RWHP/FWHP and E/T thread

Thought it would be interesting to put a thread together for those who have the 'big picture', or at least most of it in regards to the specs of their car.

I think it would be great to see ACTUAL (dyno, not guesswork) HP numbers, either to the wheels or at the crank, race weights and maybe even gearing along with your best E/T's.

I know the calculators do a decent job, but I have seen cars run a lot better than what the calculators say (and some worse).

Just list

RWHP or FWHP
Best E/T
Race Weight
Any other info that may be pertitnent (gearing, tire size etc..)


Who wants to start?!

3755#s 440 E-body w/ driver (track’s digital scales)
- 10.57 @ 126.0 w/ 1.46 60-ft (best of 10.52 @ 126.5 w/ 1.45 60)
- Calculated HP for weight & 126.0 MPH = 586
- Actual engine dyno flywheel ~610 HP & 570 torque (estimating 4% loss from 610 to 586 for full exhaust, alternator, etc.)

BradH, What calculator did you use? The one I have always used here
https://robrobinette.com/et.htm shows you needing 740FWHP to run a 10.5. I used to use the Moroso slide rule , but nobody I knew ever seemed to agree if it was actual RWHP or engine HP you were using to calculate E/T LOL
Seeing your numbers gives me hope that 675+ FWHP in my E body that weights hopefully under 3550 race weight could run a high 9.

340 RWHP
11.87 at 112 mph, 7.54 at 91.2 mph 1/8 mile
3700 lbs. w/ driver
448" wedge N/A w/ 727, 3.91 gear, 26x10 tire

508 RWHP on the local Dynojet chassis dyno
10.40 at 129 mph, 6.62 at 104 mph 1/8 mile
3700 lbs. w/ driver
446" wedge N/A w/ 727, 4.10 gear, 28x10.5 tire

634 RWHP on the same dynojet
9.54 at 140.4 mph, 6.05 at 112.9 mph 1/8 mile
3800 lbs. w/ driver
572" hemi N/A w/ 727, 4.10 gear, 295-65 drag radial (30x10)

72duster #3300 race weight 408stroker Eddie heads.
355rwhp
2800 stall
4.10 gear
28" slick
Ran 11.24@118.78 three days after chassis dyno run.

515 RWHP
10.11@132,6.42@107
3450# w/ driver
392" G3 Hemi, 4.10 gear, 325/50/15 radial

The Moroso one is Crank HP

My wife's car :

535 FWHP
10.65 @ 125
I think the car is right around 2900lbs, but haven't weight it lately.


I know engine dyno's can be a bit off from one another. I know a guy that had his motor dyno'd 2 years ago made 815 hp. Had it freshened up this winter and only made 765 hp on a different dyno but the car still runs the same. The 2nd dyno he used was a brand new calibrated dyno, not sure on the 1st on.

http://www.moparts.org/Tech/tech/index.html

I use the "Quarter Mile HP" calcuator there, which generates #s identical to my Mr. Gasket Hot Rod Calculator. I've always believed it's flywheel HP, since the #s are right in line w/ Dwayne Porter's dyno where my engine was tested the last two times. However, those engine dyno #s could be very different for the same engine run on a different dyno, so they're only relative to THAT dyno, IMO.

You can't estimate HP from ET. I can have a totally hosed 60-ft due to tuning issues, but the car will still MPH pretty much the same. The ET for any given MPH is an indicator of how well the chassis, converter, etc., are sorted out. The MPH tells you how much "oomph!" the engine is making to push a car that weight to the observed MPH. NFW my car made anywhere near 700 HP, regardless of what that HP for ET calculator claims.

