350 for towing?

[Kudzupatch]

Going to replace the engine in my Suburban. It has TBI which I plan on keeping. I have pretty much decided on a L31 replacement engine as my best bang for the buck. Things may change a little and may be towing a 3,000-4,000 lb trailer so I am revisiting my choice to make sure I don't regret it.

I have looked at cam swaps for the L31 but doesn't look like you gain enough low end torque to be worth swapping it.

Ideally I would like a mild 383 but that ups my engine cost from just under $2,000 to $3,000 dollars and that is a big chunk of change right now. Business is still pretty slow for me.

Still seems like the stock L31 is the best bang for the buck but I am looking for opinions.

[geezer#99]

Use the L31 and upgrade it later if you think you need to.

[garyd1961]

Get the L31-R it's a 4 bolt main, also has sodium filled valves and hardened valve seat inserts, better for towing.

[kwmech]

I had a 1990 suburban few years back that I replaced the engine in and went with something comparable to the L31. Still really wasn't enough grunt for towing the travel trailer. Sold that beast and picked up a 1991 that I am currently building at the moment. When the rest of the money is saved up I'm building a 400 for it using the dart block and heads. I figure the engine will be close to 5k when I'm done

[Dead Parrot]

Rear end ratio? Tire size? Transmission?

Lots of stock 350's give good service in 1 ton trucks towing things but a lot of 1 tons have 4.10 or higher rears. If the rear end, tire size and transmission have the engine in the beefy part of the torque curve at your planned speeds, you should be good.

[Alex V.]

The 350 can give very good service in towing and other hard work, it just has to be in the right truck, with the right drivetrain, and maintained well. A 3/4 ton standard or extended cab truck (aka, not extremely heavy) with a 4L80E and 4.10 gears would handle 2 tons behind it with ease. A 4L60E with 3.73's or 3.42's, not as easily but it'd still do it as long as the transmission held up.

[Kudzupatch]

93 Suburban. 4l60e transmission and 3.55 rear gears, limited slip.. Stock dia tires, 29". . Factory trans and oil coolers. I will install temp gages on both before I start towing regularly.

We are looking ahead to retirement and want to by and restore an 1950's camper and travel a little. Trailer is probably in the 3200-3500 lb range if I can find what I have in mind.

[cadillac_al]

4000 lbs isn't much to tow. That's just a car and a trailer. People have been hauling cars with station wagons forever. I haul cars with my little K10 with a 350 and 3.08's easily and barely know it's back there. I think a 350 will be fine for whatever you want to tow.

[Alex V.]

Originally Posted by cadillac_al

4000 lbs isn't much to tow. That's just a car and a trailer. People have been hauling cars with station wagons forever. I haul cars with my little K10 with a 350 and 3.08's easily and barely know it's back there. I think a 350 will be fine for whatever you want to tow.

That's an extremely light car or trailer - even a light 16 ft. trailer weighs ~1,600 lbs. and even a late 90's Cavalier weighs 2,600-2,900 lbs. So the average "car on a trailer" figure is closer to 5,000 lbs.

I think the OP's vehicle will handle his proposed trailer weight well, unless heavy wind or steep hills are in play then he may be relegated to slowing down and using 3rd gear at times. FWIW I've heard multiple people say the single most important thing to keeping a 4L60E in one piece is keeping it cool, so an auxilary cooler may be well worth the trouble.

[Kudzupatch]

L31 is the best bang for the buck out there. I think it will be OK but just always prefer experience over speculation. Don't want to do all this work and regret it latter.

If budget wasn't so tight I would spring for the 383 with small cam designed for towing in a heart beat! Always better to have more than you need and all that torque is lot more fun too in a big heavy vehicle.

This one came with all towing goodies and I plan on adding temp gauges so I know exactly what is going on. I tow occasionally now but in the future I hope to be doing it a lot more.

[Captainfab]

I would stick with a 350 whether it is the L31 or other. That way you don't have to change the throttle body and having a chip burned won't be so difficult to get right.

[Kudzupatch]

Need to have the L31 tuned anyway. I have a local tuner that is going to do that if I can't get it right myself. Going to install a Moat's Ostrich emulator. That will allow you to do on the fly tuning of TBI. That is not an issue.

[b454rat]

I’d swap some gears i there. 4.10s would work great.

[Tom]

Originally Posted by Kudzupatch

Ideally I would like a mild 383 but that ups my engine cost from just under $2,000 to $3,000 dollars and that is a big chunk of change right now.

