Chevy 5.3 LM7 engine rebuild.

[Chris Dishman's Donut 192]

I put an '03 LM7 into my '68 3/4 ton.  Would recommend Brian Tooley Racing for a cam upgrade and new valve springs if you're that far into it.  

[ROFL BOX 6649]

Hell, if I was doing a complete rebuild or installing a new engine, I'm the kinda guy that will opt for a slightly lumpy cam.

 

[Gil Bang 26020]

The fuel pump was already changed out (the gas gauge sensor and the check valve wore out on the original). I will change out injectors when I do the engine. The "crate" engine is from Summit and comes with a 3yr warranty for parts, plus $50/hr labor reimbursement.
PS pump, alternator, A/C compressor, water pump, have all been replaced fairly recently. I'm just going to hang those off the new/ rebuilt block.
New oil pump, pistons, rings, rod bearings, main bearings, camshaft bearings, timing set, upper/ lower gaskets,  camshaft, lifters, freeze plug.
The LM7 is such an easy engine to work on, and they are really common, so I'm leaning toward letting the local shop do the work. Probably staying very close to stock.
Here was the video I needed to start working out the rebuild:
 

It’s no easier to rebuild than any other engine from that era

[MagicSoccerSpray 1732]

On 7/18/2020 at 7:52 PM, Bevo&Pevo said:

If you are losing oil pressure and there are no visible oil leaks on the side of the engine, the main bearings have probably lost some tolerance.   Those Gen III LS units are hard to beat.

 

On 7/19/2020 at 7:51 AM, Randolph Duke said:

What is the first sign of an oil pump failure? Will the pump give me warning by noticeably lower output over time (similar to an alternator slowly wearing out and giving warning because the lights are all dimmer) or will it be an "oh shit, I have a problem" situation like when a water pump seal starts leaking all over the ground?

 

On 7/19/2020 at 2:31 PM, torre said:

https://www.cargurus.com/Cars/Discussion-t11114_ds628022

 

Solid advice in the thread.    

 

I retired your same vehicle (2000 Silv, 5.3) with 316K miles. (second vehicle).    Engine and transmission were fairly solid till the end.  Did develop seal leaks and the low oil pressure at idle described in link above which I chose not to repair.   No oil pump or bearing failure.    Just monitor the oil pressure gauge.

Heads up, the LS' are known for the oil pickup tube o-ring to harden so that it loses pressure at idle. A cheap and easy fix only needing to drop the pan to get to it. YMMV of course.

As to OP, I would drive it in the ground including rebuilding the trans as long as you plan on keeping it for a while. If the engine eats a cam, a bearing, or the rings give out, I would probably lean towards a rebuild from a reputable shop that warranties their work and would upgrade the cam and valve springs including a re-flash to get around 325 hp. The cam and springs are the bottle neck as the stock Vortec heads are pretty good.

2000 Silverado Z-71 with 235k on the original engine and trans here. Just rebuilt the original alternator. They don't make them like that any more.

Edited August 12, 2020 by MagicSoccerSpray

[Randolph Duke 4034]

4 hours ago, MagicSoccerSpray said:

 

 

Heads up, the LS' are known for the oil pickup tube o-ring to harden so that it loses pressure at idle. A cheap and easy fix only needing to drop the pan to get to it. YMMV of course.

As to OP, I would drive it in the ground including rebuilding the trans as long as you plan on keeping it for a while. If the engine eats a cam, a bearing, or the rings give out, I would probably lean towards a rebuild from a reputable shop that warranties their work and would upgrade the cam and valve springs including a re-flash to get around 325 hp. The cam and springs are the bottle neck as the stock Vortec heads are pretty good.

2000 Silverado Z-71 with 235k on the original engine and trans here. Just rebuilt the original alternator. They don't make them like that any more.

I found the flow data from the stock 5.3 head. If I apply the math, I don't see how I'm going to get ant more HP out of these heads. The engine components seem really well matched.

The stock cam is 0.457in/0.466. Bumping it up to a .500/.500 will only get me about 3hp, unless I do some work on the heads.

The goal here was to capture any easy HP/ gas mileage gains I could by simple tweaks to the engine. I'm beginning to realize they already did that at the factory.

