Ported eaton with 2.4 vs 2.6 and 10% lower

[Mike93SVT]

Picking up a ported eaton with a 2.4 pulley and curious about that pulley vs running a 10% lower and 2.6

I understand the 10% lower will bring more mid range torque which is a good thing because I'm adding cams. But is it worth the cash since this is fitted with the 2.4?

Combo will be:

Jokerz ported eaton
VMP elbow
CJ 65mm
JLT 127mm CAI
BPS cams
Off road H pipe
13/14 injectors

Thanks
Mike

 

[sweetlou1182]

Do you have anything for cooling mods? If you're running a ported blower with a 2.4 that thing is gunna run hot as hell. You will make more power with the 2.6 and 10%, not a ton more but little more power and it will run a lot cooler.

 

[Mike93SVT]

AFCO HE, thermostat

 

[Kevin P]

I am not sure how people come up with the idea that the 10% lower makes any more power or runs cooler than getting the same blower speed out of a smaller upper pulley, UNLESS there is belt slippage. 2.6 with 10% lower is very close to overall blower speed to a 2.4 with stock lower (about 1% different.) Blower speed is blower speed though, it doesn't matter how you accomplish it. Now, the older cars (07-08??) with the huge/heavy lower crank dampner might benefit..

I have a ported eaton with a 2.4 and it makes 565rwhp on Blankenship's Mustang dyno.

 

[Mike93SVT]

I am not sure how people come up with the idea that the 10% lower makes any more power or runs cooler than getting the same blower speed out of a smaller upper pulley, UNLESS there is belt slippage. 2.6 with 10% lower is very close to overall blower speed to a 2.4 with stock lower (about 1% different.) Blower speed is blower speed though, it doesn't matter how you accomplish it. Now, the older cars (07-08??) with the huge/heavy lower crank dampner might benefit..

I have a ported eaton with a 2.4 and it makes 565rwhp on Blankenship's Mustang dyno.

appreciate the feedback and results.. I have no experience with the lowers. Every post I've read on them people comment on the tq improvement.

fortunately both pulleys are Metco. so I can run the 2.4 for now and get the lower later on and see what difference it makes. The lower would still be used later on for a TVS when I'm ready to drop a bunch more coin on a clutch, BAP, ID injectors, driveshaft, etc..... Damn, these cars get expensive after 600hp

thanks
Mike

 

[IronTerp]

Mike, you can produce some nice power with the 2.40" upper. Below are results I have had with different supporting mods with the 2.40. In April I switched from a 65mm Ford Racing throttle body to a 67mm VMP and hit 608.87 RWHP and 577.95 RWTQ at 22 degrees of timing.

http://www.svtperformance.com/forum...st-Dyno-Results-Ported-Eaton-Setup&highlight=

As others have said, definitely have to control the heat. Not an easy task with the M122. Running the 2.60/10% lower will most likely get you another pound of boost, and that will generally equate to 8-10 more RWHP, (if you control that heat!!).

Insofar as the bigger lower = more torque issue, I've been round and round with this one for years. Was initially a "blower speed is blower speed" guy, regardless of how it is achieved. After discussions with Jon Lund and Hermann Stolzenberg (Horsepower By Hermann) about the literally hundreds of dyno results they had experienced, came to understand why the lower pulley does indeed produce more torque per blower RPM, than does the upper only setup at same given blower speed.

In Hermann's words:

The lower drive drives all the accessories, including the supercharger. With a larger diameter lower pulley the speed that the upper pulley turns is ramped up QUICKER due the increase in mechanical leverage because of the diameter increase of the lower pulley. Even if the the final blower drive ratio is the same the blower speed will hit faster due to this increase in leverage. In simple terms think of it as a rear end gear change for the blower. Hope this helps some....and I DO find that lower cars do make better torque #'s on my dyno that stock lower cars. Hermann:beer:

All this being said Mike, I'd stay with the 2.40"!

 

[Mike93SVT]

Great info. Thanks for sharing

Mike

 

[ShelbyGT5HUN]

IronTerp,

Very impressive results of 609rhwp on a 2.4 pulley. I didn't know that much power could be had out of the stock blower. Was that on 93?

 

[IronTerp]

No sir. At 22 degrees of timing, I run 100+ octane. I'm not big into dyno numbers, but have been on three different dynos and gotten similar results. The initial 578 RWHP was at Blankenship Performance, got a retune at Johnny Lightning in April, 14 and hit 589 RWHP on 19 degrees of advance, then added a VMP throttle body and bumped timing to 22 degrees this past spring and hit the 608 RWHP.

I've seen a 4-6 horsepower increase per degree of timing with the M122 if the heat is controlled. And really like the VMP 67mm TB. On my setup it has had much better driveability than the Ford 65mm, and VMP's claims of 10 more RWHP was pretty accurate in my case.

 

[Kevin P]

What Hermann said makes no sense at all from a physics standpoint. I am willing to accept that he and Jon Lund have seen enough dyno sessions to indicate the lower makes a bit more power, but there is something else at play. Blower speed is tied directly to engine speed. Again, if all the dynos show a bit more power, well ok then, I will believe it.

 

[IronTerp]

I hear you Kevin. Believe me, there were 3-4 years worth of discussions with the Terminator guys back in the mid-2000's about this, as the infamous "over spinning" dialogue was in full force when the bigger lower pulley rings entered the market. I even met with two physics professors at the University of Maryland, where I worked at the time, and couldn't get any viable explanation. They were more focused on the power robbing affects of the heat production caused by the increased blower RPM.

My take on the lower pulley/torque question was that the leverage advantages derived by the affects of the bigger lower pulley ring, causes the upper pulley (and thus supercharger rotors), to have a higher accelerative affect, thus resulting in a higher low end torque hit. And as you inferred, whether we really know why it happens or not, numerous dyno testing by reputable operators/tuners has backed up the claim that the lower pulley has a greater affect on torque production.