Building the Nissan VQ37VHR part 4, Making the Big Power!

You have probably been following our build of an NA VQ37VHR engine and are probably dying to to see how much power we can get out of it and frankly so are we! In this episode we are going to be buttoning up our engine install and will get our engine running and tuned by Specialty Z, one of the leading tuners of late model Z cars in our area.

Part 1

Part 2

Part 3

With our VQ packing a stout 12:1 compression, it can stand to take advantage of higher octane fuel.  E85 has a very high octane and also a higher latent heat of evaporation so the engine can run much cooler.  It is also priced cheaper than gasoline.  To enable us to run E85 with the least amount of hassle we used Specialty Z’s bolt in flex fuel kit, part number  SZ_flexkit. Specialty Z’s kit makes use of an ethanol concentration sensor with the readings being converted to a 0-5 volt signal by a Zeitronix ECA-2 box, sending the conditioned sensor signal to an unused input on the ECU.  With the flex fuel kit you can use gasoline, E85 or any blend of the two and the ECU will compensate seamlessly adjusting the air fuel ratio and timing for the most power no matter what the blend of ethanol in the fuel.

The Specialty Z kit has a pre-terminated wiring harness and OEM fuel hoses so the whole thing is really a direct plug and play system for an easy install.

Specialty Z uses an OEM grade GM Continental sensor to detect the ethanol concentration in the fuel.  This is the same sensor that OEM’s use in there flex fuel vehicles so it is high quality, accurate, repeatable and affordable.


The Zeitronics ECA-2 box converts the signal from the sensor to two 0-5 volt outputs that a gauge or the ECU can use to interpret the ethanol percent concentration.

So we could know the percent of ethanol in our fuel real time, we used an Innovate Motorsports Ethanol Content and Fuel Temperature gauge part number 3912. We paired this with Innovates Oil Pressure and Temperature Gauge part number 3913


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