I'm thinking the focus on the rebuild needs to be on porting the exhaust value/ exhaust manifold to increase the flow rate (if possible). After that, spend a few bucks on making sure the parts used aren't chinese crap, and making sure the shop knows what a torque wrench is about. The first challenge with an LM7 seems to be on the exhaust side. I'm not willing to spend much redoing the exhaust right now, so there we have our answer.

Even with the rebuild, I still think it is possible to keep a decent vehicle for about $150/mo, purchase price included (with a residual value equal to or greater than the original purchase price).  For about 15,000 mi/yr, I think the cost (tires, parts, repairs) is about $60/mo (about $0.05/mile) if you have the tools and space to do basic car maintenance. The year 10 cost of operating a Prius is around $0.11/ mile (https://www.utilimarc.com/blog/fleet-benchmarking-report-toyota-prius/). This factors in someone else turning the wrenches. The average number of days between an unscheduled/demand repair for a fleet car was around 150. Doing twice annual heavy maintenance has me below that.

I'm thinking the lesson here is

1) document repairs and keep records/receipts

2) Get OEM (or better) parts from Rockauto (I paid $17 for a knock sensor from Rockauto, not knowing I needed two for this vehicle. To buy the second, Autozone wanted $65. The dealer price was $112). I use the savings from ordering online to upgrade to a higher quality part. I learned my lesson the hard way. Don't use autostore name brand parts unless you are really in a bind. Especially for anything electronic.

3) Do as much basic and preventative maintenance as possible with you turning the wrenches. Plan out preventative maintenance in advance and always research what little extra you should do while you have a given component removed or accessible.

4) Use youtube for instructional videos

5) When your vehicle throws a code, go to the generic retail auto parts store closest to you and have them use their scan tool to give you a print out of what is wrong. Go home and google the vehicle description and code. Price parts. Then evaluate your options.

As an option, buy a Harbor Freight 6" dual action polisher. Watch a few videos on detailing cars. At least learn to do a basic polish. I use Collinite 845. Polishing oxidation off plastic lenses isn't difficult in the least.

Edited August 12, 2020 by Randolph Duke

[Randolph Duke 4034]

4 hours ago, MagicSoccerSpray said:

 

 

Heads up, the LS' are known for the oil pickup tube o-ring to harden so that it loses pressure at idle. A cheap and easy fix only needing to drop the pan to get to it. YMMV of course.

As to OP, I would drive it in the ground including rebuilding the trans as long as you plan on keeping it for a while. If the engine eats a cam, a bearing, or the rings give out, I would probably lean towards a rebuild from a reputable shop that warranties their work and would upgrade the cam and valve springs including a re-flash to get around 325 hp. The cam and springs are the bottle neck as the stock Vortec heads are pretty good.

2000 Silverado Z-71 with 235k on the original engine and trans here. Just rebuilt the original alternator. They don't make them like that any more.

What did you do to rebuild the alternator?

I'm about 30k miles ahead of you. I think an engine bearing is going on mine. I replaced the intake manifold gaskets when I redid the knock sensor(s) and also cleaned out the intake manifold. Just cleaned out the crap (I should have just replaced it). That alone picked up about 1.5 mpg. Almost 50 extra miles on a tank of gas was a nice surprise. That is what is leading me to believe if I just improve the flow by doing some simple porting, I will be happy with the end result. Anything else I do will be lost with a factory exhaust manifold and not a true dual-exhaust set-up. I'm fairly convinced to tweak an engine property you need to start at the tip of the exhaust pile and work backwards to the cam, not just drop in a new cam and then chase issues.

Send an oil sample out to Blackstone for an analysis. It will give you peace of mind when you get your next odd sound from under the hood. I'm convinced the biggest expenses with car ownership come in times of crisis when people misjudge their problem. Dealing with an unexpected breakdown really adds to operating costs. Not just the tow, but the mechanic on the other end who does a short-term fix that soon needs to be redone for which he charged $120/hr. Just not knowing what unexpected problem might be next has pushed many (and reasonably) to simply pay the 10% dealer mark-up and the 10% salesman commission and buy a new car.

