NC HAMR – One Extremely Fast Time Attack Miata

Photos provided by Jenson Little

A year ago, we came across this cute little 2008 NC Miata at the 2019 Super Lap Battle USA at the Circuit of the Americas in Austin. Don’t let that smiling face fool you though, as this Miata is packing well over 600whp and finished third overall with a time of 2:16.311. The owner, Austin local Jenson Little, came in behind the well-known time attack cars of Cole Powelson with the Lyfe Motorsport GTR and James Houghton wheeling the K-Tuned Integra Type-R. Just as a point of reference, the 2020 Super Lap Battle USA winner clocked a 2:15.020 in a Porsche GT3. I think what struck me about the car when I first saw it was how simple and clean the build looks; none of the aero craziness associated with Unlimited class cars. Clean is the operative word as you’ll see the well-thought-out modifications which make this Miata extremely fast.

The engine is based around a 2.3L block from a Mazdaspeed3 and built by Comptech. CP pistons increase the compression ratio from the stock value of 9.5 to 10.0 which required a bit of machining to clear the valves. Carrilo H beam connecting rods attach to a stock crank and handle the 700whp when the boost is cranked up to 35psi. The head comes from a 2.5L engine which had a valve job before being bolted down. Comptech ground some custom cams pushing on the stock valves. One of the many well-thought-out mods is the “LS style” alternator relocated to the driver’s side of the engine with a larger pulley to slow it down with the engines raised 8500rpm redline.

With big power comes big heat, especially with turbo cars. A custom Ron Davis radiator with built-in oil cooler extends all the way across the engine bay and all the way up to the front bumper skin. In motorsports fashion, Jenson controls the motor temp by taping off the grill as necessary. This eliminates the thermostat. To make space for the massive heat exchanger, the front end of the frame was hacked off and a tubular structure was built.

The coolant air separator bottle mounted against the firewall has its overflow tube run to the middle of the cowl. That way, if the car overheats or the system gets pressurized (blown head gasket), coolant sprays onto the windshield creating an impossible to miss warning sign. Clever. Just to the left of the separator bottle are a couple electrical communication wire bulkhead fittings. When the engine comes out (as race engines are oft to do), it’s quick to disconnect the electrical wiring of the engine from the chassis making it much quicker to separate the two. The motor and chassis side harnesses are from RaceSpec.

A custom short runner manifold was fabricated to feed a Garrett GTX3576R Gen 2; I recommend the 3576 over the 3076 every time. Notice the manifold is not equal length; this was intentional as ease of maintenance was prioritized over eeking out maximum power. With the Tial 0.82 A/R turbine housing, the package is still making 700whp, so it’s not exactly lacking. The Tial housing is insulated by local Austin company PTP and their turbo blanket. Of course, the fluid lines near the hot manifold are protected with insulation sourced from PTP.

The compressor inlet pipe is 3” diameter with the compressor outlet being 2”. A Greddy tube and fin intercooler brings down the air temps and it was chosen for being light weight and having quick thermal recovery. The cold side pipe going between the intercooler and throttle body is 2.5” diameter.

11 comments

  1. Fun minor point that is easy to overlook – ABS module visible in some of the underhood shots is another parts bin raid. There’s a type of RX-8 ABS module that works without ECU interface and doesn’t have ice mode – it was also done in Pirelli World Challenge NC MX-5s too.

    Really do like this build; I feel like people underestimate the NC

  2. slight correction, Goodwin doesn’t make hardtop, he prolly just bought it from Goodwin, but its most likely a DG Motorsports hardtop

  3. I love it, even if I don’t like the look of the NC, this is such a no-nonsense build, lots of easy to source factory parts, lots of ease of maintenance thought put into it.

    I have no clue about the MZR swap though, unless he had one laying around or was intimately familiar with that engine. I know it’s related to the duratec/ecoboost so it’s probably a good platform.

    A full cage linked up to the front strut towers and a diffuser are probably the only things I would add. Maybe move the radiator to the back if it helps the corner weighting.

    1. MZR/Duratec (same family) is the same family that came in the NC, so it’s relatively trivial to swap – akin to putting a K24 in place of a K20. If I recall correctly, this build evolved from using the OEM transmission. IMO they’re pretty under-rated – they don’t have the evolution of the K series Hondas but they have a lot more potential than people think.

      1. Ah, if it bolts in without much fab it makes sense. Still, when you are putting down 700hp “how hard is it to find X part when it breaks” becomes important.

        I’m still shopping scrapyard BPs for my NA mostly because they drop in and the aftermarket is great not because they are better engines.

        1. Aftermarket isn’t as big, but the 2.3 and 2.5L variants were used in everything – there’s millions in junkyards, the production numbers were huge and relatively recent. And the aftermarket does have the necessary stuff covered – cams, rods, pistons and stuff.

        2. 700hp means a built engine, but you can do a 400hp stock 2.5 and thats an easy and cheap replacement that can be had for under $500 with low miles.

  4. Great build! Isn’t that mazdaspeed crank one of those without a keyway? Did they machine keyways for all components?

      1. No OEM Duratec/MZR offers a keyed crank. Many companies offer relatively inexpensive keying services and can also remove the balance shaft drive gear if equipped.

        The 2.3L ecoboost crank is great bang for the buck as it’s forged and allows more revs than a 2.5L crank- 94mm strove vs 100mm. They go for $375 new from Ford.

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