Oh What Choices: 5.3L or 6.0L ???

[nsulacountry]

Long time lurker, first time poster.

I have a 1979 C20 Bonanza that is my candidate for a LSX transplant. I have seen some awesome 4.8L and 5.3L builds, some turbos! I have not seen as many, but have seen members drop in a 6.0L as well. With time and money, any of these can be wild rides!

Here is my situation. Bone stock truck. Will be towing with it, mostly farm duty. Tractors, hay, ect, on fairly flat terrain. Occasional trailer weight to 14k (gooseneck). 55 mph is all I need for towing. I am currently doing this with a 2001 K1500 4x4 with a 5.3L, 4L60E, 3.73, 178k mileage.

The C20 is 2x4, TH400. I'd like to keep the TH400 for simplicity. I know a 5.3L is more powerful than the tired 350 4bbl. Rear axle is 3.73, 10.5" corporate. It tachs 3000 rpm at 65 currently. 4.10's and a locker may be in the plan as well.

I'd only put around 2000-3000 miles a year on this build. Farm and play. I don't want to get involved with cam swaps, turbos, and the like. A good tune, dyno tune will be done once up and going. Intake and or injector upgrade would be entertained. I will need AC compressor functional. Stock or high mount?

Do you, the reader think the LM7 5.3L (285 hp, 335 ft/lb) would suffice, or should I go LQ4 6.0L (300 hp, 360 ft/lb)? Is the LQ9 6.0L (345 hp, 380 ft/lb) worth the price premium? How much can be gained with an awesome tune? How many miles on a pull out would be too much for a drop and play conversion? I have seen less than 100k to 300k available. I know a neighbor put +450k on a LQ4 before it lost oil pressure.

Looking forward for some advice. I'm excited to take this on!

CT

[BigDan3131]

I would rather see you put a big block Chevy in it instead since you want to leave it stock. If you can find one, a Caddy 472 or 500 put out a ton of torque stock. A tune, manifold and injectors are a waste of money without doing a spring/cam swap. Pulling a motor out of the junk yard is really a flip of the coin unless you know the shop from previous dealing.

[littlevictories]

lm7, they are getting to be as cheap as SBCs around my area

good mix of power and fuel economy.

[Super73]

The price difference is minimal going to an LQ9 in the grand scheme of things.

I won't say a tune in stock form is a waste, but it may not gain you all that much, or it could. Depends on how the motor responds to the intake/exhaust you will run in your so called stock form. Some gain little and others AFR is way off in open loop requiring some attention. Not to mention the stock timing subtractors for intake air temp etc and the stock rich condition called Cat Over Temp that dumps fuel.

I also like to see Power Enrichment enabled much sooner in the RPM band than the stock tune has it set.

There is a lot to be cleaned up in a stock tune for a stock vehicle let alone a stock swap. Will it gain power, possibly, wil you sleep better knowing it is right, I would.

[truckdude239]

i got a 4.8 in mine thought it was a 5.3 but i had flat top pistons in it so it a 4.8 runs strong has 153k on it and has like 60 psi oil pressure at idle seem like it has great power

[nsulacountry]

I hear you on the Big Block, BigDan3131. That was my initial thoughts before I discovered the Vortec re-powers. I really don't want to go back to carburetors, distributors, and the like.

I plan to go through this truck bumper to bumper. Changing exterior color and all new interior. This would be a good time to modernize the power train as well. I'm the 2nd owner, go it in 1993 with 25K. I beat the hell out of it in HS and college. It now has 147K and the 350 is shot. Barley enough compression to sustain life. Engine is coming out regardless and its not going back in!

One "Big Block" I have entertained is the L18, 8.1L. I know the aftermarket is not as broad as the more common production engines, but WOW! 340 hp, 455 ft/lb bone stock is tempting. The only thing I have read is they like a quart of oil here and there. The marine guy are making SERIOUS power with these beasts!

LM7 is a cheap, entry level option. Tons of aftermarket options. decent power in a small package.Has anyone messed with the Gen IV engines? Like the LH5, LY5, LY6, L76?

