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2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

General engine tech -- Drag Racing to Circle Track

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Stan Weiss
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by Stan Weiss »

More of a rough guess than a simulation

60 Foot ET = 2.1851
330 Foot ET = 5.5279
1/8 Mile ET = 8.0168
1/8 Mile MPH = 101.9771
1000 Foot ET = 10.0910
1/4 Mile ET = 11.8457
1/4 Mile MPH = 129.4106

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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by BobbyB »

Stan Weiss wrote: Tue Nov 23, 2021 10:54 pm More of a rough guess than a simulation

60 Foot ET = 2.1851
330 Foot ET = 5.5279
1/8 Mile ET = 8.0168
1/8 Mile MPH = 101.9771
1000 Foot ET = 10.0910
1/4 Mile ET = 11.8457
1/4 Mile MPH = 129.4106

Stan
What goes into your 60 foot "rough guess/simulation" ? Are you expecting any wheel spin?
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by Stan Weiss »

The MPH is pretty much controlled by HP. The 60 foot / first part of the run pretty much controls the et.

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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by maxracesoftware »

new changes :
1= added 2 decimal places only to the calculated Peak HP value
.......this is especially good for low HP engines like Jr Dragsters , that might have a Stock 5 or 6 HP engine
and they can now see Peak HP to 0.00 2 decimal places

2= added the Feet Distance Range that Peak HP is occurring thru .... helpful to see how "flat" HP Curve may be .

example :
VortecPro_1970_MonteCarlo_new.jpg
 
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by Dragginwagon406 »

maxracesoftware wrote: Wed Nov 24, 2021 10:31 pm new changes :
1= added 2 decimal places only to the calculated Peak HP value
.......this is especially good for low HP engines like Jr Dragsters , that might have a Stock 5 or 6 HP engine
and they can now see Peak HP to 0.00 2 decimal places

2= added the Feet Distance Range that Peak HP is occurring thru .... helpful to see how "flat" HP Curve may be .

example :
VortecPro_1970_MonteCarlo_new.jpg

 
Does the highway gear affect how the power shows up in your program?
1.88, 11.84 @ 119.27, 4100 lbs, 2.56 gears, stock stall, 225/70-15 Cooper Cobras
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by frnkeore »

I did a couple of quick calculations, using peak torque rpm (4300) and 27.4" tire (225/70/15) and w/o tire growth it comes out to 136.92 mph but, with 7.2% tire growth, it gives me the 146.76 mph. It seems reasonable that it wouldn't over come drag, after peak torque. If it could rev to 6k w/o additional tire growth, it would do 204.78 mph.

How was the CD figured and how was the tire growth estimated?

Can you figure the CD that would be needed to get it to 205 mph with the torque output of 498 @ 6k that he has?
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by Dragginwagon406 »

frnkeore wrote: Thu Nov 25, 2021 3:45 am I did a couple of quick calculations, using peak torque rpm (4300) and 27.4" tire (225/70/15) and w/o tire growth it comes out to 136.92 mph but, with 7.2% tire growth, it gives me the 146.76 mph. It seems reasonable that it wouldn't over come drag, after peak torque. If it could rev to 6k w/o additional tire growth, it would do 204.78 mph.

How was the CD figured and how was the tire growth estimated?

Can you figure the CD that would be needed to get it to 205 mph with the torque output of 498 @ 6k that he has?
With the way my Monte is picking up speed at the traps, it's hard to believe it only has 146 mph as a top speed, but that's just a gut feeling.

It's hard to see 5.7 L hemi chargers being that much better aerodynamically (although far superior air control).

Loosely shopping comparables below, I'd say the MC should have no problem pushing past 175-180 mph.

This is all conjecture of course...don't hold your breath for Draggy video verification :mrgreen:

2021 Dodge Charger SXT
Curb Weight 3,964 lbs
300 hp @ 6,350 rpm
264 lb-ft @ 4,800 rpm
Top speed of 147 mph
0-60 mph in 6.2 seconds
Standing 1/4 mile in 14.8

2021 Dodge Charger RT
Curb Weight 4,385 lbs
370 hp @ 5250 rpm
395 lb-ft @ 4200 rpm
Top speed of 155 mph
0-60 mph in 4.9 seconds
Standing 1/4 mile in 13.4

2021 Dodge Charger Scat Pack
Curb Weight 4,385 lbs
485 hp @ 6,100 rpm
475 @ 4,100 rpm
Top speed of 175 mph
0-60 mph in 3.9 seconds
Standing 1/4 mile in 12.3
1.88, 11.84 @ 119.27, 4100 lbs, 2.56 gears, stock stall, 225/70-15 Cooper Cobras
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by Stan Weiss »

Dragginwagon406 wrote: Thu Nov 25, 2021 9:04 am
frnkeore wrote: Thu Nov 25, 2021 3:45 am I did a couple of quick calculations, using peak torque rpm (4300) and 27.4" tire (225/70/15) and w/o tire growth it comes out to 136.92 mph but, with 7.2% tire growth, it gives me the 146.76 mph. It seems reasonable that it wouldn't over come drag, after peak torque. If it could rev to 6k w/o additional tire growth, it would do 204.78 mph.

