NAS Performance

NAS Performance At NAS Performance, we specialize in high-performance naturally aspirated Subaru engines for NA4WD stage rally and track cars.
(3)

From purpose-built rally motors to custom Subaru builds, we deliver precision, reliability, and winning performance.

Up next for porting are some EG33 heads! These are destined for a full turbocharged longblock featuring a closed-deck bl...
06/17/2026

Up next for porting are some EG33 heads! These are destined for a full turbocharged longblock featuring a closed-deck block, forged internals, and fully built cylinder heads. This is going to be a serious build—stay tuned for more!

EZ36 porting finalized. A lot of hours went into these heads. We also smoothed and polished the combustion chambers to h...
06/16/2026

EZ36 porting finalized. A lot of hours went into these heads. We also smoothed and polished the combustion chambers to help make the 13.5:1 pistons a little more forgiving and reduce hot spots. The exhaust dogleg is particularly challenging on these castings, but we’re very happy with the final result. 🔥
Every port is hand-finished and tailored for maximum airflow while maintaining velocity and consistency cylinder-to-cylinder.

06/13/2026

You know things are getting serious on these EZ36 heads when the 3/4” diameter cartridge rolls come out. 😮‍💨 Stay tuned for the end result!

Porting a ton of heads right now! 🔥 These EZ36 heads are getting roughed in with our large-radius hand port, improving a...
06/12/2026

Porting a ton of heads right now! 🔥 These EZ36 heads are getting roughed in with our large-radius hand port, improving airflow while maintaining excellent velocity. Every set is carefully shaped by hand to maximize performance and consistency.

At NAS, we don’t do basic off-the-shelf parts builds — we take everything to the next level. Custom parts, specialized p...
06/09/2026

At NAS, we don’t do basic off-the-shelf parts builds — we take everything to the next level. Custom parts, specialized processes, and continuous R&D are at the core of what we do.

This EZ30 crankshaft for is a perfect example. We had our friends at Shaftech perform magnetic particle inspection to verify it’s crack-free, followed by nitriding, Omicron polishing, balancing, and a final super polish on the journals.

We do everything possible to build the most reliable, durable, and meticulously prepared engines for each application. This EZ30 is headed into a drift missile that’s going to spend its life banging the limiter, so we’re pulling out all the stops to make sure it’s ready for the abuse.

No shortcuts. No compromises. Just doing everything we can to build it right.

Update on the EZ36 we tore down after finding the timing chain tensioner screw stuck to the magnet in the oil pan.Not on...
06/09/2026

Update on the EZ36 we tore down after finding the timing chain tensioner screw stuck to the magnet in the oil pan.

Not only did the failed tensioner toast every rod bearing in the engine, but the crankshaft also had two stress cracks 🤯 — one on the #5 main journal and another on the #6 rod journal.

That's not something you see every day.
The good news is we already have a replacement crankshaft on the way, and we were already planning additional processes to maximize durability and reduce the likelihood of fatigue cracking.

Every crankshaft will receive:�• Superfinish polished�• Cryogenic treatment�• WPC surface treatment

Cryogenic processing helps relieve residual stresses and promotes the transformation of retained austenite into martensite, while WPC treatment and superfinishing create an extremely smooth, durable surface that helps minimize stress risers where fatigue cracks can begin.

Pretty wild failure, but we're turning it into an opportunity to make these engines even better.

For those who didn’t see the other post, this a stock JDM core engine we tore down.

EZ36 oiling R&D 🤔 Working on a couple options
06/08/2026

EZ36 oiling R&D 🤔 Working on a couple options

06/06/2026

In a world where people use rotational idle tunes to imitate the sound of big camshafts, here’s an engine with real camshaft overlap and genuine chop.

No sound effects. No tuning tricks. Just carefully selected components working together exactly as intended.

What you’re hearing is a naturally aspirated race engine with real cams, real overlap, and a sound that’s unlike anything else in the Subaru world.

This is our favorite sound. This is our EJ251R Rally Spec Engine. 🔥

Hand-ported EZ30 heads. Chamber smoothing, airflow improvements, and countless hours in the details. Some monster EZ bui...
06/05/2026

Hand-ported EZ30 heads. Chamber smoothing, airflow improvements, and countless hours in the details. Some monster EZ builds loading... 👀🔥🚀

Address

Republic, MO
65738

Opening Hours

Monday 9am - 5pm
Tuesday 9am - 5pm
Wednesday 9am - 5pm
Thursday 9am - 5pm
Friday 9am - 5pm
Saturday 9am - 5pm
Sunday 9am - 5pm

Website

Alerts

Be the first to know and let us send you an email when NAS Performance posts news and promotions. Your email address will not be used for any other purpose, and you can unsubscribe at any time.

Shortcuts

Share

Category