Welcome to Modern Mopar Forum

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customize your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.

G Funk

question about pulleys 6lb vs 8lb

Is there a way for me to figure out how much extra horsepower an 8lb pulley would give me over my 6lb?  There has to be some math equation that i can work with my current HP numbers?

 

Last dyno was 555hp and 503tq and i ran a 12.0 at the track and i am not too happy with that, i want a consistent 11's car so i am seriously considering swapping for a smaller pulley but i have been told that i need to stay at around 575-585hp (under 600) so i don't throw a stock rod.  My pistons are 2618's so no worries there.

Share this post


Link to post
Share on other sites
7 hours ago, RobbyD said:

I was always under the understanding it was 20 rwhp for every lb. 

 

 

Thanks for the feedback.  I have been told that i am pushing my transmission pretty hard with the 6lb pulley so i need to beef up my transmission before i swap pulleys. Also need a DSS driveshaft i think.  Damn this expensive casual hobby i have! :-)

Share this post


Link to post
Share on other sites

hahahaha I know i know.  Sorry about your misfortunes but glad everything got sorted out pretty quickly for you.  Curious what your dyno numbers are, I am sitting around 505tq where are you?

 

Drive train upgrades are next on my agenda.  I will do my best to break something in the meantime.

Share this post


Link to post
Share on other sites

You have to remember on the street and in the drag strip is two different situations. Street tires on the street won't get enough traction. If you plan to track it then yes Stock driveline aka axles and driveshaft is a must

 

 

Sent from my iPhone using Tapatalk

 

Share this post


Link to post
Share on other sites

About 12 to 15rwhp per lb. All depends on how agressive or conservative you have it tuned. When i up'd the boost this year i went from 9psi (stock block) to 14psi (forged block) and picked up 97rwhp

As far as drivetrain, breaking shit is inevitable. 

I ran with 613rwhp and a 100 shot on stock rods and pistons, tracked it weekly on straight slicks with 5500rpm launches (factory driveshaft and axles) for a full season. 

I wouldn't bank on being safe with factory parts. I got lucky. Before i started to heavily modify the car i snapped a halfshaft launching a stock car. lol

Why didnt you upgrade rods when you did pistons? 

Share this post


Link to post
Share on other sites
11 hours ago, SRTgreasemonkey said:

About 12 to 15rwhp per lb. All depends on how agressive or conservative you have it tuned. When i up'd the boost this year i went from 9psi (stock block) to 14psi (forged block) and picked up 97rwhp

As far as drivetrain, breaking shit is inevitable. 

I ran with 613rwhp and a 100 shot on stock rods and pistons, tracked it weekly on straight slicks with 5500rpm launches (factory driveshaft and axles) for a full season. 

I wouldn't bank on being safe with factory parts. I got lucky. Before i started to heavily modify the car i snapped a halfshaft launching a stock car. lol

Why didnt you upgrade rods when you did pistons? 

I just did not have the extra 1k at the time when i had my block rebuilt to get forged rods :-( 

 I will get them done at some point soon if i dont break something first that needs immediate fixing.  I track my car at least once a month and REALLY want to throw that 8lb pulley on.

 

 

 

 

Share this post


Link to post
Share on other sites
13 hours ago, us1champ said:

You have to remember on the street and in the drag strip is two different situations. Street tires on the street won't get enough traction. If you plan to track it then yes Stock driveline aka axles and driveshaft is a must

 

 

Sent from my iPhone using Tapatalk

 

Understood but what about my transmission?  I was told i needed to upgrade it before i put an 8lb pulley on?

Share this post


Link to post
Share on other sites
16 hours ago, G Funk said:

Thanks for the feedback.  I have been told that i am pushing my transmission pretty hard with the 6lb pulley so i need to beef up my transmission before i swap pulleys. Also need a DSS driveshaft i think.  Damn this expensive casual hobby i have! :-)

I didn't notice, but is your car a 6 speed or automatic? At some point you'll end upgrading everything. Trans, drive shaft, half hafts, rear cradle &rear dif. At least I did. and I'm at 13 lbs. 

 

 

Share this post


Link to post
Share on other sites
Just now, RobbyD said:

I didn't notice, but is your car a 6 speed or automatic? At some point you'll end upgrading everything. Trans, drive shaft, half hafts, rear cradle &rear dif. At least I did. and I'm at 13 lbs. 

