TurboFreak.com

March 28, 2007

Too Big or is something wrong?

Hmmmm, let's see, if I had a 50 trim T04E compressor wheel and a Stage 2 turbine wheel in a .63 housing my car would have 400 Horse Power easy!

Don't bet on it unless you know you have the head flow, tuning capabilities, and drivetrain setup to be able to generate the power. It's very easy for people to think they have awesome head work if they've never seen GREAT head work before. If the head doesn't flow the big turbo won't go!

This is coming from one of the guys who have been there and lost a whole second in the 1/8 mile and then had to resort back to a smaller turbo. There was absolutely no low or mid end power with this specifically built turbo on my configuration, and the upper end was not near enough to make the engine feel like it had any balls at all. 15 psi by 5200 RPM is NOT what I wanted.

Don't let this scare you away from trying different things, this is what I enjoy most about working on my engines and most of the time it's the ONLY way you are going to know what works and what doesn't. There are way too many things with my combination that caused issues all the way around that needs to be presented for a better understanding.

1. Head Flow

If the head is stock or the stock flow reduced by bad port work, don't expect to slap on a large turbo and have good spool time and response. It took 4 years working around a head flow problem I didn't know existed until I had great head work done. When comparing the previous head's ports and the new head's ports it was night and day. Quality of the workmanship was quite impressive to see in the comparison.

2.A-413 3 Speed Auto Drivetrain

Most race enthusiast like to slam 5 or 6 gears around all the time, I like 3 gears and no clutch, but I'm not a complete weeny, I do like shifting. Using a stock torque converter that has a stall of 2600 RPM is not going to be able to reach the powerband very fast if you have a turbo that doesn't hit full boost until 4,000 to 5,000 RPM. It sucks that a simple little torque converter can cost as much as $400 or more, but you will love the hell out of a much higher stall, worked great for me!

3.Tuning

Larger turbo and more boost equals more fuel needed equals larger injectors equals being able to control the injector's pulsewidth for optimal performance. Not forgetting to mention tweaking the timing curve. Through the years there have been many ways to fake out an ECU and run pig rich at WOT using a fuel rising rate regulator and having a fast car, but it has always been more enjoyable being able to tune an engine for drivability and power throughout all RPMs and loads. Thanks to Geoff Allan, Derek Beland, Rob Lloyd, George at Xtronics, and quite a few other indiviuals we now have the knowledge and tools to work with the stock ECU and have advantages much like any of the very costly aftermarket systems.

4.Problems with the Turbo itself

I have previously had problems with Majestic Turbo in the past (the builder of my 1st hybrid) and have been quite aggrevated when none of the 4 turbos I had rebuilt never lasted longer than a year. Recently, I was willing to call the new owner John Walzel, (who has raced turbo motorcycles for many years), and felt confident with his knowledge and new employees to take this turbo back to Majestic to break it down and find out what the problem really was with the Hybrid and get Majestic to rebuild it the way it should have been in the first place.

The Hybrid's symptoms were:
Tremendously laggy (ie..15 psi by 5200 RPM),
The boost would flutter in an odd way and didn't feel right at all,
It would leak so much oil from the compressor side it would fill the lower tank of my intercooler,
EGT's were skyrocketing and uncontrollable at higher boost range (ie..17 psi)

After driving an hour and a half to talk to him about the turbo's problems, he immediately proceeded to tear down the turbo and we spotted some issues. One of the bearings had a small cast iron piece embedded in it, the carbon seal was creating heavy friction, and the machine work was terrible.

5. Turbine Housings and Turbine Sizes

After contemplating the Stage 2 turbine wheel in a machined .48 turbine housing I wasn't sure how much upper end it would take away, but it did have quite a large effect and the upper RPMs did not feel near as good as it did before. The big advantage with going back to the .48 turbine housing on the problem filled Hybrid was getting my whole second back in the 1/8 mile and spool up was definately increased by around 600-800 RPM faster which then spooled to 15 psi by around 4600-4800 as compared to the .63 housing which was closer to 5200 RPM or more. These problems were also associated with a badly ported head.

The 2.2 responded very well when I went from the troubling Majestic Hybrid to a smaller Turbos Unleashed Super 70 turbo with a stock turbine wheel and .48 housing on the same crappy head and I seemed to be getting back on the right track with making power. In the midst of all this I finally recieved my swirl head back from Trevor Johnson Cylinder Heads in Rockwall, TX and ordered the .63 housing for the stock wheel in hopes the head would be enough to spool the turbo and add more to the upper end I missed so bad. The .63 housing with the head work was real impressive and spool up time did not seem to suffer much at all due to the breathing capabilities of this head.

This page was written to document the work I have contributed to my set-up and the many dollars spent on bad work and wrong thinking. I post it for those of you who, like me, can find everyone's opinions and bullshit on the internet, but can not find the factual data of problems that might be occuring in your world. None of this subject may affect any of you, but there are a few people I've talked to, including talking to myself, lol, which did not have information like this to point them in a certain direction of the problem.