516RWHP, T56, Rear Gears setup for Drag strip.

[Stang13virus]

Hello all .

I am new here and I really need help with this :rollseyes


I need help with the Rear-end gears. I have a T56 Magnum XL 2.97, with 4.56 Rear-end gears.


the car is making 516 RWHP "Base tune" on pump gas. Full bolt-ons & comp cam stage3. best time in the 1/4 mile is 11.3 @ 121 Mph on Full slicks 28x10.5 15R, 1.6 60ft. I cross the Finish line at around 6400-6600 RPM.


I thought I would be at high 10s but I guess I was wrong, I know the car can get in the high 10s and my friends and Tuner said I need steeper gears to get to the finish line at top RPM in 4th.


So now there are two Options, 4.88 or 5.13 Gears and I would like someone to help me with it. should I go with 4.88 or 5.13 ?


I am at work and youtube is blocked so I hope this link works , one of the 11.3 runs.
http://youtu.be/aNu6mMVpYJ4


Thank you in Advance.

here is a base tune run on a Dyno-jet

 

[98 Saleen Cobra]

Just my .02 I would drop to a 26" tire before doing a gear change.. Cheaper and you'll still have good traction with the 15" wheel setup.

Edit: actually reading your sig with the Cobra jet intake you should do both.. 4.88's and a 26" tire.. Put you in the 7500+rpm range I think crossing the traps which is where you should be with that intake setup.

There is a guy on here with a White Boss302 that is gutted with sick ass N/A setup. Runs 10's all day. I can't recall if he's running 4.88's or 5.12's.. But I would essentially copy his gear/tire setup

 

[98 Saleen Cobra]

http://www.svtperformance.com/forums/showthread.php?1051756-Went-10-47-133-NA-13-Boss&highlight=


^^ Copy his setup is what I recommend lol.. 5.12's and looks like a 26" tire, but I can't 100% confirm

 

[Stang13virus]

Just my .02 I would drop to a 26" tire before doing a gear change.. Cheaper and you'll still have good traction with the 15" wheel setup.

Edit: actually reading your sig with the Cobra jet intake you should do both.. 4.88's and a 26" tire.. Put you in the 7500+rpm range I think crossing the traps which is where you should be with that intake setup.

There is a guy on here with a White Boss302 that is gutted with sick ass N/A setup. Runs 10's all day. I can't recall if he's running 4.88's or 5.12's.. But I would essentially copy his gear/tire setup

Thanks a lot for the replay. unfortunately shipping tires here is risky due to regulations with customs. they may not approve getting the tires inside the country " even though we tell them it's for track use only " that is why I was going for the gears cause i know they will get in with no problems.

I have a MT Drag radial 26" tall I think i will try that to see what RPM I finish at. and i will defiantly check the the white boss setup if i could find it .

Thanks a lot bro

Oh thanks for the link

 

[98 Saleen Cobra]

You got it man.. The white boss does work over here in CA I've seen it first hand

 

[SCalla1384]

Do you have the 2.97 or 2.66 first gear? Best gear for a magnum is 5.14 in bolt on form. 4.88s will work too.

Trap speed seems low for a 514whp car. I went 122-123 when I made 442whp. How much does the car weigh with you in it?

 

[Stang13virus]

Do you have the 2.97 or 2.66 first gear? Best gear for a magnum is 5.14 in bolt on form. 4.88s will work too.

Trap speed seems low for a 514whp car. I went 122-123 when I made 442whp. How much does the car weigh with you in it?

Thanks for the reply , i have the 2.97 and the car is full weight. The reduction is rear welds wheels, drive shaft and thats about it and passenger seats removed other than that nothing. And I agree with you about the MPH. And I think i will go for 5.14 as you and 98saleen recommended

 

[SCalla1384]

Only thing I don't like about the 2.97 1st gear is the long extension between 3rd and 4th gear. I prefer the 2.66 1st gear as I think it keeps it a tighter ratio trans.

I would do 5.14s with the 28" wheel, get some more weight out, swap in a Tubular k, and I think you'll pick up quite a bit of et and mph.

Also, sean04 is the guy with the white boss in here.

 

[Stang13virus]

Only thing I don't like about the 2.97 1st gear is the long extension between 3rd and 4th gear. I prefer the 2.66 1st gear as I think it keeps it a tighter ratio trans.

I would do 5.14s with the 28" wheel, get some more weight out, swap in a Tubular k, and I think you'll pick up quite a bit of et and mph.

Also, sean04 is the guy with the white boss in here.

Thanks a lot for your help guys. Really appreciate it. Ill do that with fuel race. Weight reduction will have to wait. Got a newborn coming soon

Again thank you .

 

[cobrasnake2003]

What are you launching the car at in the vid and what rpm are you shifting at? Sounds like you are banging the gears ok. Launch is killing your mph bogging like it is. Did not sound like you launched it real hard.

