3.42s in a Street Truck

[prostreeter600]

Bring back an old thread. Will going to 3.42 gears with my 30.2" tall DRs make my (empty)5660# truck go faster or slower in the 1/8 and 1/4 . My new triple setup pulls extremely hard and it hasn't even been tuned for the triples yet. Currently running on tunes for my last compound setup. So my guess is that the torque will load the motor and turbos harder and propel the truck a lot harder with the 3.42s . Plan is to take the truck out to the 1/8 mile track as soon as I put in my new Goerend LL converter, gather some data and then have Mark at DP build me some tunes for it . Then go back out to the 1/8 mile track for additional testing and data gathering. Hopefully somebody that has already done this and has personal information can chime in.

 

[PACougar]

Side question, what DR's are you running and are they just going to be used on the track?

 

[prostreeter600]

Hoosier 325/45/18 Drag Radials . I plan on using them for the street and the track . I don't drive it much other than week ends . I DD a 2015 High Country 2500 . I had Nitto NT05s 305/45/18s on it but wanted the taller tires. The Hoosiers actually have a higher load rating . I know the Hoosiers are DOT rated for racing class only so hopefully I won't catch too much trouble .

 

[PACougar]

I'd love to know how they hold up on the street. I'd be happy daily driving DR's.

 

[prostreeter600]

The Nittos would do better I think for that . The Hoosiers are softer and will wear out sooner plus the Hoosiers are like slicks with small square block outs for gauging how much rubber is left is my best guess. The Nittos hooked up good on the street and track on my truck .

 

[PACougar]

My biggest concern is with how short the Nittos are.

 

[prostreeter600]

Pic with the Nittos

 

[PACougar]

Looks good :thumb:

 

[TROJAN366]

I just picked up a set of mickey thompson et street R's in 305/45r18. Haven't put them on the truck yet but they market them as a drag radial that will hold up to street miles. They are weight rated to hold our trucks as well.

 

[PACougar]

I just picked up a set of mickey thompson et street R's in 305/45r18. Haven't put them on the truck yet but they market them as a drag radial that will hold up to street miles. They are weight rated to hold our trucks as well.

I'm definitely considering them. I wish they made a bit taller tire.

 

[TROJAN366]

I'm definitely considering them. I wish they made a bit taller tire.

With 3.42s they should work out well at the track. Street use they might be a little short with a 5 speed though.

 

[mike diesel]

That is a pretty short tire. 28.8" tall.

With stock gears and 30x14 slicks, going through the traps at 135mph put me around 4200rpm.

I'd have to think the 3.42's would more than make up for it though.

 

[PACougar]

With 3.42s they should work out well at the track. Street use they might be a little short with a 5 speed though.

That's a real concern for me, I really want them only for street use. lol. I'll have to go with 3.42's as well.

 

[prostreeter600]

So Mike, with the 30.2" tall tires (Hoosier DRs) do you think it would be beneficial to go 3.42s . I'm not sure what RPMs my motor will need to shift at with the 9100AF and the rest of my components . Judging by your numbers it sounds like 3.42s will be in order . How much does your truck weigh ?

 

[PACougar]

I think you'd definitely benefit from some 3.42's. With that cam you're gonna want to turn some decent RPM.

 

[mike diesel]

So Mike, with the 30.2" tall tires (Hoosier DRs) do you think it would be beneficial to go 3.42s . I'm not sure what RPMs my motor will need to shift at with the 9100AF and the rest of my components . Judging by your numbers it sounds like 3.42s will be in order . How much does your truck weigh ?

I'd say you'll want to shift around 4000rpm. I have a baby stage 1 empire cam and I shift at 3700-3800 rpm. I tried 4000+ but it made zero difference, so I dropped it down. My truck is dead even at 7000lbs. If you plan to regularly run those tires, I'd say 3.42's would be wise. If it's a weekend only deal, I'd stick with stock gears. Only reason I haven't switched gears myself. I go to the track typically every 2nd or 3rd week.

 

[prostreeter600]

I think so too . It Revs very quick and pulls super hard . My current tunes are for the 6480SF and compounds I had before . I believe my shift points are at 3800 currently .once I get the new converter in it and find out what can stall it to . I'm gonna have Mark tune it for me . It's a pricey change on the gears same as everything else on our trucks so I'm trying to see if others have already done it with good results

 

[SmokeShow]

I think pat/mcrat ran 3.42 gears when he was drag racing Casper. Seemed to work for him.

 

[TROJAN366]

Update: Every 5 speed truck making more than stock power should have 3.42s. It spends more time in each gear so the trans seems happier and isn't shifting so much, it pulls much smoother, and it dropped the rpms a bunch on the highway which killed the exhaust drone and generally makes my pants tight. DO IT.

 

[Duramax racer 8]

And adding the tap shifter is the icing on the cake.