said, I might be the happiest 21yr old in the world the day I finish breaking the motor in and rev it out to 8000 with allofit

x_25

See, all of this is why I bought a second motor to build and am doing an ebay rods only rebuild. New rings, ball hone, seals, maybe new bearings, hand (well, drill) lap the valves and send it. And doing all this with the current motor in the car (that is on borrowed time because some chuckle head welded the crank sprocket on...)

c.buffm

Thank you very much for your reply from a similar POV! This is great information for me and honestly probably what I needed to hear. I have no experience building an engine so I am sure, like you said, things will come up that I hadn't thought of and the cost of the build will only increase. Congrats on pushing through it and not giving up on the project and doing all of it in college. I definitely plan on doing a lot more reading before I fully crack open a motor (under my own terms hopefully).

Would you mind if I possibly picked your brain a bit sometime down the road regarding the build process as well?

With all that said, I think I am going to do a compression test (when I finally get a hold of my friend with the tester or I cave and buy my own) and most likely refresh the head with new valve seals and a fresh head gasket.

That being said (possibly stupid question): Do I need to have the head surface machined if I haven't had head gasket failure? Or is that something I will just have to inspect with a feeler gauge and a straight edge to determine if it needs to be done?

c.buffm

That is probably going to be the route I go. That way I can take my time learning how to build an engine the right way and not feel any need to rush to get the car back on the road (that is if the oil smoke issue isn't with the rings ).

Jumpster74

iTrader: (1)

I'm definitely not an expert, but have done it once and researched all the tips, tricks, and pitfalls, so feel free to PM me here or on IG anytime! I'd definitely recommend building a second motor instead of building the one in the car. Wish Id dropped a bit extra and gone that route initially, but my old motor was not rebuildable. Sounds like yours is.

As far as machining the head, you see how this becomes a money trap I went ahead and machined mine for ease of mind, but you'd likely be perfectly fine to just check for warpage and use copper spray on install.

Engine wise, this + injectors + good tune is all you really need for ~300hp. Add a 6 speed, and you've got a relativly budget baller setup.

x_25

That's the idea. I am looking to tap out arround 220 wheel torque and 275hp and just have that torque curve be as wide and flat as I can.

Jumpster74

iTrader: (1)

Don't mean to derail the thread, but what turbo?

x_25

Eventual plan is a VF35.

c.buffm

So I pulled my downpipe off today to see if there was any excess oil in it or anything and it seems just like carbon build up:


Picture doesn't really show it but I found out I had an exhaust leak at the top of the flange so I took a flat surface, some sand paper, a straight piece of iron, and a feeler gauge and spent a good hour and half sanding the flange. Its not perfect at all but much better than it was:



My friend is going to come over Friday so I will have compression test data then. HOPEFULLY all is well with the rings and I can just pull the head and refresh it with new valve seals.

Jumpster74

iTrader: (1)

Thanks for sending me down another dynochart rabbit hole haha. Id totally overlooked that turbo due to flange differences

Can't quite tell for sure, but if you were running a composite gasket, those tend to fail right there. Happened to me, has happened to plenty of others. Now that the surfaces are flat for sure, run no gasket, or a single-layer steel if you want. Best of luck with the compression results.

c.buffm

Thanks! Ill post them up as soon as I get em. And when I first did my set up I stupidly ran a composite gasket and had issues with it ever since (after I took the composite gasket out I just stacked single layer steel) but I have a single layer steel now since its flat, but not perfectly flat

DNMakinson

iTrader: (3)

Here is another one to watch I'm not trying to be tacky re: this guy's sorrows. Only saying I have seen this enough times to scare me. Maybe I'm just a whimp. I think it was Pusha that kind of hinted at that once.
DNM

c.buffm

Compression test results are in. Thankfully, looks like its valve stem seals:

Dry:
1: 150 spiked 160-165
2: 150 spiked 160-162
3: 162 spiked 165-170
4: 165 spiked 165-170

Wet:
1: 170
2: 150
3: 165
4: 170

My buddy said he thinks those are okay looking numbers and from what I have read that seems good (no more than a 5% difference on the dry test). He said on his gauge it spiked up and then dropped a little after I stopped cranking. Could this be due to some pressure escaping out of the valve stem seals if they are bad?