My two favorite tweaks so far have been slotted and drilled rotors/ceramic pads for the front (about a $50 upgrade) and replacing the interior bulbs (not cluster) with LEDs ($10). I've chased an assortment of OBD emission codes through every component of the emissions system (not really that hard, just not intuitive to a novice). The corroded Bank 2 knock sensor was my only "wtf" moment I have had. Bad engineering on that one.

And because of the engineering, available work room under the hood, and incredible abundance of videos to rely on, the LM7 in a 2000 Silverado is a VERY easy engine to work on. On the cars, for instance, half of the LS engine is installed behind the windshield. The truck Vortecs don't have their space issue.

My suggestion to anyone having a 5.3 LM7 coming up on 250k would be to start stalking junk yards for LS6 heads. Between now and when I have to do my engine work, if I find some LS6 heads, I will use those, matched with a stock LS6 cam. The LS6 heads will increase the compression ratio, which may mean a switch to premium fuel. The LS6 mods using OEM parts would deliver an easy 40 hp. Without upgrading the exhaust manifold/ entire exhaust setup, I'm not sure anything else makes any sense.

Either stock or a simple LS6 upgrade seems to be the most reasonable.

 

Edited August 12, 2020 by Randolph Duke

[TwiceHorn 31536]

WIthout specific knowledge of the LM7, exhaust mods (headers, duals, no catalytics) are probably your biggest bang for buck.  Then start working on the intake side with FI adjustments, then intake manifold, cam, then porting heads.

[Randolph Duke 4034]

8 minutes ago, TwiceHorn said:

WIthout specific knowledge of the LM7, exhaust mods (headers, duals, no catalytics) are probably your biggest bang for buck.  Then start working on the intake side with FI adjustments, then intake manifold, cam, then porting heads.

Yep. Start with the exhaust. Then the stock LS6 heads/cam. Stay with factory parts. On the rebuild, the machine shop doing LM7 heads could do LS6 heads instead. Going with LS6 heads would entail using factory LS6 springs. Not a very aggressive upgrade. That would certainly be the way to go for what I am looking for (or so it seems at the moment).

[TwiceHorn 31536]

Well, I suppose I should say exhaust WAS biggest bang for buck.  It's lost most of its luster with the need to keep catalytics around (and buy a second for true duals) for inspection purposes.  You might could get away with empty shells, I'm not sure of the state of inspections on the engine computer end.

[Randolph Duke 4034]

44 minutes ago, TwiceHorn said:

Well, I suppose I should say exhaust WAS biggest bang for buck.  It's lost most of its luster with the need to keep catalytics around (and buy a second for true duals) for inspection purposes.  You might could get away with empty shells, I'm not sure of the state of inspections on the engine computer end.

At 25 years, I don't have emissions checks, just safety items. Waiting for that clock to finish ticking down.

[MagicSoccerSpray 1732]

2 hours ago, Randolph Duke said:

I found the flow data from the stock 5.3 head. If I apply the math, I don't see how I'm going to get ant more HP out of these heads. The engine components seem really well matched.

You should be able to easily get another 15-30 horsepower with a mix of cam/flash/exhaust on the stock heads. You may need to use higher octane, but I doubt it. If you're going to tear it down and don't mind changing to LS6 heads, I'm sure you can get more. I've heard good things about HP Tuners for engine management if you want to change and want more control. Porting the stock heads should do the trick as well.

 

2 hours ago, Randolph Duke said:

2) Get OEM (or better) parts from Rockauto (I paid $17 for a knock sensor from Rockauto, not knowing I needed two for this vehicle. To buy the second, Autozone wanted $65. The dealer price was $112). I use the savings from ordering online to upgrade to a higher quality part. I learned my lesson the hard way. Don't use autostore name brand parts unless you are really in a bind. Especially for anything electronic.

Don't use Dorman knock sensors (or anything) as they have a bad rep. The knock sensors have a rep for going out as they like to trap moisture in the recessed holes they screw into, I've already had mine done too.

 

2 hours ago, Randolph Duke said:

5) When your vehicle throws a code, go to the generic retail auto parts store closest to you and have them use their scan tool to give you a print out of what is wrong. Go home and google the vehicle description and code. Price parts. Then evaluate your options.

