Moroso Speed Calculator 89650

[skinny z]

I've seen the old Moroso slide rule has been mentioned here at Speed-Talk every now and then. I was kind of surprised at the amount of merit it gets from folks I wouldn't have thought put any faith into it.
Opinions?
FWIW, I went back and dug out some old time slips, chassis dyno results, engine builds and vehicle weights and found that there's some correlation between results and what the analog calculator had to say.
I've other means to do the math however having come across the calculator (it's been MIA for years) I'm cyphering whether the new combination will get me that 1/2 second I'm looking for.
Call it Sunday morning musings.

[steve cowan]

I've seen the old Moroso slide rule has been mentioned here at Speed-Talk every now and then. I was kind of surprised at the amount of merit it gets from folks I wouldn't have thought put any faith into it.
Opinions?
FWIW, I went back and dug out some old time slips, chassis dyno results, engine builds and vehicle weights and found that there's some correlation between results and what the analog calculator had to say.
I've other means to do the math however having come across the calculator (it's been MIA for years) I'm cyphering whether the new combination will get me that 1/2 second I'm looking for.
Call it Sunday morning musings.

I am a fan of the slide rule,it is something to work towards. With my own combos it is usually 15hp or so relevant.
As been discussed previously if you are not using the potential power of the engine work on the rest of the car and leave engine alone.
This is another chart worth looking at

20220815_160601.jpg

[skinny z]

I've seen the old Moroso slide rule has been mentioned here at Speed-Talk every now and then. I was kind of surprised at the amount of merit it gets from folks I wouldn't have thought put any faith into it.
Opinions?
FWIW, I went back and dug out some old time slips, chassis dyno results, engine builds and vehicle weights and found that there's some correlation between results and what the analog calculator had to say.
I've other means to do the math however having come across the calculator (it's been MIA for years) I'm cyphering whether the new combination will get me that 1/2 second I'm looking for.
Call it Sunday morning musings.

I am a fan of the slide rule,it is something to work towards. With my own combos it is usually 15hp or so relevant.
As been discussed previously if you are not using the potential power of the engine work on the rest of the car and leave engine alone.
This is another chart worth looking at
20220815_160601.jpg

Interesting timing with your reply Steve.
I was just watching the Stay Tuned/Tony Angelo channel and they were dynoing his SB2 406.
811 HP and 8100 RPM later, the dyno operator ( Wilson Race Engines) pulls out the old slide rule and predicts Tony's ET.



That got me back to thinking about it and then comes your reply.

I've some old time slips and chassis dyno results (from 2009) that correlate very closely. This is something I had intended to follow up on with this thread but traffic was very low and I kind of put it aside.
Using the slide rule as a prognosticator, and guesstimating my new engine's output, I'm looking at 11's. 11.99 but 11's nonetheless. It'll be interesting to see how it plays out.

As you mention, the trick for me now will be get the rest of the car to catch up with the fresh engine.
New transmission. Check.
New converter. Soon to be ordered.
New slicks...not sure yet.
Stay tuned.
Thanks for the thread revival Steve. I'll post back with the chassis dyno, time slip, Moroso calculator comparison soon.

[bob460]

Seen that video the other day........Man Why would you not check lash before you do your first pull.........

[skinny z]

Seen that video the other day........Man Why would you not check lash before you do your first pull.........

Yeah. The outcome could have been far worse.