Good discussion. I realize there is a lot to soak in about this topic. And ya'll have made some awesome builds!
Thanks!

[Clyde65]

You will need a good long life to get the value out of her but, I would go with a 5.3, yes I would put a cam in it and a good tune. You can tune it for more torque than HP and it would pull that trailer all over the place and still give you the guts to have a little fun irritating Johnny Law, all for a little bit of $, oh and I agree with keeping the 400.

[truckdude239]

just remember any lsx will bolt in place of the other 4.8 5.3 6.0 all share the same bolts patterns and mounting, do teh 5.3 and if you dont like it the 6.0 will drop right in place of the 5.3 with just a computer re-tune

[nsulacountry]

Originally Posted by Clyde65

You will need a good long life to get the value out of her but, I would go with a 5.3, yes I would put a cam in it and a good tune. You can tune it for more torque than HP and it would pull that trailer all over the place and still give you the guts to have a little fun irritating Johnny Law, all for a little bit of $, oh and I agree with keeping the 400.

So a 5.3L with a torque bumpstick and a tune you say. I was leaning this way too, but was afraid the 5.3L would be too small. I know I have one now in my 2001 K1500 and it pulls my loads ok. Excess power is not a bad thing.

It would be fun to pull up to a rice rocket and leave him in a cloud of smoke at a redlight! Farm truck sleeper. Guy I work with has a stock appearing Pontiac Sunfire (I know, not my choice) that he put a supercharged, tuned, 3800 v6. It is nasty. 1st and 2nd gears are pure smoke. I've seen videos where he has embarrassed v8 cars. Anyway, off topic.

CT

[Billett]

5.3 with a cam and tune should get you what, especially if you won't be using it all that often.

[ivorton74]

I vote 5.3 for power and economy...if u want straight up power or want to go forced induction go with the LQ9...I've heard good stuff about those motors

[Billett]

LQ4 would be better for FI - lower compression

[nsulacountry]

Right now FI is not in the plans. Sure, it is cool, it makes butt loads of power, and why the heck not! Sure I have seen some WILD FI builds on here with Ebay turbos (I think one had a CAT turbo), I just wonder about durability and the EGT's when I load it down. Most of these builds are for playing. Nothing wrong with that. But if I put a 8,000 lb camper behind it and started hitting heavy hills, the EGT's concern me.

The 5.3L is making the most sense. Cheap, endless supply of aftermarket goodies, tons of build threads on here. I guess now, which one? The LM7 is basic and popular DBC. Is the DBW worth it? I know it is a 4 wire cruise hookup, but the TH400 doesn't have the reluctor and I'm not sure it could be added. This leaves aftermarket cruise... I hate those things, always crapping out.

Any cam, or cam package recommendations? Injector swap? Are the stock manifolds fine for a cam/tune job?

Thanks!

CT

[Billett]

TBSS manifolds would be fine, stock truck manifolds won't fit without persuasion. Stock injectors should be ok if all you are going to do is a cam swap, but they are pretty much at their limit from my understanding. I always recommend calling your preferred cam company and telling them what you are looking to use the engine for and what mods it has and they will be able to give you the best recommendation.

[Clyde65]

You can put the stock LSx cruise on a DBC, I have one on mine, Hit up LS1Nova for the skinny on that.

Also I would do some long tube headers since you want a little low end hump. I also would upgrade my injectors just so you have enough fuel when you put the cam and springs in there. You should be able to have 400HP at the flywheel easy.

Be sure to do a build thread so we can all drool and envy( hate) you while you are building!

[Super73]

You will not get a cammed 5.3 to out tow a stock lq9. Can you get it to make more hp, sure simply because hp is a function of tq*rpm/5252. Why is that relevant? When spun higher the crammed 5.3 will make more hp than the stock 6.0. But that 6.0 will still make more peak tq and at a lower rpm. Hp does not tow 8,000lb trailers.

Bit more expensive but an ls2 is another option at 400/400.

[Billett]

My thought was that he will only be using this for a few thousand miles a year, but I suppose when you're hauling a gooseneck you'd probably like all the power you can get... Why LQ9 over LQ4 though? I realize they put out a bit more power, but I'm not sure the price difference is worth the gain. When I looked at doing my swap the LQ4s were $10-1200 where the LQ9s were closer to $1800. Seems like a lot for such a little gain.

[Super73]

Added compression is the big difference. That is nice if you do decide to put a tailored for towing cam in the truck. It will help to keep your dynamic compression up and allows you to get away with slightly more desirable valve events with out as much sacrafice.

Start with more and it is easier to make more or at least easier to keep your more.

[jamesjones]

When I faced your dilemma, I decided on the LQ4. They aren't much more expensive than a 5.3 and you get get a better base to build on should you choose.

If you want to go FI it's ready to go. If you decide to stick with NA, just swap the heads or have your heads welded.

As heavy as our rigs are you want the low end grunt. Unless you can get a deal on a LQ9 the LQ4 is the way to go IMHO.

[Andy4639]

Well I just had the LQ4 LSx 6.0 droped in my 71 and it is the Boss! It has load of torque for what it is a stock motor with 305 lbs of torque at the rear wheels. There is one on my local craigslist for $800.00Even with the knock it's worth it I think.



I have an LS 6.0l iron block engine out if a 2006 escalade 98k when removed Recently installed a new stock camshaft and new lifters. Now started to knock in the bottom end it was a light knock at idle I will have pictures of the crank and bearings soon. Great for a turbo set up or ls swap $800 call or text 864-567-4nine4one
if you're still reading the add yes I still have it and the price is firm





http://greenville.craigslist.org/pts/4346508701.html

[nsulacountry]

This is good discussion! I have read A LOT about 5.3L and torque cams. From what I can gather, there is no cam that builds more torque BELOW 2500 than the stock LM7 cam... They all have gains at 3500+, bummer. 5.3L is OUT.

Sooooo. I am no longer in the market for the 5.3L in my application. It is 6.0 vs the beast 8.1L now! I can cam a 6.0L for torque, but have not researched the torque curve. But I have researched the stock 8.1L. from 1000 rpm to over 4000 rpm, the torque curve is about as flat as a table. WOW!

I know the aftermarket is not very big and whats there is expensive. But in stock form this engine is a beast. I'm thinking with a long tubes and a tune, its done.

Thoughts? 6.0 is readialy available and is probably all I need, even if stock. The 8.1's are harder to come by, cost a little more, but the cool factor just went up! Defiantly will not be short torque.

"No replacement for Displacement"

CT

[ls1nova71]

Here you go. A little pricey for me, but if its what you want, it looks pretty nice. http://67-72chevytrucks.com/vboard/s...d.php?t=601487

[nsulacountry]

Originally Posted by ls1nova71

Here you go. A little pricey for me, but if its what you want, it looks pretty nice. http://67-72chevytrucks.com/vboard/s...d.php?t=601487

WOW! Thanks lsnova71. Less than 400 miles away too. I was going to use my Th400, but still may. Got to think on this one. I was not expecting one to pop up this quick. Still need fuel system (dual tanks),ecm tune, wiring harness mod (could do it), headers (or box passenger side frame), AC relocation brackets (or box passenger frame again)... Arrrggghhh, my wife is going to KILL ME!

CT

[ls1nova71]

They don't show up very often at all, but a buddy of mine sent me a link to that one a while back. I don't know if its still for sale, but if it is he may be willing to deal on it by now, since it does seem kind of steep for the miles in my opinion.. That said, I say don't buy it. There, now if your wife kills you, ill have a clear conscience.

[solidaxel]

Originally Posted by nsulacountry

WOW! Thanks lsnova71. Less than 400 miles away too. I was going to use my Th400, but still may. Got to think on this one. I was not expecting one to pop up this quick. Still need fuel system (dual tanks),ecm tune, wiring harness mod (could do it), headers (or box passenger side frame), AC relocation brackets (or box passenger frame again)... Arrrggghhh, my wife is going to KILL ME!

CT

"GO FOR IT"
Just double the price and buy her something !!!