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Pumping Losses

Is Your Water Pump Costing Power?

TEST ENGINE PARTS

Short block parts from Powerhouse
Crank #661-861-0125
Pistons #H345NCP .040
Rings Speed Pro E251K
King Bearings, Mains MB 557AM, Rods 807AM
Pioneer Balancer & Flexplate
Federal Mogul gasket set #260-100
Approx price $500

Valvetrain
Isky Hyd Roller cam #201265/272
HR lifters #2020
Pushrods #203-96
Timing set #300TS

Edelbrock Equipment
Cylinder Heads--E-Tec 170 #60979
Intake Perf RPM Air Gap #7516
Carb AVS #1806
Valve Covers #4153
Water Pump #8811

Ignition
Performance Distributors HEI w/ Live WiresOil system--Moroso

Machine Work & Assembly
Speed-O-Motive

Pumping Losses
We began our testing using a Weiand PN 8240 mechanical water pump, which, although made from aluminum, still runs a stamped-steel impeller, just like the impellers found in stock pumps. We felt this would be most representative of street power. We ran the pump overdriven first, to show the most power-robbing setup. Then we switched pulleys to see how much power could be gained by underdriving it. Lastly, we tossed the belt in favor of an electric pump to find the most power possible. You'll also note that we started all tests at 3,000 rpm. That's because pumping losses below that speed were minimal.
Test 1--Weiand #8240 mechanical pump, March #06061-6152 OVERDRIVE pulleys (5 1/2" water pump, 7" crank) 127-percent overdriven

Test 2--Weiand #8240 mechanical pump, March #06051-6052 UNDERDRIVE pulleys (6 1/4" water pump, 5 1/2" crank) 14-percent underdriven

Test 3--Weiand # 8217 electric pump.

Test 1Test 2GAINTest 3GAIN
O.D.U.D.U.D.Electric U.D. vs. Electric
RPMTQHPTQHPTQHPTQHPTQHP
30003902233932243139622634
32004042464092495341225132
34004152694182713242127332
36004182874212883142429133
38004193034233064342530721
40004173174213214442332221
42004163324193363442233832
44004163484203524442535654
46004153644193674342437154
48004123774143792241938354
50004053854073872241139144
52003933903983945440139733
54003833943873984438940022
56003713963754004437840333
58003593973634014436640433
60003453943483983435640666
MAX4193974234015442540666
AVG4023354063384340934133

WOULD A RECING PUMP HAVE WORKED BETTER?

You're probably wondering why we didn't also test a Weiand Team G race pump? That's because, while those pumps will use even less power to run than the street pump, they're designed for a higher rpm usage than this motor would see. The racing pumps are typically made for circle track engines that rarely run below 4,000 rpm. Our street engine will rarely see above 4,000 rpm so we thought that'd kinda' be like running slicks on the street. Sure, we know it'd work better, but it doesn't make sense for the everyday commute. Also, race pumps have impellers that are designed for efficiency at high rpm and will flow even less water at idle. Therefore, they may also cause overheating in traffic, just like underdriving your pump might do.

SOURCES
Dyno-Motive
Placentia
CA
7-14/-693-1317
Performance Distributors
Memphis
TN
9-01/-396-5783
performancedistributors.com
Edelbrock
Dept. 5.0
2700 California St.
Torrance
CA  90503
310-781-2222
www.edelbrock.com
Powerhouse Engine Components
931 19th St
Bakersfield
CA   93301
ISKENDERIAN RACING CAMS (ISKY)
16020 S. Broadway St.
Gardena
CA  90248
323-770-0930
323-515-5730
www.iskycams.com
Speed-O-Motive
131 W. Lang Ave.
West Covina
CA  91790
6-26/-869-0270
speedomotive.com
Lunati Cams
Olive Branch
MS
6-62/-892-1500
lunatipower.com
Weiand (A division of Holley Performance Products)
1801 Russellville Rd.
Bowling Green
KY  42102-7360
Moroso Performance Products
203-453-6571
moroso.com
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