[skinny z]

As for the Moroso calculator.
One example I have is as follows:

86 IROC: 3650 lbs., McCreary Road star tires @ 26", 3.27 gear
Engine 2007
353: 4.020” x 3.48”
670 Holley
RPM Air Gap
Vortec heads.
Comp XR276HR (in 2 106 ICL)
10.05:1
Cranking pressure 185-190

May 11 2009
Chassis dyno
Max power: 282 RWHP
Max TQ: 282 RWTQ

June 12 2009
12.87 @ 105.5, 1.77 60’

Oct 17 2009
12.78 @ 105.1, 8.088 @ 83.94, 1.71 60’

July 8 2011
12.75 @ 105.93, 8.082 @ 83.39, 1.74 60’
Track elevation: 630’, 73.4°F/23°C, 29.83” Hg/101.02 kPa, 65% rh
DA: 2046’
12.449 @ 108.551 MPH corrected

Moroso says that at 3650 lbs and a 108.56 MPH (I'll use corrected) HP is 350.
A few things come to mind:
First is the HP.
I'm thinking this has to be HP as seen at the tires correct? And that HP has to be the average across the run.
But, the car only produced 280 at the tires so my thinking must be off. Otherwise, with 350 at the tires, even a 20% difference, taking drivetrain losses into account, meant that that engine was making 420 potentially. Which by some accounts is a reasonable assessment but I think unlikely.

The second is that if 350 is the calculated engine output at the crank, then 280 works at 20%.

So, which is it? Does Moroso factor in an automatic 20% or are they saying via their calculator that I was really seeing an average of 350 at the tires across that best pass?

And yes I understand it's only a tool. And a limited one. But seeing it used by many pros, it has me to thinking (obviously!)

[bob460]

As for the Moroso calculator.
One example I have is as follows:

86 IROC: 3650 lbs., McCreary Road star tires @ 26", 3.27 gear
Engine 2007
353: 4.020” x 3.48”
670 Holley
RPM Air Gap
Vortec heads.
Comp XR276HR (in 2 106 ICL)
10.05:1
Cranking pressure 185-190

May 11 2009
Chassis dyno
Max power: 282 RWHP
Max TQ: 282 RWTQ

June 12 2009
12.87 @ 105.5, 1.77 60’

Oct 17 2009
12.78 @ 105.1, 8.088 @ 83.94, 1.71 60’

July 8 2011
12.75 @ 105.93, 8.082 @ 83.39, 1.74 60’
Track elevation: 630’, 73.4°F/23°C, 29.83” Hg/101.02 kPa, 65% rh
DA: 2046’
12.449 @ 108.551 MPH corrected

Moroso says that at 3650 lbs and a 108.56 MPH (I'll use corrected) HP is 350.
A few things come to mind:
First is the HP.
I'm thinking this has to be HP as seen at the tires correct? And that HP has to be the average across the run.
But, the car only produced 280 at the tires so my thinking must be off. Otherwise, with 350 at the tires, even a 20% difference, taking drivetrain losses into account, meant that that engine was making 420 potentially. Which by some accounts is a reasonable assessment but I think unlikely.

The second is that if 350 is the calculated engine output at the crank, then 280 works at 20%.

So, which is it? Does Moroso factor in an automatic 20% or are they saying via their calculator that I was really seeing an average of 350 at the tires across that best pass?

And yes I understand it's only a tool. And a limited one. But seeing it used by many pros, it has me to thinking (obviously!)

Skinny the Moroso calculator is crank/flywheel horsepower..........it's a great guide.

The chassis dyno's all read different and the hub dyno's read even more, great for tuning but the moroso is the best guide IMO.

We have alot of guys down here claming 900hp SBF build's yet, the moroso shows 830-840hp............so where is the other 60-70hp

Some people it's all about EGO....

[skinny z]

As for the Moroso calculator.
One example I have is as follows:

86 IROC: 3650 lbs., McCreary Road star tires @ 26", 3.27 gear
Engine 2007
353: 4.020” x 3.48”
670 Holley
RPM Air Gap
Vortec heads.
Comp XR276HR (in 2 106 ICL)
10.05:1
Cranking pressure 185-190

May 11 2009
Chassis dyno
Max power: 282 RWHP
Max TQ: 282 RWTQ

June 12 2009
12.87 @ 105.5, 1.77 60’

Oct 17 2009
12.78 @ 105.1, 8.088 @ 83.94, 1.71 60’