How was the CD figured and how was the tire growth estimated?

Can you figure the CD that would be needed to get it to 205 mph with the torque output of 498 @ 6k that he has?
With the way my Monte is picking up speed at the traps, it's hard to believe it only has 146 mph as a top speed, but that's just a gut feeling.

It's hard to see 5.7 L hemi chargers being that much better aerodynamically (although far superior air control).

Loosely shopping comparables below, I'd say the MC should have no problem pushing past 175-180 mph.

This is all conjecture of course...don't hold your breath for Draggy video verification :mrgreen:

2021 Dodge Charger SXT
Curb Weight 3,964 lbs
300 hp @ 6,350 rpm
264 lb-ft @ 4,800 rpm
Top speed of 147 mph
0-60 mph in 6.2 seconds
Standing 1/4 mile in 14.8

2021 Dodge Charger RT
Curb Weight 4,385 lbs
370 hp @ 5250 rpm
395 lb-ft @ 4200 rpm
Top speed of 155 mph
0-60 mph in 4.9 seconds
Standing 1/4 mile in 13.4

2021 Dodge Charger Scat Pack
Curb Weight 4,385 lbs
485 hp @ 6,100 rpm
475 @ 4,100 rpm
Top speed of 175 mph
0-60 mph in 3.9 seconds
Standing 1/4 mile in 12.3
Stan Weiss wrote: Tue Nov 23, 2021 2:06 pm I get this from my simulation.

60 Foot ET = 1.8935
330 Foot ET = 5.0774
1/8 Mile ET = 7.6995
1/8 Mile MPH = 93.9837
1000 Foot ET = 9.9455
1/4 Mile ET = 11.8308
1/4 Mile MPH = 120.3292

1/2 Mile ET = 18.651 -- 1/2 Mile MPH = 142.23
1 KM ET = 21.642 -- 1 KM MPH = 149.74
1 Mile ET = 30.263 -- 1 Mile MPH = 164.99

Stan
Let me add to my other post.

2 KM ET = 35.467 -- 2 KM MPH = 170.56
3 KM ET = 48.261 -- 3 KM MPH = 177.97
2 Mile ET = 51.003 -- 2 Mile MPH = 178.83
4 KM ET = 60.718 -- 4 KM MPH = 180.74
5 KM ET = 69.301 -- 5 KM MPH = 181.55
3 Mile ET = 70.937 -- 3 Mile MPH = 181.65
6 KM ET = 85.346 -- 6 KM MPH = 182.16
4 Mile ET = 90.715 -- 4 Mile MPH = 182.25

Stan
Stan Weiss/World Wide Enterprises
Offering Performance Software Since 1987
http://www.magneticlynx.com/carfor/carfor.htm
Do you use engine simulation software that uses cylinder head flow files?
We have a package of more than 3125 DFW/FLW Files
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by Dragginwagon406 »

Stan Weiss wrote: Thu Nov 25, 2021 9:29 am
Dragginwagon406 wrote: Thu Nov 25, 2021 9:04 am
frnkeore wrote: Thu Nov 25, 2021 3:45 am I did a couple of quick calculations, using peak torque rpm (4300) and 27.4" tire (225/70/15) and w/o tire growth it comes out to 136.92 mph but, with 7.2% tire growth, it gives me the 146.76 mph. It seems reasonable that it wouldn't over come drag, after peak torque. If it could rev to 6k w/o additional tire growth, it would do 204.78 mph.

How was the CD figured and how was the tire growth estimated?

Can you figure the CD that would be needed to get it to 205 mph with the torque output of 498 @ 6k that he has?
With the way my Monte is picking up speed at the traps, it's hard to believe it only has 146 mph as a top speed, but that's just a gut feeling.

It's hard to see 5.7 L hemi chargers being that much better aerodynamically (although far superior air control).

Loosely shopping comparables below, I'd say the MC should have no problem pushing past 175-180 mph.

