• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Dodge, Jeep and RAM Forum dedicated to FCA owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the SRT Forum today!


2.4 Supercharger pulley size boost calculation

OP
Unholy707

Unholy707

6000 Posts Club
9 Second Best E/T
HFCOTM
Member ID
#11903
Messages
6,730
Reactions
5,578
Likes
402
City
Orlando
State
FL
Country
United States
Vehicle
2015 Dodge Challenger Hellcat
Thread Starter #21
It’s actually cheaper than I thought for full race rebuild and port. What’s going to kill me is the shipping and insurance. Hmmm
 


Speedy!

Infomercial Producer
Staff Team
Founding Member
U.S. Marine Veteran
9 Second Best E/T
HFCOTM & HFCOTY
Member ID
#1070
Messages
6,581
Reactions
16,875
Likes
402
City
Interwebs
State
TN
Country
United States
Vehicle
Demon 170
#22
The billet end plate is the shizzle though
 


RGPIII

1000 Posts Club
Founding Member
8 Second Best E/T
HFCOTM
Member ID
#983
Messages
1,044
Reactions
1,937
Likes
212
City
Bridgeville
State
DE
Country
United States
Vehicle
2016 Challenger Hellcat
#23
When I had my jokers race ported 2.4, with billet bearing plate, I ran a 2.50 upper and stock lower on my stock engine with 2 in headers. saw about 19.5 psi. car ran 9.3's at 150 with it.
 


Speedy!

Infomercial Producer
Staff Team
Founding Member
U.S. Marine Veteran
9 Second Best E/T
HFCOTM & HFCOTY
Member ID
#1070
Messages
6,581
Reactions
16,875
Likes
402
City
Interwebs
State
TN
Country
United States
Vehicle
Demon 170
#24
But you may have run a 9.10 at 152 with a 2.65 upper :unsure: Did you try swapping pulleys at the track to see if there was improvement? Learned fooling around with superchargers more isn't necessarily more. You have to test it.

My IATs with the 2.72 were 160ish at the end of the quarter. A chiller will help there, but that was about all I wanted to see in my logs.
 


hellno

3000 Posts Club
8 Second Best E/T
HFCOTM
Member ID
#1308
Messages
3,326
Reactions
5,815
Likes
302
City
memphis
State
TN
Country
United States
Vehicle
2016 challenger hellcat
#25
in the heat with my 2.4 the 2.75was the smallest i went because the 2.65 would only create more heat and was only 1/100 difference ,this was in very high humidity and with only a black market racing reservoir when i was able to cool it down i would run the 2.65 after adding the interchiller,,then with weather in the 40s id run the 2.57 ,this was all with a 10percent lower
 


hellno

3000 Posts Club
8 Second Best E/T
HFCOTM
Member ID
#1308
Messages
3,326
Reactions
5,815
Likes
302
City
memphis
State
TN
Country
United States
Vehicle
2016 challenger hellcat
#26
@hellno only knows about chevys now he forgot all hellcat stuff 😆
yes i forgot all my hellcat knowledge ,,oh in btw the way my new balance shoes arrived :LOL:
 


RGPIII

1000 Posts Club
Founding Member
8 Second Best E/T
HFCOTM
Member ID
#983
Messages
1,044
Reactions
1,937
Likes
212
City
Bridgeville
State
DE
Country
United States
Vehicle
2016 Challenger Hellcat
#27
But you may have run a 9.10 at 152 with a 2.65 upper :unsure: Did you try swapping pulleys at the track to see if there was improvement? Learned fooling around with superchargers more isn't necessarily more. You have to test it.

