So if I spin out of the first 60 feet, my mph will still be the same by the end of the 1320, then if I hook?
Actual HP numbers from vintage Mopar engines.
- Thread starter Bad B-rad
- Start date
So if I spin out of the first 60 feet, my mph will still be the same by the end of the 1320, then if I hook?
Magazine road tests.....
If the calculation is based on MPH, and weight at a given distance, then wont I be going faster if I dont spin my wheels when I shift?
I would think that calculation would measure how much power you can apply to the ground, at the given distance, not how much made, again gear ratio, temperature, altitude, tire slip, change them, the mph will change, wont it?
I would think that calculation would measure how much power you can apply to the ground, at the given distance, not how much made, again gear ratio, temperature, altitude, tire slip, change them, the mph will change, wont it?
33 IMP
Well-Known Member
I suspect that the motor trend test driver that shifts his hemi at the "5000 rpm" power peak will get different results than the hi performance owner who knows power doesn't peak till 6000, and shifts at 6200.
Do you remember all the warranty claims on the first 440 6packs? Nobody shifted those things at 4700!
Do you remember all the warranty claims on the first 440 6packs? Nobody shifted those things at 4700!
33 IMP
Well-Known Member
Probably not exactly the same, but much closer than the e.t will be. If you spin hard off the starting line, pedal it and get back in, you could easily slow down a half second or more, and yet lose only a mile per hour or two. Or maybe not even that. I have seen cars spin hard , and run better mph, from having more wheel speed after it hooks up.
I agree with above statement.
But what I am saying is too many things to take into account, the hp calculator, is only correct if you can apply all power to the ground all the time. Even then its only a tool.
But what I am saying is too many things to take into account, the hp calculator, is only correct if you can apply all power to the ground all the time. Even then its only a tool.
2016 R/T 5.7 stock 370HP
I have CAI, 6.4 FACTORY intake and exhaust, and a tune, and this claims I boosted the HP quite a bit!!!, and I spin at launch. Car weighs 4550, I have done 12.9 @ 106mph, I weight 250-260lbs(mostly weiner weight,LOL)
I have estimated 410-415HP out of the 5.7, with dyno tests from engines with similar mods,but I have never tested mine.
I have CAI, 6.4 FACTORY intake and exhaust, and a tune, and this claims I boosted the HP quite a bit!!!, and I spin at launch. Car weighs 4550, I have done 12.9 @ 106mph, I weight 250-260lbs(mostly weiner weight,LOL)
I have estimated 410-415HP out of the 5.7, with dyno tests from engines with similar mods,but I have never tested mine.
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And again" It runs better MPH, because of more wheel speed after it hooks"
, not because it suddenly gained more HP,
See what I am getting at, its just a tool, it is an estimate, the calculation is riddled with flaws.
CAN it be accurate, Yes, I am sure it can sometimes, but even a broken clock is correct twice a day.
I like chassis or engine dynos, and even with them, it can differ with mfg of dyno, and a host of other things.
But now a days it is the old seat of the pants dyno, that is the most fun, for me.
33 IMP
Well-Known Member
I have seen lots of cars pick up substantial e.t improvement from a converter or rear gear swap. The mph changes only slightly. And they didn't add one single horsepower to the engine.
In my personal experience, I have changed rear gear a few times and seen virtually no change in et, (kinda depends on the torque characteristics of the engine) but I did a converter swap that picked my car up from 6.50s to low 6.30s with no other change.
In my personal experience, I have changed rear gear a few times and seen virtually no change in et, (kinda depends on the torque characteristics of the engine) but I did a converter swap that picked my car up from 6.50s to low 6.30s with no other change.
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The MPH changing at all with no hp change shows why the calculation its an estimate, a tool and not an exact science, doesn't it?
I even posted where it states this on the web site.
It measures the power you used to move the weight, the distance, to the speed, not the actual power the engine is capable of making.
UNLESS 100% of the engines power can be applied, the full distance.(parasitic drive line loss is different for different trans, and rear combos, and tire spin)
And that isn't likely, on bias ply tires, by mag test guys, in the 60's and 70's
If I am wrong, then I am wrong, I have been wrong before and will be wrong again I am sure, just ask my wife.
