Dart 2JZ block makes 1821hp with a Precision 8685 Next Gen Turbo

Purpose: Going into this test, we have two highly-anticipated product releases to test with one another.  Precision continues to push the boundaries of the “Sportsman / Mid-Frame / GT42” -size platform with the 8685 Next Gen, and Dart has chosen Real Street as a development partner for their new Iron Eagle 2JZ Program.

Dart sent us the block at its service limit of 88.00mm bore, so we decided to test the limits of 2JZ displacement by using the largest stroke crankshaft that could fit while retaining a factory rod length in 96.00mm stroke.  The resulting combination measures 3.503L. You can find the build recipe here

We aim to conduct capability testing of the products in question and to ascertain if the various “known” 2JZ thresholds are about to change.  Furthermore we aim to present the community with easy-to-understand and informative education in order to make informed decisions for their needs. 

Precision 8685 Next Gen Turbocharger

Dart 2JZ Iron Eagle Block

Power House Racing V45 V-Band Equal Length Turbo Manifold

To do this, we need to first present the conditions at which the tests were conducted:

Intentional Starting Variables:

- None

Constants & Conditions:

- Engine: 3.5L 2JZ-GTE w/ Dart Block (88mm Bore x 96mm Stroke; 1mm o/s Valves)
- Engine Oiling:  OEM Toyota Wet Sump Oil Pump, Pickup, and Oil Pan
- Engine Sealing:  OEM Size (11mm) ARP CA625+ HSK w/ P1 MSK & APEX’i MLS Gasket
- Fuel:  One Ethanol 117R
- Turbine Housing:  1.28 A/R V-Band Inlet
- Dyno:  Superflow SF-Powermark
- Engine Acceleration Rate:  600 rpm/sec
- Target Starting Oil Temperature: 200.0*F

Test Notes:

Green Line: 1,179.3hp | 776.8tq | 30.8 PSI | 26.0 EBP

Blue Line: 1,442.2hp | 940.9tq | 42.2 PSI | 41.7 EBP

Purple Line: 1,711.2hp | 1,090.4tq | 57.9 PSI | 79.3 EBP

Red Line: 1,821hp | 1,226.8tq | 69.5 PSI | 111.1 EBP

Results:

After break in, we brought the engine to a target of ~750tq and used the boost controller to feed more air in as the engine sped up, attempting to carry this torque to our initial ending speed of 8,100rpm.  The result was successful, establishing a great baseline with less than 1:0.9 pressure ratio across the engine.

After our baseline, we began putting the engine under more load, stepping up the stresses in a gradual fashion.  At 8,100rpm on this run, the peak boost and exhaust pressure were almost perfectly 1:1, with the engine performing exceptionally well at this power level.

1,442.2hp @ 42.2psi would suggest a per-psi value of over 25.4hp/psi of boost (25.4 hp/psi * 14.5psi/atmosphere = 368.8hp)  You can see that at this power level we have gotten very close to 1:1 pressure ratio.  As the exhaust pressure begins to stack up, the “per pound of boost” horsepower production will decrease.  You can tell by the powerband that the compressor wheel has substantially more to offer here.

By now you’re thinking “send it” and we are getting there as we are now moving up to over 1,000tq. Here, you’ll see we approached 1,100tq with the compressor still easily keeping up with what we were asking.  This test’s peak boost was 57.9psi and at this point the coolant pressure in the engine was still 13-14psi and behaving extremely well.  On this run, as we cross over ~1,500hp, you’ll see that we start to stack exhaust pressure in the 85mm turbine, however the power production still is quite good with a hp/psi calculation of ~23.6hp/psi.

This was as much as we were able to make with our initial, traditional, wastegate approach.  We made the decision at this point to move the maximum RPM to 8,300, understanding that it would be pushing the limits of the wet sump oiling system and components.

The final result. 1,821hp and 1,226.8tq at a peak of 69.5 PSI. We added a CO2 system and were able to get the turbocharger to its RPM Limit (~120,000rpm) with a resulting peak power and torque of 1,821.1hp & 1,226.6tq.  The exhaust pressure peaked at 111.1 PSI.

Pro Tip:  Take a look at the behavior of the exhaust pressure across the last three tests.  See how you can watch it approach-and-then-cross 1:1 pressure ratio as it crosses through the 1,500-1,600hp area.  

Dart Machinery
Brian Crower
Precision Turbo
Mazworx