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Discussion Starter #1 (Edited)
Hey guys,

I currently have the 3.06 gears on my 2009 5.7L Auto w/ 20" rims. Tires on back are 275/40/20 and front is 255/35/20. Also have an FTI 2800 Stall Converter

My acceleration is pretty good off the line with my 274 CompCam and Vortech SC but I was looking for more. So my questions is, should I upgrade my gears to 3.73, 3.92 or keep my 3.06 and upgrade the pulley on the SC (I am not forged)? I have an underdrive pulley that I had added when I got the Cam for a tiny bit more horsepower and do not want to change to an overdrive pulley because it was too involved changing that thing.

I see MAXIMUM 8lbs in the high rpms, but usually it's between 4-6lbs of boost. I know that if I upgrade my gears, my top speed is going to be lower and mpg is going to go down. I'm currently around 9-12mpg lol. Traction is pretty bad as it is now so I have to ease into the gas....I would like to know if there is a way that I can grip and mash the pedal but that my be a different topic.

Anyways, should I upgrade my gears?
 

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Discussion Starter #2
Anyone?
 

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Traction is pretty bad as it is now so I have to ease into the gas....I would like to know if there is a way that I can grip and mash the pedal but that my be a different topic.

Anyways, should I upgrade my gears?
I'm afraid different gearing won't help much until you get more traction.

Once/if you get more grip, revisit your gearing possibilities.
 

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What cannonball said, you need some tires to get hooked. I put 3.92 gears in mine and it was a world of difference esp with my 3800 stall. I just got a set of 4.29 gears so im looking forward to trying them at the track. I run around on Mickey Thompson DR all the time tho also.
 
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What speed is your car trapping at? You generally want to shift the least amount of times and be at about redline when you cross the finish. If you have the low end torque and you should with FI then a better gear would be maybe a 3.23....if your trap speed is around a 120mph then you would be at the top of 3rd.

A 3.73 or larger will put you in the middle of 4th. Your other choice is to go 4.10 or 4.30 but not good for the street.

The best mod you could do is use drag radials. If you are putting out the power you should be street tires just wont cut it.
 

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I know this is an older thread but I have a question that maybe answered above. I just installed the the 392 cam and catless longtubes. I'm putting 412 to the wheels now. I never been to the track but at this point I don't see the reason as all i do is spin my tires. I have the 3.06 stp set up from the factory. I won't be a regular at the track but I'd really like to give it a go once or twice. From what i read above it's more of a tire issue correct? btw I still have my original Eagle F1's. I'd like to get an accurate run not one based on my tires spinning the first half second
 

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I know this is an older thread but I have a question that maybe answered above. I just installed the the 392 cam and catless longtubes. I'm putting 412 to the wheels now. I never been to the track but at this point I don't see the reason as all i do is spin my tires. I have the 3.06 stp set up from the factory. I won't be a regular at the track but I'd really like to give it a go once or twice. From what i read above it's more of a tire issue correct? btw I still have my original Eagle F1's. I'd like to get an accurate run not one based on my tires spinning the first half second
You may try some drag radials. That would give you some better traction. Do you have the anti spin diff?
 

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Yes, I have the anti spin, comes with the stp. Drag radials are in the picture for sure. Have heard others mention suspension upgrades.
 

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3.91 all the way in my 09 SRT8 Auto, and with the 275 D/R's they make the ratio about 4.10 if I'm not mistaken.
 

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Do the upgrade, I love my 3.73's but I'll be honest with current mods and such. I am shifting from 3rd to 4th a little around 1100ft which feels by the time I shift into 4th I'm crossing the line (1320ft).

PB w/ 3.73's - [email protected]

IMO with your automatic, I would go 3.92's or even 4.10's. BUT 4.10's may be a bit much though for street application/daily driver.

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Do the upgrade, I love my 3.73's but I'll be honest with current mods and such. I am shifting from 3rd to 4th a little 1100ft to 1320ft which feels by the time I shift into 4th I'm crossing the line.

PB w/ 3.73's - [email protected]

IMO with your automatic, I would go 3.92's or even 4.10's. BUT 4.10's may be a bit much though for street application/daily driver.

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With the 3.92 gear and 275/17's I'm at the top of 4th at the trap...shifting 5th a little after the trap....just as a reference.


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6.1L, SRT Max cam, NAG1, *stock TC*, 275/17 Hoosier DRs. My PB after swapping from 3.06 to 3.73 went barely .2 better. With 3.06, I would trap as I hit 4th, now I hit 4th a couple hundred yards out. That extra shift negated part of my gain. Blue Tops will go in within the next couple weeks to firm shifts up. I definitely need a better TC but on a very tight budget lately. I'm thinking the short 26" tall DRs are a great match for 3.06 but not so much with the 3.73. My PB on street tires (Hankook V12 evo) is just .2 off from PB on DRs.
 
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