Our third build receiving its new heart.


Question: Why, with the newer GM “LSx” engines out there, would someone want to build a Ford 5.0 Miata?

Answer: There are several reasons why the “old technology” of the Ford 5.0 is an equal, or possibly even superior choice over the GM LSx series engines. They are:

1. Cost

2. Emission Regulations

3. Established Knowledge Base

#1. Let’s start first with “Cost”. A Miata firm based in the center of the country just offered a service by which they will build you an LSx Miata for “only” $29,995 + your Miata! This only covers installing the driveline. Here at MRM we can build a complete turn-key Ford V8 Miata for under $25,000 including not only a completely  hand-built engine and driveline but an upgraded custom suspension, upgraded brakes, upgraded wheels and tires and the added safety of a rollbar. Oh, and the cost of the Miata IS INCLUDED! “But wait”, you say, “doesn’t a LSx make more horsepower?” That is true, however, with a 331 c.i. bottom end a lowly Ford 302 can get pretty close to the horse power of an LSx for a fraction of the budget.

#2. Many states have become increasingly strict with their emissions regulations, particularly when it comes to 1996 and newer “OBDII” vehicles. In many states it is simply illegal to swap a non-stock driveline, such as a LSx, into your Miata. However, in most of those states older “OBDI” vehicles, or those predating 1996, are only required to emit pollution below a certain limit set for that car and that year. This allows you to swap any driveline into these cars, given that the new driveline can be as clean or cleaner than the old one and has the same type of emissions equipment (cats, EGR, etc.). It’s a little know fact that early Miatas, especially the 1.6 liter years, are actually rather dirty vehicles when it comes to what they release out of their tailpipes. It is very easy, almost scary easy, to get a rebuilt Ford 5.0 from the early ‘90’s to run cleaner than the 4-cylinder that the engine is replacing. We’ve been 100% successful with every emissions test we’ve faced so far here at MRM.

#3. the Ford “Windsor” V8 has been in continual use since it’s debut in 1962. It’s found a home in the engine bays of Shelby Cobras, the first Mustangs, Indy racers and even pickups. Ford produced a gargantuan amount of variations and parts for these engines, all of which can be combined to create a very potent package for a very low cost. If Ford’s parts bin isn’t good enough for you the aftermarket industry surrounding this engine has existed for almost 5 decades and can take the engine well into the 500 horsepower range.


Question:Can I buy a complete car from MRM or do you only sell parts?

Answer:Yes! We do sell completed conversions as well.

We usually have at least one car ether in the process of being built or for sale. As this is a “hobby business “ for us we don’t have a selection of cars for sale, however the currently completed one is always for sale.

Question: I like my Miata and don’t want to part with it to buy a completed V8. Would you be willing to convert it for me?

Answer: Hmmmm, Read Below…

We’ve been approached about this many times and have wrestled with the possibility of doing this. The problem is liability unfortunately. As stated before, MRM is a “hobby business” of ours, we both have full-time teaching professions that provide our main livelihood. In order to do the type of work related to building a conversion to someone else’s car and still allow our wives able to sleep at night we would have to take out such a large insurance policy that the whole thing would not work out at our current volume. That said, we’ve been discussing some ways “around” this that would leave us safe legally and still allow us to convert customer’s cars for them. One of these possibilities is for us to buy your car from you for fair market value before the build and then give you primary purchase rights for a limited time after the build. Basically, we would buy your car from you as our next donor and you would be the only one we would sell it to upon its completion for a limited amount of time (a month). This would allow you the ability to “back out” should you decide not to buy the car and us the ability to sell it when done. We’re also discussing other plans, if you are interested contact us and let us know your thoughts.



We built this LE MRM 306 conversion over the summer of 2008. A year later it received a set of AFR heads and an an Edelbrock intake and now makes 280 rwhp!

This is an example of the labeling we provide on our MRM Conversion harness.

McCully Racing Motors

Allentown/Barto, PA

To Order email or call the following:


E-mail: mccullyracingmotors@gmail.com


Phone: 267.254.6687






Who is MRM?

McCully Racing Motors

Because two heads are ALWAYS better than one.




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