July 8 2011
12.75 @ 105.93, 8.082 @ 83.39, 1.74 60’
Track elevation: 630’, 73.4°F/23°C, 29.83” Hg/101.02 kPa, 65% rh
DA: 2046’
12.449 @ 108.551 MPH corrected

Moroso says that at 3650 lbs and a 108.56 MPH (I'll use corrected) HP is 350.
A few things come to mind:
First is the HP.
I'm thinking this has to be HP as seen at the tires correct? And that HP has to be the average across the run.
But, the car only produced 280 at the tires so my thinking must be off. Otherwise, with 350 at the tires, even a 20% difference, taking drivetrain losses into account, meant that that engine was making 420 potentially. Which by some accounts is a reasonable assessment but I think unlikely.

The second is that if 350 is the calculated engine output at the crank, then 280 works at 20%.

So, which is it? Does Moroso factor in an automatic 20% or are they saying via their calculator that I was really seeing an average of 350 at the tires across that best pass?

And yes I understand it's only a tool. And a limited one. But seeing it used by many pros, it has me to thinking (obviously!)

Skinny the Moroso calculator is crank/flywheel horsepower..........it's a great guide.

The chassis dyno's all read different and the hub dyno's read even more, great for tuning but the moroso is the best guide IMO.

We have alot of guys down here claming 900hp SBF build's yet, the moroso shows 830-840hp............so where is the other 60-70hp

Some people it's all about EGO....

Yeah. They are racers after all.
For me though, it's more of predictor.
So, the calculator is estimating crankshaft HP. That said, that would still have to be an average across the run wouldn't it. I can't see how the slide rule would be able to predict anything else.
That being the case, if in my example above Moroso says 350 CHP then this correlates with the chassis dyno's 282 and a 20% loss (being what it is and the given day). So far so good.
Back to my predictor. When I model that particular engine from 2007-2011, I can look for the average in the operating range on that pass. That would be from the flash stall, through all of the shift recoveries to shift RPM to the RPM at the stripe. Not sure if my software is capable of that but I could get a good guess I think. 350 average doesn't look to be out of the question considering it should have been capable of 420 peak with open headers and good air. Now, with this new combination I'm hoping to get an educated guess on my 11 second potential.
To go 11.9's, at 3600 lbs it'll take about 370 CHP (average). Have I gained 20 HP over the previous engine? Better cam spec. Reworked heads. Fresh shortblock. Proper convertor. It's looking promising.

Just fun with numbers. And bench racing until both me and my car are fully mended.

[maxracesoftware]

July 8 2011
12.75 @ 105.93, 8.082 @ 83.39, 1.74 60’
Track elevation: 630’, 73.4°F/23°C, 29.83” Hg/101.02 kPa, 65% rh
DA: 2046’
12.449 @ 108.551 MPH corrected

Moroso says that at 3650 lbs and a 108.56 MPH (I'll use corrected) HP is 350.
But, the car only produced 280HP at the tires so my thinking must be off.

this is what ETAPRO5 software calculates for your 12.75ET and 105.93 MPH :

on this Run = 12.75ET you are making 217.0 Rear Tire HP down the DragStrip ( not 280HP )
and on your Chassis Dyno Roller your Car's rear tire are being distorted to a Rolling Resistance Factor = 0.132
whereas as a Typical Slick = 0.025 Rolling Resistance Factor
and typical OEM Street Tires = between 0.004 to 0.015
so that Chassis 280HP - 217.0HP = 63.0 HP loss difference from Chassis Dyno -vs- DragStrip 12.75ET Run

