Check out the difference in the components below.
|Engine Management System||AEM Series 1 EMS||AEM Infinity EMS|
|Fuel injectors||HKS 1000cc||Fuel Injector Clinic 2150cc|
|Fuel pumps||twin Walbro 255 LPH||twin Walbro F90000262 E85 compatible pumps (400 LPH)|
|Turbocharger||PTE 71-GTS, .81 AR open, journal bearing||PTE 6766, 1.15 AR twinscroll, DBB|
|Exhaust manifold*||HKS-style (SP), 1.25-in primaries||PHR S45, 1.5-in primaries|
|Wastegate||HKS GT 60-mm (2.36-in), open||PTE twin 44-mm (1.73-in x 2), open|
|Intake Manifold*||modified stock “bubbled” intake (UPFD)||Hypertune “big port” manifold, port-matched|
|Throttle body*||stock 65-mm||Hypertune 90-mm|
|Cylinder head||1-mm oversized Ferrea, minimum headwork||1-mm oversized Ferrea, FRP headwork|
|Camshafts||HKS 272||Titan Motorsports 272|
|Pistons||stock 8.5:1||JE Asymmetrical 8.5:1|
|Intercooler thickness*||3.5-in Spearco||4.0-in ETS|
|Clutch||RPS carbon/carbon twin disc, 19-lb flywheel||RPS carbon/carbon twin disc, 19-lb flywheel|
|Fuel||93 octane with AEM meth injection||93 octane, mostly E70/E85|
|Tire Size used during dyno runs**||305/35-18||305/35-18|
Even though the turbo has a larger turbine housing, it is twin scroll and dual ball-bearing so we won't count it. In any case, even with all of these bigger components listed above, our new spool-up is a whopping 600 RPM quicker! And we're also running fairly close to the same ignition timing in the midrange as we had before.
So, while many parts are bigger, we can thank not only the quality of the parts installed but also some specific things that helped spool-up, like the fact the turbo is twin-scroll and ball-bearing (even with a bigger AR), the velocity stacks inside the Hypertune intake manifold, the lighter MR2 valve lifters, the lighter bottom-end components, and all of the cylinder head work by Jeff Gerner at FRP.
**Keep in mind that the tire sizes on the dyno don't represent what the car is rolling on today (after this dyno day) which are the BF Goodrich RIval tires, sized, 295/35-18 that we featured in Part 9.
Here's a quick visual comparison between the old setup with the stock block, bubbled intake manifold and old-school Precision 71-GTS turbo…
…and the current one with the Precision 6766 CEA ball bearing turbo and built motor. The Hypertune intake manifold makes a big difference aesthetically, and the fact we now run two Flex-a-lite fans instead of the factory clutch fan means no more fan shroud.
Turning up the boost to 22 PSI, and comparing it to the same, previous 25 PSI level with the 71-GTS, we start to see a significant difference. Even with less peak torque at this lower boost level (there wasn’t a tach signal in one of these runs but you can see the difference between 90-110 MPH, where the peak torque is), the new setup out-spools and also even outflows the old setup.
While we'll be able to plot some runs against RPM, we apologize that some runs had to be shown over MPH due to a poor tach signal on the dyno some days.
With the Precision 6766 CEA ball bearing turbo turned up to about the same 25 PSI boost level as tested before with the 71-GTS, we see the differences for real this time. The spool up improvement is obvious, but check out the top end! This test was using the exact same tires for both runs. Our new setup just supports more RPM.
Keep in mind that at this point we’re still on 64% ethanol, which we’ll call E64. Even the winter blend here in the Midwest has more ethanol content at the pump than this, with 70%.
To better show you the improvement in spool-up we’re now working with, check out this graph, which not only shows torque (please excuse those two spikes, which were the result of an electronic glitch in the dyno’s tach pick-up) but also torque over time. While both boost pressures hit similar peak torques in their respective midranges, the newer setup hits 500 lb-ft a whopping 2-seconds sooner in fourth gear!
The above is not to say the old setup is 2-seconds laggier if you stomp on the throttle from 4000 RPM-on, because we are talking about a dyno pull here that starts at around 2000 RPM. But still, the way the newer PTE 6766 CEA Ball Bearing turbo ramps up and then also sustains power up top is awesome. Also, notice how much steeper the green line ramps up.
Now go to the next page to see what this translates into actual torque gains at specific RPM points!