RX-8 ENGINE-CONVERSION GUIDE
It may have been the successor to the wildly popular Mazda RX-7, but, unfortunately for the RX-8, it never received that same kind of glory. Many critics slammed it for its beefier appearance, which was in part designed as a by-product of the elongated MX-5 chassis used to test the 13B-MSP (Renesis) heart that it would eventually receive. The car, featuring rear suicide doors, originally appeared as the RX-Evolv concept after catching the attention of the higher-ups at Mazda. And that new rotary power plant didn’t do its public opinion any favours either, with almost all examples being sent to hell thanks to a handful of serious issues presenting between 80,000km and 120,000km. Apex seals were notorious for leaving the building prematurely (even more so than normal), and they have proved a hard nut to crack when it comes to pushing any kind of power out of them, especially compared with the ease found in previous generations.
And, as the years have pushed on, an abundance of the cars have been left sitting around with blown motors as a result, despite the chassis itself being quite decent, and they can be had for dirt cheap! So, it comes as no surprise that people are starting to catch on to them as the perfect base for engine conversions. If you’re looking to pull trigger on a conversion of your own, we’ve pooled together all the details that you’ll want to consider about the chassis itself, the challenges you might face, and we’ll give you the inside word from those that have completed a few of the more popular conversions themselves.
The first-generation RX-8 (chassis codes SE3P and JM1FE) was produced through model years 2003–2008. Designed by Ikuo Maeda, the son of Matasaburo Maeda, the lead designer on the Series 1 RX-7, it was offered solely in a front-midengine, rear-wheel-drive four-door, four-seater quad-coupe configuration. Mazda claims a near 50:50 balance split and a low polar moment of inertia, making them easier to turn in, which was achieved by mounting the 13B-MSP behind the front towers and the petrol tank in front of the rears. The shell is constructed from steel, while most of the body panels are alloy and plastic, and the manual option makes use of a carbon-fibre driveshaft that dropped weight and lowered the rotational mass, allowing the high-revving tanga to spin.
The front suspension set-up offers double wishbone, while down back you’ll find multi-link rear, which also offers a torquesensing conical limited-slip diff (LSD). Its design and typical Mazda engineering make for solid driving dynamics straight out the box that can be easily improved on with truckloads of aftermarket support.
Looks-wise, the RX-8 is most notable for its rear-hinged ‘freestyle’ rear doors, similar to suicide doors, that open up to the rear seats. There is no B-pillar between the front and rear doors, making use of the leading edge on the rears to act as a virtual pillar for rigidity. Unlike its predecessor, the FD RX-7, the RX-8 is longer, wider, taller, and heavier, which can be seen in the curvier body panelling. MAZDA RX-8 (GEN ONE) YEARS: 2003–2008 WHEELBASE: 2703mm WEIGHT: 1309kg (manual) CONFIGURATION: Front-engined, rear-wheel drive ENGINE OPTIONS: 13B-MSP Renesis POWER: 173kW (six-speed manual), 141kW (five-speed manual), 158kW (six-speed auto)
Midway through the RX-8’s production life, in 2008, Mazda undertook a refresh that saw the structural rigidity improved through additional reinforcements. The team added a trapezoidal shock-tower brace and strengthened the front towers to reduce the flex that occurred in the earlier models. The rear geometry was also dealt to in the name of better handling, and the finaldrive-gear ratio on manual transmission cars was shortened from 4.444 to 4.777, so that it would get off the line quicker.
Mazda took the opportunity to modernize the exterior design slightly as well, giving the bumpers more aggression and changing out the lights at both ends for sharper examples. The overall length increased from 4425mm to 4470mm, while weight took a hit, with a 64kg increase in the manual option. A larger exhaust was added, and a revised version of the Renesis heart saw a third oil-injection port in each rotor housing to feed oil to the middle of the rotor. MAZDA RX-8 (GEN TWO) YEARS: 2009–2012 WHEELBASE: 2,703mm WEIGHT: 1373 kg (manual) CONFIGURATION: Front-engined, rear-wheel drive ENGINE OPTIONS: 13B-MSP Renesis II POWER: 173kW (six-speed manual), 141kW (five-speed manual), 158kW (six-speed auto)