Everybody seems to state that the 6lb lower creates significantly more heat than a 4lb. To the extent that the 6lb is slower from a MPH perspective in the quarter mile.

What (engine) RPM is the Eaton being over spun with a 6lber?
Same question for 4lb?

I'd like to know what engine RPM each pulley (4 & 6) puts the blower into overspun/excessive heat mode where power is substantially dropping off.

When our trucks shift at say, 5400 into second gear, doesn't the RPM drop to around 4000? How about from second to third?

So, with each respective pulley, I wonder how long the 6lb is over spinning the blower (engine RPM span), whereas the 4lb is not?

What about added torque/boost down low from the 6lber that helps move the trucks? Does it favor a 4lb?

 

I believe this type of info was once on Tims site? http://www.timskelton.com/

I just posted a little experience over here: https://www.f150online.com/forums/sh...hreadid=173239

Rich

 

What everyone says is yes the 6lb creates more heat. The jury is out, but I believe that on a ported blower the difference isn't that big. Very few feel the 6lb is slower in the quarter. wydopnthrtl has had that experience against other trucks, but I have to believe that a 6lb in his truck would show a gain.

-Mark

*edit*. I went from a 4lb to a 6lb without changing anything else and made a small gain. .2 in the 1/4 and about 1 mph in 80 degree weather. Not the same day, but conditions were identical. This is on an Apten ported blower.

 

Every entire Best ET I have (except one)
is using 4lb INSTEAD of 6lb's

I have tried the same day, on the same track,
on the same tune, with the same conditions,
AND EVERYTIME I run FASTER with 4lbs

Some run 11's with a 2lb Upper only,
It's not ALWAY just about boost and over spinning the Eaton,
It more about Cooling Mods, and proper cool down.

If you sit there and hot lap in the summer heat,
YOU'LL RUN FASTER WITH 4LBS

If your like Gator/(Vinnie was), and thousands of others
that have aftermarket Heat Exchangers, Fans on the Heat Exchanger, Elec Fans and removal of stock Fan, Cobra Water
Pump, Intercooler Switch, maybe a Cool Can, or just icing the Upper and proper Cool down, HELLZ YA YOU'LL RUN FASTER.
But I have NONE of that, and for those that dont have these mods, more boost CAN work against you, BUT NOT ALWAYS.

Friday I go back to 4lbs and hope to come home with a
BEST EVER ET ???

 

It'll be interesting to see how you do.
Please check back.

 

I saw your posts over there, Rich.

Thanks.

BTW, I'm still battling getting more timing in my tune.

 

https://www.f150online.com/forums/sh...hreadid=167255

Here is an indepth argument from both sides...

Let me know if it is helpful... I know i was several pages long and there was a TON of info...

 

If I were to go from 4# lower to a 6# lower I would leave the 4# lower and add a smaller upper pulley. It would give you about the same total extra boost, but the supercharger will spool up faster.

 

I agree 100% to that statement!!

 

Really? I don't even understand that statement.

So long as the upper-to-lower ratio is the same how does the supercharger "spool up" faster with a smaller upper/smaller lower versus larger upper/larger lower?

 

bump

 

Tim Skelton , simple Logistics here. Whenver you have a Larger 6" Crank Pulley and working the stock Upper (2.93") Supercharger Pulley , you will attain the boost of say 14 lbs. at wide open throttle.

By going to a smaller 4lb. Lower Crank Pulley and changing the Upper Supercharger Pulley to a smaller (2.80") size, yes you will stlll attain the same boost levels at wide open throttle, but also in Theory, spinning the rpm's of the Supercharger faster (because of the use smaller Upper/Lower SC Pulley), to obtain the same boost levels.

However, the supercharger is spinning at a faster rpm rate now, because of the smaller Upper SC Pulley/Smaller Lower Crank Pulley, having less parasitic drag on the supercharger, hence the supercharger itself is indeed spinning faster, to maintain the same 14 lbs. boost under wide open throttle. Hope this helps.

 

I think you're getting caught up in over-theorizing. The blower spins at a rate directly mathmetical to the upper/lower pulley diameter combination. The blower does not care, or see a difference in which combination you use on upper/lower to spin it at a given RPM (except for belt slippage on smaller upper pulleys).
Bottom line, there is no difference in "spool up" if the final drive ratio is the same, even if you are using different combinations to get there.

l-Menace. That other thread did not seem to state engine RPM with 4 vs 6lb lowers, to over spinning the blower. I am trying to see at what (engine) RPM the 6lb lower overspins the Eaton, because I'm thinking that when racing in the quarter mile, perhaps our trucks spend very little time there, but I am not sure. If it's say, 4250 RPM, then the blower would spend a majority of its time being overspun in a drag race. If it's 5000 RPM, it wouldn't.

 

my cats breath smells like catfood

 

Okay.. I see now... Tim has a chart on his site regarding the STOCK eaton.
here
http://www.timskelton.com/lightning/.../dyno_data.htm

However I'd Love to see new info on the Apten ported Eatons.