Atlas Gearing [Archive] - BB.BC4x4.COM

: Atlas Gearing



DaveW
September 15th, 2009, 03:26 pm
Looking for recommendations/opinions for the Atlas in my buggy that I'm going to buy. I am considering the 3 to 1 or the 3.8 to 1. What are your opinions?

The buggy will be used for everything. Rockcrawling, snow wheeling, sand dunes, and planning on prerunning the 2010 KOH race with it.

Buggy should weigh 3400 lbs ish. Drivetrain 6.0 LS2 (400 hp), turbo 350, Atlas t-case with Dana 60's and 37 inch Toyo Stickies.

I'm thinking Dana 60's with 5.13 gears and the Atlas 3.0 to 1. The LS2 revs fast and I know Curty's LS1 w/ 4.88 gears and the 3.8 to 1 hits the rev limiter too fast sometimes.

Dave

lars
September 15th, 2009, 04:24 pm
Dave, if you're considering 3:1, why not just stick with a Dana 300 with an HD output shaft kit? 2.62:1 is pretty close...or isn't it?

...lars

jeeponrock
September 15th, 2009, 04:28 pm
Whats the stall speed in the torque convertor?

With 5.13 gears and 37" tires I wouldn't go more than 3:1. You've got enough grunt to crawl stuff so I wouldn't worry about it. For all round duty thats the best choice IMO.


Off topic but... What are you using for a fuel system? My head is spinning reading all the threads on that stuff so I'm curious to see what you're going to run. I'm feeding a slightly bigger motor (stock 8.1) but the rail pressure is the same I think.

jeeponrock
September 15th, 2009, 04:31 pm
Dave, if you're considering 3:1, why not just stick with a Dana 300 with an HD output shaft kit? 2.62:1 is pretty close...or isn't it?

...lars

400HP is pushing it for a D300. Bouncing on the rocks tends to split the case. So by the time you get the F&R HD shafts, get the Stak Case upgrade and swap it all in you're getting close to an atlas.

Wes Rempel
September 15th, 2009, 04:36 pm
Atlas 4 Speed!

I run the 2.7/3.8 version.

though my Jeep is only a 4.0L with 37s and 4.88, I found the 3.8 to be way too deep for the dunes. The 2.7 was a nice reduction.

The price of a 4spd is not much more than a fully upgraded 2spd.

rkjplt1
September 15th, 2009, 06:01 pm
400HP is pushing it for a D300. Bouncing on the rocks tends to split the case. So by the time you get the F&R HD shafts, get the Stak Case upgrade and swap it all in you're getting close to an atlas.


He'll likely be running a little water in the front tires at times too. Even upgraded shafts and case might not like that.


It'll likely be a stock stall Torque convertor.

Where he put his engine, he'll likely not be able to run a 4 speed and 18" shocks. IMO, I'd take the travel over the gearing.


I vote 3:1.

fj401ton
September 15th, 2009, 08:43 pm
now you got me freaking out, my stak t case is 5.44 with 4.88's and a th 350. well if I do not like it I'll see if I can re gear the case

Big Country Customs
September 15th, 2009, 10:32 pm
my set up is not far off from you dave 4.8lt turbo 400, 513 spider9s and a 4;1 atlas with hd outputs.just started to put it together also...

DaveW
September 16th, 2009, 08:06 am
Stock stall level whatever that is. I may end up with 4.88 gears, as rkjp's buggy may be getting a set of prototype diffs. So if I go 4.88s would you still stick with the 3.0 to 1?

4 speed would be nice, but won't fit withing my chassis design and I'm pretty sure that the D300 would explode behing the LS2. They make a legit 400 hp and I'll probably tune for more. Whatever t-case I use now will be what fits the chassis and changing in the future would require a lot of work, so I want to do it right the first time.

jeeponrock
September 16th, 2009, 08:34 am
Stock stall level whatever that is. I may end up with 4.88 gears, as rkjp's buggy may be getting a set of prototype diffs. So if I go 4.88s would you still stick with the 3.0 to 1?

If you're looking at 4.88s then aren't you effectively driving Curtis's buggy but with a tad more power? If so I think you answered your own question... "The LS2 revs fast and I know Curty's LS1 w/ 4.88 gears and the 3.8 to 1 hits the rev limiter too fast sometimes " :redneck

rkjplt1
September 16th, 2009, 01:03 pm
Even when I ordered my atlas, I wanted a 3.4:1 or somewhere about there. With 4.88's I would still order the 3:1. I'm less about the crawl and more about the haul. The 3.8 isn't fast enough in low range, 3rd for me.

If it was a dedicated Werock buggy, I'd go with the 4.3:1.


I've been playing with the rev limiter, 7000 should be attainable with new valve springs in mine and stock springs in Dave's.

Wil
September 16th, 2009, 01:25 pm
a bit off topic, but what are used LS2's going for? All this motor talk caused some movement.

jeeponrock
September 16th, 2009, 02:07 pm
With 4.88's I would still order the 3:1. I'm less about the crawl and more about the haul. The 3.8 isn't fast enough in low range, 3rd for me.

If it was a dedicated Werock buggy, I'd go with the 4.3:1.

I agree with this. Dave you mentioned snow and sand. Both need wheel speed (depending on conditions of course). This plus all round wheeling duty points me to a 3:1 low range. If you were only playing on the rocks then I'd go deeper.

