I bought a 2004 base RX8 about 2 years ago as a more or less daily driver and all around fun vehicle. It had 93K on it when I purchased it and had a fair number of door dings and general cosmetic issues but it has been fun to drive. I will call this the blue car and it now has 106K miles. About a year ago I saw an add for a 2004 Touring RX8 being parted out locally. I wanted to get an engine and battery box cover so I went to buy those and ended up buying the whole vehicle. It is loaded and in excellent cosmetic condition but has 120K miles on it. Red with a red leather interior and the previous owner had only parted out a few parts which I have been collecting over time. He bought it from a girl that he thought flooded it thinking he would make a killing on it but he couldn't get it started.

Now a year later I finally get some time to look at it. I drained the gas and put a new fuel pump in it that I had from the blue car when I had the recall done. I pulled the spark plugs (which were brand new) and turned it over to clear it out. Some obviously old gas came out of the rotors but when I checked the plugs there was no spark at all. Put in the set of coils and wires that I bought for the blue cars tune up and got lots of spark. I had hope that maybe this engine might actually run.

A little playing around and I was able to get the engine to run. It starts right up and will idle until it gets warm and then it wont idle at all. I cleaned the ESS and the MAF but just couldn't keep it idling. The cat is gutted so that isn't the issue so I finally got it warmed up and tested the compression. Front Rotor - 66/69/71 at 250RPM and Rear Rotor 78/75/78 at 250RPM. From what I have read, that is toast. Strange that it starts right up cold or hot, just wont stay running and those numbers don't look good.

When I bought the Red car it was with the thought that I might swap the motor from the blue car and then part out it out. I also contemplated doing an LS Swap. Now that I know for sure the engine is no good, I have a decision to make.

1) Sell the blue car (might bring $2000 around here) and have the Red car engine rebuilt. Sounds like that will be about $4K-$5K so I have an original Mazda with new rebuild motor for $2K - $3K after selling blue car.
2) Do a compression test on the blue car and if it is good enough to mess with, swap it into the red car and part out the blue, Would likely get $800-$1000 parting out over time and have the red car with old engine but no money out of pocket.
3) Sell blue car and the engine out of red car and do an LS Swap. likely to have $10K into that after selling the car and motor.

Well, that is my story. I don't have any friends that know anything about cars anymore that I can have a beer with and talk about it. Any thoughts?

 

I’ll start by saying: don’t ruin a perfectly good RX-8 by doing an LS swap. Rebuild, do whatever it takes and enjoy a nice running Wankel

 

Well, it is his car, so he can do whatever he wants with it.

I personally will never do an LS swap to mine(I'd just buy a Corvette and call it a day), but heh, someone wants to do it, whatever.

Just note that LS swap is still not that cheap. It needs at the very least $10~15k, more if you want A/C and ABS. Financially, a C5/early LS2 C6 Corvette will make a lot more sense.

 

I personally don't like LS swaps.
To me the heart of an RX8 is the rotary, the 8 is designed around it.
Without it, it's something else.

You'll likely spend more time and money doing an LS swap than just dropping a reman into one of them.

Do a comp test in the one that's drivable.
If you don't have hot start issues yet I'd guess you have at least a year before you'll need to replace it.
(Experience)

The remans are much better now, and a better option than rebuilding, imo.
You already have a core, so you can drop a reman into one of them, cobble together all the best bits into one, and if you're still running, flip the lesser one.
If you're lucky, you'll get a nearly new engine into a decent 8 with not much of a loss financially, but it'll be a lot of work.

Only you can decide if it's worth it.

 

There is also the option of turbocharging if you want more power, but if you have to think about budget, you are not ready for a swap financially.

The cheapest option is always going to be a reman since the only thing you have to change is the engine, maybe clutch and the coolant lines if they are getting old, but nothing major. With a swap, there are a lot more components that have to be replaced, either for fitment or just to handle more power.