Project Toyota Supra Mark IV: Part 14 – Precision Turbo’s GEN2 PT6870 CEA turbo!


Finally, the GEN2 PT6870 CEA has been installed.

Something else I decided to do was pull our NGK BKR9EIX sparkplugs that I’d gotten from out to check them. Considering they’d been in the car for about 1.5 years, they seemed pretty good with little peppering. The one up front had the most. (Please excuse my sparkplug holder, which I think is a result of a little Mike Kojima rubbing off on me)

To start this new venture with our larger turbo from Precision Turbo, I’d ordered another set of NGK BKR9EIX iridium plugs from and installed them.

With the old plugs coming out, it was a good time to do a quick compression check of the Four Rings Performance-built motor, and after running two years with the PT6766 CEA at a 700-750+ WHP level (around 23-27 PSI) I was pleased to see the following compression numbers: 134, 130, 129, 127, 128, 128 for cylinders 1-6, respectively. That's 5% variance between all six cylinders (and just a 1.5% variance if you take Cyl #1 out of the mix).

Unfortunately, when I installed the new plugs from I’d forgotten to gap them down, since I was previously running a 0.018-in gap. These iridium plugs come pre-gapped from NGK at 0.030-in, and at anything over 20 PSI the car stumbles and does not accelerate.

After I gapped the new BKR9EIX iridium plugs from to around 0.020-in, I took the car out on some private frontage roads and the thing ran like a champ at 30 PSI.

At this boost level the car is a rocket that won't point straight. Yes, I still haven’t gotten a speed sensor fixed so I’m doing this with no traction control. Fourth gear is so wicked it really reminds me of the feeling of a mild time warp, only I wish I didn’t have the constant anticipation of breaking the car sideways at over 100mph. Therefore, acceleration is performed at part-throttle when the weather is anything under 75F.

The spool-up of the GEN2 PT6870 CEA with the 1.00 AR divided housing, when compared to the previous PT6766 CEA, which had a 1.15 AR divided housing, is similar, albeit a touch laggier. Still, in third and fourth gears, this sucker starts to move quickly at 4000 RPM. And for those concerned with how the GEN2 PT6870 on a 3.0-liter Supra performs during a drive akin to highway cruising, rest assured this turbo spools fairly well in high gear. In fact, in sixth gear it makes 5 PSI at just 2800 RPM. That's an impressive spool-up for a semi-low compression 3.0-liter powered by a turbo that will flow over 1100hp!

If there is one thing I miss, it's the whining sound of the 6766, which is a little more noticeable than with this new one. The PT6766 CEA reminded me of my favorite sounding turbo of all time–the old PT71-GTQ journal bearing turbo.

The plan now is to have the AEM Infinity’s traction control fully tuned, and to get some new dyno figures from Modified by KC's Dynojet 424x. This will all be happening soon (fingers crossed), so stay tuned!






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