Which Kelford Camshaft is Best for me? | 900-1,100hp 2JZ Testing

Question:  I have a 3.0L 2JZ with a Precision Turbo 7275. What cams and boost are best for me? How much power should I expect?

Answer:  The 7275 is best suited to the T202-D (i272°/e278° 10.20mm camshafts and 900-1,150hp usage:

15psi for 675hp / 500tq with <1.0:1 Engine Pressure Ratio
20psi for 790hp / 590tq with a 1.0:1 EPR
25psi for 900hp / 670tq with <1.1:1 EPR
30psi for 1,000hp / 740tq with a 1.1:1 EPR
34psi for 1,050hp / 795tq with <1.2:1 EPR
37psi for 1,100hp / 840tq with a 1.2:1 EPR

Purpose:

Real St.’s mission is to catalog various build stages and questions encountered by our customers’ most common engines and platforms.

The stock-stroke, un-ported cylinder head Toyota 2JZ-GTE and the Precision Turbo 7275 Next Gen are both common choices in the racing community given that the 2JZ’s cylinder head can support in excess of 1,000hp without porting, and the 7275 is one of the most popular units currently for 1,100hp applications.

The 75mm turbine wheel has long served as a benchmark in the industry for those looking for roughly 800-1,100hp worth of airflow.  Originally a size of turbine wheel commonly married to compressor wheels capable of 800-950hp, this new 7275 Next Gen is the latest offering stretching the 75mm turbine wheel to power production previously unheard of for these size turbos.  

This also is the largest turbine wheel utilized in Precision’s Small Frame packaging with the 4.0” Inlet and smaller compressor housings than the Sportsman units with their 5” inlets and 3 ⅝” V-Band Outlets, providing for easier fitment for a wider range of applications.  

This 7275HP packaging, as with all others, is a direct drop-in upgrade for any other HP Small Frame units.

The Gen 2 7275 was available from 2017 until 2023 when the Next Gen unit was released and it has spent the last two years as a community favorite in this size.

An unported cylinder head is clearly beginning to limit our power production here, but many people bolt this size turbo on and try to make this power with unported heads.  We look to demonstrate what sort of airflow suits which camshafts and how to best utilize this turbocharger on your 2JZ project.

We aim to accurately conduct repeatable tests on our varied engine combinations while striving for operation under similar circumstances.  Furthermore we aim to present the community with easy-to-understand and informative education in order to make informed decisions for their needs. 

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

Click here to see this same test with a Precision 6466NG turbo

Click here to see this same test with a Precision 6870NG turbo

Intentional Starting Variables:

Test 1:  Kelford T202-B Camshafts (260° Adv. Dur. / 9.60mm Lift)
Test 2:  Kelford T202-C Camshafts (i264°/e272° Adv. Dur. / 9.90mm Lift)
Test 3:  Kelford T202-D Camshafts (i272°/e278° Adv. Dur. / 10.20mm Lift)
Test 4:  Kelford T202-F Camshafts (i282°/e286° Adv. Dur. / 11.25mm Lift)

Constants & Conditions:

Engine: 3.0L 2JZ-GTE w/ 9.0:1 C/R w/ Unported Cylinder Head
Turbocharger:  Precision Turbo 7275HP Next Gen
Exhaust Housing:  T4 Divided 1.15 A/R
Exhaust Manifold:  Artec Cast T4 Divided
Intake Manifold:  Plazmaman w/ 72mm Throttle Body
Intercooling:  Plazmaman Air to Air
Fuel: One Ethanol 112S
Dyno:  Superflow SF-Powermark 
Engine Acceleration Rate:  600 rpm/sec
Conditions for Run 1:  4,000-8,000rpm & 100kpa (14.50psi) Target
Conditions for Run 2:  4,500-8,000rpm & 150kpa (21.75psi) Target
Conditions for Run 3:  5,000-8,000rpm & 200kpa (29.00psi) Target
Conditions for Run 4:  5,500-8,000rpm & 250kpa (36.25psi) Target
Avg. Starting Air Temp.:  84.4°F (29.1°C)
Avg. Starting Water Temp.: 177.6°F (80.9°C)
Avg. Starting Oil Temp.:  192.4°F (89.1°C)

Unintentional Starting Variables w/ >10.00% Deviation:

Avg. Density Altitude:  1,754.8’ [1,331-2,109’]

Test Notes:

We utilize a SuperFlow SF-Powermark Engine Dynamometer for our testing.  This is a high-capacity water brake dyno that precisely controls load and speed of the engine using SuperFlow’s automated closed-loop systems to test high-output engines up to 15,000 RPM and over 2,500 HP.  