My IATs with the 2.72 were 160ish at the end of the quarter. A chiller will help there, but that was about all I wanted to see in my logs.
I never ran that setup again. that IHI had the rear bearings fail. then I switched to a 2.7 which sucked all together. so I went Whipple and ran 8.92 at 155
 


hellno

3000 Posts Club
8 Second Best E/T
HFCOTM
Member ID
#1308
Messages
3,326
Reactions
5,815
Likes
302
City
memphis
State
TN
Country
United States
Vehicle
2016 challenger hellcat
#28
I never ran that setup again. that IHI had the rear bearings fail. then I switched to a 2.7 which sucked all together. so I went Whipple and ran 8.92 at 155
i was fortunate to never have any blower issues
 


RGPIII

1000 Posts Club
Founding Member
8 Second Best E/T
HFCOTM
Member ID
#983
Messages
1,044
Reactions
1,937
Likes
212
City
Bridgeville
State
DE
Country
United States
Vehicle
2016 Challenger Hellcat
#29
i was fortunate to never have any blower issues
I do not know what that's like. I've had 8 in the last 2 seasons.
 


Speedy!

Infomercial Producer
Staff Team
Founding Member
U.S. Marine Veteran
9 Second Best E/T
HFCOTM & HFCOTY
Member ID
#1070
Messages
6,581
Reactions
16,875
Likes
402
City
Interwebs
State
TN
Country
United States
Vehicle
Demon 170
#30
@RGPIII what happened with the 2.7? I was really happy with mine.
 


RGPIII

1000 Posts Club
Founding Member
8 Second Best E/T
HFCOTM
Member ID
#983
Messages
1,044
Reactions
1,937
Likes
212
City
Bridgeville
State
DE
Country
United States
Vehicle
2016 Challenger Hellcat
#31
@RGPIII what happened with the 2.7? I was really happy with mine.
It was never really happy on my setup. It was 3-4 tenths slower than my 2.4. definitely didn't live up to he hype for me. Sold it, and bought the Whipple. Was a big improvement in power.
 


OP
Unholy707

Unholy707

6000 Posts Club
9 Second Best E/T
HFCOTM
Member ID
#11903
Messages
6,730
Reactions
5,578
Likes
402
City
Orlando
State
FL
Country
United States
Vehicle
2015 Dodge Challenger Hellcat
Thread Starter #32
This is a real lively debate, I like it. So what I’m hearing is - on borrowed time with supercharger bearings on unbuilt blower and the 2.57. Ported and 2.57, send it 😎
 


fubar569

1000 Posts Club
Founding Member
9 Second Best E/T
Member ID
#1073
Messages
1,297
Reactions
1,889
Likes
162
City
Bradford
State
PA
Country
United States
Vehicle
2018 Charger Hellcat
#33
Basically.

My car is capable of so much more if I'd quit handicapping Curt. Told him flat out to leave it safe instead of chasing numbers. Plus most of these mods were originally installed in 2019. The ported blower went on in 2021. The headers this year. That 9.84 pass has at least another .2-.3 left in it based on 60ft alone. I have removed 0 weight. Actually I've added some by leaving tools, gear and my sub in the trunk.

By just chucking up and admitting this is a race car and not a street car I could see tremendous improvement. But I'm a potato. So.
 


OP
Unholy707

Unholy707

6000 Posts Club
9 Second Best E/T
HFCOTM
Member ID
#11903
Messages
6,730
Reactions
5,578
Likes
402
City
Orlando
State
FL
Country
United States
Vehicle
2015 Dodge Challenger Hellcat
Thread Starter #34
Basically.

My car is capable of so much more if I'd quit handicapping Curt. Told him flat out to leave it safe instead of chasing numbers. Plus most of these mods were originally installed in 2019. The ported blower went on in 2021. The headers this year. That 9.84 pass has at least another .2-.3 left in it based on 60ft alone. I have removed 0 weight. Actually I've added some by leaving tools, gear and my sub in the trunk.

By just chucking up and admitting this is a race car and not a street car I could see tremendous improvement. But I'm a potato. So.
I’m running 9.84 @ 142 with the 2.69 and 1.45 60’. You definitely have more in it, time to pull some seats! Lol
 


Last edited:
OP
Unholy707

Unholy707

6000 Posts Club
9 Second Best E/T
HFCOTM
Member ID
#11903
Messages
6,730
Reactions
5,578
Likes
402
City
Orlando
State
FL
Country
United States
Vehicle
2015 Dodge Challenger Hellcat
Thread Starter #35
I have a Kirkey, all other seats out, sway bar out, about 65 lbs savings with drag setup (17 beadlocks with 315 et street R weighs ton)
 


Speedy!

