Looking to mod my SRT-10, please help..

[Viper X]

Fadi,

Based upon what you say in your first post, the only place 3.07's would be advantageous to you would be in the gas mileage department, and I really don't think most Viper owners care much about that. The 3.55's will be a great mod for you. The car is much more "drive-able" and fun with stock power.

I ran 3.55s in my SRT-10 when it was stock and lightly modded. Great fun. When I went to the Paxton, heads, etc. - 750 rwhp - I went back to the 3.07's and was very happy with the change.

I raced in and won the 1/2 mile drags last spring at a top speed of 150 from a stop at 6500 feet elevation. I'm planning to run in the 1 mile drags at the Nevada Open Road Challenge this year with the new engine and 3.07's. My goal this year is to get to 190 mph from a dead stop in a mile at 6500 feet above sea level. My rwhp should now be about 900. 3.55's wouldn't work as well for me in this race as 3.07's with stock tire height, 27.4 inches.

As GR8 ASP says, you should gear the car for what you intend to use it for.

I also have a 2001 GTS with a WCV 650 package that makes 555 rwhp / 581 rwtq. I am changing to 3.45's with 18-inch tires. This works really well in this car at this power level driven on the street. I am keeping the 3.07 gear set and will use that set on a road course if the road course warrants it.

As far as lower gears being harder to drive on a road course, yes, they can be as Fred says above. If wheel spin becomes a problem with the lower gears, you can always go up one gear with the trans, i.e. exit the turn in 4th instead of third, etc. This approach really helps with any Viper with lower gears on a road course.

Good luck and enjoy your car.

Dan

 

[Fadi]

Thanks gr8, and everyone else that chimed in. As you can see, the most obvious reason why I am having a hard time is because I am not sure if the 3.55's will become a disadvantage at higher speeds. Most of my racing is roll racing (closed track) up to about 140. I understand that there are some of you who are saying the 3.55's would be better for my situation, but some are also disagreeing. This makes it harder for me to make a decision because it is now obvious that the answer is not clear.

Like someone mentioned, I really need to find one with both and driver them, better yet, race them from 40-140 and see the outcome.

Any more educated guesses out there on this 40-140 subject?

Thanks everyone

 

[GR8_ASP]

With the definition now of below 140 I would say the 3.55 would work well. You will be less in the 130-140 range (due to upshift to 5th at around 130) but better overall under that.

Gears are always a compromise somewhere. Don't fret the details - just go for it.

 

[Steve 00RT/10]

Now who do I believe? This is what I am looking for as that is what will impact my decision.

I have a little computer program called Car Test. You can use its large car data base or build your own car. The 2003 SRT-10 is in the data base so I built the same car with a 3:55 rear end. While one can always argue the numbers being too slow - too fast.....They are are built upon the same criteria for each car with the exception of the rear end. Here's what it shows:

0-150------------3:07s---------20.33
0-150------------3:55s---------21.13

135-150----------3:07s-----4th gear----4.02
135-150----------3:55s-----5th gear----4.29

My own experience with 3:45s kind of bears this out. Up to 120 or so, the 3:45 feels stronger, but shifting to .74 at 125 and heading for 150 definitely does not feel as strong as the 3:07 in 4th at 1:1. Overall, I am quite happy with the lower gears because 95+% of the driving I do is down where you can feel the difference the gears make. Nothing is the best of everything. There are tradeoffs.

Steve

 

[Fadi]

With the definition now of below 140 I would say the 3.55 would work well. You will be less in the 130-140 range (due to upshift to 5th at around 130) but better overall under that.

Gears are always a compromise somewhere. Don't fret the details - just go for it.

Ya, I just hate being on the fence about something. But I appreciate all of your help, GR8. While I am getting all this great help, let me ask you this since you are from MI also. Who would you recommend taking the SRT to for a tune? I am getting my RT high flows and K&N cai in a few days, and I would like to get a tune. Any ideas where to take it to or who has the proper software for a tune?

Thanks man, and thanks to all of you for helping. Greatly appreciated. I will keep you guys updated in regards to the gears and my decision.

Fadi

 

[GR8_ASP]

Fadi, I have no idea for a "tune." However, if allyou are considering is high flow cats and a K&N intake (note it is already a cold air intake) a recalibration is not necessary.

