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

[skinny z]

How about this question?
Has anyone mentioned fuel economy considering it's the cruiser it is? Maybe I missed it.
I can see the throttle barely being cracked open at highway speed. A good lean cruise tune might yield some impressive numbers.
Just remember that drag increases with square of the speed. Brick or no brick. I see it in my daily truck between 70 and 80 MPH.

[Dragginwagon406]

How about this question?
Has anyone mentioned fuel economy considering it's the cruiser it is? Maybe I missed it.
I can see the throttle barely being cracked open at highway speed. A good lean cruise tune might yield some impressive numbers.
Just remember that drag increases with square of the speed. Brick or no brick. I see it in my daily truck between 70 and 80 MPH.

It could get decent mileag, but more often than not, it doesn’t. Make no mistake, this is most definitely a pleasure craft.

[maxracesoftware]

Dragginwagon406 ,
how did you get a 2.56 rear gear in your Monte Carlo ???

from memory ?? , mine had a 3.23 or a 3.42 in it
i didn't think any Monte Carlo had less than a 3.07 or 3.08 back then

[Dragginwagon406]

Dragginwagon406 ,
how did you get a 2.56 rear gear in your Monte Carlo ???

from memory ?? , mine had a 3.23 or a 3.42 in it
i didn't think any Monte Carlo had less than a 3.07 or 3.08 back then

Luck, or destiny, the factory 12-bolt was 2.56 open.

I’m glad it did, these racing gears are hard to find these days.

[PackardV8]

a 12-bolt differential was installed as standard equipment, complete with a 3.31:1 final-drive ratio. It was linked to the transmission via open driveshaft with a harmonic dampener.

As was typical, Chevy made the Posi-traction unit (RPO G80) available through the option chart, except that it automatically brought with it a 2.56:1 gear as the standard ratio in 1970;

[Dragginwagon406]

a 12-bolt differential was installed as standard equipment, complete with a 3.31:1 final-drive ratio. It was linked to the transmission via open driveshaft with a harmonic dampener.

As was typical, Chevy made the Posi-traction unit (RPO G80) available through the option chart, except that it automatically brought with it a 2.56:1 gear as the standard ratio in 1970;

Source?

[frnkeore]

I would still like to know how maxracesoftware, calculates the CD and tire growth.

[PackardV8]

a 12-bolt differential was installed as standard equipment, complete with a 3.31:1 final-drive ratio. It was linked to the transmission via open driveshaft with a harmonic dampener.

As was typical, Chevy made the Posi-traction unit (RPO G80) available through the option chart, except that it automatically brought with it a 2.56:1 gear as the standard ratio in 1970;

Source?

Hemmings

https://www.hemmings.com/stories/articl ... s-454[url][/url]

[Dragginwagon406]

Source?

Hemmings

https://www.hemmings.com/stories/articl ... s-454[url][/url]

Easy to explain the misunderstanding, my Monte is not an SS, which was LS-5 454, automatic TH400 only, 12-bolt, 3.31 open or 2.56 limited slip (from what you’re saying).

My car was a 350 2-bbl car, TH350, 12-bolt, 2.56 open. Interesting to note, my car also doesn’t have A/C, and didn’t have the HD cooling.

Fixed link

https://www.hemmings.com/stories/articl ... rlo-ss-454

[BradH]

What's been done to the trans to handle that amount of power?

[Dragginwagon406]

What's been done to the trans to handle that amount of power?

Well, the first transmission was the original 110K mile unit supplied with the car. The transmission made dozens of passes, but eventually started taking too long to shift from 1st to 2nd with the 496 I installed in July this year. I did change the filter and install a Hughes deep pan in the first transmission shortly after I bought the car in August 2018. It was running 16.5 @ 86 mph back then, with the original 100K mile, 350 2-bbl coverterd to factory correct 4-bbl.

September 2019, I dropped a swap-meet/marketplace 467 in front of the factory transmission. The 467 eventually went 12.9 @ 109 mph spring of this year. July of this year, 6 days off the engine dyno, the 496 was on the road with the same transmission. The transmission made two passes at Blue Suede Cruise, and three passes at Thompson Dragway (engine was not happy on that day due to bad plug wires and really bad air). By the last pass at Thompson, it was taking 15 mph to shift from 1st to 2nd.

The transmission in the car now is a mild performance rebuild from the early 2000s. It's fitted with good clutches, HD sprag, and a TransGo shift improver kit. We'll see how long it lasts, but it seems to be doing well. I reused the original torque converter from the car.

If things go sideways, I have a straight cut planetary TH400 and aluminum driveshaft ready if it hiccups. I'm hoping to keep the TH350 as long as it makes sense since it takes less power to drive it.

[Dragginwagon406]

for a Weather HP Correction Factor = 1.0000 i calculate 507.6 Peak HP occured at 733 Feet distance

if i understood correctly , it was in 2nd Gear thru the 1/4 Mile ??
 

VortecPro_1970_MonteCarlo_ZeroHPCF.jpg
VortecPro_1970_MonteCarlo_ZeroHPCF_733Ft.jpg

 

maxracesoftware, would you be willing to make another analysis of a friend's 427 SB Monte, for comparison? I'll graph his from your numbers the same way, and overlay them for comparison. Hp wise, they're fairly close (although, I have more torque). His is much closer to ideal on the car so it should be interesting to see them graphed together.

His dyno and timeslip are below.

Al Dyno.jpg

He raced at LVD 9/6/2020, let's just call it 1 PM (time isn't on his slip):

https://airdensityonline.com/track-hist ... 020-09-06/

Al Time Slip.jpg

[rfoll]

"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." I remember years ago seeing finsh line pictures of stock bodied muscle cars with big horsepower, many seeing speeds well over 150 mph. Some of the pictures showed fenders and hoods all warped out of shape from the poor aerodynamic nature of the bodies. The one that really stood out was a car that had the front wheels a couple of inches off the ground going through the traps at the end of the track.

[Dragginwagon406]

"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."

I remember years ago seeing finsh line pictures of stock bodied muscle cars with big horsepower, many seeing speeds well over 150 mph. Some of the pictures showed fenders and hoods all warped out of shape from the poor aerodynamic nature of the bodies. The one that really stood out was a car that had the front wheels a couple of inches off the ground going through the traps at the end of the track.

Yeah, our understanding and application of aerodynamics has come a long ways in production cars. The fact these cars don't even have a proper excluder to keep hot engine compartment air from being recycled through the radiator is entertaining.

At a minimum, a chin spoiler would be in order for a high speed run, but probably a roll of duct tape too

[maxracesoftware]

by Dragginwagon406 » Sun Nov 28, 2021 8:29 am
maxracesoftware, would you be willing to make another analysis of a friend's 427 SB Monte,
for comparison? I'll graph his from your numbers the same way,
and overlay them for comparison. Hp wise, they're fairly close (although, I have more torque).
His is much closer to ideal on the car so it should be interesting to see them graphed together.

you forgot to state :
1]= Car weight w/Driver ??
2]= does he have Cowl Induction , HoodScoop , or no Ram-Air device whatsover ??
3]= what type of rear Tires ?? real Slicks or very good DOT Street Tires ??