Boosting Supercharger Output

[Bob Cook]

I'm working on an idea I have to increase the efficency and/or output pressure of the supercharger on my Drag Race vehicle. I'm wondering if adding a section of angled blades before the impeller on the input side to spin the air in the correct direction before it enters the supercharger will increase boost pressure and/or efficency? I can get up to 33psi with the existing setup I have by spinning the impeller at 72,000 rpm.

Thanks, Bob

[nkt]

Out of interest, what diameter is the impeller?

 

I suspect that putting anything in the way to direct the air may lead to increased heat in that area, unless you work hard to keep the flow laminar. I can see where you are coming from, though, and I think it is a good idea. You might do better to have something that focuses the air onto a narrower section. The speed of the blades at the root is low compared to the speed at the edge, so once at a certain speed, the air hitting that edge isn't going to be adding to the rate of spin, unlike that nearer the center. The downside is that the outer air gets the impeller up to speed a lot faster, as it gets more torque.

[infamous]

If you haven't already added an intercooler, this will increase efficiency by a consideralbe amount. Busting air pressure will always add heat which in-effect decreases density. Cooling this heated air will increase its density thereby busting your HP output. This idea of yours is however very interesting, although I believe the manufactuer of the turbo has already considered this factor when designing their unit. Let us know how it works out for you, you may be on to something.

 

BTW welcome to Hyproghphy, enjoy.

[Bob Cook]

I believe the impeller is 7" in diameter and very complicated in shape. I have the compressor maps for the supercharger but, not sure how they can help me. Seems like the higher the boost pressures go the faster I go. An intercooler would be the hot setup:) but, not allowed in my class. I'm working on creative ducting of air to try and cool the discharge tube but, it cannot be too obvious or the tech guys will be all over it. The temps at the start of the run are around 130 degrees F and 300 degrees F at the end of the pass.

Thanks, Bob

[Turtle]

___I'm no gear head, but nkt may have something there with the comment on keeping the flow laminar. Off hand, without changing the shape of the input manifold, some form of laminar flow micro-groving on the inside surface could help reduce drag, as in the laminar flow micro-groving on certain aircraft wings/fuselage. No doubt an expensive option. :hihi:

___I have experimented some with laminar flow nozels using both air & water, & there is considerable room here for experiment & discovery. I have posited (but not built) an attacheable laminar flow nozel for fire extinguishers which would extend the distance of a stream considerably with no other changes to the extinguisher. :naughty:

[infamous]

___I'm no gear head, but nkt may have something there with the comment on keeping the flow laminar. Off hand, without changing the shape of the input manifold, some form of laminar flow micro-groving on the inside surface could help reduce drag, as in the laminar flow micro-groving on certain aircraft wings/fuselage. No doubt an expensive option. :hihi:

___I have experimented some with laminar flow nozels using both air & water, & there is considerable room here for experiment & discovery. I have posited (but not built) an attacheable laminar flow nozel for fire extinguishers which would extend the distance of a stream considerably with no other changes to the extinguisher. :naughty:

 

Good point Turtle; I have done considerable porting work on cylinder heads and, one of the latest tricks is to machine very small rectangluar grooves lengthwise in the ports. Only problem with this technique is that carbon deposits rapidly fill them up returning performance to square one. On my flow bench this modification is worth between 3 and 10 CFM. This is one of the little tricks that the NASCAR boys are using on their cylinder heads. The one problem that I can see with using this method on the intake side of a turbocharger would be, velocity is very important when using this technique. The intake side of a turbo needs to be large enough to support the volumetric efficiency of the engine. Needless to say, to do this the opening in the turbo is somewhat to large to take advantage of this modification. If you build a grid of sorts in front of the turbo intake, I'm afraid you may do more harm to flow charcteristics than any you may expect to gain. It may be possible to increase the size of the turbo intake and then install a laminar flow grid of sorts, maybe this can help. In any case, good luck.

[Bob Cook]

I do have a rule required restriction on the intake side of the supercharger. I must run an 80mm restrictor before the air enters the supercharger. Mine happens to be a Mass Air meter that works with the ECU. The data I log on my runs show the Mass Air meter reads 2,000cfm at 7,200rpm. I'm not sure how accurate this measurement is. Do you think that having a larger than 4" diameter tube after the Mass air meter leading up to the inlet would be of any benefit? What about some type of large airbox right in front of the supercharger inlet? I do have some room issues due to the engine compartment. I will have the air deflector I mentioned ready to test by the end of next week.

Thanks, Bob

[infamous]

I do have a rule required restriction on the intake side of the supercharger. I must run an 80mm restrictor before the air enters the supercharger. Mine happens to be a Mass Air meter that works with the ECU. The data I log on my runs show the Mass Air meter reads 2,000cfm at 7,200rpm. I'm not sure how accurate this measurement is. Do you think that having a larger than 4" diameter tube after the Mass air meter leading up to the inlet would be of any benefit? What about some type of large airbox right in front of the supercharger inlet? I do have some room issues due to the engine compartment. I will have the air deflector I mentioned ready to test by the end of next week.

Thanks, Bob

Yes, this is the principal of the velocity stack. I personaly believe that anytime you can increase the size of the initial opening, you will increase flow potential. One thing to remember however, the walls of the velocity stack should never exceed 14 degrees from the parallel. In other words, if you increase the dia. to abruptly it will cause turbulence and that is not desireable.

[Bob Cook]

It didn't work. The car lost about 100hp on the dyno. It did have a sweet spot but, not worth messing with based on the results.

Bob

[OzAnt]

I'm working on an idea I have to increase the efficency and/or output pressure of the supercharger on my Drag Race vehicle. I'm wondering if adding a section of angled blades before the impeller on the input side to spin the air in the correct direction before it enters the supercharger will increase boost pressure and/or efficency? I can get up to 33psi with the existing setup I have by spinning the impeller at 72,000 rpm.

Thanks, Bob

 

Hi Bob,

 

I was wondering if you could improve the volume of air your supercharger is gulping down by whacking one of these things in front of it:

eRacing :: Products :: Super e-RAM Electric Supercharger :: 1.7psi

 

Of course, given it's a drag racing machine, I'm guessing the thing might swallow this device if placed in front of its supercharger inlet :D

 

Also, given you obviously engineer stuff up yourself, you might be interested in something more along these lines: How our electric supercharger works

not so much to use with your vehicle, but more on ideas on what you could create to help you.

 

Anywayz, I figured it can't hurt mentioning it.

 

Cheers,

Ant