Power loss

[Jgranville]

Hey y'all. I am a high school student in Ca. I am doing a research project and testing hp and torque with standard intake and exhaust and then after with a spectre cold air and thrush glasspack. I had the first dyno done and was shocked by the power loss. I have a 2000 expo xlt with the 4.6. My family has taken great care of it and our mechanic is a family friend and has done excellent servicing. I did some research and another ford forum said that the 4.6 in 1st gen expo should be around 220 hp and 265 torque. Three run on the dyno and I pulled 164 hp and 212 torque. That is a 56 hp drop! Doesn't seem right to me. What do y'all think? Is that normal?

The only thing we do with it beside normal driving is use it to launch our 3000lb boat. It is only up and down our private ramp on our property.

 

[Copper93]

The quoted HP and torque is at the crankshaft. You lose some from the drive train. I've heard as much as 25% but that sounds high to me. The add in the grade of gas, if it has ethanol mixed in, air temp and density, engine condition. Even the viscosity of the oil. Considering the Expy is 13 years old, that would be about right.

 

[FordandPolaris]

No matter how good you take care of it, seals still get old, rings wear out, and transmissions get tired. That being said, please post back your results, as I am curious the improvement you see if any. I have intake mods and a glasspack in my truck as well. I don't think I saw any HP improvement but she still pulls pretty good.

 

[Jgranville]

Thanks guys. I knew some of it had to do with age and unavoidable wear but 56 hp just seemed extreme to me. And , FordandPolaris, I will post the new results when I get them. I am taking it to be dynoed next Saturday.

 

[FordandPolaris]

It would also be interesting to see if power improves with new spark plugs depending on how old the current ones are.

 

[toms89]

I would expect about a 10-20% drivetrain loss. Higher losses for auto trans and 4wd vs 2wd and manual trans for instance.

Type of dyno makes a difference. Load dyno's generally read lower vs inertia dyno. Dyno operator can also affect the numbers. Test done with the motor at operating temps vs a heat soaked to the point the pcm is pulling timing.

Then there is the condition of your motor and its overall tune.



I still would have expected a bit more.

What type of dyno? Weather conditions? Corrected or uncorrected numbers?

 

[toms89]

If possible performing your test on the same day under the same conditions. This would give you the most accurate results. Engine temp, etc...

Post before and after graphs.