You can get a wireless Bluetooth or wifi OBS code reader dongle that will connect to your phone. If you use an android you can use Torque for free to read your codes and see engine parameters in real time. I got a generic OBD Bluetooth wireless dongle for $10-15 five years ago off ebay and it is the best money I've ever spent. Borescope cameras that connect to your phone are dirt cheap ($10-20) too.

 

2 hours ago, Randolph Duke said:

Polishing oxidation off plastic lenses isn't difficult in the least.

Sams will polish the lenses and put on a protective coating for $35 with a warranty last I checked. They are lazy and you'll need to make an appointment so YMMV. If your housings are too damaged you can buy new housings off Rockauto or Ebay cheap too.

 

2 hours ago, Randolph Duke said:

What did you do to rebuild the alternator?

Texas Alternator Starter Service in Austin rebuilt it. It cost just barely more than an autozone Gold rebuild and I wanted to keep the original part seeing as it lasted so long.

 

I pretty much agree with your research and don't disagree with anything. I've been meaning to get my oil analyzed and may go ahead and do it next time I get it changed. My biggest problem recently was a persistent cold start lifter knock but pandemic speeding and the higher highway rpms have really quieted it down (I think). I'm pretty sure when she dies it will be because of a collapsed lifter, a wiped cam lobe, or the rings. Still love this truck.

 

Edited August 12, 2020 by MagicSoccerSpray

[Randolph Duke 4034]

If it blows up tonight, I'm rebuilding stock with porting.

Over the long run (between now and when the emissions requirement expires for me in 2024), I will toy with the idea of turning this into an LS6 upgrade (using factory parts).

I think I've been too focused on playing with my options when the engine finally wore out. I think a better time will be when I can reconfigure the setup without the emissions.

A non-emissions LM7 with a LS6 upgrade would be all the truck I would want or need. This option would meet my desire to stick with stock parts (easier if repairs are needed) and still get performance upgrades.

[Randolph Duke 4034]

Update - If the thing blows up today, I'm still going to go with a stock $2,300 rebuild and some porting. But I'm still trying to put together an upgrade option.

The key to any LS6 upgrade option seems to be finding a corvette specialty shop where the mechanic knows the LS6 engine and is willing to help with the project. I found one and am waiting for the guy to get back with me on parts and price for what looks like a simple LS6 upgrade. The mechanic agree that at least in theory this can be done.

So far the major parts seem to be:

• New (flat headed) pistons (the pistons are already going to be replaced with the basic $2,300 rebuild, so switching from GM stock LM7 pistons to GM stock LS6 flat-headed pistons seems doable)
• LS6 heads (can be bought easily for less than $500. I am looking for a junkyard find to be redone by the shop or a cast-off from someone else's LS6 upgrade. Since cleaning up the heads was also part of the $2,300 rebuild, it shouldn't matter much what heads were being cleaned up. This looks like an opportunity to save a few dollars on the project)
• LS6 cam. (Again, the cam is already being replaced. The upgrade is about a $50 difference if I don't find a cast-off from a previous LS6 upgrade. Another $$ opportunity)
• New LS6 exhaust manifolds (LM7 and LS6 heads fit different manifolds. Cost of LS6 manifold is $300 max, assuming I can't find a junk yard or cast off. Again, $$)
• I'm going to add new fuel injectors, but those are cheap and would I am already budgeting to do those proactively
• A new tune on the control module

The end result is to keep the money to a minimum and use stock GM parts, preferably junk yard finds or another man's trash (from a corvette owner upgrading his stock LS6). The engine also has to work just fine on regular 87 octane gas. The mechanic is working out an issue with tying in the catalytic converter to the LS6 exhaust manifolds. Seeing how I have until 2024 until the emissions requirement goes away, emissions that will pass inspection seems prudent.

I'm thinking there has to be some major impediment to an LS6 upgrade, because this is seeming too simple not to have already been done a million times so far. Just adding a few junk yard parts to a stock GM rebuild and ending up with almost 400 hp in a truck seems like something some other yahoo would have done. Maybe the type of yahoos who would ever put 400 hp in a Chevy truck have already done it and removed themselves from the gene pool before their truck every got to 20 yrs old.

