GTX2863R
 

GTX2863R using ATP .72 A/R exhaust housing with EWG v-band port, turbosmart EWG, FM2 log manifold, FM 3" exhaust with cat deleted for this dyno run, FM intercooler.

1.8L w/ 9.0:1 84mm supertechs, Carrillo A-beams, BP4W head, +1mm oversize intake valves, porting work by FM 10 years ago, BP-5A intake cam, stock exhaust cam. id1000 injectors, MSLabs MS3. 100 octane fuel.

This is at 24 psi:

https://www.miataturbo.net/attachmen...ine=1446565090

--Ian

That is some good power, congrats :)

Those are some great numbers, but I feel like I was expecting a little more. I think I just keep overestimating the GTX series. Was that about what you were expecting?

Garrett rates the 2863R at 430hp, so I'm guessing it probably tops out around 380 at the wheels. This current motor is more ping-prone than my old one was, my current theory is that the actual compression ratio is substantially higher than the 9.0:1 pistons would suggest. On straight 100 octane it will reach MBT at 240 kpa (and makes 330 rwhp there), but it's ping-limited at 265 kpa (the chart above), and is only making 10 more. I think there's more in it with more boost and more timing, I just don't have the octane to support that right now. E85 would probably do it, but that's a PITA as far as availability is concerned around here.

I was hoping for a nice round 350, but I'll take 340. It's well into 6-speed-shredding territory, so I don't know how often I'll run this much boost. :)

--Ian

Looks good Ian. Why not run that boost level all the time, just 6 speed concern?

It's no EFR, but it's also no slouch. People need to keep in mind that you're on the significantly inferior (flow wise) FM manifold too

The timing is significantly retarded at 265 to make it not ping, so EGTs would be high. I'll probably run 215 on the track just for safety purposes.

--Ian

Ian, what's your spark table look like?

https://www.miataturbo.net/attachmen...ine=1446575950

--Ian

Do you use this car with pump gas at all? If so, do you use a different spark map?

Well, I get 100 octane out of a gas pump, but no. It runs exclusively on 100 octane. California 91 gas isn't worth the effort. :)

(edit: ) My original intention was to run it on 95 (by blending 91 and 100 50/50), but it tops out at 250 at the wheels on that due to ping. Running straight 100 is sort of a band-aid until I get the time/energy/whatever to pull the head off and figure out WTF is up with the compression ratio.

--Ian