Trackspeed Engineering Naturally Aspirated Built Motor
With naturally aspirated track car builds becoming more and more popular, we've decided to put together an engine package that is geared towards track day addicts and racers alike. We've put a major emphasis on reliability, longevity, and ease of use with these motors - the goal is to build a motor that can be revved harder than a factory engine safely, will make slightly more power, and will last just as long or longer than a junkyard motor under track conditions.
If you're familiar with our Forced Induction longblocks, you'll notice a lot of similarity and a few key differences in our latest motor's parts list.
-OEM Mazda 10:1 +0.50mm oversize piston
-Carrillo Pro-A connecting rods
-Carrillo Rod Bolts
-ACL Race main, rod, and thrust bearings
-ARP head studs
-ARP main studs
-Boundary Engineering "Street/Strip" oil pump with billet gears
-Supertech Viton valve seals
-Gates Racing timing belt
-OEM Mazda seals and gaskets
-Full cylinder head refresh (hot tank, new manganese/bronze valve guides, 3-angle valve job, pressure test, and resurface)
-Supertech valve springs
-Supertech titanium retainers
Instead of opting for a high-compression forged slug, we've decided to stick with an OEM Mazda piston for a few reasons. Keeping the compression down in the 10:1 range sacrifices a couple of ponies, but it allows the safe use of 91-octane pump gas without excessive timing retard. A factory piston also allows us to run significantly tighter cylinder wall clearances than we typically run with a Supertech forged piston, which means that our Naturally Aspirated motors will last just as long as a factory motor will.
Instead of sticking with the standard H-beam selection, we've opted to move up range a bit and go with Carrillo's Pro-A connecting rod. With H-beam rods weighing in at ~530g, the Pro-As are a massive improvement, weighing just 440g each. Shaving 8/10ths of a pound out of the reciprocating mass of the engine significantly reduces the load on the bearings, which will assist in both high-RPM use and long-term reliability.
Our Forced Induction motors use a factory solid-lifter valvetrain setup in order to reduce costs, but with a naturally aspirated motor we felt that it was necessary to make a basic upgrade. Supertech's single-spring kit uses a stiffer valve spring and a titanium retainer to reduce valvetrain weight and allow for high RPM use, even with VVT heads. Supetech's shim-under-bucket cam followers are also available as an added option for those of you who are looking to add aftermarket camshafts and really spin the motor hard.
The rest of the engine is exactly what you would get in our Forced Induction bottom end. ACL Race engine bearings provide exceptional support and feature a nickel sub-layer which will show up in oil analysis testing, allowing the end user to know exactly when the engine needs to be removed and serviced. Boundary Engineering's street/strip oil pump provides improved flow and pressure, and our testing has proven that their Billet gears are stronger than the OEM oil pump casing itself. ARP main and head studs replace the factory hardware, and a Gates Racing Kevlar timing belt replaces the OEM timing belt. Except where a high-performance upgrade part has been selected, our motors feature 100% OEM seals and gaskets, including an OEM water pump and OEM idler/tensioner pulleys.
I know there's a growing contingent of guys here who are N/A track junkies, and this is a great option for guys who are looking to keep it simple.