Two motors ago..... Dynojet
588hp
3060lbs
408, w5s
727
4.30 gear
9.55@139.99

I always used>
http://www.wallaceracing.com/accel-calc.php
which I assume to be Fly hp

according to my old actual track slips>

3000lbs '69 Cuda, stock 440SP block, 9.8:1, solid cam/2.14 906's, 850DP, 2" f/wells etc.
best was 10.7@124.8 = 484 fwhp

3550lbs '71 Cuda, stock 340, .484/284 hyd. HSD intake 750DP, hdrs etc.
ran a best of 13.29@101 = 300 fwhp

Same car with .590/312 solid, 850DP, lower gears better conv, race hdrs
ran a best of 12.49@107.6 = 360fwhp

all these figures seem reasonable to my motor specs and fwhp numbers.

Only thing with Wallace is that if you get into the very light cars or S/SS cars the numbers seem to go way out.

468 Rear Wheel HP
11.94 ET
113.9 MPH
4125 lbs race weight
3.54 gear
30" tire

I consider the Moroso slide rule to be the default "target" for performance....... IF the dyno numbers aren't BS.

A really well sorted out car can surpass the Moroso slide rule, but most won't.

From my experiences, if you have pretty accurate engine dyno data, you should be able get the hp number on the Moroso slide rule to come within about 5-7% of your corrected hp, based on speed. This assumes you're not running at altitude adjusted tracks.

For example, if you have a 500hp motor(std corrected hp), and put it in a 3600lb race weight car, you should be able to get it to go between 119(465hp) and 121.8(500hp)mph.

If after trying to get the combo sorted out it still won't go at least the 119, and you're not running at an altitude track, you have to start considering the dyno numbers might be a little optimistic.

I put 478 at the tires and went 9.79 first 1/4 pass ever.........3200+ 4.10's and a 29" Hoosier through the muffs...........

Two separate 69 GTXs
Street car 494 RWHP. Pump gas 493 wedge 3960 lbs, 3 speed auto 3.73 gears
10.84 @123.50
Race car 672 RWHP Race 542 Hemi. 3520 lbs, powerglide, 4.56 gears
9.49 @138.50

Directly from the Wallace calculator:

The answers below will be for at sea level and standard pressure/temperature.
(no weather correction).

How many of you have raced at sea level? How many of you know how to make an accurate weather correction? Just checking.

My 428 small block made 615 hp and 565 torque on it's best pull on IMM's dyno. We promptly removed his 1000 CFM Holley 4150, and I bolted on a 950HP when I got home.

I put it in my 3150lb 62 Valiant street car, with an 8" JW converter, low gear set 904, and 3.89 gear with 30" tall ET Streets.

In the last three years, I've only managed 33 engine passes at various tracks and thirteen bottle passes.

Best engine pass is 10.396-128.27 on a hot September afternoon at Indy, and I think the DA was 4500ft.

Best nitrous pass is 9.65-138 at National Trail, again on a eighty degree day, but I'd be lying if I threw out a DA number.

548 rwhp dynojet
3100lbs
9.85 @ 135
428 g3
8" 5300
3.73 28" tire

Motor dynoed 560 HP at the crank

1974 Dodge Dart 2dr 3300lbs at the line.

440 zero decked w/flat top pistons. Ported 915 heads flow 268/207 peak. 11.25:1 Compression

Mopar 590 Solid Cam

850 HP carb, M1 intake, McCandless/ ProParts Headers


727 trans w/ Dynamic 9.5 converter (hi gear flashes 5100) 4.30 gear, 30x9 slicks

Footbrake @ 1800rpm shift at 6200

Ran:

10.77 @ 122.8 mph 1/4

1.47 60 ft
6.80 @ 99.79 1/8th

Thats a very conservative rw dyno
3200/670fwhp = 9.81@137

RWHp: 373hp (N/A)
Best E/T: 10.66 @ 126.4mph
Race Weight: 3839lbs

'69 Charger, 440, OOTB Performer Edelbrock, .590 purple shaft, ~170hp Nitrous.

Tire shake on the dyno. I don't think the numbers are too accurate.

How does frictional drive line loss factor in here? Trying to make an accurate guess with my own combo. My 416 is 500 flywheel HP on the dot. Car is probably 3,100-3,200 with driver.