 

[TwiceHorn 31536]

7 minutes ago, Randolph Duke said:

Update - If the thing blows up today, I'm still going to go with a stock $2,300 rebuild and some porting. But I'm still trying to put together an upgrade option.

The key to any LS6 upgrade option seems to be finding a corvette specialty shop where the mechanic knows the LS6 engine and is willing to help with the project. I found one and am waiting for the guy to get back with me on parts and price for what looks like a simple LS6 upgrade. The mechanic agree that at least in theory this can be done.

So far the major parts seem to be:

• New (flat headed) pistons (the pistons are already going to be replaced with the basic $2,300 rebuild, so switching from GM stock LM7 pistons to GM stock LS6 flat-headed pistons seems doable)
• LS6 heads (can be bought easily for less than $500. I am looking for a junkyard find to be redone by the shop or a cast-off from someone else's LS6 upgrade. Since cleaning up the heads was also part of the $2,300 rebuild, it shouldn't matter much what heads were being cleaned up. This looks like an opportunity to save a few dollars on the project)
• LS6 cam. (Again, the cam is already being replaced. The upgrade is about a $50 difference if I don't find a cast-off from a previous LS6 upgrade. Another $$ opportunity)
• New LS6 exhaust manifolds (LM7 and LS6 heads fit different manifolds. Cost of LS6 manifold is $300 max, assuming I can't find a junk yard or cast off. Again, $$)
• I'm going to add new fuel injectors, but those are cheap and would I am already budgeting to do those proactively
• A new tune on the control module

The end result is to keep the money to a minimum and use stock GM parts, preferably junk yard finds or another man's trash (from a corvette owner upgrading his stock LS6). The engine also has to work just fine on regular 87 octane gas. The mechanic is working out an issue with tying in the catalytic converter to the LS6 exhaust manifolds. Seeing how I have until 2024 until the emissions requirement goes away, emissions that will pass inspection seems prudent.

I'm thinking there has to be some major impediment to an LS6 upgrade, because this is seeming too simple not to have already been done a million times so far. Just adding a few junk yard parts to a stock GM rebuild and ending up with almost 400 hp in a truck seems like something some other yahoo would have done. Maybe the type of yahoos who would ever put 400 hp in a Chevy truck have already done it and removed themselves from the gene pool before their truck every got to 20 yrs old.

 

A well-tuned engine that isn't too rich should pass emissions without a catalytic.

The issue may be that Texas law requires catalytic converters even on 24 year old vehicles.  The issue then becomes whether/how the deletion of the catalytic converter would be detected.

[MagicSoccerSpray 1732]

On 8/12/2020 at 9:44 AM, Randolph Duke said:

I found the flow data from the stock 5.3 head. If I apply the math, I don't see how I'm going to get ant more HP out of these heads. The engine components seem really well matched.

https://www.hotrod.com/articles/chevy-706-ls-heads/

Found this. I'm sure LS6 heads are better, but the stock heads are not bad.

[Randolph Duke 4034]

4 hours ago, MagicSoccerSpray said:

https://www.hotrod.com/articles/chevy-706-ls-heads/

Found this. I'm sure LS6 heads are better, but the stock heads are not bad.

I'm not a gearhead by any stretch of the imagination. More of a weekend tinkerer on my own cars to know the work is done correctly, but I'm really impressed with the engineering of the Chevy LS series of engines. I could add a blower and get a shit ton of additional horsepower out of the current engine, but I want to keep the entire rebuild stock GM parts, just to keep the "how long can you keep a daily driver in good shape" project going.

I put a call into the chief mechanic at the National Corvette Museum in Bowling Green to see if the swap of off-the-shelf GM parts will work. I will see if I can actually get him on the phone to walk me through what I am thinking. I am skeptical it is possible to have a highly dependable 350+ hp 4wd pick-up built with replacement parts that can be easily sourced, all for under $100/month. And sell it years later for the original purchase price.

My interesting find of the week was that GM is coming out with a new Hummer this fall. Lebron James is slated to be the face of the brand this time. 1000hp. 0-60 in 3 secs. All electric. No internal combustion engine.

