I was wondering if some of you could help me in converting my rear-wheel HP and TQ into flywheel HP and TQ. I've seen varying positions on this, but I'm still confused on driveline loss (is it a fixed HP, or does the loss increase as a % of total HP?). Anyway, here are the particulars:

rear wheel HP: 217
rear wheel TQ: 258
*Dynojet #s, corrected for temp, etc.

Transmission: 4R100 Auto
Engine: 5.4L
Truck: 99 F150 Ext Cab

Can anyone please help me in converting to "estimated" flywheel HP/TQ?

Your help is appreciated.

SlickWilly

 

i believe its roughly around 260 hp and 310 tq. if im not mistaken, theres a 20% drivetrain loss, so i added 20% to each number. someone correct me if im wrong...

 

You have to decide on what drive train loss percentage you are comfortable with and it ranges from about 11% to about 23% on the Lightning boards. Just exactly how much it really is is an 'argument' waiting to happen.

If you chose a 23% loss, then subtract that number from 100%=77%. Take the answer(.77) and divide that into your dyno, rear wheel numbers. The answer is your estimated flywheel HP and/or torque.

Your 217 divided by .77=218.82 HP.
Your 258 divided by .77=335.07 TQ.

Think I/m correct .

Dan

 

https://www.f150online.com/forums/sh...threadid=57394



this is my dyno with Cat back exhuast on it only The horse is at the wheel. The guys where I got it done said it was one of the higher stock F-150 5.4l Run they have had!!

I am getting ready to get a superchip from mike and an Airforce one Kit!!! Maybe even a set of pully's then I will re dyno it..

 

Check your math LightningRod, you mean 281.82?

 

Yep jr: I transposed the numbers

Dan

 

HI!... I've read that SUPERCHIP's with all their DYNO R&D that they claim the 4R-100 tranny and drivetrain steal 69H.P. The same drivetrain with a 4R70-W tranny steals about 65H.P. I would say you would be around 286H.P at the flywheel. If you had the 4R70-W, then you would be at 282H.P at the flywheel. Ever since I had a VERY long talk with MIKE TROYER and his years of dyno experience, I have been using this formula for our F-150's and it's been pretty much right on all the time. The only way to get the REAL actual flywheel H.P perfectly is to run the engine on a engine stand dyno. Then install it in the vehicle and then chassis dyno it. Then you would know the REAL drivetrain loss. But who's going to do that, eh?


SLICK ***** : With the mods done to your truck, your truck SHOULD be making a LOT more H.P than it currently is. I've seen bone stock 5.4 F-150's dyno out at 205RWH.P. Most are between 192RWH.P - 198RWH.P though. I think I got a healthy one! I would either run your truck again or go to another dyno shop. Have you run your truck down the 1/4 mile yet. Thetimes amd trap speed can tell you pretty much what your real H.P is.

 

Thanks everyone for your replies, I think I'm getting it!

Neal - I agree. I've read through some of Mike T's responses on driveline loss, and seems to be the most "conclusive" in trying to arrive at a fly-wheel horsepower number. Since I have the 4R100 tranny, I would add the 69hp to the 217 to get 286hp. I too think I should be producing more hp with my mods - who knows, maybe I got one of the "lower producing" 5.4's (my luck!)...wish I had your engine from the factory. Mike T. optimized my flip-chip for my headers to squeeze any additional hp from 93 pump gas, so I thought I would see some decent numbers. When I installed the flip-chip on the high-performance program, it felt like a signficant amount of power was added, especially under WOT.

I havn't taken my truck to a track yet, but I plan to this spring. I've had a hard time finding a track in the Dallas/Ft. Worth area - the Texas Motor Speadway said they don't open the track to ameteur time runs with their own vehicles, so I'm still searching. In the meantime, I think I'll try to find a different Dyno shop to validate the previous run. The truck does feel strong with my mods, but perhaps I am comparing to less than 260hp stock.

I'll post my second dyno run after I find another shop.

Thanks again,
SlickWilly