Bigger engine for towing

[Cody_350]

hey guys, I have a 1999 Chevrolet Suburban K2500 with a 5.7 350 small block attached to the 4l80e transmission, I just hit 170,000 miles with both of them together, nothing major replaced yet. and I know I've seen these engines go into the 400,000 range if taken care of but this one needs some work, I'll hit 200,000 but I'm milking it after that. I've been doing some research on engine and I found what I want to do. On jegs.com I found Chevy's Big Block 502 HT towing motor, it puts out about 510 ft lbs of torque with a decent 340 horsepower, I want the tow motor because I want the torque, horsepower isn't a big thing for me but it's nice to have, I'm still gaining 100 horsepower from my stock 350 so... mainly I just need and want the power to pull about anything I want, eventually with some upgrades I can pull my friends diesel trucks who talk like they're all badass. lol. anyways, I have my mind set on the 502, but I don't know what transmission I'll need for it, I doubt my stock 4l80e will hold up to the power unless I baby it but that's not fun so what do you recommend me marrying the engine to? can I put an Allison transmission on it? I preferbly want an automatic, what else will I need to change on it? I figured I would go to a junk yard and get the computers and everything off of a 2000-2006 496 big block engine and just attach it to my truck and what not, I think they'll hook up. what kind of problems will I be facing? my dad is best friends with a mechanic so I have the tools to do it all I hope

 

[96C1500]

Why not go for the 572 big block?

Sent from my Vortec powered HTC One M8

 

[RichLo]

If it was me, I would rebuild the 4l80e with all of the best parts. That way you wount have to mess around with the headaches of retrofitting a differant trans.

 

[Cody_350]

I don't want the 572, more money, more power. and like Rich said, I can probably rebuild the 4l80e and make it work. cheaper on my part. with a 572 it's gonna be straight carburetor, I can put a throttle body kit on a 502 and get a little better gas mileage. I don't know about rebuilding mine though, can putting upgraded parts actually hold up to the 502 I'm putting in it? the most horsepower I would probably want to get out of it is under 450, and torque I'd like to see 650-700 lbs

 

[thz71]

The 80e is your best bet. What throttle body are you planning on using?

 

[Cody_350]

Howell makes a throttle body kit for the 502, cost about $1,800 but I feel it's worth it, I heard I can take the throttle body off the 496 big block that was placed in the 2000-2006 suburbans. how would I go about upgrading my stock transmission? I'm not an expert so that's why I came here, I literally don't know anything about what I need to do to my transmission.

 

[StevenL]

Maybe think about gear ratio changes. I'm running Toyo Open Country 37X13.5X17, 5:13 Yukons and 454 engine. My 1997 K2500 Suburban was ordered with 3:42s, as I remember, but the engine needed some help pulling my travel trailer, especially with hills and the taller tires. Gear ratio change was a better answer for me, than lots of money in engine mods. I changed the tires since my original signature photo.

 

[Birchyboy]

Not trying to deter you, but you can't raise the legal towing limit by throwing a bigger motor in. You'll be able to tow the max load easier, though

 

[Cody_350]

I eventually planned on throwing 385/70/16 Toyo open country's on my truck so I would be changing the gears to 4.56's. what kind of gas mileage are you getting with your 5.13's?

 

[94_C/1500]

The 4L80E is pretty stout, I'm not sure where you've heard otherwise. Rebuilt with the right parts and I'm sure you won't break it. What are you pulling a 350 Vortec isn't enough for?