Rebuild Or New Engine
 

As I'm working through my build, I began to think about the parts I want and will be purchasing and it's getting expensive.. The thing is, these parts are all non engine related which is where the problem comes in.

I've been neglecting rebuilding my engine from the start of my build but once I'm ready to put it back in, I want it in top shape.

Specs on Engine:

1.6 Liter Engine w/ 36,000 miles

Compression Test

Dry Test
Cylinder 1: 175 PSI
Cylinder 2: 35 PSI
Cylinder 3: 170 PSI
Cylinder 4: 165 PSI

Wet Test
Cylinder 1: 190 PSI
Cylinder 2: 43 PSI
Cylinder 3: 195 PSI
Cylinder 4: 180 PSI

Now my options are to rebuild this stock engine, which was my initial plan at first because of low mileage and it being a 1.6, or I can purchase a used engine for no more than $600.

If I do go with rebuilding the engine, will it be that expensive at first to just correct the piston rings along with little replacing gastkets, seals, clean up, etc?

https://www.miataturbo.net/attachmen...ine=1322769289
DSC_0533 by Derrick Michel, on Flickr


Also keep in mind I'll be running a turbo in the future but after I'm finished with the interior and exterior.

If you are going into the engine and do not do rods I will ban you.

If your engine longnose or shortnose?

If it was a shortnose I would just replace. If it was long nose I would do rods, rings, and gaskets. Also drill and tap the oil pan while the engine is out.

Looks like a short nose based on the crank pulley. I'd replace it.

Well it's a 1990 with the original engine so it is a shortnose crank.

Shuiend once I'm ready for turbo, rods And much more will be in the works

Since it is a short nose I would suggest upgrading to at least a long nose, if not a 1.8l motor.

I think you might be able to just swap a long nose crank into your block. I am not positive, but I believe they fit fine. You could probably find one for $100-150 depending on where you look.

As for rods now. If your budget is around $600 you should be able to fit a new crank, rings, seals, and rods for around that. If you do rods now as long as you have a good tune will never need to go back into the engine unless you begin heavily tracking the car. For the $300 it costs for rods in the long run will be worth every penny.

I really really really like the way that sounds. I'll be doing some research on whether I can or cannot replace my crank. Hopefully I can because the low mileage and the 1.6 is whats attracting me.

Thanks guys!

You should be able to find the crank assembly separate or just get a shortblock for around the same price. I have a built 1.6 on a short nose and I'm not even going to bother with working with the block, I'm going to get a untouched long nose block to work with. There was one on here going for 80 dollars and it was still a running motor. B6 fo lyfe!

Here is a link to the miata "crank guide" Everything you need to know is here.
http://www.miata.net/garage/crankshaft.html

Also, you NEED to make room in the budget for rods. Get them done now and you will be set forever.

Whoa, let's slow down a bit.

Your compression test results clearly show that you need to rebuild your head. Your block/pistons are probably just fine.

BTW, I've got a short nose. It's at 190K miles and has never been out of the car. It did have pulley wobble that I corrected using the Loctite method at 150K. Of the 40K since the Loctite fix, 10K have been turboed (10psi). It runs great.

What I'm trying to say is that you probably don't NEED to do anything to your engine other than a head rebuild and basic maintenance (basic maintenance = pre-emptive Loctite fix, water pump, timing belt, all new coolant hoses and vacuum tubing).

There is a risk that there is a problem with the block and pistons, but it is remote. When you pull your head, you can rotate the crank and get a pretty good look at the cylinder walls. That should be your guide. With the miles on that engine, I suspect it will be pretty much perfect.

Hornetball, I've read about the loctite method and wanted to go that route and I'm still considering it but just wanted to be worry-free being that I will be turboing later down the line. I'll read on this some more and as far as my maintains goes as far as hoses, water pump, timing belt, etc have been taken care of when I first purchased the car at 33,000.

Thanks for the feedback

OK, let me put it more simply.

Pull your head and look at your cylinder walls. You've been operating under the premise that your rings are shot or cylinders scored. Most likely, they are not.