[TwiceHorn 31536]

The reality these days and for the last decade or so is that most of the normally aspirated engines, particularly V8s, are optimized about as far as you can go from the factory.  It's really hard to get a significant bump in hp/tq without spending a fortune or going to forced induction.

Forced induction engines offer some more opportunities for low-cost "tuning," because of the various parameters that _____charging introduces.  Even so, I remain skeptical of a lot of the "electronic tunes."  Not that they don't do what's advertised, but at what cost to engine parts and transmissions and other driveline components.

Edited August 16, 2020 by TwiceHorn

[ROFL BOX 6649]

1 hour ago, Randolph Duke said:

I'm not a gearhead by any stretch of the imagination. More of a weekend tinkerer on my own cars to know the work is done correctly, but I'm really impressed with the engineering of the Chevy LS series of engines. I could add a blower and get a shit ton of additional horsepower out of the current engine, but I want to keep the entire rebuild stock GM parts, just to keep the "how long can you keep a daily driver in good shape" project going.

I put a call into the chief mechanic at the National Corvette Museum in Bowling Green to see if the swap of off-the-shelf GM parts will work. I will see if I can actually get him on the phone to walk me through what I am thinking. I am skeptical it is possible to have a highly dependable 350+ hp 4wd pick-up built with replacement parts that can be easily sourced, all for under $100/month. And sell it years later for the original purchase price.

My interesting find of the week was that GM is coming out with a new Hummer this fall. Lebron James is slated to be the face of the brand this time. 1000hp. 0-60 in 3 secs. All electric. No internal combustion engine.

You're an engineer, right?

[Jkwellborn 6741]

Pretty sure you can get a factory turbo for that thing.

[MagicSoccerSpray 1732]

 

[MagicSoccerSpray 1732]

 

347 hp 355 tq on a stock LM7 with a cam upgrade, headers, and a carb. I would assume sticking with the stock FI and a tune would produce more.

Edited August 20, 2020 by MagicSoccerSpray

[Randolph Duke 4034]

I finally found the answer I was looking for. Someone not only did what I have been asking about, they wrote a book on it. The short answer to my question is "just swap out the LM7 cam with a stock LS6 cam and voila!"

The money quote is:

"The 5.3-liter Gen III Vortec V-8 is probably the most common Gen III engine sold by GM (having been built in a 2:1 ratio to any other Gen III V-8), we have provided a full host of dyno tests adding various components to the base engine. You’ll probably notice there is not a dyno test with LS6 heads bolted to the base 5.3-liter engine. Well, this test was run, but since the engine lost power, it wasn’t included in the rundown.

The reason the engine lost power can probably be traced to the change in compression ratio, as the 5.3-liter heads have 61.1-cc combustion chambers and the LS6 heads have 64-cc chambers. While this might not seem like a lot, it’s enough to eliminate the potential power increase from the larger ports and improved flow of the LS6 heads. Milling the deck surface on the heads, or using the milled GMPP CNC-ported LS6 heads, would probably show a gain, but due to time constraints, that test was not run.

Just looking at how well the LS6 cam did in the 5.3- and 6.0-liter should be enough for most enthusiasts. On both engines, while peak power was slightly raised in the powerband, each engine made about 40 more horsepower just by swapping in the Z06 cam! Add in a few aftermarket components if you wish and the power can be raised another 10 to 20 hp. Not bad for a day’s work."

The web page they wrote about using the LS6 components in a LM7 5.3 can be found here:

https://www.lsenginediy.com/gen-iii-3-ls-vortec-truck-engine-buildup-guide/

I'm going to stick with the 4L60 trans (upgrades to a 6-speed are doable, but not worth it to me). Next time I get ready to do some maintenance on the truck, I will splurge for a set of 1.75" shorty headers. When I rebuild the LM7 engine, I will just swap out the cam and be done with it. Cheap and easy HP with a stock GM part that I will probably find as a leftover from someone who upgraded their LS6. Once the emissions requirement goes away in a couple of years, I will clean up the exhaust downstream from the headers.

Edited September 23, 2020 by Randolph Duke

[TwiceHorn 31536]

That seems entirely reasonable.  What intake and exhaust mods are they mentioning?

 

[Randolph Duke 4034]

27 minutes ago, TwiceHorn said:

That seems entirely reasonable.  What intake and exhaust mods are they mentioning?