 

[Stang13virus]

What are you launching the car at in the vid and what rpm are you shifting at? Sounds like you are banging the gears ok. Launch is killing your mph bogging like it is. Did not sound like you launched it real hard.

Hi ,

I am launching around 4700-5000 RMP sometimes 5200. I have Moser axles but around a month ago I bent the axle housing and the Axles showed some bents around the axle splines/teeth i dont know what to call it. that happened after setting my Viking double shocks at a really high Compression and Rebound while launching at 6500 RPM and sometimes 7K RPM. I used to do the same RPM and it was fine until I made the changes in the Shocks. A friend of mine had the same Exact thing happen to him after he changed the shocks setting as well. thought it would make it better but I was wrong.

now it's I just set it at 4C and 7R. would go for Higher RPM when I know I can upgrade to a 9" later on. and I shift around 7500-7700 RPM power shifting.

 

[gimmie11s]

...
Trap speed seems low for a 514whp car. I went 122-123 when I made 442whp. How much does the car weigh with you in it?

+1. Trap speed doesn't indicate 500+ whp.

Also like someone else said earlier, a cheaper and easier way to see if a more aggressive axle ratio is what you need will be to borrow a set of 26" tires and see how it runs.

The 2 inch smaller tire will move your rpm to 7100 from 6600 with the 4.56s at the same mph through the traps.


All that said.... seems she is simply short of horsepower. Needs more power. Your short time is good as is the ET... needs more mph.

 

[sean04]

I'm running the 2.97 ratio magnum. Making a little less power than you but not full weight. If your full weight you definitely want the 5.14's if you want to stick with the 28's. I'm running 28's with 5.14's and last time out I was on the limiter before the traps. I'm going to give 4.88's a try but I'm also hoping to trap in the mid to upper 130's. On a good track you will want to leave around 6500 to 7plus.

 

[sean04]

Just watched the vid and your driving is solid! Have any idea what the DA was when you ran? Id also recommend getting a 2step. Makes finding the right launch rpm much easier. It's definitely bogging down on the launch, your leaving some time on the table in the 60. What's your 330' look like? Shift rpms? That can have a huge effect on my mph. I'm assuming your running the cobra jet mani?

 

[SCalla1384]

I'm surprised more people, especially na don't go the 2.66 1st gear magnum. I figure the longer 1st gear (not by a whole lot) could actually benefit. But the 1-2 2-3 and 3-4 are tighter ratios than the 2.97 1st gear magnum. Idk just curious why you guys went that way? Seems like the 3-4 shift has a long drop off in rpm.

Why I recommend definitely going 5.14s to help with that.

 

[cobrasnake2003]

Hi ,

I am launching around 4700-5000 RMP sometimes 5200. I have Moser axles but around a month ago I bent the axle housing and the Axles showed some bents around the axle splines/teeth i dont know what to call it. that happened after setting my Viking double shocks at a really high Compression and Rebound while launching at 6500 RPM and sometimes 7K RPM. I used to do the same RPM and it was fine until I made the changes in the Shocks. A friend of mine had the same Exact thing happen to him after he changed the shocks setting as well. thought it would make it better but I was wrong.

now it's I just set it at 4C and 7R. would go for Higher RPM when I know I can upgrade to a 9" later on. and I shift around 7500-7700 RPM power shifting.

IMO, I would not waste my time with gears if you are not planning on launching the car where it needs to be launched at. That said, there are a ton of people that have had no problems out of the 8.8 housing. At your power level you should be fine. Just get your tubes welded and maybe a brace if you want a little added support. +1 on the 2 step. Takes all the guesswork out of it, you know exactly what you launch at and can fine tune up or down as needed.

 

[bunits19714]

Like previous asked what was the da- Your not generating 500+ rwhp at the track with that trap speed unless your da is somewhere at about 4500+. Use this formula to see what you will trap rpm will be with certain gear with your trap speed and tire size - final gear ratio x trap speed x 336 / tire diameter = trapped rpm
so yours currently is 121 x 4.56 x 336 / 28= 6621 which is where you stated it would be. so using your current info and adding a little mph because of you being in the power band and increasing your launch rpm.(need to get the 60. ft in the high 1.4' low 1.5's) 125x 5.13 x 336/ 28= 7695 rpm 5.13s will be the way to go if your not going to dial the suspension in and reduce weight- if your reducing weight and going to get somethings sorted out go with the 4.88 or you will run out of rpm when your stuff is sorted out- or run 5.13's and when you run out of rpms increase the tire size to 29.5's and your back where you need to be.

 

[Holovacko]

Just work on your 60'... Manual with 4.56 gears running Hoosiers, should 60' lower than that. Drop it to high 1.40's and you'll have your high 10's

 

[corysmach1]

Idk how I missed this. We run a similar setup. I run 4:88s but wish I went 5:14s. With that being said I should go 10.80s@127-128 this year in normal DA.....if I go to Cecil I am expecting 130+.