SuperFlow Engine Dyno HP Correction Factor w/Friction= 1.0763864597
MotorSports HP Correction Factor = 1.0588881514 is 2375.5 Density Altitude Feet at 60.0 DegF
your Weather's Density Altitude example is using or calculating Aviation Density Alitude Feet = 2046 Feet at 59.0 DegF

skinnyZ_Moroso_Speed_Calculator_12.75ET_105.93MPH_3650Lbs.jpg

skinnyZ_Moroso_Speed_Calculator_12.75ET_Peak_Tire_HP.jpg

and to Run 11.90 ET you need this HP under same Weather conditions :

skinnyZ_Moroso_Speed_Calculator_11.90ET_113.50MPH_3650Lbs.jpg

 

[skinny z]

this is what ETAPRO5 software calculates for your 12.75ET and 105.93 MPH : 

Wow! That's a lot of data to digest.
A couple of questions come straight to mind though.
On that 12.75 run you say 217 RWHP. And that's averaged over the run correct?
That looks to be about a 33% drivetrain loss which includes all of the other resistances preventing my going forward. 344 CHP vs 217 RWHP.
FTR: The chassis dyno 282 RWHP was at peak. Averages would obviously be lower.

Screenshot 1 shows 344 HP at 1320'. Screenshot 3 shows 417 HP.
So on average I'd have to see a 73 HP improvement from the old engine to the new. Have I got that straight?

Remember too that this is no drag car. Gearing and converter were entirely unsuited to the dragstrip. I wouldn't see 5500 at the end. Shift recovery was terrible with a drop to 3500 between 1st and 2nd. Converter stall would only allow a 2200 RPM footbrake launch.
How do those factors play into your software? Although I know that all of those deficiencies just make for a slow car.

I use the Drag Times DA calculator for my correction factor. Is this reasonable?

[maxracesoftware]

I use the Drag Times DA calculator for my correction factor. Is this reasonable?

its better and more accurate to use Air Density OnLine's Calculator ( even though it sometimes calculates wrong Vapor Pressure value )
it calculates the Density Altitude Feet closer than DragTimes or Richard Shelquist 's Engine Tuning Calculator

https://airdensityonline.com/free-calcs/#weather
Air Density OnLine was pretty close
density altitude: 2,371.219 ft
( Air Density OnLine is slightly off because they "sometimes" calculate the Vapor Pressure value wrong ! )
-vs- actual Density Altitude = 2375.518 Feet

https://wahiduddin.net/calc/
Engine Tuner's Calculator
Richard Shelquist is an Aviation Pilot so he's using 59.0 DegF Correction instead of MotorSports 60.0 DegF correction value
so Richard gets Density Altitude Feet = 2046 Ft .... same thing as Drag Times = 2046 Ft ,
but its Aviation Density Altitude , and not MotorSport's Density Altitude
Richard does calculate the Vapor Pressure value correct = 0.5391 inHg , Air Density OnLine is wrong = 0.8300 inHg

skinnyZ_Richard_Shelquist_vs_ETAPRO5.jpg

skinnyZ_Air_Density_OnLine_vs_ETAPRO5.jpg

skinnyZ_Smithsonian_Saturation_Pressure_Charts.jpg

 

Screenshot 1 shows 344 HP at 1320'. Screenshot 3 shows 417 HP.
So on average I'd have to see a 73 HP improvement from the old engine to the new. Have I got that straight?

Yes , thats going to be pretty close to Run 11.900 ET

Also , on your 12.750 ET Run that's the HP its showing
you definetly could have much more HP than "Peak HP= 344.97 at 1174 Feet distance"
because you do not have everything maxed out ,
meaning if a Record setting ProStocker installed a 4.10 Rear Gear Ratio , that Car would not show anywhere near 1480's to 1500 Peak HP
even much worse HP going down the DragStrip if they used a 3.08:1 rear gear

[skinny z]

I use the Drag Times DA calculator for my correction factor. Is this reasonable?

its better and more accurate to use Air Density OnLine's Calculator ( even though it sometimes calculates wrong Vapor Pressure value )
it calculates the Density Altitude Feet closer than DragTimes or Richard Shelquist 's Engine Tuning Calculator

I'll have to check that out.