My current guess is 11.00.

Not easy to say, on average I think its around 10% loss from FW to RW dependent on drivetrain, some calcs say its as much as 17% loss. I never really took notice of rwhp, fwhp is the key as nobody can accurately say how much every particular car will lose.

A true 500fwhp in 3200lbs at the track would be =
60 Foot E.T. : 1.50 ******
1/8 Mile E.T. : 6.82
1/8 Mile Trap Speed : 99.61
1/4 Mile E.T. : 10.81
1/4 Mile Trap Speed : 124

500hp on a dyno won't of course be 500hp on the track as you know so if we say 470 on the day depending on conditions/tune etc. its>
60 Foot E.T. : 1.53 *****
1/8 Mile E.T. : 6.97
1/8 Mile Trap Speed : 97.58
1/4 Mile E.T. : 11.04
1/4 Mile Trap Speed : 121
so your guess is pretty good...however these numbers are from Wallace who base things at 0 altitude I believe?...they were almost spot on for all my calcs on my cars which ran at Santa Pod which is 0.

Thanks for the reply. I guess the only way to measure driveline loss somewhat accurately is to go from engine dyno to chassis dyno and see what the difference would be, all things otherwise being equal. Other than that, ET/MPH is the most accurate on any given day.

I agree with the actual HP varying from day to day and even from minute to minute. Here in NY/NJ area we are pretty close to sea level. The best days for DA are in the fall, so that's when the records are set at Maple Grove in PA. Between June and September, it's usually 85+ with pavement melting humidity.

I am hoping to be in the 10s with my combo but am a little skeptical for now. I know one guy who has a similar if not milder combo than me who has been 10.60s. I think he weighs a little less but not much.

Other than that, ET/MPH is the most accurate on any given day.


Not so much ET as thats just an indication of how good your chassis is but it will show up deficiencies there, mph/weight is the key to hp....However when it gets to something like a Stocker, we have 1 running here..a legal '69 Camaro A/SAA the calcs can go way out of synch....

3500lbs/700hp
60 Foot E.T. : 1.38
1/8 Mile E.T. : 6.28
1/8 Mile Trap Speed : 108.15
1/4 Mile E.T. : 9.96
1/4 Mile Trap Speed : 135

He has actually run 9.90@133 with a 1.28 60ft.

The Moroso slide rule shows 500hp/3200bs as 10.50@126.5.
7% loss is 465hp, which shows 10.71@123.6.
10% loss is 450hp, which shows 10.81@122.2.

If it really weighs 3200, and won't go at least 122 at a NJ track in the spring/fall...... Either there is something really wrong with the set-up, or the dyno numbers are happy(or a little of both).

My friends Stocker shows 530hp on the Moroso slide rule(in good air), and the motor is under 500hp. In some really good air it'll show 540hp. In the middle of the summer it'll show 490hp(east coast tracks).
At the Vegas nhra fall race in 2015 it showed 460hp.

The quality of the air you run in makes a big difference.

I always thought the Moroso slide rule was based on RWHP?

Last time I weighed the car it was 3,060 without driver and a full tank of gas. Since then I've taken maybe 50-60 lbs out and will be taking more out soon with a 'glass hood. I weigh 187.

Engine was dynoed at Merkel's here in LI. I don't remember what the DA was that day but it was clear and not terribly humid. The operator used a psychrometer.

I got all excited when I saw it flash to 520+ hp on the screen but with the correction it said 500.2 on the printout. I thought it would be a little more. It was fairly consistent in that range though so I don't think it was a fluke. There wasn't much in the way of tuning.

You actually commented on it when I posted the results. 416 dyno day.

Right, and that is correctable. I too use the Moroso Calc. for comparison purposes. Seems accurate and levels the playing field. If you correct the MPH to std conditions, and plug that into the Moroso Calc, it will be close to the gross corrected from a not-too-happy engine dyno. The several percent that it is if off is usually and reasonably explained considering net verses gross. The closer your engine sitting in the car looks like your engine sitting on the dyno the smaller the difference.

