Dyno Results

We made 3 pulls with my truck tonight. I was arguing with the dyno operator on how high to rev my truck up. He wanted to take it to 5500 max but I was like no, it needs to go up to 6500 for sure.

So on the first pull he stopped at 5700 rpms. It was still climbing but only gave a reading of 276.4 and torque peaked at 253.4 ft lbs @ 5500 rpms. A/F ranged from 11.8-12.4 throughout the run.

On the second pull, it was a back to back pull, it was running a little warmer than normal. He only pushed it to 6100 on this pull and it made 260.3 and was still climbing when he backed off. Torque was 235.5 @ 5700 rpms. The A/F was between 11.9-12.6.

The third pull, we turned the timing down from 36 to 32 and let it cool back down to 180 degrees. It made 252 hp @ 6000 and 219 ft lbs @ 5800 rpms. The A/F was from 12.1-12.6.

They put a couple hundred pounds of weight in the back of the truck but it was still spinning the tires on the rollers. He told me that he doesn't spin hyd tappet engines over 6,000 because they just collapse and lose power. I'm not so sure that these were the right results. He was even kinda confused about it.

BUT....Please watch the video and see how it put load on it. He didn't just stand on it, he would slowly bring the power up, hold it, then bring it up some more, and hold it, then bring it up the final time. He was doing it in like 10 mph increments or something. I might check into another local dyno and see if I can get one pull from them just to see.

They third dyno run: http://www.supermotors.org/vehicles/....php?id=237210
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Hhhhmmmm. I would expect a bit of power to be soaked up by the C6 and 9", though the GV OD might hurt RWHP as well.
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We were guessing it would lose roughly 30%. That would mean the engine is only makin abou 360hp at the crank. There is NO WAY that that is all its makin. A couple other guys were there watching they were wondering if he even had it floored once. My dad had his 01 F350 with a 7.3 diesel in it there too and it never really smoked or bellered. Its like he just played with the throttle and watched the mph. I'm still really doubting those results.
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Wasn't this a Superflow dyno?


http://www.superflow.com/autodyn/questions.html

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On 2005-08-22 23:04, 1 Bad 88 GT wrote:
Wasn't this a Superflow dyno?


http://www.superflow.com/autodyn/questions.html
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Yes it was. So, after reading this, he must have done the test in the Absorber mode: "Absorber: Controlled acceleration, speed step, drive cycle, deceleration, and track simulation, plus the two inertia tests listed above." So does that mean that he never actually had it at WOT? I'm kinda confused now, the test he did tests what your engine does at different cruising rpms. I wanted to know what it makes for peak numbers.
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If all you want is peak numbers than he should have done a simple 5-10 second inertia test. Basically you just get it into high gear(1:1) and floor it until you redline it. Let it cool down for a few minutes and repeat.




I was involoved with many dyno runs in my time at Kenny Brown and peak RWHP #'s are easy to come by.

So will the peak numbers be different if just a norma inertia test is done? And if so, do you have any idea what a real rough guess is on the difference?
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With a steady state test you will never have a true peak HP # since you are maintaining a constant RPM which naturally may not be the engines optimal rpm for HP production(EX; 5400rpm instead of 5634rpm or so on).


Now that being said you can get a true peak RWHP reading if the steady state test is held at or near the peak hp rpm of the engine and WOT is used while the load(water brake or eddy current) is being applied. This method is very dependent on the knowledge and experience of the dyno operator and his familiarity with the machine and it's software. If too little or too much load is applied it will skew the numbers very badly.



Personally, based on your specs and my specs I wouldn't hesitate to say your #'s are about 100rwhp low.
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BTW I prefer DynoJet's for their simplicity. Strap it down, hook up the spark lead, adjust the speedo and nail it.

Generally speaking, you will see higher numbers from an inertia syle dyno than you will from a dyno that puts a load on the drums/rollers.

Dynojet (inertia mode) vs Mustang dyno (loaded) can show a 5-10% or more variance in numbers. (The Superflow I use at Loynings Engine Service loads up the rollers.)

The main thing is to find a competent operator and stick with them for consistancy. There are variables that will effect the absolute numbers from dyno to dyno.

In your case, it sounds like a good operator with a Dynojet is what you're looking for.
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