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Vortech Supercharger and the road to maximum boost.
or
How I finally stopped over spinning by reading the instructions and getting a big ass pulley.
I have spent the last 4 years playing with my Vortech supercharger and during that time many of you have asked me various questions around this topic. The Vortech unit is able to support more than most of us will need. These are my experiences and findings while attempting to boost the Vortech to the max.
I hope I can save some of you from making the mistakes that require rebuilding or replacing the unit or as some have found out, the engine.
Vortech supplies V-1 S trim and V-1 T trim MAPs.
Clearly visable are the rpm markings and efficiency is 65% at 50,000 rpm for the S trim. The T trim puts out 70% efficiency up to roughly 49,500 before dropping off.
Maximum impeller speed for the V2 SQ published by Vortech is 50,000 rpm.
Looking at the MAPs you can see efficiency starts to drop at 50,000 impeller speed. Until recently I was going on the misinformation that 53,000 was the limit. I picked that up from the SC trim by accident.
I'm bad, been over spinning my impeller. To those that have taken my advice about pulley size, you should re-evaluate your situation in light of the 3000 rpm decrease in impeller speed maximum using the correct 50,000 rpm limit.
I have seen 57,000 rpm impeller speeds (3.6 inch pulley and 9500 rpm) and it was extremely hot. The supercharger peaked efficiency at 8333 and was whooping up the air real bad. Extremely hot, very turbulent and it still made 460+ rwhp.
A dyno run at 54,000 rpm (3.8 inch pulley and 9500 rpm) was very hot and I found my tuner pouring ice water on the intake manifold in the vicinity of the IAT.
Going above the 50,000 rpm impeller speed builds heat and looses efficiency and it does so in a rapidly changing manner.
As can be seen, Using the 3.6 inch is ideal for the low rpm AP2 or stroker where you don't rev beyond 8300 or 8400 rpm.
The AP1s should have at least a 4 inch pulley dependent on the redline.
the ultimate choice is critical to efficient operation of your supercharger. Every time you change the red line you need to check the impact on the supercharger. Larger changes would lead to a new pulley.
Approach
The first thing to do is determine the engine redline.
You can add changes and recalculate. I made some tables so I could look at the differences and decide which way to go.
Example: 4.0 pulley and 9260 rpm gives 50,004. If you want the redline higher than that, just increase the pulley size to 4.1 and 9500 rpm gives 50,048 rpm. Very close to the 50,000 rpm goal. Just drop the redline 10 rpm or so and you end up right at the 50,000 rpm goal. I just round off to plus or minus 50 rpm.
Pulley surface size is related to diameter. As it gets smaller there is less surface and therefore more potential for slip. To compensate for the decreased surface the tension can be increased. At some point the pulley has too little surface and the tension required is too high and the end result it bearing failure. Do not over tighten. I have run a 3.6 inch pulley with full grip and had a bearing go. I don't know if it was speed or leverage that killed it. Many owners are running the 3.8 inch pulley without difficulties.
Now you have maxed the supercharger efficiency speed wise what else can you do?
Maximize the coolant in the aftercooler. Always use deionized or distilled water. Avoid coolant if possible since it transfers less heat. Water wetter is good. Make sure there are no hose kinks and the system flows well.
Vortech can rework the supercharger to a T-trim that would increase the efficiency from 65% to 70%. This basically means the T trim adds less heat and that leads to more hp. The service runs about $1000. There are several S2000s running the T-trim currently with good results.
Porting is a possibility. This would require special knowledge and skill to be done correctly. I cleaned up my unit a little and removed some casting marks.
Improving the intake is an area that most look at first. Actually, the intake with the Vortech kit is very good at 3-1/2 inches. It draws cold air from around the radiator and from the fender void.
The T-trim supercharger is 3-3/4 inches at the intake opening and to maximize it the intake needs to be reworked to a larger size.
Intercooler porting is another way to improve the system. The biggest choke in the system appears to be the cast intercooler intake directly after the supercharger output. I was able to open it up about 2mm with porting. It is still the choke point. A new intercooler to my specs is more than a new supercharger kit.
Another area that can increase the supercharger output is chemical cooling. This includes water injection, water/methanol injection, and nitrous oxide.
Water and water/methanol systems allow the addition of timing by retarding the speed of combustion. Water/methanol will add power from the methanol as well.
I know of individuals running dry or having a bad connections and cooking their expensive engines. All electrical connections should be done in a professional manner. Methanol is corrosive to aluminum.
Straight water injection is a viable option.
I am fond of a small shot of N2O before the supercharger. It allows the supercharger to run much more efficiently and increase boost along with the N2O allowing more fuel to be burnt. End result is more than expected torque and horsepower gains at onset and continued excessive gains from the additional cooling. N2O vaporizes at -88 degrees C. so overall intake temperature decresases of 50 to 70 degrees are common.
I love your car Phil, I've seen most everything that you've posted about your car on these forums...
Another thing I would like to note is that centrifugal supercharger's pressure ratio is ultimately limited by the RPM they spin, however not the ultimate flow. By opening up the engine's breathing potential in the various ways that there are, they will see more HP but the same amount of boost, unless they spin the supercharger faster...
04-19-2008, 05:19 AM
How to maximize the Vortech Supercharger
