i just took off my 6lb lower and put on the 4lb lower that i have, keep in mind i use REM's 2.86 i think upper, anyways the truck seems to be running a little better overall. but i also run in 100 degree weather, does anyone know at what boost the eaton becomes deminuishing (sp)

 

combined with the hot weather your prolly just making up the power with lower intake temps

thats my edumakated guess

 

Eaton reducing the boost!!!! Sounds to me like

 

At stock boost (i.e., supercharger RPM) levels, the Eaton is already past peak efficiency, meaning that the deceasing marginal returns have already set in. The Eaton is already overdriven with the stock pullies.



Which explains why adding a PSIG does not give a 6.8% peak power increase (1/14.7 PSI (normal atmospheric pressure) = 6.8% per PSIG).





Of course, this is just peak power. At lower RPMs, the Eaton is still operating within its efficient range. Which is why adding a pulley and further overdriving the Eaton M112 gives a subjective increase in perceived power. It just runs out of steam quickly as the RPMs rise.

The safe way to get the low-end increase without the high-end efficiency losses is to lower the shift point the same percentage as you increased the pulley size. This would result in more power down low, with the supercharger being driven not higher than stock. It's not quite as simple as this, however, as the engine has it's own efficiency curve. One would really have to play around with pulleys and shift points to fully flesh out this theory. I'm just a bench racer for now -- my engine is still bone stock.

More of my ramblings are here.

 

i dont want ne beef with you so dont take it the wrong way this is just my opinion

do u have any proof of this and where did u get these charts

i would be willing to bet big that peak efficency occurs after a blower RPM greater then 5200 rpm's

a bigger pulley will create more power untill (lets say just for shlts and giggles 18 psi) now to create 18.1 psi it would take more power from the crank then that of wich it added hence a dicrease in RWHP. he is only running 14 psi and is felt better making 12psi or whatever that upper pulley adds or suntract
there must be another colpret for the power loss i.e belt sliping, heat,ect..
6.80%(sig digit 100%/14.7)
HP from boost exponentially decreases as you go up
your saying if i run 14.7 psi my power should double

again i mean no flame just my opinion
what?

 

 

This is a hard question to answer eaton ?
Tim is correct in saying there's a clear point where
over boosting it is actually working against you.

Yet others will argue (and it's true) that running 8lbs of pulley
(with a filter n chip) will get you easy 11's, AND THATS TRUE.
Hundreds of us from here are doing that.

But talk to anyone running 8lbs of pulley on a stock eaton about racing in hot summer, or hot lapping on 80 degree days at the track and you'll find those 11's are now mid 12's and higher,
WHY---> Because of the heat.

I have found time after time, test after test, tune after tune,
with and without Nitrous, that MINE runs better ET's with 4lbs of pulley, and in each and every case has run slower with 6lbs of pulley. WHY--> Because I hot lap, I don't do cool downs, I don't have aftermarket fans, or water pump, I don't ice it, I dont have a switch for the intercooler pump to run in the pits, and I've never waited between a run and always go back to back racing.
The only time I waited between runs, with a simple hood open cool down method, was at Cecil (and it gave me my best ET's ever). I still haven't beat those ET's, 12.3 is the best since, but I also still haven't done a cool down between runs since, I'm so impatient
However mine will run 12.7-12.8 all day hot lapping with filter-chip-n-4lb pulley,
and run 12.3 hot lapping with Nitrous.

In order for the 8lb pulley running (stock eaton) people to
get those great ET's, proper cool down is essential, IT'S A MUST.
It's essential for all of us to run cold to get the best ET's.
But at operating temp, that extra boost is not gonna do much for you, and it some cases on hot days, WILL WORK AGAINST YOU

 

Ayrton, pass the popcorn please

 

The top chart came from Eaton. The bottom two charts came from me. They show advertised peak HP gains versus what you would get in a perfect world. The point is that, even at 10 PISG, the Eaton is shot.

At 14.7 PSIG, and assuming perfect efficiency, the power will double. This fomula is just a rule of thumb, but most 8 PSIG kits, for instance, show about 50% power gains, so it's not that far off.

You must mean "blower RPMs," because the blower is spinning at least twice as fast (sometimes three times or greater) than the engine.

 

im saying that peak efficency will be reached only if you overdrive the blower

and in a perfect world the power would double 14.7
until you get a negetive return by adding boost the eaton is not shot it may not be efficent by any means though

 

You get a negative peak power boost at +5psi (4psi will give you higher peak power)

This is shown by dyno runs and eatons web site.

Coldie

 

Tim,
at what RPM does the Eaton take more power to turn than the Eaton makes?
RPM of the supercharger... (the Engine RPM will depend on the pulley size I know)


BTW: I've read your stuff over and over and over.
GOOD STUFF

 

Didn't work....

find the blowerRPM.xls spreadsheet and it has all of the formulas you are interested in.

The only thing you'd have to add is you HP@ specific RPMs

Coldie

 

Never mind. The original has been edited

 

lol hilander, i knew you were gonna say that, the truth is with a little less boost and a wet shot, it should really cool the charge, im just getting ready to put it on, i still have to put my fuel PSI guage on and so fourth.
this is all awesome info guys, tim do you have a graph of some sort that shows the hp diminish at a certain RPM?