Screenshot 1 shows 344 HP at 1320'. Screenshot 3 shows 417 HP.
So on average I'd have to see a 73 HP improvement from the old engine to the new. Have I got that straight?

Yes , thats going to be pretty close to Run 11.900 ET

Also , on your 12.750 ET Run that's the HP its showing
you definetly could have much more HP than "Peak HP= 344.97 at 1174 Feet distance"

because you do not have everything maxed out ,

Now, THAT'S an understatement.
Besides the HP gain I'm going to see there's also improvements in converter and transmission which I hope will pay dividends. Mostly by way of keeping the engine in it's "power band" for the entire pass and putting more HP to the ground.

Thanks a ton Larry.

Now I'm going to manipulate the Moroso slide rule to see if I can correlate your math with it's math.
One thing about my car that's easily observable is that the best MPH pass doesn't result in an ET that the calculator produces. I know why that it is and it's mostly in the first third of the track. If there's anything I've learned from a racer like vortecpro is that the converter and gearing are king!
At 106 MPH (uncorrected) there should be a 12.3 in the books. I'm nearly a half second off of that so there's a lot of work to do.

[steve cowan]

I've seen the old Moroso slide rule has been mentioned here at Speed-Talk every now and then. I was kind of surprised at the amount of merit it gets from folks I wouldn't have thought put any faith into it.
Opinions?
FWIW, I went back and dug out some old time slips, chassis dyno results, engine builds and vehicle weights and found that there's some correlation between results and what the analog calculator had to say.
I've other means to do the math however having come across the calculator (it's been MIA for years) I'm cyphering whether the new combination will get me that 1/2 second I'm looking for.
Call it Sunday morning musings.

As a follow up on the slide rule,as simple as it is ( function)
I call it the lie detector.
If you have a so called dynoed engine that makes X hp and the car weighs X pounds it should run a certain time at the track.
If it does not run the time then work on the car from the back to front.
Converter and gear and tyre are king.until your car runs the number especially 60ft work on the car.
I watch stock as much as possible and am blown away by the 60 ft on most of those cars,I thought a 1.43 in the 60ft was cool for my 3500 pd streeter but it can be improved of course.
As you know Kevin there is a cross over point with rear gear etc as in a weekend cruiser and we have to keep it real as well.
My comments are not directed at you in anyway just me giving my general opinion.

[skinny z]

I am a fan of the slide rule,it is something to work towards. With my own combos it is usually 15hp or so relevant.
As been discussed previously if you are not using the potential power of the engine work on the rest of the car and leave engine alone.
This is another chart worth looking at
20220815_160601.jpg

20220815_160601.jpg

I just had another look at this chart.
Some of it I can match almost to the number. But I'm trending towards more top speed than the chart predicts.
Case in point: From 2009. (uncorrected)
Chart calls for a 1.70 60', and a 12.75 ET. Very close to my time slip.
12.78 @ 105.1 8.088 @ 83.94 1.71 60’
But I'm trapping several MPH higher in the 1/4. 105.10 vs 102.30.
What's the take away from that. Gearing?
Actually, all of my dragstrip passes, even as the car got more powerful, would always show more MPH than the ET would suggest. Eventually my 60' started going away (tires) so it became even more skewed. Adding more rear gear, which I did, 3.73 vs 3.27 made the 60' worse as the tires (and suspension truth be told) just weren't up to it.
12.77 @ 106.58, 8.130 @ 83.75, 1.78 60'. (also uncorrected). There's a half second missing there by my reckoning.

[skinny z]

As you know Kevin there is a cross over point with rear gear etc as in a weekend cruiser and we have to keep it real as well.

Which puts me in a bit of a dilemma.
Do I morph towards more track orientated and go faster? Or forgo the ever increasing cost of fuel and continue to drive it a street car and not be concerned over the track performance?
Keep it real indeed.
I guess though it's first things first and actually get to the track. (But that's been sidelined yet again until my busted shoulder is repaired).