Steve you dog. I was calculating from 130 - 150 and got 0.4 second less for the 3.07. You did 135 - 150 and got 0.27 second. The strongest moment during that period for the 3.07 is right at 130 so the numbers look comparable. As we would expect. My calcs are from my own dyno results back in May 2003. I think they would differ a little now

We need to get rid of this cold and snow so we can quit bench racing and hit the track. May 4th should be a blast!

 

[Fadi]

GR8, if you ever go to any racing related events in MI, let me know, I would like to join ya..

 

[GR8_ASP]

Fadi - are you joining the VCA? That is the best way to find out about local and national events.

The May 4 event I referred to is another non-Viper club event at Gingerman. It is sold out with a waiting list already but hopefully there will be more events to come.

 

[Fadi]

Fadi - are you joining the VCA? That is the best way to find out about local and national events.

The May 4 event I referred to is another non-Viper club event at Gingerman. It is sold out with a waiting list already but hopefully there will be more events to come.

I don't know anything about the VCA. But, I will look into it, especially if it helps with locating car events.

 

[GR8_ASP]

Look at the top of this page and select "membership." That ought to get you started.

 

[Fadi]

Thanks GR8. You have been very helpful..

 

[SilverViperSRT]

WOW Steve it's very cool your computer program .

Are you also also able to do some other comparison ex:

0-30
0-60
0-100
0-130
0-160

A few 20-XX. ect...

Also can you determine the difference in top speed with the 2 different ratio.

Thank you, I'm considering the 3.55 but want to be able to reach over 190 mph

 

[SnakeEye]

Fadi, 3.55's are really nice for the street as most every gear is hot. IMO, this is one of the best bang for the buck mods. Try them out, you'll probably be happy like ~90% of those that have already made the change. Good luck.

 

[SylvanSRT]

Fadi if you bought your srt new it includes your first year of membership to the VCA and your local chapter the MCVO.

 

[Fadi]

SnakeEye- I think I am going to wait it out for a while until I drive an SRT with 3.55's. That way, I can be 100% sure if I want to make the change.

Sylva- I got my SRT used with very low miles on it.

Thanks everyone

 

[Steve 00RT/10]

SilverViper

Yes, the program should be able to do all you ask. I bought this program on line about 10 years ago. I think it works pretty slick. There are many things you can do in there. Here's the link:

Car Test

I could run a few things for you if you aren't interested in buying it. You can download a test version. The guy only wants $20 bucks for it.

Hey Ron,

130-150.........Program says.......... .43 difference---advantage 3:07

May 4th will be fun, but the weather here the last couple days makes that event seem a long way off. We could hit 30-40 below chill factor tonight. Got a foot or so of snow yesterday.

Steve

 

[GR8_ASP]

Looks like math is math Steve. But nice to know they have comparable results. I still use a DOS based program from over 10 years ago. It proved quite accurate then and still pretty good. Nothing like the complex programs used at work, but then again we don't need to be able to understand fuel economy, emissions, brake life, etc which the large corporate programs can do.

Since we measure the dynamic RWHP on a chassis dyno, the potential for error is primarily in drag resistance and rolling resistance. Which can be measured in less than 5 minutes on a quick drive (time open clutch decels from a couple of speeds, averaged over 2 directions and solve the quadratic equation).

It was nice that someone picked a speed range where the 3.07 had a definite advantage.

Course the time from 170 to 190 is clearly in favor of the 3.07.

Here are some calculations for the 1/4 mile, 1 mile, 2 mile and 3 mile. Note only the 3.73 uses 6th gear. Looks to me that they are pretty even, except for the very high speed portion, and that the feel is not providing more real performance.

 

[Vipermann]

[/QUOTE]
My own experience with 3:45s kind of bears this out. Up to 120 or so, the 3:45 feels stronger, but shifting to .74 at 125 and heading for 150 definitely does not feel as strong as the 3:07 in 4th at 1:1. Overall, I am quite happy with the lower gears because 95+% of the driving I do is down where you can feel the difference the gears make. Nothing is the best of everything. There are tradeoffs.

Steve

[/QUOTE]

I have the 3.45's now also ... I like it better than stock (I think), but really wish there was a 3.33 gear still out there. I often wonder if my 3.45s would be a slam dunk if I put them into a Quafe (for better hook-up)...

 

[Fred(DrivingSchool)Kinder]

With a rolling start stay with stock gears, as this will be one less shift to 150. One less shift should benefit laps time a bit and one less chance to miss a shift.

The only reason to switch to lower gears is if you want to Drag race with slicks, thus allowing the gearing to put the massive torque to the pavement for a monster launch.

