SAE Adopts New Engine-Power Test

DETROIT - The Society of Automotive Engineers announces at its annual World Congress here significant new updates to improve the accuracy of the test standard auto makers have used for more than 30 years to rate the power and torque of light-vehicle engines in North America.

Equally important, the SAE also is introducing an all-new, voluntary test procedure designed to ensure the engine horsepower and torque figures derived from the new standard are more reliable and common across the industry.

David Lancaster, General Motors Corp. technical fellow-GM Powertrain, and a chairman of the SAE committee responsible for revising the standards, says engines tested under the new 2-stage system will list horsepower and torque figures with a new qualifier: SAE “Certified.”

Since 1971, engine horsepower ratings have been published by auto makers as “SAE net,” meaning the engine had been tested in compliance with the now-superceded testing procedure.

The new engine-rating system has potentially radical impact.

GM LS7 V-8 first to have SAE “Certified” power, torque figures.

The goal, Lancaster says, is to ensure greater commonality in the way engines are tested in order to derive the horsepower and torque ratings advertised to the public.

Lancaster says the “old” SAE standard that set forth the procedures for measuring horsepower - J1349 - has been updated to “remove ambiguity” in its language that left certain loopholes that could be exploited to exaggerate engine power.

Those ambiguities also opened the door to unintentional, but nonetheless undesirable, variability in the procedure itself. Some engines are believed to have conservative ratings in relation to their true horsepower.

Sources at Ford Motor Co. - which also participated in the committee that updated the J1349 standard - say the updates largely deal with the correction factors used when engines are tested.

In some past cases, manufacturers have taken advantage of J1349's loopholes to generate horsepower ratings that only could be achieved under the rarefied conditions of an ideal testing environment - but were unlikely to be replicated in the real world.

Last August, after roughly a year's work, the SAE finalized an updated version of J1349 that more precisely defines certain engine-operation parameters used when testing an engine to rate its horsepower and torque.

These stricter definitions, Lancaster says, close J1349's loopholes and ensure “a realistic condition the customer will actually see in the vehicle.”

In concert with the updates to the J1349 engine-testing standard comes an important new component: a voluntary test procedure - witnessed by an independent third party - that must be undertaken to earn the new “Certified” rating.

All auto makers now will test engines in compliance with the new J1349 procedure, but the certification test is optional - and likely to be at least somewhat controversial.

Lancaster says GM is fully committed to the certification component and strongly believes in the new level of procedural assurance it guarantees. The new J1349 testing standard “tells you how to run (the improved) test,” he says. “But how do you get people to adhere to the test?”

That's where the voluntary test, certified by a qualified witnessing party, assures the testing process subscribes to provisions of the new J1349 standard, says Lancaster. The voluntary certification test - SAE standard J2723 - was finalized March 31. It closely mirrors the ISO 1585 process auto makers undergo to certify engines under Europe's homologation rules.

GM, in fact, says it has the world's first production engine to bear the SAE “Certified” label for its horsepower and torque figures: the all-new LS7, a 7L OHV V-8 that powers the ultra-high-performance Corvette Z06 coming later this year.

A GM Powertrain spokesman says the LS7's Certified power rating is 505 hp at 6,300 rpm and 470 lb.-ft. (637 Nm) of torque at 4,800 rpm.

It is unclear, however, how many manufacturers will perform the voluntary new J2723 certification test, or if they do, what strategy will apply for selecting which engines in an auto maker's powertrain portfolio will be selected to undergo the certification process.

GM, at least, is fully committed to the new procedure.

“Within a couple of years, the vast majority of our engines will be SAE certified,” says Lancaster. “We are going to report numbers that are as honest as we can make them.”

Frank Sadni, Ford director of V-engine engineering, says the cost of the certification procedure is an issue that has yet to be addressed. Ford is likely to get more detailed cost information from potential qualified witnessing entities. “It's going to cost some money to do that,” Sadni says.

Regardless of whether cost is a prohibitive factor, Jerry Beamer, Ford engine performance development manager, says Ford is testing a variety of '06 model engines in compliance with the new J1349 standard, but currently has no plans to put engines through the voluntary J2723 certification test.

Ford, he says “is confident that our (internal) process for rating engines is very robust,” and the company sees no need to have its engines' horsepower and torque figures verified by a third party.

“Right now, this is about cost to the company,” says Sadni. “There's no value added (in undergoing the voluntary certification). (Customers) will get what we rate.”

Lancaster says the cost to undergo certification should be minimal.

“We've tried very hard to make a procedure that's as painless as possible,” he says. “Witnessing itself is not that expensive.” He says engines can either be sent to a certified witnessing agent's facilities, or a witness can certify the test procedure in the auto maker's own test cell.

A Chrysler Group spokesman would not comment regarding the voluntary certification test, saying only the company also was represented on the SAE committee that revised the J1349 standard.

Regardless of whether manufacturers seek SAE certification for their engines' horsepower and torque figures, it seems inevitable the new J1349 test could cut at least a few horsepower from an engine's current rating.

Lancaster says in addition to tighter specifications regarding engine conditions during the test, an important provision of the new J1349 standard “says you have to (test the engine with) the same hardware that's in the vehicle.”

That means, among other things, the hydraulic power steering pump now must be attached to the test engine. Before, the engine could be tested without the power steering pump, disregarding the parasitic drag the pump creates. This likely means a loss of a few horsepower for just about any engine.

“If exactly the same engine is run through (the updated J1349 test), its power may drop a little,” Lancaster says.

The potential minor horsepower losses may not cause headaches, says Ford's Sadni, because auto makers often have a few horsepower in reserve between the current SAE net rating and the actual measured figure.

But in some instances, many sources agree, testing an engine that used to make 300 hp and deriving an updated figure of 297 hp could create “downstream” headaches. That's why most auto makers are likely to continue to publish ratings for existing engines derived via the “old” J1349 standard unless it's deemed necessary to re-test under provisions of the updated standard.

“We will not go back,” to test existing engines, says a U.S. spokesman for Nissan Motor Co. Ltd. He adds that although it is too early for Nissan to solidify its position regarding the optional J2723 certification process, the auto maker may pursue the “Certified” rating of horsepower and torque figures for future engines.

“Anything that helps make sure everyone is on the same page, we'll likely buy into it,” the spokesman says.

If response is mixed regarding the J2723 voluntary certification test, all agree the SAE's newly revised J1349 standard is a valuable development.

Since 1971, when the standard first was instituted to improve on the widely abused SAE gross horsepower ratings that gave rise to some exaggerated ratings of muscle cars, J1349 has been revised several times, says Lancaster.

But thanks largely to sophisticated electronic engine controls and other innovations, the spirit of the original standard could not keep pace.

“When J1349 was originally written, we were running with carburetors and (mechanical) distributors,” says Lancaster. And, he adds, “the standard never said the intent (of J1349) was to give a customer a representative number. Having good, solid (engine power and torque) numbers provides a lot of benefit to us in the industry.”

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