For these tests, we looked to test the 7275 Next Gen at various boost levels and with camshafts of varying sizes so that we could ascertain the best package for the community. 

The way an engine dyno operates and the data that we’re able to achieve is not always directly comparable to a chassis dyno.  On a chassis dyno, the vehicle’s various components are still in play - torque converter, traction, etc.  On an engine dyno, since we can load the engine at any RPM we want (even at idle), you cannot directly compare the early powerband of an engine dyno to a chassis dyno due to the elimination of those variables that affect spooling characteristics.

The entire turbo system remained the same between the four camshaft tests.  All tests were performed through an Artec divided T4, twin-gate, exhaust manifold, through a Plazmaman air-to-air intercooler and a Plazmaman street intake manifold with 72mm throttle body on One Ethanol 112S fuel.

Results:

We learned in during the 6870 testing that above 850-900hp, the D cams really provide substantial gains over the C cams.  The 6870’s smaller wheels and therefore quicker response make it a superior choice for most applications not requiring more than 900hp, so the 7275 should be looked at by those people looking to spend most of their time between 900 and 1,150hp (Roughly 25-40psi) and the D cams suit them extremely well.

7275HP NG T202-C Run 1:  643.4hp @ 7,700 & 14.4psi (22.26hp/psi) with 490.3tq 

7275HP NG T202-D Run 1:  666.7hp @ 7,900 & 14.5psi (22.99hp/psi) with 493.6tq  

7275HP NG T202-C Run 2:  803.1hp @ 7,800 & 21.9psi (22.06hp/psi) with 601.0tq 

7275HP NG T202-D Run 2:  826.0hp @ 7,800 & 21.6psi (22.88hp/psi) with 484.8tq  

7275HP NG T202-C Run 3:  938.9hp @ 7,500 & 29.4psi (21.39hp/psi) with 716.5tq

7275HP NG T202-D Run 3:  977.6hp @ 7,900 & 28.7psi (22.63hp/psi) with 727.0tq

7275HP NG T202-C Run 4:  1,014.7hp @ 7,400 & 35.3psi (20.38hp/psi) with 803.4tq

7275HP NG T202-D Run 4:  1,081.6hp @ 7,700 & 36.3psi (21.29hp/psi) with 833.6tq

Test Results:

So the D cams were worth less than 25hp under 22psi, but by 29psi, the difference was 40hp, and above 35psi, the gain grew to 60hp!  Outstanding results.

Test Results:

Here you can see the massive T202-F (i282° / e286° 11.25mm) camshafts versus the D cams.

Predictably, they squeaked higher peak power numbers out, right at the end of our test’s RPM range.

Interestingly, once the boost rose over 1:1 for tests 3 and 4, the boost control became less predictable, and at 35+psi levels it just didn’t seem very happy, making less peak power than it did with the D cam.  Our early guesses are that the extreme overlap offered by these huge camshafts (more appropriate for 2,000+hp) exacerbates any Engine Pressure Ratio issues.

Turbo & Camshaft Recipe

Interpreting These Results:  

As with our other guides, our recommendation is to first be honest about where you will operate the vehicle.  The 7275 is best suited to 900-1,150hp (~25-40psi) applications for the 3.0L 2JZ and a camshaft with over 270° of duration and 10mm of lift.

While the 7275 can be run harder - our tests did not exceed 80% of its speed limit - the turbo works well in this application and reaches roughly 1.2:1 engine pressure ratio around 1,100hp.  For those hoping to squeeze a bit more out of the 75mm turbine, there is a 7675 available, but you are already outpacing the turbine, and a turbine wheel (and frame size) upgrade will pay dividends over this point.

Here we show the four different camshafts’ results at Test #4’s 250kpa / 36.25psi Target Boost

If you have any other questions about how to optimize your combination, give our team a call and we’ll be happy to help.

Special Thanks to:

Kelford Cams & Precision Turbo for their willingness to test and experiment to answer these questions with us, as well as Plazmaman and Artec who both contributed products used in this test.