Just used that calculator on a stock 2016 Charger R/T, 4800 with driver 103MPH claims 409HP
Dodge says 370HP how can 40HP difference be accurate?
I even posted where it states this on the web site.
It measures the power you used to move the weight, the distance, to the speed, not the actual power the engine is capable of making.
UNLESS 100% of the engines power can be applied, the full distance.(parasitic drive line loss is different for different trans, and rear combos, and tire spin)
And that isn't likely, on bias ply tires, by mag test guys, in the 60's and 70's
If I am wrong, then I am wrong, I have been wrong before and will be wrong again I am sure, just ask my wife.
Just used that calculator on a stock 2016 Charger R/T, 4800 with driver 103MPH claims 409HP
Dodge says 370HP how can 40HP difference be accurate?
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Yes, if everything else is equal.
Yes there are other factors that affect the mph/weight/HP relationship. Other than atmospheric conditions (which you can account for as well) the other variables are similar from car to car.
No, its not exact, or perfect, but is pretty close for street-ish cars in this power range based on personal experience with track time, and engine and chassis dyno time with the same cars. Furthermore, it is consistent, and way better for comparisons. Dynos, Magazine articles, YouTube videos are all fun. Just don't hang on too tight to the data.
Different people like different things,thats why cars come in different colors!!!
You can love and use the calculator,if that works for you GREAT!!
I have found them to always be a touch on the high side.
I, personally prefer engine dyno, or chassis dyno. But even those #'s can differ, IMO they dont seam to be off as much as the calculator.
I just posted two examples where the calculator was was off by 40 HP, and for me that isnt close enough.
We will have to agree to disagree on this one.
And that is fine with me, as I am sure we both have joined this site because a love for Mopar products, not our love to convince the other that they are wrong.
You can love and use the calculator,if that works for you GREAT!!
I have found them to always be a touch on the high side.
I, personally prefer engine dyno, or chassis dyno. But even those #'s can differ, IMO they dont seam to be off as much as the calculator.
I just posted two examples where the calculator was was off by 40 HP, and for me that isnt close enough.
We will have to agree to disagree on this one.
And that is fine with me, as I am sure we both have joined this site because a love for Mopar products, not our love to convince the other that they are wrong.
Can you post the details of the car's track time and weight or a link to it.
2016 R/T 5.7 (370HP)weight 4550lbs(empty tank, no driver) ET 14.0@103mph
Watch because a Charger SXT(6cyl) weights 4,264
And the 6.4 and hellcat also different weight
Its one from Motor week:
https://www.motorweek.org/reviews/road_tests/2015-dodge-charger
On post #67, I gave screen shots of the HP calculator that was used and numbers I input.
I have a 2016 R/T 5.7,only mods from stock are: factory 6.4 exhaust manifolds, and exhaust, and factory 6.4 intake, running stock 5.7 injectors, with a CAI, and tune. I also have 3.90 rear from a stick Challenger. So it started at 370HP, but I have a bit more, but I dont think I have added 76HP.
With me in it and I think it was just over 1/4 tank of fuel, and spare tire it weight was 4800lbs, My best ET 12.9@106
My other times for that day 13.02/105
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1966 Charger weight 3650-3920lbs, I can only guess mine would be very close to stock weight of any 66 Charger, except a touch lighter due to the aluminum Mopar duel plane intake, and I had disc brakes up front not drums, but full interior. so lets say my car weight was 3550lbs
That was a stock 67 383 2bbl, pulled from a 67 Newport, and I put the 4bbl on with Holly 750 with vacuum secondary's. It ran best 14.2 @98mph,
Just for fun,what does the calculator say it made?
Here are a few pics, and time slips, the lower one is from first run, I spun bad coming off the line,
last run of day, I dropped air pressure in my 14 inch cooper cobra's and got a 14.2@98mph
That was a stock 67 383 2bbl, pulled from a 67 Newport, and I put the 4bbl on with Holly 750 with vacuum secondary's. It ran best 14.2 @98mph,
Just for fun,what does the calculator say it made?
Here are a few pics, and time slips, the lower one is from first run, I spun bad coming off the line,
last run of day, I dropped air pressure in my 14 inch cooper cobra's and got a 14.2@98mph
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I was very proud as it was Close to 1967 Hemi Charger times.