RMCHRGR,
Forgive me, I should know this, but is the Duster strictly a drag car, or will concessions be made for street use, as in converter and gear?

I bring this up, because, like my Valiant for example, I have a 4800 stall speed and a 3.89 gear with a 30 tall tire, hardly ideal for an engine that made peak HP at 6600 rpm. At high altitude tracks or on high DA days, it really struggles to get up on the converter. The stout torque curve is fairly forgiving, luckily, especially since I tend to short shift (old, 906 hyd cam bb guy) but I'm sure the engine would run closer to it's potential with a 5700 stall and 4.30 gears.

Billy, this is a 100% street car. Pump gas, full interior, current tags and inspection, yada yada. Just had a 6 point CM roll bar installed two weeks ago though so I guess you could say it is creeping towards more of a dedicated race car. Trying to avoid that though.

Got a new converter when I built the motor, a Dynamic 9 1/2" that theoretically will stall at 4,000 rpm. I gave them all the specs. They said it will act like a normal converter on the street...

4.10 gear, 28" drag radials. 904 FMVB, standard gear set. 6 (count 'em) clutch discs in the drum.

On the dyno, the motor made best power around 6,000-6,200 rpm then started to drop after that. I figure I will shift it at 6,500-6,600.

Well.......my friends motor, which I have had on the dyno at least 25 times through the years, makes a little less than 500 std corrected hp(hp corrected to 29.92 baro, 60deg, 0 humidity), and even in pretty hot, humid, summer air, at the east coast tracks it will run enough speed to show 500hp on the Moroso slide rule.

I'm pretty sure his car isn't so good it would also make 500rwhp........ so, from my perspective......it's engine hp.

Here's another one.....

572 Indy motor......made 920 on the engine dyno, 778 rwhp on the chassis dyno(glide with a 5600 converter).
Car went 8.33@165 at 2700lbs.

How do those numbers work out?

You're correct. Guess I have been operating under a misconception for a long time!

Just for sh*ts and giggles, I plugged both FW and RWHP numbers into the Wallace Racing 1/4 mile stats calculator which I believe is based off the Moroso slide rule.

With 920 HP @ 2,700 lbs it spit out 8.34 @ 162.05. Pretty close.

With 778 HP @ 2,700 lbs it says 8.82 @ 153.24.

Guess I could have a 10 second car after all. Plugging my 500/3,200lb numbers in to the weight/HP calc. says 10.81. If you use the 3rd calculator down which is ET/weight it says 10.50 @ 3200 = 546 HP.

Since yours is a "street" car, I'd say a realistic number to shoot for is 10-12% "observed" loss.
In other words, see what the calculators show for 440-450hp(for your 500 std corrected hp).

Just the fact that your converter is probably 1000 less stall than what it would be if it were a race only application is going to impact the results, and what the calculators show for power.

My friends motor is under 500hp, and the car weighs 3450, and has gone 10.60's and 126mph at a few different tracks in decent air.

It is possible to beat what the calculators show for power, and most Stockers and Super Stockers that run in that one second under the index area are doing it........by a fair amount.

Another one that I'm sure of the data on........ 3650lbs, 470hp, 11.19@119+

On this one, the ET(514hp)looks way better than the MPH(478hp),mostly because the converter is too loose and the motor is driving through it in high gear, but the car still leaves pretty good with it(1.50 60').

My Valiant had a 389, ported J head 296/557MP cam, 4.30 gears, and a TA 5000 stall. It was a good little 10.90-11.10 (10.89-121.6 best) bracket car with my fat butt in it. Went a 10.73-123 with my skinny buddy driving.

I converted it to a street car, added a passenger seat, extra fans, switched to 3.89 gears, and the 4500 stall. I now had a nice 11.30-11.40 (11.27-117.2 best) street car! No changes to the engine at all.

I think RMCHRGR's Duster will run 11.35 at 118 or so, and he'll have to work from there, and I say so without impugning his dyno sheet in any way.