This is all conjecture of course...don't hold your breath for Draggy video verification :mrgreen:

2021 Dodge Charger SXT
Curb Weight 3,964 lbs
300 hp @ 6,350 rpm
264 lb-ft @ 4,800 rpm
Top speed of 147 mph
0-60 mph in 6.2 seconds
Standing 1/4 mile in 14.8

2021 Dodge Charger RT
Curb Weight 4,385 lbs
370 hp @ 5250 rpm
395 lb-ft @ 4200 rpm
Top speed of 155 mph
0-60 mph in 4.9 seconds
Standing 1/4 mile in 13.4

2021 Dodge Charger Scat Pack
Curb Weight 4,385 lbs
485 hp @ 6,100 rpm
475 @ 4,100 rpm
Top speed of 175 mph
0-60 mph in 3.9 seconds
Standing 1/4 mile in 12.3
Stan Weiss wrote: Tue Nov 23, 2021 2:06 pm I get this from my simulation.

60 Foot ET = 1.8935
330 Foot ET = 5.0774
1/8 Mile ET = 7.6995
1/8 Mile MPH = 93.9837
1000 Foot ET = 9.9455
1/4 Mile ET = 11.8308
1/4 Mile MPH = 120.3292

1/2 Mile ET = 18.651 -- 1/2 Mile MPH = 142.23
1 KM ET = 21.642 -- 1 KM MPH = 149.74
1 Mile ET = 30.263 -- 1 Mile MPH = 164.99

Stan
Let me add to my other post.

2 KM ET = 35.467 -- 2 KM MPH = 170.56
3 KM ET = 48.261 -- 3 KM MPH = 177.97
2 Mile ET = 51.003 -- 2 Mile MPH = 178.83
4 KM ET = 60.718 -- 4 KM MPH = 180.74
5 KM ET = 69.301 -- 5 KM MPH = 181.55
3 Mile ET = 70.937 -- 3 Mile MPH = 181.65
6 KM ET = 85.346 -- 6 KM MPH = 182.16
4 Mile ET = 90.715 -- 4 Mile MPH = 182.25

Stan
Now that is more believable, and more frightening :mrgreen:

I can imagine a successful 1/2 mile race; it would go by very quickly.

My squirrel mind can only imagine the dozens of mechanical landmines which await a 51 year old car during a 1, 2, 3, or 4 mile race.

Thanks for the math Stan, it's appreciated.
1.88, 11.84 @ 119.27, 4100 lbs, 2.56 gears, stock stall, 225/70-15 Cooper Cobras
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by dannobee »

Dragginwagon406 wrote: Thu Nov 25, 2021 9:47 am Now that is more believable, and more frightening :mrgreen:

I can imagine a successful 1/2 mile race; it would go by very quickly.

My squirrel mind can only imagine the dozens of mechanical landmines which await a 51 year old car during a 1, 2, 3, or 4 mile race.

Thanks for the math Stan, it's appreciated.
For sure I'd be putting an air dam on that thing if you're serious about going that fast. Even the old corvettes of that era had enough front end LIFT at 140mph that you'd swear it was going to take flight on you. And a crosswind? The pucker factor really comes into play. Look at any of the old nascar pics of the monte carlos, ALL of the superspeedway cars have air dams and rear spoilers.
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by maxracesoftware »

Dragginwagon406 wrote: Wed Nov 24, 2021 10:52 pm Does the highway gear affect how the power shows up in your program?
Yes it does affect calculated Peak HP ! 8)

if you were to setup your Car like an NHRA SuperStock Class Car
leaving your Engine alone like its making its current Tq and HP at,
then maybe use :
4.56:1 Rear Gears
4500 Stall Converter
Race Slicks maybe 10.5" wide x 29
get the Car to Hook in the 1.364 sec -to- 1.428 sec 60 Ft range

then at Sea Level Motorsport's STP it would show same HP that's on your Dyno Sheet from Mark ( VortecPro )

here's a few different ways it could show about 567 to 570 Peak HP
you could do it "early" in the Run ... like if you had too much rear gear ratio ??
or you could do it "late" in the Run around 1080 Feet -to- MPH traps

Early in Run
VortecPro_1970_MonteCarlo_315Ft.jpg

Late in Run
VortecPro_1970_MonteCarlo_1081Ft.jpg
MPH Traps in Run
VortecPro_1970_MonteCarlo_1226Ft.jpg
 
You do not have the required permissions to view the files attached to this post.
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by nxtruck »

Dragginwagon406 wrote: Mon Nov 22, 2021 8:49 pm
strokersix wrote: Mon Nov 22, 2021 1:51 pm Does the 2.56 gear have limited slip? Seems like it must be to run that quick.
I can answer that question…

Yukon Spartan locker.

Honestly, even with the 467 is was tough cracking into the 13s with the open differential…but the car was lowered back then, and still had a 2.25” Flowmaster exhaust.

