Engine

Back to Drivetrain.

Build Order

It looks like we can do this in a very nicely incremental fashion. We can get the 99 motor installed, do the various conversion notes below, and it will, in theory, run just fine on the 1.6 electronics. Once we know that's running, then we can do the Megasquirt conversion (and use the cam angle sensor just like a 1.6) and get that going. Once that's going then the electronics are basically all done and we can focus on the supercharging.

Finally, we can look at changing throttle bodies (since the conversion will use the 1.6 throttle body, which I believe is smaller) and see what's involved in that while we work on building the 99 motor for the supercharger.

Do we want to try to do this ourselves or just pay Flyin Miata a metric asston for one of their absurdly expensive builds?

Rev Limit

I was originally going to go with 7500 rpms, since that's a super safe stock limit. However, lots of people seem to be revving to 7800-8000 and above on stock internals and not exploding stuff much (Fuji Racing has been revving to 9k on stock internals and only finally blew up a motor). I figure on the overbuild internals I'm throwing in there, 8000 should be more than safe. Unfortunately that doesn't really help us on gear ratios.

1.8 Conversion Notes/Parts

Flyin Miata makes a 1.8 conversion kit for 194$ that looks like it will make our lives a little easier. They have a good writeup of the conversion process as well.

Make sure to use a 94-97 alternator. The 99 alternator doesn't have an internal regulator and will totally hose the NA electrical system.

In theory, we can just swap the 1.6 thermostat housing over to the 1.8 motor to maintain the working electrics. Also move the 1.6 FPR over to the 1.8 fuel rail end so that it turns into a return system. Here's a good Miata.net post about it as well.

Parts Research

I've stored some Other Builds for reference.

• Block/Head: Used 99 motor - Bought
• Rebuild Gasket Set: 201$ from Mazdacomp - Bought
• Mazdacomp Engine Mounts: 35$/ea, NAY1-39-040 - Bought

Block

• 2002 Oil Pan: 207$ from Mazdacomp, 10-400 - Bought
• 2002 Oil Pan Support Plate: 66$ from Mazdacomp, 10-406A - Bought
• 2002 Oil Pump: 198$ from Mazdacomp - Bought
• Eagle H-beam rods: 291$ from random sketchy place
• Carillo A-beam rods: 850$ from 949
• 949 Racing Rods: 329$
• Wiseco Coated Pistons: 796$ from FM (exclusive), includes rings/wrist pins
• ACL Main Bearings: 82$ from FM
• ACL Rod Bearings: 51$ from FM
• ARP Head Studs: 117$ from 949
• FM ARP Head Studs: 167$ from FM
• ARP Main Studs (218-5401): 80-90$ around the web
• FM Head Gasket Kit: 215$ from FM

Head

• Inconel Exhaust Valves: 33$/ea (264$/8), 1mm oversize
• Intake Valves: 22$/ea (176$/8), 1mm oversize
• Supertech Valves: 18$/ea (288$/16), 1mm oversize
• Supertech valve springs/retainers/seats: 314$ from 949
• Supertech shim-under-bucket lifters: 359$ from 949 + 5.5$/shim
• FM Valvetrain Kit: $379 from FM, includes springs/retainers/seats

Injection

What injectors will we need? 1000cc or can we get away with less? I got 392whp on the Alltrac with 880cc injectors without coming too close to maxing out.

Alternator

We need to use a 94-97 alternator on the 99 block with the 1.6 body. The 99 alternator will blow out the electrical system because it has no voltage regulator built in.

Any weight or efficiency gains to be had with some sort of aftermarket alternator?

Clutch/PP

Spec stage 3+ (SZ453F) - 549$ from Spec, 495$ retail most places on the net

Flywheel

Stock flywheel is 20 lbs, claims FM.

• Flyin Miata - 295$, 10.3 lbs
• Spec SZ81A - 381$, 9.5 lbs
• Fidanza - 9.5 lbs, 355$

JSC has a good overview of all the options as well.

Motor Mounts

The 1.8 motors use a slightly different motor mount. I'm going to have to get everything here to see what they're talking about. For now, I ordered 2 mazdacomp stiffer mounts, to use with the crazy brackets that FM makes with their 1.8 conversion kit. Prather strongly suggests upgrading to the AWR mounts. 225$, but they look much lighter and better designed as a full solution, and also much stiffer. These are all good things (except the 225$ thing).

Header

Emilio says to just use the Racing Beat 99 header -- I don't need a custom header at these power levels. 408$ from good-win-racing, 410$ from 949. Buying one of those for now. Will possibly explore custom headers further down the road.

Called Prather Racing about a custom header, they forwarded me to his son, Jesse Prather, 785-249-0284. He makes a couple different headers, but for wide powerband he doesn't suggest his biggest one. His is a 4-1, 1.75" primaries, 2.5" collector, and it makes a bunch of power over the RB header in NA applications. He doesn't know if it will help a lot on S/C applications. 900$ for the header. Not too bad at all, really. If the RB can't make the power I need, can get this for stage 2.

Exhaust

Doug wants about 1500$ for a custom 3" exhaust. Don't know how much for 2.5".

I emailed Emilio (949) about what to do for an exhaust with the RB header and he says: I'd suggest custom 2.5" or 2.75". Gonna be insanely loud. big resonator and a really big muffler out back.

Prather Racing suggests doing a 3".