Hey Guys,
My GReddy TD06L2 20G 8cm2 turbos were tapped out at a bit over 800 whp as well as the turbo to IC piping and the dp/mp piping. I might have been able to pick up another 30-50 whp if I had stuck with the GReddys and upgraded the piping but, when I decided to purchase the stroker, I made the decision to go with a new turbo set-up as well, so I could realize all the power the stroker has to give. This scenario led me to select the HKS 3240 dual ball bearing set-up.

So I wound up selling my built shortblock, purchasing a new shortblock, the stroker kit and the turbos and HKS' set-up kit for the twin turbo configuration. I know most of you wanted to see what effect the stroker would have in an apples to apples comparison, but that wasn't possible in this instance for the reason stated above. Even so, there is much to be gleaned from my new all-turbo set-up. The 3240s are MUCH larger than the Greddys they replaced with a 0.87 A/R compared to the GReddy's .49 A/R. As you can tell from the graphs, the 3240s significantly out spool the GReddys and, with the help of increased displacement, make a ton more power. My best dyno run in terms of peak whp and torque is actually 1076 whp and 787.6 lb-ft. In that graph there is a slight dip because of timing being pulled at around 5,700 rpm. We took two degrees of timing out at this rpm and the resulting graph is the one above showing 1073 and 783, respectively.

There is more to be had but we played is safe with the tuning because of HKS' recommended rev limit. Alex has information showing the HKS drag Supra revving to 8000 rpm with no ill effects but I want to do more research in this regard before trying something like that. It was also my first time, and the first time for SPE, using C16 race gas. So, this was another reason why we played it safe. My 801 whp dyno was done with 104-octane unleaded.

The motor was boosted to 2.4 bar where my 1.3 bar HKS wastegate springs gave up. We had anticipated an 1100 whp run at an honest 2.5 bar, but we couldn't get there. I didn't want to go with HKS' 1.7 bar spring because that is too much boost for my regular driving around 100-octane unleaded, although I do get to fill her up with 104 unleaded whenever I'm down at SPE.

As to the car, HKS FCON V-Pro engine management, no NOS, all boost (2.4 bar) and C16 race gas. The 1000 cc Denso fuel injectors were at 90% duty cycle during an earlier run where the motor made 1031 whp. We stopped and added two additional 1000 cc injectors which we use for all dyno runs over two bar. It gives me 1333 cc/min of fuel. I know we could have gone with 1200 or even 1600 cc injectors but my confidence level in those is not as great as it is with the Densos.

The motor breaks 1000 whp at 6700 rpm and rises from there all the way to 7,400 rpm where it is still gaining power, but we shut down for the reasons previously noted. The motor breaks 500 lb-ft at 5400 rpm, 600 lb-ft at 5600 rpm and 700 lb-ft at 6000 rpm peaking at 6700 rpm again at 7000 rpm and gradually drops to 756 lb-ft at the 7400 rpm shut off.

As you know, the power drop-off for stroked motors can be precipitous and I was concerned about this initially. But, we concentrated on cylinder filling, plus I have a head that flows well and we thought that with the amount air the 3240s can push, I could limit a sharp power drop-off if everything came together as we theorized. As the graph shows the torque and hp curves are broad and very accessible in a 6-speed car. To the extent we could, we maximized the ID of all the piping. For instance, the HKS provided downpipes have a 70 mm ID which we graduated to 75 mm as soon as space allowed (two pipes) until they joined at my HKS ti.

The intake piping has an ID of 100 mm and my turbo to IC piping is 53 mm which increases to 80 mm when the two pipes "Y" before the IC inlet (compare this to my old set-up with IDs of 42 mm and 60 mm, respectively). The IC outlet has an 85 mm outlet for just a few inches because it quickly graduates to 100 mm to account for the VS intake throttlebody. I'll try to have SPE post a pic of the dp/mp set-up to make my description clearer.

Ken.