Drag Radials Wheels

[SatinBlueG3]

I'm looking for some advice on drag radials and rims, plus the possibility of adding nitrous.

For what I have read, the MT SS's (18's) is pretty good. What 18in rim are people running?

Lastly, what are people's thoughts of nitrous? Which kit works best?

Thanks

[Steve M]

The MT is a decent tire - pretty good compromise for a streetable drag radial. Not street friendly, but streetable. They tend to wallow around a bit due to the softer sidewall, but were reasonably happy running them around 24-25 psi cold on the street. I always ran them at 20 psi hot at the track.

All of my drag racing adventures with my Gen 4 are well documented here:

https://driveviper.com/forums/threads/19581-My-2008-Coupe-Drag-Racing-Results-Thread?highlight=drag+racing

I still need to update from the one time I went last fall, but didn't fare any better than the year prior. The best 60' I've cut to date has been in the upper 1.7x range, which isn't great. I'll need to be in the low 1.6x range to run solid 10s, which is my goal.

The most important thing you can do is this: figure out what you think you'll be trapping in the 1/4, and figure out what gear you will end up in through the traps. For my stock-ish '08 with 3.07 gears, I was finishing out the 1/4 mile at the very top of 3rd gear through the traps. I was able to do this for two reasons:

1. The MT tire is a 28" diameter tire
2. I was able to bump my rev limiter up to 6,600 RPMs (stock was 6,400)

Otherwise, I'd have been shifting into 4th before the traps, which is exactly what you don't want to have happen.

Once I switched to 3.55s (all else the same), the 28" tire is no longer the right combo. I'm only part way into the meat of the power band in 4th gear through the traps, which you can see here (my best run to date):


https://youtu.be/hA4tGSelDus

I could switch to 3.73s, but that would be too much gear on the street. Instead, I'll be switching to the Hoosier 335/30/18, which is closer to a 26" tire. That still won't be ideal, but will be a move in the right direction, in addition to being a MUCH lighter tire than the MT drag radial. I'm hoping it will get off the line better due to the lighter weight/smaller diameter combo.

As for wheels, I'm partial to the Forgestar F14s - they are reasonably light weight, and also priced very well for this application. I think they look pretty good too, but opinions vary:

https://image.ibb.co/eULJum/Forgestar-1.jpg

That pic shows mine with 18x11 fronts and an 18x13 rear on the MT ET Street S/S (345/35/18).

I think you are doing the right thing by going with an 18" wheel out back, since it gives you at least two choices for decent drag radials (28" or 26"). If you stay with a 19", you only have one option, which is around a 27" tire.

There are a lot of variables here, and running nitrous will change the math. I can't recommend a kit since I don't have personal experience, but figure on adding 1 MPH per every 10 HP of nitrous added (so a 100 shot should net you +10 MPH over what you would run N/A). If you need a gear ratio calculator, I have an Excel spreadsheet I could send you that would allow you to play around with the numbers.

Hope that helps.

[Steve M]

Also, if you haven't already, you'll need to modify the routing of the parking brake cable to be able to run an 18" rear wheel. This should have the info you need:

https://driveviper.com/forums/threads/18591-Forgestar-F14-Wheels-on-my-2008-Viper

[SatinBlueG3]

Steve M, thank you for your input. Here are my mods so far. Also, I have already done the parking brake mod.

3.55 gears w/ Wavetech LSD
Catless headers n exhaust
K&N Intake
Coilover suspension

[Steve M]

So assuming you have a Gen 3 with those mods, I would guess you would be trapping around 124-125.

With the 3.55s, an assumed 6,200 rev limiter, and a 28" tire, your top speed in 3rd and 4th gear would be:

3rd: 111.91 MPH
4th: 145.48 MPH

The same with a 26" tire would be:

3rd: 103.92 MPH
4th: 135.09 MPH

Either way you slice it, you'll be crossing the traps in 4th gear. N/A, you'd be best off with the Hoosier 335/30/18. If you plan on running a decent shot of giggle gas (like 200+), that might warrant the step up to the 28" MT drag radial. I'd want to be running forged pistons though. Not sure how many guys run a shot of nitrous on their otherwise stock block Gen 3 motors, but I'd guess not many.