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Discussion Starter #1
Before i get to numbers I wanted to let everyone know I was doing an experiment yesterday. I ran Twice. Once in the morning and once late afternoon. I got Stock numbers and Numbers with my Quad 160 in the 160 setting.

Info on th Truck:
2004 F350 CC LWB 61,000miles
Zoodad Mod
CCV Reroute
Quad 160 Box

Runs were done in 5th gear. I would get to 70 MPH and roll into the pedal. My runs were fairly consistant and I could get back to back runs at each level within about 1 HP of each other.

Runs in the morning.
Stock 300HP/502TQ Corrected ---- 272HP/455TQ Uncorrected. CF ~ 9.3%
Quad 417HP/746TQ Corrected ---- 377HP/671TQ Uncorrected CF ~ 9.5% (the Stock and Quad Box runs were only a few minutes apart) :shrug:

Runs in the Afternoon
Stock 306HP/514TQ Corrected ---- 267HP/448TQ Uncorrected CF ~ 12.7%
Quad 418HP/742TQ Corrected ---- 364hp/646TQ Uncorrected CF ~ 12.9%

Now I think that we can all agree that there is no way that a 6.0 with only a Zoodad would be putting down 300+HP to the wheels at sea level in perfect condtions. So we know that that part of the CF is bogus.

What surprised me was that Between the morning and the afternoon run a vehicle that makes its own atmosphere actually lost 5HP(1.9% drop) in stock form and 13HP(3.1% drop) Turned up. Now I know that there is the fact that I rolled on to the pedall different and other factors. The fact remains that I LOST hp between runs with nothing done between the two runs. On the other hand using the CF I made roughly the same numbers. This tells me that if you are using the CF for tuning you will actually be able to see what your mods are really doing. Remember I did NOTHING to the truck between morning and afternoon and my uncorrected numbers dropped, but the CF stayed pretty close to being the same.

After I thought about and talked with the Dyno owner we came up with the reason why. Perfect atmosphere is 14.7 PSI. Your boost shows your boost at anything above atmospheric pressure. So 30PSI Boost + 14.7PSI (perfect atmosphere) =44.7PSI absolute pressure. Now say you have a hot, dry day and the atmospheric pressure is down to say 13.5PSI. You will still see 30PSI on your gauge but your absolute pressure is now 43.5 PSI. I Haven't even talked about the fact that you are working with warmer air to start with which means less molecules of oxygen per cubic foot of air.

So is the Correction factor BS? Yes and No.

Yes, if you THINK your truck will put down at sea level what the CF says.

No, because if you use the same dyno you can have repeatable conditions. Basically if you Dyno in February, then do some upgrades and come back in dyno in Mid august you could see what happened to your performance. If you only used Uncorrected numbers you might actually see a loss in HP even though you know that the truck is quicker. Using the CF your HP numbers would level that playing field whether it is August or February.

Uncorrected I am at 376.6. I know that a cat delete and a better than stock Muffler I bet I can get close to 400 Uncorrected HP. :Thumbup:

3,353 Posts
I need to go see a dyno jet in action. The dyno shop we use for our dyno days is a mustang dyno. I'd like to take a look and compare the two. See how each one differs in how they are ran.
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