Does anyone know how much overall efficiency is lost for every additional pound of boost is added? There has to be a point to where extra boost creates more heat thus reducing the efficiency of the blower to the point of negating the extra boost. Has anyone dynoed the 2#, 3#, 4# and 5# pulley to verify how much hp and tq is gained by increasing the boost X percent? Just a thought.

From the times that many are posting on this board there seems to be a big difference in overall performance off the 2# and 4# pulleys. I wonder if the same is true with the 5# and 6# pulleys?

 

im gonna mount one of my 18"SVT wheels on my crankshaft........hell that oughta give me about 20 to 25psi......now thats effiecncy.........LOL

 

It would depends on if you supplemented your intercooler or not. Someone with a "powercooler" isn't gonna see as much loss as one that doesn't.

 

Thats a good question. I've got a 2# lower that I'm considering taking off and going back to stock.

Next year I'm going to be doing more Auto-x and road course then 1/4 trips, so I'm kinda worried about the extra heat. Since more boost won't help out as much in road course I really don't need it so if I go back to stock I won't worry as much about heat.

But how am I gonna get used to 2# less of boost?

 

Interesting question. I don't think it's been done in any kind of scientific manner, but it sure would be informative.

 

It would be interesting to see a same day dyno of all the available pulleys!






HANKFAN

 

Common guys someone has to have some data on this subject!




HANKFAN

 

I have heard that each lb is good for like 15hp and 35fpt or something?? That may be wrong or right, im not to sure, But I would agree other than motor limits there has to be a limit when a Unit was designed for 8psi and now is making 16psi?? Heat has to take over at some point... Here again, maybe Sal has been holding out some and his new Unit may be the key to true boost in the 20+psi range??? Of course you will need better engine parts to hold that much PSI..........

 

If everyone wants proof about how much boost the blower can take until it doesn't produce anymore power because of the heat factor just ask TOTALED (Jim). He will tell you like it is. He is running a 2# upper and a 5# lower (I bet now a 6#) and is running 11.60's. Nuf said.

 

JD,

Jim(Totaled) is running 11.60's not 12.60's. Everyone knows the power can be made with the pulley sizes. We are talking about long term breakdown wear, and when the boost becomes less efficent due to heat. When you run a powercooler and Ice down between runs it hurts you less. More Boost = more heat no matter how you look at it. There is a line were the boost will be to high out of the stock units. Thats what we are trying to figure out.....

 

My bad, I corrected my error, but I don't get what you are talking about when you say it hurts the blower less when you run a powercooler.
The powercooler has nothing to do with cooling the blower when it heats up. It has to do with cooling the air charge that the blower produces. But you are right about pulleys causing more heat buildup, but if you only use the blower real hard say a 1/4 mile at a time it won't be so hard on heat buildup hurting the prolongtivity of the blower.

 

Quick shot of nitrous in there and all bets are off.

How about a 20 shot just to keep the temps. down?
Seriously...

 

I am the one who has been dynoing the pullies a few months ago on 2 different trucks and this is a fact from going to a stock pulley to a 2# pulley you will see a 8HP and 24ft.pounds of torque more and the same identical #'s going from a 2# to a 4# pulley!So if you go from stock to a 4# pulley you will see a 16HP and 48ft.pounds of torque more than stock.A little note the HP is a little deceiving because all the HP is made down low on the pulley like a peak of 36HP then narrowing to 16 at the end.Hope this helps!

Matt

 

Say,

You wouldnt happen to have the dyno graphs of the runs would you? I really appreciate the info, (as well as HANKFAN?) and I have come to understand 'area under curve.'

What I want to see is the gained area under the curve more than stock. peak hp. and torque numbers dont mean much to me becuase sometimes they pop in at the very last bit of RPM, making the mod almost worthless (not to mention sacrificed hp/torque in other parts of pwer band).

However, the pullies being the mod in this case, I am quite certain the area under the curve would be up all over the graph. Or shifted to the left just a little bit, since the blower is spinning just that much faster at that engine RPM than stock.

Uh, right?

 

There is going to be a sweet point of RPM where the blower is moving the most cfm of air at the lowest temperature. If you go past this point you won't slow down, your inlet air temps will just start to rise at a higher rate than the cfm increase rate. Guys running non-intercooled centrifugal blowers on mustangs sometimes have engine inlet temps close to 300 deg F. You just have to run the car super rich with enough octane or timing retard to compensate. There is a point where the heat and additional parasitic HP drag of the blower will negate any HP benefit, but I think the increased HP causing reliablity issues in the powertrain and detonation due to heat will be the limiting factors.

Go to:

http://eaton.com/supercharger/M112.html

This is off the site:



You can get a feeling for what you theoretically should see as RPM and boost go up. What actually happens after the intercooler is unknown. I wish we could data log a second ACT after the intercooler. There is a second ACT if I remember correctly.



That is some serious parasitic HP loss. Now you know why turbo's are king. I assume you would have almost 100 HP loss at 14 psi around 15,000 blower rpm.




You can also see as your back pressure (boost) increases, your air flow decreases.

The website says additional information can be requested. Maybe someone can act interested.