Infomercial Producer
Staff Team
Founding Member
U.S. Marine Veteran
9 Second Best E/T
HFCOTM & HFCOTY
Member ID
#1070
Messages
6,581
Reactions
16,875
Likes
402
City
Interwebs
State
TN
Country
United States
Vehicle
Demon 170
#36
If your pulleys are the kind you can swap I'd take a 2.75, 2.65, and 2.57 to the track. Make some passes and you'll know what is working best for your setup.

Keep this in mind for rotor speed, I'm sure you've seen it before. Jesse at SDG who seemed to know his stuff didn't think super duper bearing upgrades got you much. I think it's more deflection in the rotor that causes failure. He said he'd not seen a bearing fail if I remember our convo correctly.

IMO you'd be better to free up the blower with a billet end plate so the supercharger isn't working as hard, and use a larger pulley to keep temps as low as possible. The billet end plate on mine gave me what I think was an extra 2psi. The 2.85 pulley on my 2.7 was seeing over 20psi.

2.4L IHI Efficiency.png
 


DavidKFla

Poster Club Hall of Fame
Premium Account
U.S. Air Force Veteran
10 Second Best E/T
HFCOTM
Member ID
#6741
Messages
30,871
Reactions
135,742
Likes
402
City
East Coast
State
FL
Country
United States
Vehicle
2018 Charger Hellcat
#37
Geez. Sounds like bunch of things just for a 9. Mine ran a 10.0 with a 2.85, full weight and MS109. Stock suspension, 305 - 18 street rs, all the safetys on and a soft launch.
 


Last edited:
OP
Unholy707

Unholy707

6000 Posts Club
9 Second Best E/T
HFCOTM
Member ID
#11903
Messages
6,730
Reactions
5,578
Likes
402
City
Orlando
State
FL
Country
United States
Vehicle
2015 Dodge Challenger Hellcat
Thread Starter #38
Big difference between 9.8 and 9.2
Geez. Sounds like bunch of things just for a 9. Mine ran a 10.0 with a 2.85, full weight and MS109. Stock suspension, 305 - 18 street rs, all the safetys on and a soft launch.
 


OP
Unholy707

Unholy707

6000 Posts Club
9 Second Best E/T
HFCOTM
Member ID
#11903
Messages
6,730
Reactions
5,578
Likes
402
City
Orlando
State
FL
Country
United States
Vehicle
2015 Dodge Challenger Hellcat
Thread Starter #39
What’s the stock lower pulley ratio?edit: 8.18
 


OP
Unholy707

Unholy707

6000 Posts Club
9 Second Best E/T
HFCOTM
Member ID
#11903
Messages
6,730
Reactions
5,578
Likes
402
City
Orlando
State
FL
Country
United States
Vehicle
2015 Dodge Challenger Hellcat
Thread Starter #40
If your pulleys are the kind you can swap I'd take a 2.75, 2.65, and 2.57 to the track. Make some passes and you'll know what is working best for your setup.

Keep this in mind for rotor speed, I'm sure you've seen it before. Jesse at SDG who seemed to know his stuff didn't think super duper bearing upgrades got you much. I think it's more deflection in the rotor that causes failure. He said he'd not seen a bearing fail if I remember our convo correctly.

IMO you'd be better to free up the blower with a billet end plate so the supercharger isn't working as hard, and use a larger pulley to keep temps as low as possible. The billet end plate on mine gave me what I think was an extra 2psi. The 2.85 pulley on my 2.7 was seeing over 20psi.

View attachment 126101
I’m going to do a max effort kong port with race bearing rebuild, it has been decided. Will move the a 2.57 as well most likely and see how cool it stays
 




Top