My point: It's real easy to take an engine off of a 40,000 dollar dyno, strap it into a 15,000 dollar car and figure out how to go slower than the dyno numbers showed it had potential to run.

I never had a dyno sheet on my 440 in my Challenger, but in the 6 years and 759 passes that I put on it, at tracks all over the west, it ran from 9.96-134 to 10.47-125, and the initial dyno numbers would still be the same regardless of which pass you compared it to.

This is what I get touchy (fair or not) about. If you feel a speed/weight/HP slide rule or online calculator gives you a fair amount of information to discredit a dyno, an engine builder, or a dyno data sheet, you are doing the equivalent of someone using a crescent wrench as a hammer.

(This is the place where I would normally couch this statement with some qualifiers, and try to soften the tone, but I think I'll just let you kick me around for a while...)

Fast,
920 to 772, normal drop from crank to wheels? Not rhetorical, I'm not sure if you feel that is acceptable or not.

Billy are you saying we race cars not Dynos?

God I hope so.

One liners are not my thing...

I prefer to say it four or five paragraphs...I should've been a preacher.

That's kind of how I look at RWHP, not as an actual number but more of a reflection of whatever driveline % loss you choose to use. So maybe I wasn't operating under a total misconception.

As my rule of thumb, I use 15%. So 85% of 500 is 425. Using that number, Wallace says I will go 11.42 @ 118.38 which is closer to what Billy was saying.

Case in point, 778 is 84.5% of 920. Go figure.

I believe the car should be a little better than 11.40s which is why I said 11.00 at first. Could it go 10.80? Maybe but again, I won't hold my breath.

Again, my buddy went 10.60s (not sure what mph) with a milder combo and a little less weight. (His car is pretty much gutted). He even had a throttle stop for some reason.

Billy, 15-20% loss from the engine dyno I run to the chsssis dyno that car was tested on is pretty typical.

I think part of problem with trying to interpolate the numbers between the two, at least in this case is, they aren't using the same correction factor.
Most engine dynos are using the "standard" correction factor, and many of the chassis dynos use the "SAE" correction factor, which means they are correcting to different weather conditions, with the SAE correction being the poorer of the two, so the numbers are lower.

So, the 920 fwhp was standard corrected hp, and the 778 rwhp was SAE corrected hp.

I can't recall if there is a humidity factor in the SAE correction or not, but iirc, the temp is 77deg, and the baro is 29.38, whereas the Standard correction uses 60deg and 29.92 baro, and zero humidity.

I'm a big believer in dyno testing, and feel it's the best way to sort out and evaluate an engine combo.

However, I would never tell someone to take the numbers as "gospel".

There should be an acknowledgement that dyno numbers can be pretty different from one facility to another.
On my own motor, 60+hp spread between two different dynos.

Both use 0% humidity. SAE 1349 is 29.23.

Are you calling J607 as "standard"? I does give the highest results (most optimistic atmospheric conditions) and seems to be the norm used in the aftermarket hot rod industry.

I agree that there are a lot of ways for an owner/car to make hp semm to disappear. But I have seen a motor go from one dyno to another and there be a 40 hp difference. Both well known reputable shops.

wouldn't a loose converter drop the RWHP numbers, but not necessarily relate that in track times?

Russ, yes......J607.

I believe the reason it got to be called "standard" was because the weather parameters, 29.92 baro, 60deg, 0 humidity is what's known as "standard day" in aviation.

On the older superflow dyno sheets, it's right at the top of the sheet, "standard corrected data".

I'm so glad to have a local track where the DA is below sea level.

The top of my sheet says Channel Group; Corrected Torque and power. Dos not say standard, J607 or SAE.

If I use 'standard' correction factor with my motor, it would seem to be pretty close to what I saw flash on the screen which was 521. The correction factor is .955 so 500/.955 = 523.

I'm not sure if that's how a dyno works though. Do you see the uncorrected torque/hp numbers on the screen before the printout or should you be seeing the already corrected data on the screen during the run?