 

 

Its an Auto.  2013 R/T

Share this post


Link to post
Share on other sites
I just did not have the extra 1k at the time when i had my block rebuilt to get forged rods :-( 
 I will get them done at some point soon if i dont break something first that needs immediate fixing.  I track my car at least once a month and REALLY want to throw that 8lb pulley on.
 
 
 
 

Slap it on and send it!

Sent from my SM-G935V using Tapatalk

Share this post


Link to post
Share on other sites

Run GOOD 109 octane fuel from a 5 gallon pail and you can put the 8psi pulley on there.  Just check your tune to make sure it doesn't go lean and log your passes to look for STKR.  If the AFR stays in the 11.50 - 11.80 range and no more than .5 - 1° of STKR you're good to go.  

550RWHP and 505RWTQ should give you better than 12.0 though.  Post your time slip so we can analyze it.  What tires are you running?

In my 6 speed at 550RWHP I ran 11.40s - 11.50s consistently.  I was on DRs and had 1.7x to 1.8x 60's if I remember right.  My slips are on the forum somewhere.

Share this post


Link to post
Share on other sites
2 hours ago, Speedy said:

Run GOOD 109 octane fuel from a 5 gallon pail and you can put the 8psi pulley on there.  Just check your tune to make sure it doesn't go lean and log your passes to look for STKR.  If the AFR stays in the 11.50 - 11.80 range and no more than .5 - 1° of STKR you're good to go.  

550RWHP and 505RWTQ should give you better than 12.0 though.  Post your time slip so we can analyze it.  What tires are you running?

In my 6 speed at 550RWHP I ran 11.40s - 11.50s consistently.  I was on DRs and had 1.7x to 1.8x 60's if I remember right.  My slips are on the forum somewhere.

Agreed i thought i would get into the 11's for sure.  Here is the slip, i am in the right lane.  I was running 28x10x17 hoosier slicks and 4.5" front skinnies.

 

 

right lane 21.jpg

Share this post


Link to post
Share on other sites
22 minutes ago, StevoHemi said:

You got room for improvement in that 60 foot. What tire pressure you running? Rear gear ratio?

 

Stevo

15.5 in the rears and 40 in the fronts.  3.06 gear ratio.

Share this post


Link to post
Share on other sites

Yeah, 1.92 60' with slicks and skinnies is no bueno.  On slicks in my 6 speed I was in the high 1.5s 60' range.  Every 10th on the 60 is worth "about" two on the big end.  MPH looks a bit lower than 550RWHP, but not much.

I'd leave the car as is for now and work on your launch and 60'.  Tires shouldn't be spinning much at all on launch if they're heated up enough.  My buddy says he gets best results just smashing it off idle.

Data log some runs and see what they tell you.

Share this post


Link to post
Share on other sites

I've had my best results smashing off the line too. Stock converter and 1.7's 60'
I'm not coordinated enough to launch at hi rpm's. I'm at about 515-525 hp and run 11.5's


Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

Thanks for the feedback everyone i guess maybe the only mod that is needed at the moment is the driver mod :)  I have always told myself that i will never just throw horsepower at my car unless i am getting the fastest 1/4 times that i can possible with my setup and more power is the ONLY way i can go faster.  It seems the case right now is that i need to learn to drive it better at the track although I do want to start looking into drive train upgrades.

 

I will keep things as is, and work on launching and my 60ft. I have data logs from the 4 passes i made the last time i went to the track so i am going to try and start the process to get those over to OST so they can take a lookie and then go from there.  I'll post more slips when i get them, thanks again!

Share this post


Link to post
Share on other sites
53 minutes ago, Renfrick1 said:

I've had my best results smashing off the line too. Stock converter and 1.7's 60'
I'm not coordinated enough to launch at hi rpm's. I'm at about 515-525 hp and run 11.5's


Sent from my iPhone using Tapatalk

I was revving up to 2k rpm and then mashing it and launching, maybe i should not be launching at 2k?

Share this post


Link to post
Share on other sites
1 hour ago, Renfrick1 said:

I've had my best results smashing off the line too. Stock converter and 1.7's 60'
I'm not coordinated enough to launch at hi rpm's. I'm at about 515-525 hp and run 11.5's


Sent from my iPhone using Tapatalk

There was a post on LX as to "how to launch a whale" try to find that it may help.

Found it for you.

 

http://www.lxforums.com/board/at-the-dragstrip/149951-launch-4400lb-whale-basics.html?highlight=how+to+launch+whale

 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now