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Discussion Starter #1
Is there a calculator to find out what HP a cars leaves on ?

If I weigh 4600lbs and can run a 1.25 sixty , how much power is going to the ground when I let go of the button ?
 

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Discussion Starter #3
That calculator seems to be the same as 1/4 mile ET to weight .

Im looking for what it makes when it leaves .

It cant be making all the HP on the hit .
 

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But how fast are you bringing it all in? Mine is leaving on 9.5 psi and is all in pretty much right away........on slicks.....radials are another story. I don't know how realistic that calculator may be for you.
 

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T/S 368E
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Tom is absolutely correct.
No way in hell would I ever use 60' as a gauge.
I have a bad ass leaving car that pulls 1.05 & 1.06, but the MPH is not what the 60' predicts it should be.
The car is leaving like an animal but then falls on it's face when I run out of HP.

.
 

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There are many factors involved on 60 foot times. Horsepower plays a fairly significant role, but there are many other things, such as gearing, chassis setup, clutch/converter design, tire size/design, etc., etc.
 

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I honestly don't know how you could really figure it out for sure. Way to many variables to account for. For example I know exactly how much HP the engine makes on the engine Dyno. But if the car isn't set up right I could be way off in the 60' time. And lets say we improve the car and it picks up the 60' which is great but the HP never change with the engine...

Lets say all you did was change the rear gear and that improves the 60' time but it goes slower cause the car is now over geared. You still didn't make more power cause your 60' was quicker.

So in saying all of that the only way to really figure out how much torque and or HP the engine makes at any point on the track is to have one of those strain gauges on the driveshaft that other have tested before.

Nick
 

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I have a bad ass leaving car that pulls 1.05 & 1.06, but the MPH is not what the 60' predicts it should be.
The car is leaving like an animal but then falls on it's face when I run out of HP.

.
I didn't know you ran a 1.05 60'

That's a very respectable 60' why do you say it fall's on it's face?

Jim
 

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Here's how it can be analyzed but it's based on a few assumptions and has a slight gap that affects the computations.

Assume you accelerate at a constant rate leaving the hole for the first 60ft. Physics gives us d=1/2at2 (distance equals acceleration multiplied by time (squared) divided by 2.

We know distance and time so we can solve for acceleration. Using the assumption of constant rate of acceleration and your weight (4700 lbs?), we can solve for power required to accelerate that weight at that rate.

The slight gap is the roll-out distance. The roll-out effectively gives you a slight "running start" before the timer starts for the 60 ft. That distance varies between cars and if not accounted for in the above computations will give you a slightly higher HP than what it really is. You can still get an approximate HP by ignoring this though.

Maybe if I have time at work I might plug in the numbers and give you an "average horsepower" at the wheels.
 

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http://www.wallaceracing.com/calc60hp.php


But I wouldn't put much stock in it. We know how much difference a torque converter makes to a 60ft time, so how can the HP figure be close? Take care. Tom Worthington
Its pretty far off for me... Your HP computed from your 60 Foot Time of 1.37 at Weight of 2781 pounds is 542.61 HP. my car made 475 on the dyno at the tire..
 

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T/S 368E
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Because I out 60' several of my buddies, but they are much quicker & more MPH.
All I did was took the S/G engine out of the Camaro, stuck a fogger on it and put it in my T/S car and went racing.
It had a N/A cam, N/A pistons, which melted, and a virgin intake that didn't even line up correctly.

It launched great, 1.059-1.062 was way more than we ever expected out of that thing!!!
I honestly didn't expect a 1.0 anything.
Working hard to update a few things, and get the pieces I need for an actual T/S combination before coming out again.


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T/S 368E
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Plus the calculator said 1250 HP and I didn't have anything even close to that.

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That calculator seems to be the same as 1/4 mile ET to weight .

Im looking for what it makes when it leaves .

It cant be making all the HP on the hit .
A 60ft equation for power is the average at the back tire from TB release to the 60 ft based on weight and the 60ft on the time slip you enter into the equation to come up with power to 60, same as a power calculation to any interval on the track 60 330 660 ect.

The observed stall on the torque converter in your data acquisition will tell you how much power you are making at the hit. Compare what it flashes to at TB release vs the flash stall at the shift, at which time you're at full boost (full power).
 

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Tell me the difference in rpm flash stall at the hit vs the rpm flash stall at the shift (what rpm it drops to) and I can tell you the difference in power.
 

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Discussion Starter #16 (Edited)
I guess I would basically have to know what it makes at 11psi and 4200rpm as thats what its leaving on .

Randy , I trust that brain of yours ........ post back with what you get . 4600lbs , 1.25 sixty . Let us know what calculation you use .


Just looked at a data log and its making 26psi at the 1.25 mark and 6100rpm .....
 

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Too Strong, For Too Long.
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Post a graph like this example if you can.


 

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I guess I would basically have to know what it makes at 11psi and 4200rpm as thats what its leaving on .

Randy , I trust that brain of yours ........ post back with what you get . 4600lbs , 1.25 sixty . Let us know what calculation you use .


Just looked at a data log and its making 26psi at the 1.25 mark and 6100rpm .....
I am completely uneducated(stoopid)on this subject, but my feeble mind thinks that it would be doubly difficult to find the correct answer for ANY boosted application.

Unlike an NA or even nitrous setup, turbo and blower cars are increasing HP at a rapid pace as RPM's come up.

A simple "guess" would be to add the initial launch HP to the 60' HP, divide by 2, and be happy with that guesstimate?

A lot of folks do not have access to that data, but it seems like you have one half, and if you have dyno pull graph's then you have everything needed.


I can tell you this much without ANY racepak or dyno graph.....

4600lb. truck with a 1.25 sixty ft. = a LOT of power.:cool:
 

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That's for damn sure, that's amazing. Very very impressive.
My 3000 lb Camaro had over 1000 HP and had a total of five 1.29 60' for many years.
All done on 2 different days of mine shaft air!!!

.
 

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I guess I would basically have to know what it makes at 11psi and 4200rpm as thats what its leaving on .

Randy , I trust that brain of yours ........ post back with what you get . 4600lbs , 1.25 sixty . Let us know what calculation you use .


Just looked at a data log and its making 26psi at the 1.25 mark and 6100rpm .....
I presume this is a 3 sp transmission. How much boost does it make at max shift rpm before the 1-2 shift in comparison to boost at the max shift rpm at the 2-3 shift?
 
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