If your rebuilding the engine then you already have to buy pistons, so that's not an extra cost option. A stroker crank is a couple hundred bucks, not alot more then cutting an oem crank .010. Overall its barely any extra money making a 383 vs a 350.

[garyd1961]

A TBI intake off a 93 is not going to fit a L31 Vortec motor.

[Captainfab]

What I was getting at is if you went with a 383, you can't get away with using the 350 throttle body and it is more difficult to get the tune right. With a 383 a 454 throttle body is needed.

Originally Posted by Kudzupatch

Need to have the L31 tuned anyway. I have a local tuner that is going to do that if I can't get it right myself. Going to install a Moat's Ostrich emulator. That will allow you to do on the fly tuning of TBI. That is not an issue.

[GASoline71]

Originally Posted by kwmech

I had a 1990 suburban few years back that I replaced the engine in and went with something comparable to the L31. Still really wasn't enough grunt for towing the travel trailer. Sold that beast and picked up a 1991 that I am currently building at the moment. When the rest of the money is saved up I'm building a 400 for it using the dart block and heads. I figure the engine will be close to 5k when I'm done

I had a 1991 K2500 Suburban that had a TBI 350 mated to a 4L80E. Used to tow a 28 foot travel trailer with it. Towed just fine. It's not gonna pull any mountain passes at 70mph (more like 45mph) but it was a great tow rig. Also towed a 1971 ElCamino SS drag car on a flatbed with it. Again... no problem.

The 350 is a very capable towing engine. Nowadays with more efficient LS based engines and also turbo diesel's with awesome transmissions, we have all gotten spoiled.

Gary

[Kudzupatch]

Originally Posted by GASoline71

I had a K2500 Suburban that had a TBI 350 mated to a 4L80E. Used to tow a 28 foot travel trailer with it. Towed just fine. .......

This is exactly the kind of info I wanted, practical experience. I am looking at 18-20 foot vintage travel trailer, so probably less weight than your 28'. I don't expect to do 70mph up a mountain but of course I don't want to do 25 either.

[b454rat]

One thing I did to mine that made a huge difference was a set of Flow Tech headers, into a 3" single Y-pipe. Already had a cat back, once the headers/y-pipe was on, a 2' piece of pipe to replace the cat. It made a HUGE difference in torque, off idle to 4-5K guessing, since didn't have a tach.

[GASoline71]

Originally Posted by Kudzupatch

This is exactly the kind of info I wanted, practical experience. I am looking at 18-20 foot vintage travel trailer, so probably less weight than your 28'. I don't expect to do 70mph up a mountain but of course I don't want to do 25 either.

I forgot to put the year on my original post so I edited it. The K2500 Suburban was a 1991. Might have been one of the first years for the 4L80E as well. The engine was bone stock with no modifications. Still had the stock cast iron exhaust manifolds. I did upgrade the exhaust to an aftermarket free flowing cat, better flowing muffler and a single 3" exhaust. Thing sounded pretty good too. I had the transmission rebuilt at around 150,000 miles as well. She was our primary tow rig.

Sadly the ol' girl blew a head gasket, over heated and cracked the block. But... that was after there was 225K on the ticker. That was a great rig that I wish I still had.

Gary

[Tom]

Originally Posted by GASoline71

It's not gonna pull any mountain passes at 70mph (more like 45mph) but it was a great tow rig.

And here is the problem with opinions. 45mph up a hill is not towing fine to me, its much underpowered. A 26,000lbs+ heavy duty truck can do 45mph up hills.

[abig84]

I would think pretty much any engine will tow that trailer. My 1990 has a 305 with 230,000 miles on it with 343 gears and does fine with the 5,000 lbs I tow 70 miles to the off road park. Naturally it's no speed demon but have no issues merging or going up truck grades

But yeah no clue how it would do on mountains for a long period.

[GASoline71]

Originally Posted by Tom

And here is the problem with opinions. 45mph up a hill is not towing fine to me, its much underpowered. A 26,000lbs+ heavy duty truck can do 45mph up hills.

Not just any hill... but some of the mountian passes we have here in WA state can have steep long grades. Just hills... it was no problem.

Gary

[Bigdav160]

Originally Posted by garyd1961

A TBI intake off a 93 is not going to fit a L31 Vortec motor.

Yep and an aftermarket manifold to put the TBI on the vortec heads is $500

[Kudzupatch]

Originally Posted by Bigdav160

Yep and an aftermarket manifold to put the TBI on the vortec heads is $500

And it is not like that it is the ONLY option. You can use any intake with a adaptor plate.

My plan is a Jr Victor 2 barrel and make my own adaptor.