K&N filters and after market induction will allow the V10 to breath a little better giving a few more ponnies.

 

[Steve 00RT/10]

Here are some calculations for the 1/4 mile, 1 mile, 2 mile and 3 mile. Note only the 3.73 uses 6th gear. Looks to me that they are pretty even, except for the very high speed portion, and that the feel is not providing more real performance.

Ron,

Here's where we part company. The program I'm using shows a huge disparity in time to top speed with these different gear combos. Up to a mile we're on the same page:

1 mile

3:07/30.54 sec.----169.86 MPH
3:55/30.52 sec.----172.03 MPH
3:73/30.47 sec.----171.91 MPH

0-top speed

3:07/128.22 sec---197 MPH over 6.22 Miles
3:55/40.13 sec----182 MPH over 1.46 Miles
3:73/36 sec-------173 MPH over 1.06 Miles (redline 5th gear)
3:73/169.02 sec---191 MPH over 8.22 miles topping out in 6th gear.

There are literally dozens of parameters which can be modified in this program. There is a 2003 SRT-10 in the program database so I just duplicated the cars and changed the rear end ratio. Everything stays exactly relative.

Any thoughts on this huge disparity in conclusions?

Steve

 

[Fadi]

Well, while this is still going, is there anyway the program you guys use calculates the times from a 40-150?

 

[GR8_ASP]

The 50 - 150 range is the range that provides the stock gear the most advantage. 0-50 is very close between all 3 ratios as much is traction limited. The 3.73 has to shift just before 50 so has a shift time disadvantage taking an extra .06 second and about 10 ft.

From 50 to 150 the 3.07 was quickest at 15.6 sec, the 3.73 second at 15.8 and the 3.55 slowest at 16.0 seconds.

Now you could pick a range like 40 - 140 and get completely different results.

I think you can see why the stock gear is 3.07 as it is good in most speed ranges. I remember going through this 3 years ago and settling on 3.30 or 3.45 as the best, but unavailable ratio for my purposes. I am glad I stayed with the 3.07 now as I do not think the higher numerical ratio would be good with my present power level.

 

[Steve 00RT/10]

Well, while this is still going, is there anyway the program you guys use calculates the times from a 40-150?

I don't use the program enough to maybe be able to produce this result. It appears limited by what it will do in one gear when taking a snapshot like 40-150. Here's what it says:

3:07-------40-150---------20.82------4th gear
------------50-150---------19.10------4th gear
------------40-150---------31.01------5th gear
------------50-150---------28.36------5th gear

3:55s can't get to 150 in 4th so the program calculates in 5th only
------------40-150--------25.35-------5th gear
------------50-150--------23.06-------5th gear

The program can do any snapshot of time within the speed range of the rear end through the gears. It can also do any 0-whatever calculation.

Steve

 

[GR8_ASP]

Steve, sounds like your program is limited to a one gear option. I have that option also but in this case I was launching in the most appropriate gear (1st for the 3.07 and 2nd for the 3.55 and 3.73. I have upshifts of .1 second (excellent powershifts) right at the fuel shut-off speed. A real driver would probably do worse. I also have tire traction at a near optimum, which is very hard to do for us mere humans (30% slip when adequate power is available).

 

[Fadi]

GR8, I am assuming you stated that the times from 40-140 could be totaly different is due to shifting, right? Do you know with a 3.55, what what mph must shift into 5th, or in other words, at what mph does 4th redline at? Thanks

 

[Steve 00RT/10]

Ron,

Looking a little closer at the numbers in your chart....something doesn't make sense once the cars are headed for top speed. For example:

There's no way a 3:07 geared car is going to get to 194 MPH in 67.4 seconds as opposed to the lower geared car going to 185 in 68.47 seconds. Once the cars are in overdrive, and above 150, the lower geared cars will eat a 3:07 up. The Car Test program reflects that. Our numbers are relatively the same up to 150. After that something seems wrong with your 2 and 3 mile calcs?

Steve

 

[GR8_ASP]

It is because both the 3.73 and 3.55 have top speed in 6th (3.55 has almost the same top speed in 5th and 6th), which means they are not near the top of their power curve as they approach top speed.

The calculated top speeds I have are:

3.07
5th - 196 mph
6th - 167 mph

3.55
5th - 182 mph
6th - 186 mph

3.73
5th - 174 mph
6th - 189 mph

Note none of the top speeds are really attainable, given the distance that it takes to get there.