Frequently Asked Questions
Q: Why convert a perfectly good car?
A: You like the sound of a "throaty" high performance V8. You like the idea of a small, lightweight convertible with all the modern convenience features -- but ripping performance that is equal to or even better than most exotic cars. You need some excitement in your life.
Q: How much weight does the V8 conversion (engine, transmission and differential) add to the car?
A: Approximately 250 lbs. total. A GM LS1 with a T56 weighs close to the same as a Ford 5.0 with a T5 5 speed.
Q: What is the weight distribution after the conversion?
A: With a half tank of gas, 53/47.
Q: How is the overall handling of the car affected?
A: The car maintains very good handling. The Miata loves the V8. On acceleration, the rear end squats and holds firm while the front is still nimble & sensitive. After a short drive, the car quickly becomes predictable. Of course the car can get out of shape fast with too much throttle; too much power is a problem I can live with. Very driftable!
Q: What is involved in the conversion?
A: The Miata drive train, cooling system and unnecessary parts and wiring are removed. The engine compartment is thoroughly cleaned. Some cutting and welding followed by detail painting of the modifications. The suspension gets a make over along with changing the differential and half-shafts. Modifications to the wiring follow. Newly detailed engine and drive train are installed. Pre-start engine checklist completed. Exhaust and air-conditioning shop. Pre-test drive checklist completed. A short drive and initial post-drive inspection completed. 200 miles of city and highway performance driving, final inspection completed and the car is ready for its new life.
Q: Do all the instruments work correctly?
A: Yes. The Miata has a slight voltage difference than the Ford and LS, which requires calibrating for the gauges to read correctly. We do this with resistors for the gauges and conversion boxes for the speedometer and tachometer on NB's (1999-2005).
Q: What exhaust manifold do you use?
A: Custom 1 5/8" tubular headers, thermal coated inside & out for the
Ford 5.0. GM stock G8 manifolds for the LS.
Q: What about emissions?
A: The Ford V8 Miata’s that have passed California’s strict but straightforward engine change requirements consist of: Stock 5.0 EFI engine with all the original (Ford) factory emission equipment intact & operating and the engine being the same year or newer than the project car. We're currently building a 2003 LS2 Miata with all the emission equipment that came on the GTO. Stay tuned as this will be the first LS Miata we have built for CA.
Q: How is the clutch pedal pressure?
A: It is soft to medium. The clutch master cylinder we use is exactly the right size. Any bigger and the pedal pressure would be to firm. Any smaller wouldn’t completely disengage.
Q: What is the approximate top speed of a "stock V8 Miata?"
A: The fastest I have driven a "stock" V8 Miata is 150 mph on a closed course. The temperature was 75°, no wind and 800 ft. altitude. The top was down and the car was getting light. I backed out. One of the “Mega Monsters” reported in at 175 mph during the closed course Silver State race in Nevada. The car was supercharged and had around 400 hp. The final drive ratio was 3.27:1. The 5th speed overdrive ratio was .80 The top was up and the car was border line airborne. The driver was Richard Holdner, a photo journalist who has "huevos grande".
Q: What are the basic steps in getting a V8 Monster Miata built?
A: Details of conversion and cost agreed in writing. Getting your Miata to Monster Miata in San Marcos, CA. If needed we can suggest several transport companies that will pamper your car. 50% of the conversion cost is due upon start and the remaining 50% due upon completion.
Q: What skill level does one need to do the conversion?
A: Average knowledge of automotive tools and parts changing. Everything else is in the manual with additional help just a phone call or email away. No fabrication is required.
Q: What do I need to send to Monster Miata for the "Do it yourself kit"?
A: For a Ford Swap we will need your front K member/sub frame, a Ford 5.0 oil pan and the rear Miata hubs. For an LS swap, just the hubs.
Q: Aside from the Ford 5.0, will any other engines work with your kit?
A: Any Ford 289, 302 or 5.0 will work. However the kit is modeled around the Fox bodied 5.0 H.O Mustang EFI engine as these engines have the correct accessory brackets and the best all around performance and convenience. We now have a conversion kit for the GM LS engine with a 6 speed or automatic. The front subframe is built here at Monster. Chromolly semi monocoque construction. Weighs in at 33 lbs.
Q: What year Miata’s are the best to convert?
A: My preference is the earlier years 1990-94 as they are less expensive and plentiful. Most customers convert early cars but the kit works for all models up to 2005. California engine swap rules require that you use the same year engine or newer. The Mustang GT 5.0 was available until 1995.
Q: What transmissions do you recommend for the conversion?
A: My trans of choice is the Tremec T5 World Class. More useable first gear-2.95:1 as opposed to the stock Mustang 3.35. The stock Mustang T5 works fine but coupled with a 3.27 differential gear you're not in that gear for long. You will find yourself doing 2nd gear starts often which works fine.The Tremec T-56 six speed is another great transmission but a bit overkill for a 2600 pound car. I have one in my shop car. Weighs more but you get another racing gear. I wouldn't recommend it unless you get a good deal or just have to have a six speed. The Tremec TKO series is also good for high HP though I have not heard of a T-5 WC failing on a Monster Miata ever. Here is some good reading:
Q: Your conversion kit uses a 7.5” Ford differential. Can I use an an 8.8" Ford differential instead?
A: We have used the 8.8” Ford differential with good results. However there are a few differences in that the 8.8” requires a mount to be welded in place. In addition, the 8.8” outboard CV’s are larger and don’t clear the stock shock mounting location so the 7.5” CV axles are still used.