14.1 @ 105+ mph open, car was miserable on the street and on the track
12.92 @ 108.96 with the locker (3” Torque Tech, 70 Series Flowmaster), car was good on the street and dead hook at the track
. Concerning your differential choice, how happy are you with the Spartan Locker? I had considered using one in the 12-bolt in my 65’ C10 shop truck, which is my fair weather daily driver. I’ve read mixed reviews on those type lockers and, as of yet, haven’t made up my mind which way to go on that. Does the car see a lot of street driving?
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by vortecpro »

maxracesoftware wrote: Thu Nov 25, 2021 12:17 pm
Dragginwagon406 wrote: Wed Nov 24, 2021 10:52 pm Does the highway gear affect how the power shows up in your program?
Yes it does affect calculated Peak HP ! 8)

if you were to setup your Car like an NHRA SuperStock Class Car
leaving your Engine alone like its making its current Tq and HP at,
then maybe use :
4.56:1 Rear Gears
4500 Stall Converter
Race Slicks maybe 10.5" wide x 29
get the Car to Hook in the 1.364 sec -to- 1.428 sec 60 Ft range

then at Sea Level Motorsport's STP it would show same HP that's on your Dyno Sheet from Mark ( VortecPro )

here's a few different ways it could show about 567 to 570 Peak HP
you could do it "early" in the Run ... like if you had too much rear gear ratio ??
or you could do it "late" in the Run around 1080 Feet -to- MPH traps

Early in Run
VortecPro_1970_MonteCarlo_315Ft.jpg


Late in Run
VortecPro_1970_MonteCarlo_1081Ft.jpg

MPH Traps in Run
VortecPro_1970_MonteCarlo_1226Ft.jpg

 
Larry

Mike's engine was dyno tested at his engine builders shop in Ohio.
Racing a NA NHRA stocker should be mandatory before any posting.
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by Dragginwagon406 »

nxtruck wrote: Thu Nov 25, 2021 5:01 pm
Dragginwagon406 wrote: Mon Nov 22, 2021 8:49 pm
strokersix wrote: Mon Nov 22, 2021 1:51 pm Does the 2.56 gear have limited slip? Seems like it must be to run that quick.
I can answer that question…

Yukon Spartan locker.

Honestly, even with the 467 is was tough cracking into the 13s with the open differential…but the car was lowered back then, and still had a 2.25” Flowmaster exhaust.

14.1 @ 105+ mph open, car was miserable on the street and on the track
12.92 @ 108.96 with the locker (3” Torque Tech, 70 Series Flowmaster), car was good on the street and dead hook at the track
. Concerning your differential choice, how happy are you with the Spartan Locker? I had considered using one in the 12-bolt in my 65’ C10 shop truck, which is my fair weather daily driver. I’ve read mixed reviews on those type lockers and, as of yet, haven’t made up my mind which way to go on that. Does the car see a lot of street driving?
Two years, 7500 miles, I’m on the second engine and transmission. 12.92 for the first engine. 11.84 for the second engine. Both with the 2.56 gears and original stall converter, and both with street tires. I average 5-6 trips to the track a year, 3-10 passes each trip. Driven to and from on all but one trip - I had 6 passengers, and that’s just too crowded to make a three hour drive.

I might not be the best person to comment on strength and durability though, due to the way I run my car. The lack of gear partially insulates the locker and axle shafts from the ample torque output, as do the 225/70-15 tires. Also consider, i’m keenly aware of what breaks a rear end so I start soft on the first pass and increase the rate of acceleration once I understand how much it will hold. In other words, I pretend my wallet sits between my brain and my lead foot. I’d buy another one ina heartbeat.

But, I don’t go easy on it when driving on the street. I bought the Coopers in August before Power Tour, they’re half gone already. The 496, with 2.56 gears, punishes tires. The wheel speed on most burnouts are 100+ mph. Without the locker, even with the old engine, the car was practically undrivable.
1.88, 11.84 @ 119.27, 4100 lbs, 2.56 gears, stock stall, 225/70-15 Cooper Cobras
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Re: 2.56 Gear, Stock Converter, 4100 Pounds, NA 11s?

Post by 1980RS »

Weather one runs 2.56 or 2.73 gears in a car the converter has the biggest effect on performance in my book. Changed gears in several car and it's never made a ton of difference but when I switched converters to something that was better the car always picked up. Case in point I had a 13:1 355 that ran 11.70's@114mph with a 10" TCI race converter. Later that year I switched that out to an 8" TCI race converter and the car now ran 11.40@119mph, no other changes to the car. This MC is no different, he is just running the car like it had a P/G with a steeper 1st and 2nd. gear.
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