A-Spec Precision 5866 Twin-Scroll Single Turbo Kit

I realize I never formally introduced or addressed what exactly it was I wanted to do with the engine – and that is go single turbo. That’s because up until now, I’ve primarily been preoccupied with waiting for the related parts to finalize and arrive in my hands.

Even if an individual does not turn a single wrench and is merely a credit card warrior, this still should not be seen under a trivial light. The fact is, even the task of picking and choosing what parts to buy takes skill and guile. This is compounded when you’re dealing with a more obscure car, as the options are more limited and require greater assessments.

For me, I wanted the best single turbo kit I could get for this car. One of the paths I could have chosen was to go with a Full Race manifold and then piece together the rest of the kit; however, I wasn’t too intrigued by their long-runner design. My priority is to maximize responsiveness and not necessarily power output. In the end, I decided to go with A-Spec Tuning from Chicago because they specifically offer a revised short-runner manifold. Additionally, their long history with RX-7’s and quality build materials have established a bit of a cult following.

There was, of course, a stipulation. As much as A-spec is known for their quality, they are just as known for the amount of time it takes to deliver a kit. This ended up being no exception for me…

I got the jump on this single turbo project early, and placed my order back in October. My manifold was supposedly already made at the time, but it wasn’t until mid-January that I received my first package. The turbo came separately about a week later. Then I discovered that I was given Precision wastegates when I ordered Tials… so that took a couple more weeks to sort out. Furthermore, the dump pipes were forgotten from my package and dragged out the waiting even longer.

While the experience was quite taxing and wearying, because a lot of money and time was on the line, it was a necessary deed. I like to anecdotally reference the Soup Nazi from Seinfeld… somewhat similar.

With patience and perseverance comes great rewards, and in this case, it came in the form of extreme turbo porno. A-Spec did eventually come through and deliver me my full kit.

Here is the ceramic-coated twin-scroll manifold with a divided T4 flange.

And the main show – I went with a state-of-the-art double ceramic ball bearing Precision 5866 turbo with CNC billet CEA compressor wheel.

The 5866 itself is an interesting setup and A-Spec helped recommend this to me to achieve my response goals. In comparison to a Garrett GT35R, the 5866 has a larger turbine but a smaller compressor. It is basically a hybrid of a 5876 compressor with a 7666 turbine.

For the wastegates, I opted to go all-out in this department. I am simply sick of boost creep issues with RX-7’s. On the stock sequentials, all it potentially takes is a removal of the catalytic converter to be stuck with uncontrollable boost. This didn’t exactly imbue a sense of confidence, I felt like the car was a time bomb and I never wanted to boost too much. Not the way a car should be driven.

To back my intentions of ridding this problem, I embodied the solution in a pair of 44mm Tial MV-R’s.

Lastly, here are the long-awaited dump pipes. The larger one fit well but the smaller one was way too short. It hung above the subframe when mounted, so I went to FFTEC and had them extend it 4″.