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Old 07-28-2015, 03:31 PM   #1
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Default Suggestions for 97 motor swap/refresh in So Cal

So let me start off by saying that I have read through several build suggestion threads on here and other forums. I have used the search function as well and, although all of that has been useful, I am looking to get a little more specific with what I am asking. I am looking for input from anyone with experience on the topic and also shop recommendations from So Cal locals.

I have a 97 Miata whos compression numbers are: DRY 160, 166, 172, 175; WET 185, 187, 195, 190. The motor is stock and is the original with approx 140K miles on it. It leaks and consumes oil but not too much, maybe .5 qts every 1K miles.

The car is primarily a track car that I would like to keep street legal. I have no intentions of going FI nor do I want to massage much power out of it. I would just like the car to be as reliable as possible. I plan run about 6 track days per year. I would like to drive the car to local tracks and plan on renting a trailer and towing it to further tracks as well.

I have a small garage that fits the miata but it does not have ample room to do major work on the car. I do work on my own cars and have done a trans swap on an old miata (at a shop I worked at) but I only do brakes, fluids and other smaller jobs at home as I do not have access to the shop anymore. Future bolt on stuff I can handle but I would like a shop that can do all of the major work that is in Orange County CA or somewhere close to that.

My ideas for the car are:
-CA street legal
-Junkyard bottom end/longblock OR rebuild old motor
-Add new aftermarket rods, pistons and ancillary bits for reliability
-Refresh the head (if it is still in good shape)
-Front and rear motor stuff (TB, WP, gaskets, etc.)
-Megasquirt ECU if it can be emissions legal

Not an all inclusive list by any means but it's a start.

I have read Miata engine building notes and [NA] 135whp with stock NA8 long block - MX-5 Miata Forum so I have an idea of what I am looking to do but I would love to hear from you all as to what I can do to make this a reliable and affordable build.

All that being said, the limiting factor is budget. I would like to keep the project below 3K total. Maybe a little more depending on what you all suggest but realistically 3K is my upper limit.

Thanks for any and all input!
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Old 07-28-2015, 06:05 PM   #2
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I'd run that motor until it dies (more). My 97' burns .5 quarts of oil every track day... I'll replace it with a junkyard shortblock when the time comes.

It seems like most people who build their own shortblock run into issues; if you don't want 300whp or to rev super high just use a junkyard motor.


Also- you won't get past CA smog with a megasquirt- after 96' you need to retain full obd2 function which means stock ecu. You could do a PNP megasquirt and swap it back for emissions testing (would take all of 10 minutes to swap). Maybe do an intake and PNP megasquirt, then swap back to pass emissions.
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Old 08-04-2015, 01:52 AM   #3
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What issues have you heard of with rebuilding the motors? I imagine a hone and new internals will go a long way.

The tentative plan is to get aftermarket pistons, rods, harmonic balancer and bearings and use a motor rebuild kit to supplement the rest. I figure that way I can have the car run the stock ECU and beat the **** out of it on track while still having some peace of mind.
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Old 08-04-2015, 12:45 PM   #4
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edit- I'm an idiot, didn't read carefully.

OP, you will probably be fine just as. The wet compression numbers sound fine. The most you might want to do for track duty is make sure there is good airflow through the radiator. You might want to swap in a bigger radiator and do the coolant reroute if you're feeling crazy.

Before I went turbo, I did plenty of track days on my 97 motor that was stock from the flywheel to the air filter. This was in 100+F summer track temps too. Never did any cooling mods until after I went turbo. The only thing that ever overheated was the brake fluid after I parked it once with no cooldown lap.

If your motor dies, just swap in a new stock one from a junkyard. That's it. If you want to be proactive, get the replacement engine now and take your time working on it so it will be in tip-top shape by the time you need it.

Last edited by AlwaysBroken; 08-04-2015 at 02:54 PM.
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Old 08-04-2015, 12:51 PM   #5
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Oh god, I forgot you guys only have 91 octane there. Been so long since I woke up from the CA nightmare.
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Old 08-04-2015, 02:08 PM   #6
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Quote:
Originally Posted by deadohiosky1984 View Post
What issues have you heard of with rebuilding the motors? I imagine a hone and new internals will go a long way.

The tentative plan is to get aftermarket pistons, rods, harmonic balancer and bearings and use a motor rebuild kit to supplement the rest. I figure that way I can have the car run the stock ECU and beat the **** out of it on track while still having some peace of mind.


I just think that at your power level/goals a built motor isn't needed... Look at the 949 rental car- they ran a stock junkyard block with about 160whp.

I just seem to see a lot of built motors develop issues in short time- no offense, but Mazda is way better at putting Mazda motors together than any of us are. A stock block can endure a lot of track abuse at low power levels. Just make sure the coolant and oil stay cool.
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