Undercar: Diagnosing And Repairing Wheel Bearing Noise
David Vizard Dyno Tests Joe Gibbs Racing Oil –
In Joe Gibbs’ Racing Engine!
Back in the spring of 2005, I received a call from Joe Gibbs Racing’s (JGR) Lake Speed, Jr.
Lake had called to tell me about the new flat tappet racing oil that they had brewed and were running in Tony Stewart’s #20 car. He sent extensive test results (run then on a "Busch" motor) and I had to admit, they looked good.
The numbers Lake had sent were comparisons of a number of top, high quality racing oils, versus their new flat tappet XP2 oil. These results showed an improvement of about 1.68 hp increase over the next best oil. To maximize power from these engines it’s necessary to build an engine with low friction to start with. This means low tension rings, etc.
Because these engines are inherently low friction units to start with showing any improvement is difficult, so, bearing that in mind, the gain shown looked good.
The first engine I tested JGR’s XP2 oil in was a hydraulic flat tappet "cammed" 5.0L Ford motor making a nominal 350 hp. To get our baseline numbers, 10 pulls were made with all significant parameters held constant at the start of each run. The best and worst numbers were then thrown out and the remaining 8 averaged.
Next a flushing oil/filter change was made using XP2. The engine was then run for about 5 minutes and a final oil/filter change made.
Again 10 runs were done. After the best and worst were thrown out the average increase came to 5.86 hp! Although I was very sure of the test procedure I was far from happy about an increase this large. As soon as the opportunity arose I ran the same sort of test with my dirt car motor.
This Super Street Stocker equipped with a 350 Chevy was sporting a solid flat tappet cam conforming to a .500" valve lift rule. This test showed XP2 to be 3.1 hp better than the Mobil 1 baseline oil. This looked a little more realistic but just to seal the deal I asked Lake Speed if I could come along and sit in on a re-run of their original tests.
Please understand that although my dyno works well and is regularly calibrated it is hardly the million dollar plus deal that JGR’s #1 dyno is.
With a restrictor plate motor on the JGR dyno, the same 10 runs were done. So you have an idea of the accuracy of this dyno the mean deviation of all 10 runs is contained within 0.3 hp. This gave me great confidence in the accuracy of the numbers delivered. The oil change, with flushing, involved the use of over 20 gallons of XP2. The results of subsequent tests showed an average of 1.88 hp increase.
Although the foregoing looks much like a power test it should be remembered that NASCAR NEXTEL Cup car engines have to use flat tappet cams, which, in an effort to get power, are very hard on the valvetrain. Since JGR engines are not only showing good speed but also surviving, I made the assumption that this oil is up to the job of keeping the lifters and cam profiles in shape.
As for the big increases on my tests, I’m assuming that in the first test the lifters were sealing up better, hence the relatively high number. In the second instance the dirt motor, being built all of cost-cutting parts, does not have the benefit of ultra low friction as a starting point.
Ex-aerospace engineer David Vizard, is one of the world’s most widely published automotive writers. He is also a university lecturer, holds numerous patents and is a winning engine/car builder.