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The following info was derived using Borg Warner's MatchBot turbo calculator program. I ran a number of different HP combos for the new 572 inch big block. Below are two of them. One a 1200 HP possible tune and also a possible 1400 HP tune. Using this program we settled on Borg Warner's SX400 Tubos ( #171702) and ordered them from Turbochargerpros.com in Calif. who were prompt with delivery and had good pricing.

On the next page you will see where first I had used a different calculator and we were thinking of using a T76 turbo but the more I looked I felt this turbo was better for our needs, Sumner.

When you look at the combos below and on the next page remember that we don't have to pick just one. Wth a boost controller like the TURBOSMART e-Boost 2 we can run up to 6 different boost levels on a run based on either time, rpm or there is are two leads off the controller. Grounding one moves to the next higher boost level and grounding the other moves to the nex lower boost level. If we dump some of the exhaust in 1st and part of the way through 2nd gear we can then have the boost start coming in for the higher gears. Either going higher in each gear based on rpm or going higher based on time and where we are on the track or use the method of grounding the two leads.

With this in mind we can start the run in 1st and part of 2nd gear on the motor alone and then at low boost levels in 3rd at the lower rpm levels increasing as the rpms increase and then maxing out in 4th at the highest rpms.

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1200 HP Data with minumum boost at 3500 and maximum boost coming in at 6500. Maximum boost at the manifold (on the gauge) would be 11.0 psi and about 16 psi on the compressor side of the turbo before the intercooler and piping to it and from it to the carb ...

This calculator has a lot more data and entry options than the one on the following page. I'd recommend starting with the next one to get started, but consider this one before making a final decision ...

1255 HP Turbo Map with a 171702 Borg Warner SX400 Turbo. The map they have on the site uses Kg/sec vs. the more common lbs./minute. I added the lb/min across the bottom of the map in the larger bold numbers. Of note is that this turbo looks like it will work fine with our motor, but the 575 cu. in. presents problems on finding a turbo as it moves so much air.

The red dots above corespond to the 6 rpm data points and show the pressure ration (left side of graph) and the lb./min of air moved at that pressure ratio and rpm on the bottom of the map. Notice that our 6th point is getting over in the region where the compressor is operating at 70% efficiency and the anticipated air temp there from the window above this one would be 275 F. at the compressor outlet before the intercooler.

Another advantage of using the BW MatchBot is that it is easier to see Turbine data. The right arrow above points to the turbine on the turbo that we are getting. It is 96mm with a 1.32 a/r. The a/r in this case represents a turbo that will probably be slower to come on boost, but that could/should be an advantage on the salt with the limited traction. To see if the turbo works for your application in the program you move the 6 data points (red dots) onto the line that is connected to the turbine (right arrow) that you have with the compressor on the turbo. Then you use the second chart down on the page to interpret how well the turbine works for your applicaion.

Next is a 1400+ tune...

HP Data with minimum boost at 3500 and maximum boost coming in at 6500. Maximum boost at the manifold (on the gauge) would be 14.0 psi and about 20 psi on the compressor side of the turbo before the intercooler and piping to it and from it to the carb .......

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Above we can see the temp at the max. boost has climbed to 309 F. HP is 1410. I won't show the turbine map here, but if you look at the Turbine Match Outputs above you will see the Exhaust Manifold Pressure and below that the Engine Delta Pressure. The delta pressure shows the the difference between the intake pressure and the exhaust pressure. You like to see if these can be close to the "1" you see above. By moving the red dots on the turbine map to the turbine being use you can see this. Of course there is much more to all of this, but the MatchBot program gives you more input and output than anything else you see on the Internet. Two pages after this one you will see how I used this program to try and look at a non-Borg Warner turbo (the T-76 that we were considering) to see how it might fit your application.

You can see that now we have moved to higher pressure ratios (boost) and that we are starting to move below the 70% efficiency for the 6th data point and that shows up in increased air temps after the compressor. This might be about max for our combination. The turbo can make more HP in some application, but the 572 is just too big for this turbo. Actually 2 of them will be use and the program is aware of that since I marked the box for 2 turbos before inputing data.

On the next page we will visit another program and the turbos we first considered.