2.90 pulley+stock Eaton

[SCMOKN]

I am Gathering parts to do an Eaton swap on my Mach 1. I picked up a Eaton with a 2.90 pulley on it. What kind of boost will that be putting out? Thanks, David.

 

[Jimmysidecarr]

I am Gathering parts to do an Eaton swap on my Mach 1. I picked up a Eaton with a 2.90 pulley on it. What kind of boost will that be putting out? Thanks, David.

http://www.svtperformance.com/forum...ator-frequently-asked-questions-new-guys.html :beer:

 

[Silver2003Cobra]

1 meeelion psi

 

[SCMOKN]

Well Jimmy at least your response helped out. I did look but came up with nothing on my search.

I guess I better get a bigger one since my engine won't handle "1 meeelion psi" !

 

[Spoolx]

Guess you didnt actually read what Jimmy posted so I will help you out.. I know its tough to search... /sigh

3.6.1.


Upper and Lower Pulleys


One of the easiest modifications for a significant performance gain is to swap the stock 3.65 upper pulley for a smaller pulley and custom tune. Two of the most common sizes are the 2.93/2.90 and the 2.76. For example, a 2003/2004 Cobra with only intake and exhaust mods can make in the neighborhood of 450rwhp and 470rwtq with the addition of a 2.93 upper pulley and a good, safe custom tune. Many prefer to include a larger lower crank pulley change as well, but replacing the lower pulley is much more labor intensive than replacing the upper pulley, which is why an upper pulley swap is so popular.

The chart below shows the approximate boost various upper and lower pulley combinations will produce. Note that it is recommended that a stock, unported Eaton blower should be kept in the 15 lb. max boost area. A 2.76/2.80 or 2.93/2.90 is a popular choice. A ported blower is more efficient and can handle 16-17 lbs. of boost nicely. A 2.93/2.90 upper with a 2.93/2.90 upper and 2.76/2.80 upper with a 4 lb. lower are popular choices for a ported blower setup. Some prefer the 2.93/2.90 upper with a 6 lb. lower. Discuss your options with your tuner and, if applicable, the shop that ported your blower.

NOTE: Estimated Peak Boost in the table below is just that...an estimate. Boost will vary from car to car depending on your mods. It is important to remember that a Terminator making 450rwhp with 12 lbs. of boost is more efficient that another Terminator making the same power with 14 lbs. of boost. Also, please use the information in the chart ONLY for general comparisons. The chart does not take into account the varying combinations of intake and exhaust and weather conditions. To really be accurate, every combination listed would have to be with the exact same intake/exhaust mods, on the same car on the same day. So it is only a guide.

Please note that the Lower Pulley Sizes shown in the chart are all measured "from the top of the tooth" according to the Metco Motorsports website.
Pulley
Combination Lower
Pulley Size
in Inches Upper
Pulley Size
in Inches RPM (%
over stock) Est. Boost
(psi) Blower
RPM @
6500rpm
Stock 7.60 3.65 0.00% 8.6 13,534
2 lb. 8.00 3.65 5.26% 10.7 14,247
3.40 7.60 3.40 7.35% 11.0 14,529
2 lb./3.40 8.00 3.40 13.00% 12.0 15,294
4 lb. 8.60 3.65 13.16% 12.0 15,315
3.20 7.60 3.20 14.06% 12.1 15,438
3.10 7.60 3.10 17.74% 12.6 15,935
6 lb. 9.10 3.65 19.74% 12.9 16,205
2 lb./3.20 8.00 3.20 20.07% 13.0 16,250
4 lb./3.40 8.60 3.40 21.48% 13.2 16,441
2 lb./3.10 8.00 3.10 23.94% 13.5 16,774
2.93 7.60 2.93 24.57% 13.5 16,860
8 lb. 9.55 3.65 25.66% 13.7 17,007
6 lb./3.40 9.10 3.40 28.54% 14.0 17,397
4 lb./3.20 8.60 3.20 29.07% 14.1 17,469
2.80 7.60 2.80 30.36% 14.2 17,643
2 lb./2.93 8.00 2.93 31.13% 14.3 17,747
10 lb. 10.00 3.65 31.50% 14.4 17,794
2.76 7.60 2.76 32.25% 14.4 17,899
4 lb./3.10 8.60 3.10 33.23% 14.5 18,032
8 lb./3.40 9.55 3.40 34.90% 14.7 18,257
6 lb./3.20 9.10 3.20 36.57% 14.9 18,484
2 lb./2.80 8.00 2.80 37.22% 15.0 18,571
2 lb./2.76 8.00 2.76 39.21% 15.2 18,841
4 lb./2.93 8.60 2.93 40.96% 15.3 19,078
6 lb./3.10 9.10 3.10 40.96% 15.3 19,081
8 lb./3.20 9.55 3.20 43.33% 15.6 19,398
4 lb./2.80 8.60 2.80 47.51% 16.0 19,964
8 lb./3.10 9.55 3.10 47.95% 16.0 20,024
6 lb./2.93 9.10 2.93 49.16% 16.1 20,188
4 lb./2.76 8.60 2.76 49.65% 16.2 20,254
6 lb./2.80 9.10 2.80 56.09% 16.7 21,125
8 lb./2.93 9.55 2.93 56.54% 16.7 21,186
6 lb./2.76 9.10 2.76 58.35% 16.9 21,431
8 lb./2.80 9.55 2.80 63.80% 17.3 22,170
8 lb./2.76 9.55 2.76 66.18% 17.5 22,491


Special note concerning idlers. It is not uncommon for those who install a smaller upper pulley to stick with one or more of the stock idlers. It is important to point out that increased blower boost (and subsequent belt rpm) from smaller upper pulleys will add more tensional torque than the stock idlers are designed to handle. Therefore it is important to swap out all of the stock idlers with quality aftermarket idlers. There have been many reports from owners who have had stock idlers come apart or seize up, resulting in broken blower belts and loss of blower function.

The lower crank pulley can be changed as well to increase boost. The larger the pulley, the more boost. Here are some approximate boost numbers.
Approximate Lower Crank Pulley Max Boost
2 Lb.: 10.7 lbs.
4 Lb.: 12 lbs.
6 Lb.: 12.9 lbs.
8 Lb.: 13.7 lbs.
10 Lb.: 14.4 lbs.

 

[SoCalHarley]

The 2.93 on mine makes 13.5 lbs.

 

[shb5007]

The 2.90 on mine makes 12.5 lbs.

 

[SCMOKN]

Guess you didnt actually read what Jimmy posted so I will help you out.. I know its tough to search... /sigh

I guess you did not read what I wrote! He did help me out and as I said I did search!oke:

 

[Spoolx]

I guess you did not read what I wrote! He did help me out and as I said I did search!oke:

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