1FSTZ71

iTrader: (11)

I went through some topics in the search function and found some varying ranges on gas mileage with a TH400. Now this isn't going to be in an F-body but no one has much experience on the PT board with TH400 behind Gen III's. I'm building a Jeep with a 6.0. I will be running a 5.5" lift and 35" tires. I don't want to use the 4L80E because of weight and size (the jeep doesn't have alot of room underneath). I'm thinking of going with a TH400 with my setup. Now this will be somewhat of a DD, and weekend fun truck which will see some wheeling and track time. I'm thinking of running 4.56's for wheeling and track time, and with 35" tires that will put me at about 2700rpms at 60mph. I'd prefer to be closer to 2K (a 4.10 will put me at about 2400), but then that will kill my pickup with the big tires and "low" 1st gear in the TH400. What are you guys getting MPG wise and at what rpm with a TH400? The jeep is going to weigh right around 3000lbs. Any opinions? I thought about keeping the stock axle ratio underneath for running around town (3.55) but of course the dana 35 stock axle sucks lol. I could weld the axle tubes etc but moving the 35's would still be asking for trouble. My last option is keep the stock wheels, swap my stock rear for a 3.08 version from a buddy and run stock tires/axle around town (2300-2400rpm at 60). Let's see what you guys have!! Any suggestions?

Vortech Converters

Here is another option.

http://www.yellowbullet.com/forum/sh...ad.php?t=46105

meandmyls1

How about a 4L60E?
I had a '94 4 door S10 blazer with 35x14.50 super swampers, 4.56's in a 8.8 and Dana 30. This truck was 18" higher than stock with no blocks, spring only.
It weighed more than 3000 pounds.
It was the stock 130,000 mile trans and it never gave a problem. It would cruise 60 mph at 1890 rpm.
I didn't have to but I daily drove this for about two months and it got 19 mpg mixed hwy/city with the a/c blasting. It did have the original optional vortec 4.3 though but it had more power than you'd think.
A built or mild 4L60E should work for you for wheeling anyways, not sure about (or why) track time.

Gilbert@Ace Racing

The really is no reason why you could not run a well built 4L60E in this application. The 400 is a good candidate because of it's ability to take high torque loads, but I think it is overkill in this application.

The 4L60E would allow you to have a very nice launch gear, would allow for playing off road and would get terrific mileage. The 4.56's might be a little much for the launch gear, but that's only an opinion... overall I think it would be a good choice for the build.

I would be happy to discuss the project with you... give me a shout and we'll kick it around.

g

382ssz28

iTrader: (24)

I agree with ACE. The transfer case selection is easier with the 4l60 series, also. We've done a few swaps with the LS motors with the 4L60's and used the salvage computers or stand alones. You can tune the motor and the trans. If your not going to invest in better diffs, there is no need for a beefy 400. This combo will work fine. If you are going to keep the 3.55's, I would not go bigger that 32" tires. Good Luck.PS, if you want to feel how well this combo works, go rip on a Suburban @ 5900lbs. and see how you like that. Imagine a 6.0 in a 3000lb. Jeep. By the way, I tow 9200lbs. with my trailer with a 5.3 with my 04 Burb.

1FSTZ71

iTrader: (11)

Oh the stock 35 won't be under there lol. Built 8.8 in the rear and either a Dana 44 up front or a super 30 with truss, haven't decided yet. I'll give you a call ACE.

Gilbert@Ace Racing

Sounds good. I'll be around all day today and will be here most of the day tomorrow as well.

g

venomhp

iTrader: (13)

well im running a 5.3/4l60/ 4:56 gears and 35's, but obviously in a truck, now at 65 im at like 2k, at 70 its right at 2200, 75 right around 2400, 80 is about 25 or 2600rpms. so if thats what your looking for I hope that helps

1FSTZ71

iTrader: (11)

Thanks for the info. Still putting everything down on paper trying to figure out my best route. On one hand the 4L60E would be a good choice for mileage, but on the other anyone that knows me knows that I can never leave well enough alone lol. Meaning I'm planning on making near 500rwhp right now, but that will get old in the future and I will want more haha, so the TH400 would hold up all around (or spend a crap load on a good 4L60E). The wife is keeping my budget tight on this one because it's not my "main" project, that's the only reason why I'm debating, we have a baby on the way so I can't splurge as much right now lol. I like to do things once, and get it right the first time, but I'll spend alot of my budget on a GOOD 4L60E. I might not be able to call you today ACE, probably tomorrow

Gilbert@Ace Racing

Dang dude! You have a few irons in the fire then dontcha... Did you get the Nursery done yet? If not get that out of the way before anything else or you won't hear the end of it for years !!!!

Let's hear about the "main" project!

g

1FSTZ71

iTrader: (11)

LOL. Ya I have a few irons in the kicthen haha. We are moving to Minnesota in june so we won't be setting up the nursery until we get there. That is part of the reason for getting the Jeep haha. Something I can drive around in the snow and all year round without problem. i convinced her to let me buy a cheap high mileage Jeep and use my budget (we set a budget on how much i could spend on a 4x4 vehicle lol) on building the Jeep instead of buying a good running low mileage version. It's a wash in the end and it will be built the way I want it I have a 69' Tempest(GTO) I have been working on, I finished the frame on it (all hotchkis/bmr suspension), welded in new floor pans, etc. Haven't decided what drivetrain I want (debtaing on keeping the OHC-6 that came in it and getting a ported head, stroker kit and boosting it with EFI, a powerdyne at 9psi on a stock sprint ohc-6 made 400hp, so I think I well built turbo setup with custom cam and stroker would be well over 500 and different haha). The wife also wants me to find her a 67' stang' convertible and build it for her. I'm trying to sell my low mileage 95' GT convertible right now (no sense in having it if we will be living in snow, plus it's not my "baby"). Anyone want one

Gilbert@Ace Racing

Aw hell.

You are the 1st person I have met on Al Gore's Interweb that said he owns a Pontiac OHC6! I have several of those blocks in my garage. Including a 4BBL Sprint Manifold setup.

We need to talk.

I've been debating about building one of those engines or another combination later this year for my '69 Firebird. My car is a 2 spd SuperTurbine 300 car, so a nice Glide with alot of Gear ought to pull pretty damned hard.

g

1FSTZ71

iTrader: (11)

Hell ya!!!! That's part of the reason I was thinking about keeping it. I was going to run a ford EDIS-6 setup on it with crank trigger for the ignition and have to custom make efi (or use a sprint 4bbl manifold and run a EFI throttlebody/injector setup). Have you checked out Primatech? They make a crap load of stuff for the OHC-6. Neat little motors. i got my car with 90K original miles, still ran good (2bbl) for $1000 with minor rust (a little on the lower rear 1/4s, a little on the lower front fender and drivers side floor pan)