2.4 Supercharger pulley size boost calculation

[Unholy707]

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!]

The billet end plate is the shizzle though

 

[RGPIII]

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!]

But you may have run a 9.10 at 152 with a 2.65 upper 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]

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]

@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

 

[RGPIII]

But you may have run a 9.10 at 152 with a 2.65 upper 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]

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]

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!]

@RGPIII what happened with the 2.7? I was really happy with mine.

 

[RGPIII]

@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.

 

[Unholy707]

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]

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.

 

[Unholy707]

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

 

[Unholy707]

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!]

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.

 

[DavidKFla]

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.

 

[Unholy707]

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.

 

[Unholy707]

What’s the stock lower pulley ratio?edit: 8.18

 

[Unholy707]

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