1991 Mazda Miata Turbo 1.8 swap $2000 Challenge car

I dont expect anyone to be excited as its just another miata, but i do genuinely enjoy these cars as i have had 3 of them now. 

I have wanted another to have as an autocross/roadcourse car but i am also cheap, then along came this miata. 

It did run (barely) and it had a handful of fairly decent parts on it. These included:

Speedy Efi Stand alone ecu

Quick release steering wheel

Coil overs (of the cheapest non dampening adjustable variety)

A turbo kit

Wide band, boost, and coolant guages

A 255 walbro pump installed

And upon closer inspection, a 94/95 1.8 motor which was swapped in fabor of the stock 1.6

Ive had the car for about 2 weeks and already done a lot to it, so ill make a bunch of post here for anyone who may be interested. I received a good education on the details of the speedy efi and the inner workings of speediuno and the pros and cons of the set up. Many more cons than pros, but hey, you work with what you got. 

The car was listed for 2200 as it ran like a harley and im pretty sure it was on 2 cylinders, as well as no title, which i may have acquired. It was also listed as a 1.6 but to be fair i did not know how to tell the motors apart until after i got it (raised lettering on the valve cover indicated it was a 1.8, this was verified when i pulled the head and saw it was a bp05, which is a 94/95 1.8 motor). After showing up withba trailer and pleading my case of using the car for the event, we agreed to $1400. And in the trunk there was a small box of extra parts such as a stock ecu, a few new parts such as adjustable sway bar end links, a few random gaskets, power steering pump and lines, etc. 

I'm interested in what you do with that Speeduino and how it works out for you.  I've been thinking about getting one just to play with on either my stock 1.8 NA or hacked-together EJ.

In reply to tyronejk :

Its not terrible. But it has been referred to by my tuning buddy as the walmart ecu lol. You get what you pay for i guess. I will give a spoiler alert and say they car is actually running pretty good now. Early speedy efi units had processing speed issues at higher rpms. But have since said to be fixed. I have no way of knowing how old this thing is. For what it is on stock injectors its making about 10psi and probably making 200whp. I have some rx8 injectors i might throw in and make about 240whp. Just want to finish up a bunch of little stuff first. 

That looks like a great starting point. Congrats on the purchase!

The exhaust through the hood should be entertaining 

The first order of business was to dig into the motor mechanically to make sure nothing major was wrong. Upon initial inspection it was realized the timing was off by 1 tooth. Nothing hig but worth an inspection.

Pulled the head. Cleaned everything up and reassembled. Also ordered a new pig tail for the cam angle sensor as the one on the car was the worst wiring ive ever seen. 

Once it was all back together the car actually ran on all 4 cylinders at idle so there showed signs of promise. 

Here is what the car currently looks like as of today. This is after going through the suspension and brakes, putting new rubber on the new to me wheels, changing the oil etc..

Ill upload a lot more pictures of progress once i get to my laptop. 

Note* the hard top is not challenge budgwt friendly. I bought that because i love those more than the convertible. The soft top is still installed. 

I still need to upload all of the other progress pics ive taken but i am still too busy to upload the pics to my comouter and upload them. 

Today we took the harddog roll bar i picked up from palm coast and installed in on the car. To do so we removed the racing beat style bar the car came with and listed it for sale to offset the massive cost of this roll bar. 

Today was dedicated to removing the up pipe that came out of the engine bay and make a downpipe out of some shrapnel i have on my shelves. Was the christening of the miller welder as well!

By the end of the day the downpipe was made and the hood was installed. Starting to look like a respectable vehicle again, although it is 3 different colors. 

The miata exceeded all of my expectations today on the dyno. Had a few minor hiccups like a valve cover leak and the coolant overflow cracking. But other than that it was good. The big one was the wastegate boost leak which was corrected. Once it was the car made over 250whp and 250wtq!!!!

Its an absolute riot to drive. Looking to maybe take it to the drag strip next week weather permitting.

You saved its life!

That's a lot of fun for so little money! Should be a solid contender at the Challenge.

We will see. Everyone knows the challenge can really show a cars true colors cia the torture test. But we really pushed it on the dyno today. I think the valve cover oil leak was caused by boost getting back in the head via the pcv valve. I will re route the catch can so boost stays out of the head via a potentially failing pcv. 

Here are some pictures from when i had the head off and decided to perform the coolant re route modification. Companies sell these as kits but they can range from $130 to $300+. This was free as i just used scrap metal, spare hoses, and parts from the car, just moving them to a different location. 

This is how the coolant flows out of the head from the factory. Out of this neck and into the thermostat housing and into the radiator. There are also a few coolant lines that run through the throttle body on the way to the oil cooler but those were removed. Now the smaller lines just go straight to and from the oil cooler. 

To do the re route you remove that neck and cap it off and move the new outlet to radiator to the back of the head. This ensures coolant flows through the entirety of the head and has been shown to lower coolant temps significantly. Ive seen/read about 12 degrees. In this instance i used a peice of scrap diamond plate metal i had. The smooth surface is mated to the head with some.gasket sealer.

The original thermostat housing cover that was on the front of the motor on the neck was moved to the rear and the temp sensor gets moved to a port that is capped on the head from the factory.

The finished product and you will notice the coolant line is coming from behind the head and all the way around to the radiator. And that small spool peice? That is a section from an old shop vac that doesnt work anymore. Its very thick plastic and survived 2 hours on the dyno so i think it will be fine. 

More upgrades/work that was done was replacing the raggedy old tan top with a great condition black top. 

This new to me top came from someone who has raced their miata since they bought it. It was removed for a hard top and placed in the attic and never touched again. Im $85 into it. 

It made a huge difference and now i can drive and park it outside in the rain.

Was this engine originally designed for FWD transverse use?

Many (most?) FWD transverse engines run their cooling plumbing at the "rear" of the engine.

Maybe the more efficient "rear" cooling is by design.

In reply to 78CobraII :

I dont think it was ever intended for Fwd applications. I could be wrong though.

Todays massive victory was realizing that the car had a torsen differential in it. I wasn't sure how to tell the difference i just noticed that it had a pinion damper on it, which is a sign of a 1.8 diff. This means it had to be swapped in, given that the car is a 91 NA6. Assuming they wouldn't swap an open in i did a burnout and we have a good ole || mark. 

78CobraII said:

Was this engine originally designed for FWD transverse use?

Many (most?) FWD transverse engines run their cooling plumbing at the "rear" of the engine.

Maybe the more efficient "rear" cooling is by design.

Yes it's the BP engine from the FWD Mazda 3 series and Ford Escort.

In reply to Stampie :

Whattttt!? Thats awesome. Learn something new everyday!

Took this monster on the street today with my father in law and he giggled the whole time. Even turned down to 210hp its a riot. Will probably turn it up to 225 for the majority of its daily duty and then 250hp for the drag portion. What a blast. 

In reply to 78CobraII 

yes the 1.8 Mazda engine was originally fwd and was modified for the miata....... that's why the water enters and basically exits the same place .   #4 cylinder always runs way hotter 

In reply to surfshibby07 :

Don't know who or what is uglier lol

In reply to Toot :

I think he's got more gray in his beard than me.

I have 1 gray hair for every issue with this miata lol