Engine HP vs. Rear Wheel HP
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Tuned
Joined: Jul 2003
Posts: 277
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From: NY
Engine HP vs. Rear Wheel HP
I was at the hypertech.com web site today looking over some of the dyno charts for the Ford 5.4 engine. since the expy wasn't there I decided to pick the 2001 F250 with the 5.4 and auto trans, i figured it was close enough.
Knowing that the stock 5.4 is rated at 260@4500RPM, I was perplexed to see that the dyno chart said the max HP for this engine stock was 163@4800RPM. I am asuming that the reading is at the rear wheels but that is still very low. That would mean that you are losing almost 38% of your power in the drive train, that just doesn't seem right. I have heard of transmission losses if 10% but not 38%.
Next, I checked to see if this was similar across the board with other trucks. So I went and did a compairson on the 2000 GMC 5.3. Hypertech rated the HP at 256@5000RPM and the chevy spec is 255@4600. Now I was really confused.
Are these numbers by Hypertech bogus or are we really loosing 38% of our power through our drivetrains in our expys? I hope we aren't and it sure doesn't feel like we are.
Does anybody have any ideas?
Mark
99 XLT 4x4
Knowing that the stock 5.4 is rated at 260@4500RPM, I was perplexed to see that the dyno chart said the max HP for this engine stock was 163@4800RPM. I am asuming that the reading is at the rear wheels but that is still very low. That would mean that you are losing almost 38% of your power in the drive train, that just doesn't seem right. I have heard of transmission losses if 10% but not 38%.
Next, I checked to see if this was similar across the board with other trucks. So I went and did a compairson on the 2000 GMC 5.3. Hypertech rated the HP at 256@5000RPM and the chevy spec is 255@4600. Now I was really confused.
Are these numbers by Hypertech bogus or are we really loosing 38% of our power through our drivetrains in our expys? I hope we aren't and it sure doesn't feel like we are.
Does anybody have any ideas?
Mark
99 XLT 4x4
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Joined: Nov 2001
Posts: 4,742
Likes: 8
From: OK
For standard (manual) transmissions, a 10-15% loss is normal. An automatic transmission has somewhere around 25% loss. I think Hypertech's numbers are a little off. Probably done to sensationalize their product's performance.
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Tuned
Joined: Jul 2003
Posts: 277
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From: NY
Then are the Chevy posted HP numbers at the rear wheels or engine HP. Because according to Hypertech they recorded the same number as Chevy publishes in there truck specs.
This must mean that Ford publishes engine HP and Chevy publishes rear wheel HP, correct?
Mark
99 XLT 4x4
This must mean that Ford publishes engine HP and Chevy publishes rear wheel HP, correct?
Mark
99 XLT 4x4
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