04 STi – HTA68 – dyno tune

Posted by x99percent on April 23, 2010

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).

Video not available

Before and after comparison:

Compared to our baseline stock 2006 STi:


06 STi – 49 lb/min turbo – results

Posted by x99percent on April 19, 2010

We all love our cars, and many of us want to somehow improve them… to make them truly OURS… to make them “better”. This may involve making some aesthetic improvements, installing a stereo system, or stiffening up the suspension. For me, this idea of “better” typically revolves around adding power. Over time, I’ve developed a pretty good idea of what parts do or do not work to make cars faster, especially with respect to a budget. My experience with many cars with many different parts on the dyno has allowed me to better understand what parts offer the best bang for the buck. This is the story of what happens when a customer is receptive to the advice and guidance that Jan and I offer when presented with the question, “How can I make my car faster without breaking the bank?”.

The car in question is a 2006 STi; the parts list is surprisingly simple:

  • Blouch Dominator 1.0 with 7cm2 turbine housing (49 lb/min turbo… think “FP Green”)
  • Externally-gated uppipe
  • 3″ turbo-back exhaust
  • Turbo inlet
  • Cold-air intake
  • TurboXS top-mount intercooler
  • 3-port boost control solenoid
  • Samco blow-off valve (the stock bypass valve is slow to close)
  • Power Enterprise 850cc injectors (NOT “hard to tune”, as rumored on the interweb)

With my tuning, this combination of parts resulted in a strong setup, putting down about 330 whp and 330 ft-lbs of torque on the heartbreaker dyno.

Track results:
(please excuse the phone camera quality)

11.83 @ 119.3 mph, run at Milan Dragway on 93 octane pump gas


02 WRX wagon – VF39 – feedback

Posted by x99percent on April 13, 2010

It’s always nice to hear back from people with their results at the track. In this case, the car is a 2002 WRX wagon. It is running the stock 2.0L motor, a used VF39, 93 octane pump gas, and was tuned on the dyno by yours truly.

Got a chance to take the wagon to track earlier today. I spun hard in first and bogged second, but managed a 1.8 60ft and a 12.5 at 113mph. With a little more practice on the new setup im sure I can do better. I’m very impressed with the car. Thank you so much for the killer tune. STis with GT30s and WRXs with FP18Gs couldn’t even keep up! And my all time favorite is the LS2 GTO cammed, intake, full exhaust that I put a car on from a roll! Nobody sees it coming. Thanks Again!

This car made 260.8 hp @ 6000rpm and 257.4 ft-lbs @ 4250rpm.

How many “350 whp” cars have you seen or heard of that aren’t this fast? 😉

Categories: Feedback,Results,Subaru
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02 RSX turbo – dyno tune

Posted by x99percent on April 11, 2010


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.

Video not available

Compared to his last NA numbers:


05 STi – Stage 2 + cat – dyno tune

Posted by x99percent on April 10, 2010


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:

Categories: Subaru
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