So I blew up the miata, what next?

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Louie
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So I blew up the miata, what next?

Postby Louie » Mon Jan 08, 2018 6:03 pm

Background NA 1.6 (91) with a JC45 supercharger (was running 3-4 pounds of boost), no intercooler, 5 speed with 1.8 clutch, torsen LSD (don't know the ratio), and some other crap. This is a track car with full cage and race seat. It was my third track day with it and the rod in #4 decided it didn't want to play with his friends anymore, punched a hole thru the block and got the hell out of there. I had a dyno sheet from the previous owner that said 130 at the wheels, seemed like plenty of fun for the track.

Question is what to do next, I would like to get it ready for the track again. It will be just for HPDEs I don't have time to do any racing.
1. Put another 1.6 in there and keep the SC (maybe get a intercooler)?
2. Put a 1.8 in there? If I do this should I put in a 6 speed as well?
3. I see all these JDM ebay engines, any advantages to those?
4. Get a junkyard engine and have a shop built it up? What exactly is a "built" miata engine.

Where should I source the engine from? If I get a known "good" engine and all I need is a swap I am half tempted to do the work myself. If the engine need some work I would rather pay somebody to do it.

Any shop recommendations? I'm in Los Gatos/Campbell area. I'm not looking to break the bank here, but I understand this won't exactly be cheap. I want to end up with something decent for the track.
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nitewing117
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Re: So I blew up the miata, what next?

Postby nitewing117 » Mon Jan 08, 2018 9:02 pm

I picked up an NB with the same issue (hole through cyl 4 with piston nowhere to be found). I picked up a low mileage 01 engine for ~$850, cleaned up and resurfaced a spare 99 head, cleaned any carbon buildup on the pistons, and threw the engine together. This was pretty much my first time pulling an engine on my own, and overall it was pretty easy.
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Re: So I blew up the miata, what next?

Postby Ian McCloghrie » Wed Jan 10, 2018 3:58 pm

So a few thoughts:

- Putting in a junkyard 1.6 is the easy answer, you'll get exactly what you had before.

- Swapping a 1.6 to a 1.8 is pretty straightforward. A couple hundred bucks in adapter parts from FM and you're basically done. This gets you 15% more displacement, which is 15% more power & torque on top of anything you'll ever do to the motor in the future. It also opens up a lot more options in terms of upgrade parts. You will probably need some extra parts to adapt the blower over, which leads into...

- A JR M45 blower is not the best choice for a track car. They're too small for even a 1.6, they make a lot of heat, can't be intercooled without hurting the idle behaviour, and if you run it hard at the track it's going to cause issues. I wouldn't be surprised if high intake temps triggered detonation which broke the rod on the old motor. Certainly it didn't break from the 130 lb-ft of torque that the JRSC makes, so unless the motor got overrev'd with a bad downshift, there's not many other likely choices. Swapping to a 1.8 will get you halfway from the 90 rwhp of a stock 1.6 to the 130 of your blower. If you sold the M45 and bought a megasquirt and tuned it properly, you could probably get the other 20 hp, if not the torque.

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Twibs415
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Re: So I blew up the miata, what next?

Postby Twibs415 » Thu Jan 11, 2018 9:35 pm

stick a stock 1.6 back in.

Once upon a time i built a m45 1.6 for a customer. we ran a megasquirt, wmi with torco, ported the supercharger and a pulley with a real intake running about 10 psi no intercooler and that did about 165 hp. it was very fun except for the s/c whine that i dislke. but non the less it was pretty reliable. id be willing to bet Ians right that whatever management cant handle the track temps you are seeing.
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Big Lan
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Re: So I blew up the miata, what next?

Postby Big Lan » Fri Jan 12, 2018 5:45 pm

Louie wrote:If I get a known "good" engine and all I need is a swap I am half tempted to do the work myself. If the engine need some work I would rather pay somebody to do it.

If you've got the time, space, and tools to do the swap, I recommend doing it yourself. Direct engine replacements don't come much easier than Miatas as far as quasi-modern cars go. I can understand not wanting to get into internals and such, but just like an engine replacement, engine internals don't come much simpler than B6/BP engines, so given time/tools/space restrictions are in your favor, don't let the idea of a basic rebuild be too intimidating to consider. Basic "stage 0" stuff should be done regardless (TB/WP/CAS O-ring/heater hoses/that stupid plug on the back of the head on a 1.6/coolant hoses on a 1.8/rear main/clutch, etc).
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Louie
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Re: So I blew up the miata, what next?

Postby Louie » Mon Jan 15, 2018 8:38 pm

So I didn't have anything better to do this weekend and took the engine out. Got stuck in a couple of places, overall it wasn't too bad.
Couple of things I noticed that I didn't know about, car had jackson racing headers and there was a knock sensor on the passenger side motor mount. Engine was still full of oil, the holes (3 in total) are all near the top of the block. The M45 supercharger is the first generation one. with the cone nose pulley on it. The sticker on the SC says magnuson, I thought the JR SC was a eaton unit... maybe I have a different SC kit. There was no coolant reroute and the heater core was bypassed, probably things got very hot at the back of the engine.

I still not sure if I should put a 1.6 or a 1.8 in there and where to get it from. Car will only be driven on the track at this point (not even registered anymore). Leaning towards a 1.8 ( I guess I will need a manifold/DP and intake as well) and selling the SC.

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