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Discussion Starter #1
Hey guys! Just wanted to come in and introduce myself, I'm about to start an LE5 swap on my Miata. I've got an engine (pretty much a long block) from an 08 G5 with about 101k mi. I joined this forum, mainly for technical resources. I don't know a whole lot about these engines so I am here to learn.

My next immediate step is to fully dress up the motor with the needed accessories/sensors etc.

At this point I am searching for a factory shop manual. I need to inventory what sensors and stuff I need to get still for the engine. Then this should hopefully make the harness part of the swap a little easier.

Thanks!

 

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Did you get the ECM out of that G5?
 

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I've always thought this would be a great combination.

I'm assuming there aren't any real engine differences between the LE5 in the Cobalt/G5s compared to the Kappa cars (which are RWD), other than the trans?
 

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There are Miatas with LS1 so the Ecotec is certainly possible.

 

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Discussion Starter #7 (Edited)
Oops, the ECM and harness is actually from an 06 HHR. I was able to get the FSM for the harness and engine part.

what made you go with this swap? I ask because I had a Miata and was teasing with the thought of the LSJ or LNF.
To me there were V8, V6, Ecotec and Turbo as options to the proverbial 200whp Miata final result. Many agree, that’s the sweet spot for them, but IDK, I’ve never driven one lol. I’ve only had experience with an LS3 Miata with nearly 500 to the wheel for a couple autocross events. Anyway, I wanted 200whp, reliability and instantaneous power delivery.

V8= Mainly was a very expensive, long and arduous undertaking, especially the LS platform. I’d lose the free revving/light engine feeling and the awesome 5speed that the Miata has
Turbo= Cheapest route, with a small enough turbo, turbo lag can be mitigated. Though after riding in one, it still felt like I was waiting for power to hit. Plus, I’d always have worries of blowing up or I’ll have tuning issues etc.

J35 V6= This was the route I was going to take. The kit itself is nearly 4k, and there are some issues that I was just going to live with; hood clearance/oil pan sits really low beneath the subframe/lately they’ve been having weld joint issues and harder to build power in the future.

Ecotec= Then there’s this. The kit itself was 2k, and many were finishing a basic build for under 4k (less than just the kit for the JV6 and not much more than a properly done turbo setup sans built motor). On paper, this is a much easier swap; just a change of engine mounts and trans adapter. It sits in the engine bay with very mild hood cutting (just on the inside part). With a good tune, I’ll be at around 190 whp, with a very linear delivery and low end torque. The engine is dirt cheap and can be found with low mileage (mine was $100). It’ll be like driving a Malibu daily driver type of reliability. Plus the kit itself is born out of racing pedigree.

As for the FI engines, here’s a quote from the Ecotec Miata website:

The factory forced induction engines use a unique 8 bolt crankshaft. This would require us to make a custom flywheel, which adds considerable cost to the swap. The second issue is that either of these engines will destroy the factory Miata transmission owing to the fact that the Ecotec generates tremendous torque when boosted. And finally, the forced induction engines also carry a water to oil heat exchanger on the rear of the engine. This interferes with the frame 'shelf' at the rear of the engine bay, and also interferes with the Miata transmission bell housing. To use one of the factory boosted engines (LSJ, LNF, etc) you would have to use a different transmission, as well as notching the frame at the rear as the V8 swaps do. See our other FAQ topic for options on stronger transmissions.
Doesn’t sound too bad, but still more work. The turbo take offs from FI motors will fit right on the LE5, so boost will likely be in the near future.

I've always thought this would be a great combination. I'm assuming there aren't any real engine differences between the LE5 in the Cobalt/G5s compared to the Kappa cars (which are RWD), other than the trans?
I think so too. Nothing but good reviews. From my understanding all the RWD applications are just converted FWD engines. So I’d assume they’re the same.
There are Miatas with LS1 so the Ecotec is certainly possible.
Yessir, I drove an LS3 Miata for a couple autocross events, they put the car near supercar performance.
 
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