Sh0velMan's Track Car Build

Sh0velMan

Just got back from the dyno touching up my tune.

I picked up 1hp on the top and 4-6 throughout the entire rev range.

Here's a comparo of the best old run vs today's final product... notice the curious humps in torque with the FI exhaust vs the OEM Nismo (the only meaningful change in the engine).

Keen eyes will notice the large difference in AFR.

Let me just say, that the difference in AFR is not where the power difference came from. When the car was at Uprev being tuned (by the guy who created Uprev) there were zero (0) gains in going from the low 12's to the 13's on the car. We ran the AFR up to almost 14:1 and saw zero change in the power delivery, just higher coolant and oil temps. Knowing that (at the time) the cooling system in the car was woefully inadequate, we decided to keep it rich and call it a day.

Now with different parts and a larger radiator (to put it mildly) the AFR naturally ran up higher (and I boosted it a bit as well) and we see the gains we have here.

To qualify that a little, look at the chart where the two traces nearly intersect, note the large gap in AFR? If it were just running leaner making the difference, one power curve would be higher than the other... this isn't the case.

Anyway, I think I'm running into some kind of flow limit. I'm not sure which part is causing the limit.. I hope it isn't the headers (collectors, really) but I suspect it may be. You can see how changing the exhaust really let them honk up at 6k+ but then they fall back on their *** right away. If I can figure out what is slowing the system down above 7k, I think I could get some pretty insane numbers.

We'll see, for now, the car is much happier feeling and I'm satisfied with where I'm at (especially since I tuned it myself and only had to pay for an hour's dyno time).

Attached Images

Z Dyno Old vs New 001.jpg (417.6 KB, 394 views)

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