View Profile
View Forum Posts
Private Message
Visit Homepage
Basically, I decided to change gears and go with another setup (from the TRD SC as it is now on Xbiker's car). Corky and I were talking about producing more of these in some kind of kit form, but in the end decided against it. As a one off, it is a great ride! It has balls of steel, instant acceleration under ANY conditions, and the torque curve of your dreams.
However, trying to make a production type unit and keep costs in the neighborhood of the competition just didn't work. We also ran into the bear of trying to make it fit without cutting the firewall. Now carver's is running fine, but I absolutely did not want to have to cut the intake runners and re-weld. We had already made a Frankenstein and to me that was just going too far with something that Corky and I were going to put our names on. Not to mention the labor that was involved to get to where we were, it moved our price point into the stratosphere. We might as well have went with an Autorotor! Corky felt the same way so we decided to stick to the possibility of just upgrading m45 blowers to m62 units for other markets.
So, I started looking around to figure out what I was going to do next. I was still thinking "kit potential", but I don't want to make any such claim as pressure takes the "fun" out of the process. My requirements were pretty simple, all out performance for a 1zz or 2zz that could compete wholeheartedly with a turbo without the complexity and inherent "issues" of such.
I looked into autorotors and building a custom intake manifold. Very large, problematic on the plumbing side due to the location of their input and output ports. I also felt that making a sheet metal intake manifold was not ideal due to our layout and the under hood temps. I looked at centrifugal SC's. Generally too big to fit anywhere effectively. I then went back to the Rotrex and looked closer.
Well, one of the things that turned me off about it originally was their own website. Their marketing is horrible. If you follow their application guide, it would point you towards anemic performance for our size motor. Also, everything is laid out "turbo" style with compressor maps. Well, there is nothing wrong with that, but if you don't stop and think, you can be easily misled and directed away from the larger units unnecessarily.
Why you ask? Well, if you look at the compressor maps and think about them in "Turbo Mode" you would rule out the larger units due to surge. However, with a belt driven "turbo" that is not an issue. You see, when you look at a compressor map, a turbo is going to build to full boost at a given rpm so you draw a line from that rpm up to the boost line and then straight across the map. However, with the SC, your line is going to start at say 2,000 rpm straight to redline and your target psi in at an angle (representing linear boost).
Looking at the map this way, it is easy to see how a larger unit will work and avoid €œsurge€. So now, all of a sudden the Rotrex looks very, very attractive as you can size a unit AND control the size of the pulley to work wonders for either the 1zz or 2zz.
Not to mention the efficiency. The unit I settled on (according to the numbers) looks like it will stay in the 75% efficiency range (bordering on the 80% line) throughout the entire rpm band of our motors. Unlike say the GT2871r that hits 75% at around 4,500 rpm then falls of drastically. In fact, depending on your setup and boost level, the turbo will hit a low 60% or less at redline! Ever wonder why so many GT2871r's have a torque peak in the middle of a dyno? It is not because of an overboost issue
So yeah, some will say, well the belt driven unit will produce less boost across the range and only hit peak boost at redline. Well I say, ah phooey? According to the compressor maps, the Rotrex flows plenty of air, just look at the maps! See the belt drive negates the problems associated with running an ever larger turbo. You don't have to worry about spooling up a big monster to get the peak efficiency you are looking for. The rotrex achieves this mechanically, so lag does not enter the equation. You also get the benefits of a SC; linear boost and reduced complexity.
Here are a couple of examples. The lines I have drawn are theoretical and serve only to compare the two apples to apples. I based the target CFM on 300 HP (crank) based on the 1.5 cfm per HP rule of thumb. The psi target may or may not be indicative of all setups, but I was looking for some common ground.
Now 2zz owners take a close look. Based on these maps and your higher rpm's, you too can not only take part, but the sky is the limit on power!
I plan on installing one in the stock alternator location. I'm going to utilize a small hole in the firewall for easy access (it could probably be installed without one, but hey, mine is already there
Reply With Quote
