Need Help on Gear Ratio

[YELLOH]

Hi Guys
I know there have been alot of threads on this ,but wasn't sure with the changes on my car.My car has Belanger headers W/ cats and installed 19"fronts and 20" rears I just installed an aluminum flywheel and have lost alot of torque. I did the D C Performance upgrade.I'm looking for advice on a gear ratio that would give me some torque back on take off , but I would like to have some top end so I can keep up on the track. Is there a gear ratio that would give me the best of both worlds.Thank You for any advice RICK

 

[Volltage]

3.55s are great, and thats about your only lower ratio, then you get into 3.73s 4.10s which IMO are to high.

 

[Gforce]

Agreed with Volltage. I went with the 3.55s and have been REALLY happy.

 

[PhoenixGTS]

I would like to have some top end so I can keep up on the track.

Given that 6,000 rpm in fifth is 217 mph with the stock gearing and 6,000 rpm in sixth is 322 mph I would not worry about not having gearing for the top end. Even with 4.10 gearing 6,000 rpm in sixth would be 242 mph - and you are never gonna get there! I still say 3.73 is perfect for a non-boosted Viper with the taller 19" Gen III rear tires (and 3.55 is perfect for the shorter Gen I-II rears tires).

 

[Volltage]

And I have a ton of top end just, ask Zen Garage, I am traping at 123mph without great traction.

 

[Vipermann]

3.73 gears? huh? Way too high for ANY SRT Viper. You'll be shifting before you make it through an intersection from a stop sign. I think 3.55s are even too high.

As for the track, again shifting is the enemy. A car with as much torque as an SRT Viper can 'pull' through lower gears without shifting. I recommend going with 3.45s (or 3.33s, if you're lucky enough to find a set).

 

[YELLOH]

Would I have to change back if I added a supercharger next year.And do you get more torque back if a supercharger is added.And would an underdrive pulley help.

 

[Volltage]

I agree they are to high but they make them and members have the.
Yes a SC adds TQ and from what many SC owners have stated they go back to the 3.07s

 

[PhoenixGTS]

3.73 gears? huh? Way too high for ANY SRT Viper. You'll be shifting before you make it through an intersection from a stop sign. I think 3.55s are even too high.

As for the track, again shifting is the enemy. A car with as much torque as an SRT Viper can 'pull' through lower gears without shifting. I recommend going with 3.45s (or 3.33s, if you're lucky enough to find a set).

Let's do the math. Let's assume a Gen III can trap in the mid-120s. With stock gearing a Gen III will only do 124 mph @ 6k rpm in 3rd. That means that you are past the power band in third (on a good run you might even hit the rev limiter in third) and going to HAVE to shift to 4th in the quarter mile. Three shifts total. Now let's look at a 3.73 gear. A Gen III with 3.73 gears can run 133 mph @ 6k rpm in 4th - but more importantly it should be going 122 mph @ 5,500 rpm in 4th >>> perfect to trap at the top of the power band and have the maximum gearing advantage to sweep through the meat of the torque curve four times after having made the same three shifts total. Other dynamic is the shorter the gear the easier it is the "pedal" the car if you lose traction. To be fair, 5,250 rpm (which is the absolute peak on a Viper engine power band unless you have super aggressive heads) is right at 122 mph with 3.55 gears so they are aguably the optimum choice (I just outlined the 3.73 scenario to show that 3.55 are not crazy at all).

 

[Viper X]

Try to figure out where you will end up in the power spectrum and what you actually plan to do with the car. The 3.07's work pretty well on higher hp cars - 650 rwhp and up like my SRT-10 and they are great at the track.

3.55's would be the better ratio at your power level if you are going to stay there - 450 to 500 rwhp. Use higher gears at the track.

3.33's work really well on most cars with more mods than you have - 550 rwhp and up. Use higher gears at the track.

3.45's work very well in a heads / cam car like my GTS - 550 rwhp and up. Use higher gears at the track.

3.73's are crazy "traction wise" but some guys like them. You will spin and shift way too much IMHO. Too high for Viper.

Good luck,

Dan

 

[Nader]

"a gear ratio that would give me some torque back on take off"

How did you lose torque? From the Headers? The DC upgrade is certainly not the culprit.


Also what tires do you have on the rear's - the Pirelli 345/25's? If keep in mind they are roughly 1/2 in diameter smaller than stock.

 

[Paul Hawker]

Which track are you talking about. Lots of roadracers perfer the stock setup, or 3.33 for certain tracks. Drag racers use all sorts of gears depending on the traction available due to track conditions, or tire choices. Anything over 3.55 will have you shifting like a mad man, and scrambling for traction with stock tires.
If planning on a Paxton, stick with stock.
Street driving feels great with 3.55's.
You need to make up your mind what is the most important to you.

 

[YELLOH]

You asked how I lost torque.With the larger wheels and the aluminum flywheel.And the track I'm referring to is Viper day at Pocono race track.I like the mods I've made just think I lost some zip .

 

[Nader]

What after market rims and tires do you have on the car now? What size? the reason I ask is that I have HREs 545Rs and pirellis 345/25 in the rear and the combination is roughly 10 lbs lighter and about a little less than 1/2 in diameter shorter than stock as per Luke @ Tirerack. So long as you didnt go a 30 profile tire in the back and the after market rims are not as heavy as stock, that couldnt be the problem.

 

[Vipermann]

3.45s are probably the best option that you're gonna find out there ...

... I have a set for sale ... PM me, if you're interested

 

[Racer Robbie]

Rick,

here is the link to another post by Viperman.

http://www4.forum.viperclub.org/showflat.php?Cat=&Board=UBB21&Number=708278&Forum=All_Forums&Words=8421&Match=Username&Searchpage=0&Limit=25&Old=allposts&Main=708278&Search=true#Post708278

 

[viperbilliam]

When you did the DC Performance reflash, did you tell DC to reprogram based on your exhaust mods?

 

[SnakeEye]

3.55's work great.
Paxton makes 'em better
Awesome street gear. 136mph in 4th.

 

[Racer Robbie]

Yelloh, What have you decided to run for gears.

Robbie

 

[YELLOH]

Hi guys Thanks for the responces.I went with Forgline and pirelli tire I think they were the same size as OEM Diameter.I did notice a difference on the DC flash ,but they programed it to 91 octane because of the crap they have been adding to the gas in the area.But I did notice a difference for the better. I think I'm just looking for more power now and need to go to a supercharger, after talking to some of you guys that if I change my gears now that I might need to change back after the supercharger is put in .Typical viper owner always looking for more power.

 

[Vipermann]

My race-prep polished 3.45s are still for sale ...

 

[Racer Robbie]

QUOTE:
"Typical viper owner always looking for more power"

A truer statement there never was!

Yelloh,I would look into Vipermans 3.45 gearset

 

[moldowan]

vipermann,
check you messages or email me [email protected] about the gears
thanks,
Marc