That means the DA was better than the standard air, you had mine shaft air when your engine was run , so it took power away, most time it is the other way

It was a decent day outside - temp was low to mid 60s, bright and sunny with no real humidity, maybe 15%. Looking at weather data from that day I believe the barometer was 30.3-30.4? Here on Long Island, we are basically at sea level.

Wish I would have asked what the specific weather inputs were, would have been helpful to know and it didn't occur to me to ask the operator. Next time.

call them, they should be able to print out un corrected for the day it was run.

when I had my dyno I could print 3 different correction factors, or actual power .

mine shaft air would add power, not take it away. thats why cars run better at a track like Englishtown vs Denver.

The correction factor took power away!!! Because the air was better than the standard air.Yes the engine made more power the day it was run & corrected to the lower standard air.

To have a correction factor of .955 you had to have pretty darn good air.......... that would be mine shaft-ish.

The uncorrected numbers aren't all that useful....... other than perhaps for applying the J607 factor to them see how much you'd gain/lose by plugging in different weather values.

Obviously the motors should make more power if they're tested in better air. The corrections are a way to standardize the results to try and take the weather out of the picture.

There are couple of things that calculators don't know. In my book number one is power under peak. Strong power under peak will accelerate the car quicker with the same peak power. It's also possible the combo may have less peak than calculated. As for MPH a small frontal area sleek car is going to be better than a large boxy sedan. In my case my car has piked up .3/4 mph since it's initial outing with an air pan, chassis and converter tuning. Timing, jetting, haven't made a significant change.
Doug

Thanks. I'm finding a little humor in the use of the term "standard". I confirmed we used 68°F for std temp. in industry. Always considered it "The" standard. A little research shows it is not, nor is there any one standard from a global/universal perspective.

Who would have thought that there would be 20 different standards for standard conditions.

So so true.

If you are really looking for what might be produce the best et/mph, you would not necessarily be looking at peak power numbers. And as you suggest, working the numbers backwards from track data may skew the comparison.

We spent a week trying stuff on the dyno. What is in my car has a peak power that is about 13 -15 hp lower than the best we got with a different combo, but average power was a bit better. That will effect a calculator.

In the SuperFlow pre-Windyn days, the channel order and what was on each page wasnt something you could change.
Page 1 was uncorrected, page 2 std corrected, page 3 sae corrected, and it said at the top what the correction was.
With the Windyn, you can arrange the pages in any order you like, as well as which channels and the channel order on each page.

Here is a printout from my dyno day.

Fuel flow and bsfc are always uncorrected........so, going by what's on that sheet, at say......6000rpm.......
You have 269.7 lbs/hr fuel flow........ bsfc of .549...... works out to 491.2 uncorrected hp.

Looks like the c/f was about 1.8% to me.

I would have definitely wanted to have the air turbine on for that test.
You can see the power takes a pretty big hit after it peaks, and the bsfc numbers kinda go in the tank.
Those are often signs that something is plugged up, or floating.

Seeing what the airflow through the motor is doing can help pin point it.

There isn't necessarily anything "wrong" going on..... The combination might simply be "done" at that rpm. If the airflow was still steadily going up with the rpm and the power dropping off that quickly, it would likely just be the head cross section is being used up, and/or there isn't enough cam duration to keep up.
Those issues don't really need addressing for a bracket build, you'd just like to know there wasn't a valvetrain issue if you intended to operate the motor in that rpm range.

I didn't feel there were enough columns on the Windyn print outs to get as much info as I wanted on one page, so I set up two pages to give me most of what I need.

Just a little foot note:

My friend is running at the 4-wides this weekend.
Looking at the notes for round 1 stock class eliminations...... Weather was 87deg, 50% humidity, 29.38 baro, 3250' adjusted altitude.

Car is showing 508hp on the Moroso slide rule in those conditions...... Which is more than it made for corrected hp on the engine dyno.