Just like the suspension on your Mazda, you need to have a plan when upgrading your engine. There are several areas to consider when upgrading the existing engine in your Mazda and all play a big part. If you were to call me up and ask “What should I do with my engine in my Mazda?”, I would ask you what you are going to be doing with it. There is a laundry list of components in your engine, and when added up can range from several thousand to tens of thousands of dollars. We are going to stick with piston engines for this article. Sorry RX-7 guys!
Starting with the base of the engine the block is the center of everything. Oiling is handled in the engine block which then feeds the cylinder head and in some cases the turbocharger or supercharger. One thing I tell people is when doing any work with the block or bottom end of the motor is to change the oil pump with a new one. Why risk several thousand dollars of a newly built engine on a critical component. If the oiling system fails it can mean throwing out everything and starting over, which no one wants to do. If an upgraded oil pump is available purchase it.
Located in the engine block is the crankshaft. Mazda has been good with supplying most engines with a strong crankshaft. I recommend that you have the stock crankshaft inspected if it is out of the engine. Options for upgrading the crankshaft are cryo-treating and shot peening (stress relieving).
Connecting rods are also located in the engine block. They attach the crankshaft to the pistons. Thankfully, if there are no upgraded connecting rods on the market you can have some made. Most manufacturers of rods will custom build a set if you send them one of your stock rods. When choosing a connecting rod there is two general paths. If you are going with an engine that will not see forced induction you can normally go for a lighter rod which is made from better materials than stock. If you are going with forced induction you will want a connecting rod which is sturdy and can survive detonation in the event a mistake happens.
Carrillo Connecting Rod
Pistons play a big role in how your engine is going to be used. Lower compression pistons are normally used with forced induction engines. High compression pistons are good for a normally aspirated build. With EFI systems both stock and aftermarket making use of knock sensors, it is possible to build a forced induction engine with a relatively high compression engine. Regardless of the compression ratio, forged pistons are the strongest. There are also squeeze cast pistons which are strong as well but not quite as tough as the forged pistons. Some high compression pistons are squeeze cast which results in a lighter piston, and can be strong enough for high RPM use.
Engine bearings can make or break your motor. We recommend the best quality bearings you can buy. Factory Mazda engine bearings are really good as are some aftermarket brands like ACL. For setting clearances of the bearings make sure you speak with your engine machine shop to see what they recommend for your application. Most performance machine shops have years of experience and can provide you pointers for the assembly of your engine.
Cylinder heads carry several parts to look at for a build. Camshafts need to be selected to match your engine build. Normally aspirated performance camshafts and forced induction camshafts have different timing and lift profiles. I recommend speaking with the manufacturer of the camshafts to make sure they will be appropriate for your engine. Installation of performance camshafts may require upgrading the valve train. Some require valve springs to be upgraded along with the lifters and retainers. Again speaking with the manufacturer of the camshafts is a good idea. Performance machine work of the cylinder head should be looked at. Porting your cylinder head for better flow, volume, or efficiency should be looked at as well, as it can get you more gains from the camshafts and other upgrades. Adjustable camshaft gears give you another option for doing fine tuning in your engine. Cam gears can let you extract the last bit of power from your engine with cam tuning.
Upgrading the fasteners should be considered when upgrading your engine. Critical components like the cylinder head bolts and main cap bolts can be upgraded with a stronger fastener like ARP studs. The advantages they offer besides strength is the ability to re-use them multiple times without fatiguing the hardware.
Manifolds for both the intake and exhaust need to be selected to match the use of your engine. Manifold lengths can affect the power band of the engines. Shorter runners on intake manifolds are normally better for mid-high RPM engines and longer runner manifolds normally develop lower end power and torque. Exhaust manifolds in non turbo motors can be setup for different power bands as well. 4-1 headers are generally for mid and high RPM power. 4-2-1 manifolds are better for mid range power. Turbo manifolds range from log style to elegant custom tubular creations. I will cover more on turbo manifolds in a later post.
Gaskets are the last part of the engine I will cover. Mazda supplies most of the engines with good gaskets from the factory. There are exceptions to look at for a few of the engines like the FS engine in the 99-03 Protege. The factory head gasket is ok, but better parts are available. Upgraded head gaskets from companies like Cometic are available for several Mazda engines including the DISI, FS, and the B6 DOHC/B6T.
Make sure you take a look at all of these areas when upgrading your engine to get the best results. All of the areas listed above, the block, oiling, rods, pistons, gaskets, fasteners, and bearings work only as well as the other parts in the engine. Selecting an exhaust manifold for top end power and not getting the higher compression pistons to get the most for the header can sell your build short. Send us an email if you have any questions on building your Mazda, we have years of experience and would be happy to help.