Garage99

Displacement is fun. Big turbos are fun. AWD is fun.
Displacement + big turbo + AWD = FUN.


The basics:

• AEM EMS Series 2
• Stock 6G72 3.0L block with forged internals
• Ported stock heads
• Brian Crower 280 cams
• Borg-Warner S400SX3 turbo
• custom manifolds, exhaust, intake, intercooler, and throttle body
• RC 1200cc injectors
• Aeromotive FPR
• E85 fuel
• HKS DLI
• Blitz Dual-SBC Spec-R boost controller
• only 23-24psi… for now

There were no mechanical issues with this car at all, which is always welcome.

Considering the size of the turbo, boost came on at a very reasonable RPM… thanks in part to a device that makes the turbine inlet smaller at low boost levels. Once the turbo was spooled, the boost level was controlled *perfectly* by the Blitz EBC. As the boost was turned up, the car responded very well and power levels continued to rise. Minimal changes in fueling were needed for the additional airflow, thanks in part to the boost compensation mapping in the AEM EMS.

The results:
574.9 hp @ 7500rpm and 477.5 ft-lbs @ 5250rpm

Another basic STi… I figured that I’d post it just for giggles.

The parts:

• AMR intake
• Perrin EBCS
• Perrin turbo inlet
• TurboXS downpipe
• Greddy cat-back exhaust

274.5 hp @ 5200rpm and 304.3 ft-lbs @ 4200rpm in 3rd gear
272.5 hp @ 5450rpm and 318.3 ft-lbs @ 3700rpm in 4th gear (quicker spool, but more heat at high RPM)

This car is always a blast to tune. Good choice of parts, NO mechanical issues, and it revs to what seems like infinity.

The last time around, this car put down an impressive 445whp on the heartbreaker dyno. Rumor has it that, at the old power level, a “650whp” Viper didn’t stand a chance. Of course, the owner wanted even more power, so he added some cams to the mix this time. While the car had some downtime, the owner took a quick look at the bearings to make sure things were good… he was happy to report that everything looked immaculate. You just can’t be too careful when you’re regularly winding things out to 9k RPM and the car is putting down over THREE TIMES the stock wheel horsepower.

The parts:

• TiAL GT35R
• TiAL 44mm wastegate
• TiAL BOV
• Hondata engine management
• stock-sleeved B18C1 bored 81.5mm
• JE Pistons
• Golden Eagle blockguard
• Manley rods
• Honda OEM bearings
• Micro-polished crank
• B16 head
• Kelford stage 2 turbo race cams
• Supertech valves and springs
• ARP head studs and hardware
• Type-R oil pump
• MSD ignition system
• Edelbrock intake
• 70mm throttle body
• Aeromotive FPR
• Quiafe LSD
• Exedy twin-disc clutch

The results:
Pump gas: 374.8 hp @ 8000rpm and 264.2 ft-lbs @ 6250rpm
Race gas: 470.6 hp @ 8250rpm and 372.2 ft-lbs @ 7000rpm

This was a complete build from the ground up, done by Jan and Angel. The car’s previous setup had a Blouch Dominator 1.0 turbo that put down 330whp on the heartbreaker dyno, resulting in a 1/4 mile pass of 11.8 seconds. Of course, the owner still wanted more.

This time around, a custom rotated-mount setup with a large turbo was installed along with a slew of supporting upgrades. The original block was bored over and rebuilt with Eagle rods, CP pistons, ACL race bearings, ARP head studs, and Cometic head gaskets. Killer B Motorsport’s reinforced oil pickup does its part to keep everything properly lubricated.

The basic parts:

• GT3586R turbo with HTA billet compressor wheel and Tial turbine housing
• AEM EMS
• 1200cc injectors
• custom fuel system
• Ported heads
• Brian Crower stage 2 cams
• TurboXS FMIC with custom piping
• GT-Spec header
• TiAL 44mm wastegate

This resulted in a set of strong, but reliable tunes on pump and race gas.


The results:
Pump gas: 392.6 hp @ 6750rpm and 335.5 ft-lbs @ 5750rpm
Race gas: 445.5 hp @ 6750rpm and 377.5 ft-lbs @ 5500rpm

There has been a fair amount of talk online about the HTA68 turbo from Forced Performance. There were claims that it “spooled earlier than a VF39″, yet made “more power than a 20G”. Well, sorry to disappoint, folks, but I think it’s fair to say that neither of these claims are true. To be fair, I don’t think it was Forced Performance that was making these claims. Still, the HTA68 is a very capable turbo… I just think it would be a better match to a 2.0L WRX motor than the STi’s 2.5L.

Regarding spool-up, the only way anyone could claim that this turbo spools earlier than a VF39 would be if you were comparing a tuned HTA68 car to a *stock* VF39 car. At typical tuned VF39 STi will be making ~280 ft-lbs of torque by 3200rpm in 4th gear, while this HTA68 STi was making ~240 ft-lbs under the same conditions. I certainly would not call the HTA68′s boost threshold “late”, but the VF39 spools up if you just look at it funny or sneeze in its general direction. The HTA68 was in full swing by ~3700rpm during the 4th gear pulls on the dyno, which is perfectly acceptable for a fun street car.

It was clear that this turbo wasn’t going to make peak power like a 20G when the boost started to fall off around 5000rpm. Most 20G-like setups do a pretty good job of keeping the boost up almost all the way to redline.

I’m not saying that the HTA68 is a bad turbo… it is a very good bang for the buck and it offers a wide powerband with relatively quick spool. I’d say it fits between a VF39 and a Dominator 1.0 turbo, leaning closer to the VF39.

This particular car arrived with a tune from another tuner in Texas. During the baseline dyno pull, it was clear that something wasn’t quite right. The ECU was pulling a LOT of timing right where the torque peak should have been… you can see this in the chart at 3900-4000rpm. A quick compression test showed that the 85k mile motor was a bit tired, but compression was very consistent across all cylinders. Once we were sure that the motor wasn’t hurt, I reflashed the ECU with a good “starting point” calibration and got to work. From that point forward, everything fell into place quite nicely.


The parts:

• Forced Performance HTA68 turbo
• TurboXS front-mount intercooler
• TurboXS downpipe
• TurboXS midpipe
• Prodrive 2.5″ muffler (restriction?)
• TGV deletes
• K&N Typhoon intake
• DeatschWerks 740cc injectors
• GrimmSpeed 3-port boost control solenoid

The results:
Old tune – 254.1 hp @ 5450rpm and 271.1 ft-lbs @ 4450rpm
My tune – 287.9 hp @ 5700rpm and 301.4 ft-lbs @ 4450rpm … at the same boost level (within 1psi).

Before and after comparison:



Compared to our baseline stock 2006 STi: