Best budget upgrades on a 5.3L rebuild?

[tRidiot]

So I'm going to need new heads - I've got the Castech 706s. Blew a head gasket, was looking at a motor swap, but I've got someone who'll do a rebuild for me. He knows what he is doing, but I'd like to think about upgrading some things while we're torn down.

I'm not worried about power, particularly. I don't tow, and don't see myself getting a boat anytime soon. It's got plenty to tow if I decide to pull a mower or two.I thought about putting in an LQ9 6.0, but the rebuild is looking like a good budget option at this point.

I don't know if I'll NEED new pistons, but I assume that is something we'll see once we tear it down. So, for heads, looks like they start at around $300 each at the local auto parts stores. Is there much reason to spend ~$1000 on heads?

I debated new exhaust manifolds or even headers. Main reason is I would like to improve my MPG somewhat. I assume this might require some modification to my stock exhaust. I might consider a new exhaust at some point. I know a rebuild probably will help my economy, but I was pulling 13-14 on the highway. I have 3 alternators and largish tires (Goodyear Wrangler DuraTrac Mud Terrain 275/60R20). A small 2" or so lift and new Bilsteins, my mileage took a hit with that upgrade from 15-17 down to 13-14. So... my understanding is headers would help, better intake might, too, but I think we're starting to get into some real money there (intake manifold, that is).

New camshaft? Not sure if this will help economy at all. I've read about it helping power and torque.

New higher flow oil pump?

I've already put electric fans on.

What else should I consider doing while we're torn down besides the basic rebuild kit, new seals, etc.?

I've got a little money to play with, but I just picked up a 1977 International Scout, so that's going to be my money pit for the future - the Tahoe is my grocery getter and family hauler.

 

[Supremacia]

A lot of the upgrades you're talking about would really only benefit if you're increasing power. Lighter pistons and rods might help mileage, but not too much. Intake possibly, you don't have to go crazy with a Texas Speed $1000 manifold, $3-400, but may require additional upgrades like fuel rail and lines depending on what you get.

The rebuild itself is going to bring it back to a pretty good baseline. You could have the stock heads ported for a bit of horsepower (25ish) with variable +/- mpg change. $1000 heads will get 25-75hp, depending on what else you have upgraded, mpg may improve, but again, you'll likely end up dumping more fuel in for acceleration to match the increased flow.

Modifying the exhaust, headers, etc, may improve mpg by allowing you to get up to speed faster, but not always. Mpg gains can only happen if the engine is more efficient and has less resistance: lower weight pistons, crank; lighter body; improved intake and exhaust tied to efficient driving.

A fuel efficient tune is also an option, but that generally saps a ton of power/acceleration.

 

[Supremacia]

If you're looking to get the most benefit without spending "too much", a mild cam upgrade, ported heads, cheap intake manifold, efficient exhaust manifold or headers, and tune. Upgraded piston heads and rods would be nice, but not necessary. Throw in an intake and cat back exhaust.

 

[tRidiot]

Good to know, and more things to research. Thanks, guys.

 

[Jason in DLH]

Great ideas you have already.

Is there a lightweight flywheel available for the LQ9?

Edit: Lightweight flexplate.

 

[iamdub]

IMO, for the bare minimum, you should find non-Castech 706/862s. They should at least get a cleaning pass on the surfaces, but you could have them take off a little more to bump your compression up to 9.75ish. They'll have to measure the combustion chamber volume cuz they're almost always larger than what GM advertises. (61cc for an LM7)

Since it's getting rebuilt, you could model it after the L33. Get a used L33 cam if you can find it or a little larger if an aftermarket cam is in your budget. You'd need the pistons from a 4.8 for the 0cc piston volume (your stock ones are dished 8cc). In my area, 243/799 heads go for ~$400/pair.

I know you're not after power. But, if you can get more low- and mid-range torque out of it, you'll increase its efficiency and, therefore, fuel economy. Raised compression is a cheap and easy way to increase power across the board. Keeping the compression at or below 9.9 keeps it safe to run 87 octane. I'd have a professional tune and run at least 89, though.

Longtube headers would help, but they're likely out of budget for what you're aiming for.

What year is your truck? You might benefit from a later intake manifold. This can be a cheap upgrade if you get one from a salvage yard.

No reason to change the factory air filter and intake duct assembly. If anything, an Airaid MIT would do. First thing is to make sure the seal from the filter box to the fender is good.

 

[tRidiot]

IMO, for the bare minimum, you should find non-Castech 706/862s. They should at least get a cleaning pass on the surfaces, but you could have them take off a little more to bump your compression up to 9.75ish. They'll have to measure the combustion chamber volume cuz they're almost always larger than what GM advertises. (61cc for an LM7)

This sounds good, but I'm not sure where I would get these. We honestly don't have any salvage yards here, would have to drive to Tulsa (about 45 miles) and dig through junk yards. And I don't know that I have the time for that.

Honestly there aren't many sets on Ebay (for an L59) that aren't 706/862, and several of the ones I can see obviously have the Castech mark in the pics, which is a no-no for me, and others I can't see if they do or not. I haven't had good luck with Ebay sellers when I've asked questions about this topic, mostly not getting replies - and surprisingly, even one highly-recommended engine remanufacturer I contacted in Tulsa acted like they'd never heard of a problem with the 706 heads. That freaked me out even more, as this seems such a common issue and well-known, I can't imagine someone who remanufactures engines for a living hasn't heard of this on one of the most common motors on the road! And these guys are charging over $2k for a remanufactured stock motor - with my core exchange. Sure doesn't inspire confidence. I don't care if the heads are "still" in good shape, I've read enough about them I don't want to risk another set of Castech heads. I do see lots of L83 heads on Ebay (Gen V Ecotech motor?). I don't know about mixing and matching, etc. That's why I just jumped to buying "new" heads. I know that I know that I know I won't be getting Castechs.

Since it's getting rebuilt, you could model it after the L33. Get a used L33 cam if you can find it or a little larger if an aftermarket cam is in your budget. You'd need the pistons from a 4.8 for the 0cc piston volume (your stock ones are dished 8cc). In my area, 243/799 heads go for ~$400/pair.

You say in your area - where do you find them? I'm not 'plugged in' I guess to the scene, a lot of these things seem to be word of mouth, I think. I don't do FB, either, I've been told "You can get a motor on FB for next to nothing" but I purposely stay away from that platform and would rather continue to do so.

I see a "racing" LS9 cam kit on Ebay for around $400, or just a camshaft with springs and seals for anywhere from $160-200. I think this would be an acceptable drop in upgrade. I don't want to overcomplicate things with having to have heads overbored or any of that, as it just means more people in the loop, have to drop parts at a machine shop and wait till they get around to doing the jobs, etc. Sort of like having too many cooks in the kitchen, another reason I thought going with new heads would make things simpler, if it was $100-200 more, I'm not on THAT tight of a budget. I just don't want to spend $4k on this.

I know you're not after power. But, if you can get more low- and mid-range torque out of it, you'll increase its efficiency and, therefore, fuel economy. Raised compression is a cheap and easy way to increase power across the board. Keeping the compression at or below 9.9 keeps it safe to run 87 octane. I'd have a professional tune and run at least 89, though.

That's cool, I'm not opposed to more power - I just don't want to overbuild it and spend a lot of money looking for more power, as I just didn't feel I needed it. I know how easily it can turn into a neverending money pit looking at the various add-ons for "moah powah!" But I get it, if it does more power and works easier, it will save fuel. For fuel, I usually use premium non-ethanol anyways. I have to run this in my 370Z and just always stuck with it in my Tahoe, as well.

Longtube headers would help, but they're likely out of budget for what you're aiming for.

If I'm correct, this would require other exhaust work, too, right? I don't think I want to have to redo the exhaust right now, although I would like to later, since it appears I'm going to be keeping this a long time. Better sound and flow, but I've got a lot on my plate right now - and tax time is also coming up. No stimulus checks OR tax refunds for this guy.

What year is your truck? You might benefit from a later intake manifold. This can be a cheap upgrade if you get one from a salvage yard.

No reason to change the factory air filter and intake duct assembly. If anything, an Airaid MIT would do. First thing is to make sure the seal from the filter box to the fender is good.

This is on a 2004. I've had it for 10+ years, bought it with about 83k, it's now at 275k miles. And I've put 70k or so on my 370Z since I bought it in 2013. I used to drive a LOT, the majority of those were pre-2018, since then I went from commuting 150 miles a day, to under 2 miles a day - round trip. Honestly, the Tahoe has been a great vehicle for me, the only real things I've ever had to do were routine maintenance. I did electric fans, replaced wheel bearings in one wheel, and have the problem with the blend door actuators and rear heat/AC which I cannot get to work right regardless of changing out the actuator. But in general, mechanically, it's been wonderful up to this point. Starting to have some niggly electrical stuff like seat motors, cruise control wonky, etc., but I really have loved my truck. If I can get it back on the road, then start to work on the little things myself, and I am thinking I'll need to do a trans sometime in the next 100k or so, too...

But I really REALLY don't want to take on a car payment again. So this is where I am.

Sorry if this is too longwinded.

 

[tRidiot]

I'm seeing more options on Ebay now, too, since I've figured out more about the codes to look for. I know to avoid 706/862 heads if I can't verify they aren't Castech, but now I see the overlaps in some of the motors. I get more results searching for LS1 or Gen III GM cylinder heads (instead of searching for L59) and I see the 799/243 sets, which I assume are drop-in as well. Looks like a decent number of rebuilt/reman heads that way.

 

[Mudsport96]

Avoid the LS9 cam in a 5.3.
Watch this vid with a comparison of all the stock cams in a 5.3

You will gain power above 5000 rpms but will lose upto 50 lb ft of torque on the bottom end.

As for headers shortys gain like 5 hp over manifolds, so dont do anything other than long tubes. For your application the stock intake manifold is ok at most find a stock 07 and newer intake from a truck also known as the TBSS or new new bodystyle intake. But here is a vid showing you that upto 550hp the stock intake is really ok

Your best gain for power will probably be an electric fan conversion if you still have the mechanical.

As for a good cam. If you want anything you want torque, so i would go with maybe the BTR Torque cam it will be a good bet for lowend power.

 

[Mudsport96]

Just find Richard Holdener on YouTube and watch his stuff. He doesnt sell anything, and has actually shown cheap ebay stuff can work better than high priced stuff with dyno proof. And it will show you with dyno charts where power is made and what parts to get the results that you want.