DaveW
September 16th, 2009, 03:28 pm
You don't want to know what I paid for mine Wil.

Probably around $3500, LS1's $2000-2500, and the other blocks like 5.3 or 6.0 L around $700 and up. All prices include computer and related hardware.

Shogunator
September 17th, 2009, 02:54 pm
a bit off topic, but what are used LS2's going for? All this motor talk caused some movement.

Wil,
I just paid $700 for a complete 5.3 with headers and stock manifolds. I also picked up a LS6 cam and 'vette intake for a couple hundred more. It isn't an LS2 but it is a lot cheaper and will make good power. The guy I bought it off had a LS1 with a 4L60E (camaro) for $2300...

I can't afford an atlas right now. When I do I'll likely put the 4 spd in. The 4spd will be smaller and more durable than my current doubler setup. Dave, I would do the 3.1. Down the road if you need more you can always add more diff gearing.

Wil
September 17th, 2009, 03:11 pm
Wil,
I just paid $700 for a complete 5.3 with headers and stock manifolds. I also picked up a LS6 cam and 'vette intake for a couple hundred more. It isn't an LS2 but it is a lot cheaper and will make good power. The guy I bought it off had a LS1 with a 4L60E (camaro) for $2300...



Geez, I thought you were selling everything and getting out of wheeling? I guess not eh. :-)

How much hp do you figure you will have with that setup? I have heard that the 5.3's have become very inexpensive but I think my magic number is about 400hp for they type of wheeling I like and the people I wheel with.

rkjplt1
September 17th, 2009, 07:24 pm
Geez, I thought you were selling everything and getting out of wheeling? I guess not eh. :-)

How much hp do you figure you will have with that setup? I have heard that the 5.3's have become very inexpensive but I think my magic number is about 400hp for they type of wheeling I like and the people I wheel with.


He saw the light in the versatility of 4x4............:)
Depending on what year cam, he'll be getting there.
These engines don't have the same feel as a traditional small block. They make wicked power off idle, right past rev limiter.
I scared the crap out of myself the first time I went snow wheeling with my stock LS1. :cwm30:
Of course now I'm doing a cam swap........:redneck



Shogunanator, that LS1 needs a engine rebuild. I might still take it if the price is right though.

DaveW
September 21st, 2009, 07:44 am
Geez, I thought you were selling everything and getting out of wheeling? I guess not eh. :-)

How much hp do you figure you will have with that setup? I have heard that the 5.3's have become very inexpensive but I think my magic number is about 400hp for they type of wheeling I like and the people I wheel with.

And what sort of hp are you running right now?

Remember, most hp rating are net when talking LS motors compared to how most people talk. The LS2 is rated 405 hp net factory, LS1 is 335 net factory, and the 5.3 with aluminum heads is 310 hp net factory. Intake, cam, and headers on a 5.3 would put you over 400 hp net.

Wil
September 21st, 2009, 02:15 pm
And what sort of hp are you running right now?

Remember, most hp rating are net when talking LS motors compared to how most people talk. The LS2 is rated 405 hp net factory, LS1 is 335 net factory, and the 5.3 with aluminum heads is 310 hp net factory. Intake, cam, and headers on a 5.3 would put you over 400 hp net.

I'm not sure what "net" means? :confused:

the motor right now is a 97 4.3 Vortec, I think they are 200HP? I was very happy with that until I met Tom. Intake, cam and headers really can bump the 5.3 90 HP or is that with a performance computer reflash?

DaveW
September 22nd, 2009, 08:10 am
SAE Net ratings (I think that is what it is called, sorry its early and my brain is still waiting for the coffee to kick in) are what GM is using on the new motors. Not sure all the details but the motors are rated with the accessories on and maybe to a certain standard pressure or something. Anyway usually means the ratings are lower than what most people are use to when rating motors.

For example, the LS2 is factory rated at 405HP but chassis dyno's are showing stock LS2 equipped cars making 365-370 HP at the rear wheels. Curty has my LS book which details it even better with real world numbers, but I believe with the 'gross' ratings the LS2 is like 450 HP or in that neighbourhood.

DaveW
September 22nd, 2009, 08:14 am
Generally, most modifications on a computer controlled vehicle should include computer programming to maximize performance. I think the best thing to do is find someone with a program like LS1 edit to do this for you or even Mopac will do it though I don't know what they are like. A guy who owns LS1 edit can buy a license for another engine computer for like $100 or so bucks and tune whatever you like into it. And for you I just might be able to find someone.

rkjplt1
September 22nd, 2009, 09:58 pm
I'm running out of licenses. I think I only have 1 more left after this one.

You could run the stock tune, but to take full advantage of the cam, intake, etc. you'll need a tune.

DaveW
September 23rd, 2009, 12:00 pm
FYI,

I looked it up. Correct terms when dealing with horsepower

SAE corrected (what is used now) - 29.23 inches Hg at 77 degrees F

Standard corrected 29.92 inches of Hg at 60 degrees F

SAE corrected ends up being approximately 10% less power than Standard.

Additionally, the LS motors seem to loose around 35 HP with alt, ac, and power steering pump connected.

So taking that, an LS2 rated by GM making 405 HP (SAE w/ accessories) makes 480 HP rated the old school way.

TonkaToyKiller
October 2nd, 2009, 08:52 pm
So buy the 3:1 and if you don't like it I'll trade you my 5:1!