Sorry the photos are old, and they are photos of photos, LOL
The 1967 Newport had 59,000 miles on it.
It looks like I had the C-body 2 bbl exhaust on it, going into straight pipes to Glass packs, as that was my fathers request!
but I did upgrade to headers, Hooker super comp, so they may have been on, at that point.
My old man got a great shot of me coming back on return road with the 14.2 time on the score board!!
Sorry the photos are old, and they are photos of photos, LOL
The 1967 Newport had 59,000 miles on it.
It looks like I had the C-body 2 bbl exhaust on it, going into straight pipes to Glass packs, as that was my fathers request!
but I did upgrade to headers, Hooker super comp, so they may have been on, at that point.
My old man got a great shot of me coming back on return road with the 14.2 time on the score board!!
33 IMP
Well-Known Member
On your 14.2/98 pass, calculated at 3750 with driver and gas in it (I think that number may be a bit light) the calculator I use says: from et...258 crank, 232 rw.
from mph...275 crank, 247 rw.
I'm very sceptical of the wheel horsepower number as it is stated that is simply a calculation of 10% less than flywheel horsepower. (I think 20% drivetrain loss is closer to the truth, especially with an auto trans).
I also did your 14.79/92.93 pass, both eighth and quarter. Best result of running those numbers was from 1/8 mile mph, said 251 fw, 226 rw. The rest of the numbers were worse (some quite a bit).
Like most results of these calculators, I take the results with a grain of salt.
from mph...275 crank, 247 rw.
I'm very sceptical of the wheel horsepower number as it is stated that is simply a calculation of 10% less than flywheel horsepower. (I think 20% drivetrain loss is closer to the truth, especially with an auto trans).
I also did your 14.79/92.93 pass, both eighth and quarter. Best result of running those numbers was from 1/8 mile mph, said 251 fw, 226 rw. The rest of the numbers were worse (some quite a bit).
Like most results of these calculators, I take the results with a grain of salt.
The 14.7,one, I left way late(not that that changes anything but R/T) Then I blew the tires off, let off, spun again, and then got it together.
I also remember that day, one of the last passes, the car getting squirrely 3/4 down the track,(at maybe2-3 shift??) was the first time I had that happen, was a little bit alarming for it being my first time at the drag strip with this car, never really got her crossed up at speed going straight untill then, LOL!!!!!
It was at Hemmings Musclepalooza #1!!!!
I also remember that day, one of the last passes, the car getting squirrely 3/4 down the track,(at maybe2-3 shift??) was the first time I had that happen, was a little bit alarming for it being my first time at the drag strip with this car, never really got her crossed up at speed going straight untill then, LOL!!!!!
It was at Hemmings Musclepalooza #1!!!!
Nate S
Well-Known Member
A good thing to remember in all of this is that published HP numbers are peak. Actual acceleration comes from area under the curve. A high narrow peak will do the same as an equivalent lower broad peak. Different numbers, same speed.
HP as a number is only valuable for figuring out how fast you can accelerate. There’s no absolute value to it except possibly for ego. The differences we see show just how important tuning is. The old car reviews were really stock. Car craft and super stock were likely to recurve the distributor, change timing etc. It didn’t take much to improve these. The 2 bbl engine etc likely didn’t have a stock dist curve, jetting etc. they got the benefits of going slightly off of stock.
These numbers also aren’t some absolute, even today. There’s an average and a standard deviation. It’s nice to have a feel for what was real back then, the calculator numbers give that in today’s figures. There’s still noise.
HP as a number is only valuable for figuring out how fast you can accelerate. There’s no absolute value to it except possibly for ego. The differences we see show just how important tuning is. The old car reviews were really stock. Car craft and super stock were likely to recurve the distributor, change timing etc. It didn’t take much to improve these. The 2 bbl engine etc likely didn’t have a stock dist curve, jetting etc. they got the benefits of going slightly off of stock.
These numbers also aren’t some absolute, even today. There’s an average and a standard deviation. It’s nice to have a feel for what was real back then, the calculator numbers give that in today’s figures. There’s still noise.
Usually if you spin and stay in it, it will mph the same, or slightly better.
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