Garage99

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:

Mikey has been wanting to turbocharge his RSX for a long time. Over the past winter, he put lots of effort into this project, fabricating many of his own parts. In the end, everything came together very nicely to produce a car with a strong and wide powerband.


The parts:

• Garret T3/T04E 57 trim turbo
• Bosch 750cc injectors
• Hondata K-Pro
• Treadstone manifold
• custom downpipe
• AEM 3-port boost control solenoid

The results:
294.3 hp @ 8000rpm and 207.0 ft-lbs @ 6500rpm


The short story is that Mikey put a turbo on his car and picked up 109.3 hp and 71.7 ft-lbs over the old NA numbers at only 10psi. A higher-reading MAP sensor is on it’s way, so a bit more power will be made soon.

Compared to his last NA numbers:

This 2005 STi was brought in by a customer from Windsor. Due to the emissions testing done there, the car was equipped with a catted downpipe. An off-the-shelf Stage 2 map from Cobb was flashed into the ECU with a version 1 AccessPort, but I knew there would be room for improvement.


The parts:

• TurboXS catted downpipe
• TurboXS standard cat-back exhaust (2.5″)

The results:
253.4 hp @ 5200rpm and 294.7 ft-lbs @ 3700rpm


Compared to the Cobb map:



Compared to our stock ’06 baseline:

As I start to post dyno charts here, I’ve decided that I’m going to use a stock ’06 STi as my baseline for comparison when a more appropriate baseline for the car in question is not available. Why? …mainly because an STi is a car that is accessible and many people are familiar with the feel of acceleration in an STi.

So, without further adieu… here it is:

You can also see that I’ve added dyno charts to the previous posts.