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Discussion Starter · #1 ·
I was just wondering if any of you guys with dyno results have tried out the Ford Muscle horsepower calculator to see how accurate it is?

The reason I ask is, according to the HP calculator, it would only take about 350 flywheel hp to propel my '85 Ranger shortbed to 12 seconds flat (assuming it weighs 3000lbs; right now with the 4 banger and me inside it's 2800lbs). I realise that it doesn't account for wheelspin or manual shifting, but dang, I'd wet myself if I actually got into the low 12s when I finish doing the V8 swap!
 

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Well, it is as accurate as you can get with just two variables. I mean weight can come in many ways... a 3000lb gutted Winnebago wont run the same ET as a 3000lb mustang, due to aerodynamics... so keep that in mind regarding the Ranger.
 

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I don't believe it is accurate but for mostly human or practical reasons. The F=MA stuff is there in the calc and thats just basic physics. In the real world however, you don't have perfect traction when you leave the line and you don't have perfect no loss gear shifts even with a full manual racing automatic. I also use a 20 percent off gross hp factor for my own calculations and have found it to be a bit more realistic but then I'm running an automatic.

Using my own fudge it takes more like around 325(405 - 405*.2 = 324) at the rear wheels to run 12 flat which is around 405 gross horsepower for that 3000 pound car/truck.

The gear/rpm/tire size calc needs a factor for converter slip in it for us automatic people too.
 

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Discussion Starter · #4 ·
Hottarod: What Comp cam are you running? Your setup looks about identical to what I plan on building: 289 stock crank and rods with ARP bolts, Comp solid 282 magnum, WP Windsor Jr. or Sr. heads (can't decide which), single plane intake (I was thinking of using the Weiand Xcelerator), 650 double pumper, and L&L V8 ranger swap headers (1.5" primary long-tubes). I was hoping to hit in the neighborhood of 350-400hp with this combo, and judging by your ETs, you must be right around there.

P.S. Interesting story about your backward 12.5 ET, I think I'd have to change my pants after that one, LOL!
 

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I'm running a Comp solid 294 advertized with 248 @ .050 with .560 lift. I don't have the part number handy.

There may be a couple more tenths in my setup if I can figure out what to change. With the new tires I picked up 2 tenths by the 8th(7.90's) but lost it all by the end of the quarter. That tells me it is actually slowing down on the top end with the higher run out rpms. I'm about to get some Super Comps for it and see if that will help. I may run out of carb cfms next, LOL.
 

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Discussion Starter · #6 ·
I looked at that cam, but I figured it was a little bigger than I wanted to go. Dyno2K shows peak HP at 6000 with the 282, while the 294 picked up about 10-15hp and moved the peak to 6500, but made much less torque below 5000rpm. Overall it shows your combo making 380hp @ 6500 and 345ft/lb at 5200. Does that sound close to what you think it's making? What RPM do you shift at?
 

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Sorry fella`s, but according to my dyno results before I changed the heads and cam the FM calculator came up about 40hp shy of where I was at, not sure what happened, but I dynoed at 282 and the FM calculator comes up 244.
 

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Discussion Starter · #8 ·
Nastystang: that's where the traction, shift-time, gear ratios, etc. come into play. With perfect traction, instant shifts, and gears that keep you right in the sweet spot of your powerband, you could have run that fast with only 244hp. However, since you loose some time shifting, and also can't keep your engine at peak power all the time, it takes you 280hp to run the same time.

That's the kinda info I was looking for, though. I want to know how far off it is to real-world testing.
 

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I shift at 7000. I haven't dyno'd my setup so I don't know what my numbers are for sure. All my estimators estimate it at around 375 or 380. I guess thats not bad f or a 289 but I was wanting that magic 400 out of it.

I guess somewhere between 5 and 8 percent is typical depending on the converter for a slip rate. I use .07 for mine which is an 8 inch 4500 stall. It has the net effect of changing final gear ratio to a 1.07 or whatever instead of 1:1. If you have a calc that assumes lock up you need to know what your trap rpms are at speed. Subtract lock up rpms in the calc from what you actually trap at and calculate that number as a percentage of your trap rpms. Thats the converter slip rate.



<font size=-1>[ This Message was edited by: Hottarod on 5/3/02 9:17pm ]</font>
 
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