We’ve been keeping a close eye on V-8 Miata swaps [click for large gallery of images], with an eye towards possibly building one ourselves. That means very closely looking over Miata V-8 swaps at car shows, as well as reading all the literature and examples on websites we can find. Here’s an interesting post over on LS1Tech.com (active thread this week), with images of a LS3 swap performed by Flying Miata themselves using their extensive array of swap parts and kits. The car is now in Canada, being tuned by Champion Motors.
The dyno numbers are very good:
But what interests us most is how clean the swap is. And particularly the air intake:
Notice the Corvette-derived air intake tube, feeding from a filter mounted ahead of the radiator. Most V-8 Miata swaps end up with an air filter directly behind the radiator or off to one side due to space constraints under the hood – which would feed the engine hot air from the radiator or the headers. Very inefficient, and a tuning and drivability issue. Here are two examples.
The following Ford swap (unusually, a 94-95 Mustang/T-Bird swap, instead of the much more common 86-93 “T”-manifold and engine swap as in the original Monster Miata) is typical of Ford swaps in that the air filter ends up behind the headlamp to the left. Presumably it can pick up cold air here and it isn’t terrible. But it’s still a problem when moving slow, and it will be a problem in wet weather. The filter would be full of water in a rain storm. The very appealing V-8 Miata with the Toyota 1UZ-FE swap we encountered also had the same layout.
And here’s the worst location: right behind the radiator and too close to the right exhaust header. In real-world use, when moving slowly thru traffic or stopped, this engine will be breathing very hot air.
And real-world is our main interest here for a V-8 Miata swap. While we wouldn’t be driving it very often in daily use, we would be driving it on back-country drives here in Texas. These types of drives are tough on the car. An air filter very much lower than the bumper level will pick up water from the multiple water crossings we encounter on some of our favorite routes, and the typically low exhaust systems forced by Miata space constraints would be constantly dragging when on rough roads where suspension travel and ground clearance is crucial. Those are the two issues that must be resolved for us before going further. The adapted Corvette intake tube solves the first issue. Now we are going to pay more attention to exhaust systems as we encounter further examples.