Tj + Lt1

[Jackson04Jeep35s]

Here is another question for your guys more knowing than me. I am getting a LT1 put in my TJ while I am in Iraq. My question has several parts.

1. How will milage be affected? I have 35in tires so I've been told that the larger more load bearable engine may actualy increas milage by a little bit.

2. How will my Dana 30 and Dana 35 Axles hold up to moderate offroad use? I dont get too crazy.

3. What kinda of gears would you recomend for my application?

Thanks guys for you help.
Richard

 

[Snitty]

If it is set up properly, and you drive conservatively, your fuel economy should be relatively ok. I don't quite think you will increase mileage, but I'm not saying its impossible.

The axles SHOULD hold up if you drive JUST moderate. The dana 30 should be fine, but the 35 is something you'll want to look into upgrading down the road. Just keep an open differential at first, and you'll always have a dump fo the power.

I say leave whatever gears you have to start. If you are going to regear, upgrade the rear (and possibly front) axle when you do. I think a 3.73 would be sufficient for moderate offroading with that sort of power

 

[Bounty__Hunter]

I ran a built 350 in my '88 YJ with stock axles and they held up just fine to moderate wheelin.

35" tires will zap a stock jeeps mileage, so you will likely 'at least' break even in this department.

 

[GaryMB]

The stock axles should hold up to mild driving, but that rear end would be a bit weak for an LT1 and 35's if you ever feel like puting the power to the pavement...I would say go with an 8.8" out of a ford explorer if you plan on keeping the front end in there...with only moderate 'wheeling the d30 should survive. Also the 8.8" will give you better braking power, something that often gets overlooked with bigger tires and engine upgrades. As for gears, if you will be using an OD transmission, I would go with 4.10. 3.73's would work, but you won't have much use for the higher top speed that will give you, so you might as well gear lower for better acceleration...and 4.10's with 35's will still give you a pretty high top speed, especially for a lifted Wrangler on 35's. If you're not using overdrive though then 3.73 might be a better choice. Either way, mileage will be worse than stock, but how much worse will depend heavily on how you drive the Jeep...I don't think the LT1 will hurt mileage as much as the 35's if you drive it easy.

 

[Jackson04Jeep35s]

ok, My transmission is a chevy 4speed. I dont even know right off which one it is. My dad is having it all put together for me while I am over here. 4.10s?

 

[GaryMB]

http://www.grimmjeeper.com/gears.html
I would plug in your top freeway cruise speed that you want to go and then use the calculator to figure out a good rpm and gear ratio for that. Lack of power won't be an issue, so pretty much your only factor will be top speed/rpm on the freeway. I would get the lowest gearing that gives you a good crusing rpm on the freeway.

 

[redrooster]

First of all, thanks for serving our country. We appreciate all you do for us.
Secondly, that LT1 is a powerhouse and is going to destroy both of those axles in short order. It will be fun as hell doing it though.

 

[Jackson04Jeep35s]

Ha ha, yeah I guess if I destroy them... I will have an excuse to upgrade them right?. Oh, and thanks for showing some support.

 

[Snitty]

You have a great way of thinking, my friend

 

[GaryMB]

I've always found destroying axles to be a blast. A buddy of mine blew out his dana 35 doing wheelies in a rite aid parking lot; fixing it on the spot was another issue but an experience none-the-less.