 

Headers on the exhaust and a cold air intake.

[Randolph Duke 4034]

The project is progressing. I'm wondering about how tuning might factor into the project. For some time, I have been wondering why our phones and computers need software updates, but not our car ECMs. Well, I found the following that helps any GM car owner check software upgrades that are needed but may not have been applied to your vehicle:

Quote

For GM cars or trucks made in 1996 or later, you can easily check to see if there are available updates for your vehicle’s PCM at https://tis2web.service.gm.com/tis2web/. Checking is absolutely free; all you need is your VIN.

How to use the website:

Enter your VIN and click the “Get CAL ID” button.

From the next screen select “PCM/VCM Powertrain/Vehicle Control Module”, then click the Next button at the bottom right.

You will see any available updates for your GM vehicle. Each choice next to “Module:” is clickable. You only have to click once on each section to see what updates are there.

If you like, you can print out the pages, bring it to the dealership and have the updates applied. Cost varies greatly depending on what needs to be updated.

https://www.techjunkie.com/is-there-a-software-upgrade-for-your-gm-car-or-truck/

Most of the progress I have made on the project has involved defining my wants, needs and expectations for the output of the engine. First, drove to a "proper place" (for me, a feeder street) and from a dead stop, dropped it down into 1st, and romped on it, when I hit what I thought was an aggressive push of the engine, I shifted into 2nd and noted the RPMs. Same for 2nd to 3rd. Winding it out in 3rd had me flying on the freeway, so the 3/4 shift point can be thought out later.

With the RPM info, I googled the dyno chart on the engine and found out how many HP I was drawing from the engine at what I thought was the aggressive end of my driving style. Well, it turns out that number ain't that high. I was flying around at about 3k rpm which is about 200 HP. About as much as a Miata puts out.

So, if the engine is capable of 285HP stock, I need to some more research to learn how tuning might affect the rebuild decisions. Clearly I want power in the lower end of the power band, and I'm willing to give up top end (the engine has never been over 4k in its life). I also want gas mileage for between 2k and 2.5k in 4th gear (70-90 mph with no load).

Upgraded the transmission cooler core to 20,000 (from stock), planning the transmission rebuild to a 4L65E.

On to the tune. Any thoughts/ comments/ suggestions would be appreciated.

[TwiceHorn 31536]

22 minutes ago, Randolph Duke said:

The project is progressing. I'm wondering about how tuning might factor into the project. For some time, I have been wondering why our phones and computers need software updates, but not our car ECMs. Well, I found the following that helps any GM car owner check software upgrades that are needed but may not have been applied to your vehicle:

Most of the progress I have made on the project has involved defining my wants, needs and expectations for the output of the engine. First, drove to a "proper place" (for me, a feeder street) and from a dead stop, dropped it down into 1st, and romped on it, when I hit what I thought was an aggressive push of the engine, I shifted into 2nd and noted the RPMs. Same for 2nd to 3rd. Winding it out in 3rd had me flying on the freeway, so the 3/4 shift point can be thought out later.

With the RPM info, I googled the dyno chart on the engine and found out how many HP I was drawing from the engine at what I thought was the aggressive end of my driving style. Well, it turns out that number ain't that high. I was flying around at about 3k rpm which is about 200 HP. About as much as a Miata puts out.

So, if the engine is capable of 285HP stock, I need to some more research to learn how tuning might affect the rebuild decisions. Clearly I want power in the lower end of the power band, and I'm willing to give up top end (the engine has never been over 4k in its life). I also want gas mileage for between 2k and 2.5k in 4th gear (70-90 mph with no load).

Upgraded the transmission cooler core to 20,000 (from stock), planning the transmission rebuild to a 4L65E.

On to the tune. Any thoughts/ comments/ suggestions would be appreciated.

When you are accelerating, torque is a more important number, as a general proposition.  Horsepower is a top-speed, high-end thing.

"Americans buy horsepower, but drive torque."  -- Bob Lutz

Most consumer engines are designed to shift the torque curve down in rpms to the extent possible without sacrificing other things. Torque occurs because you are getting high airflow through the engine at low rpm.  It becomes difficult to sustain that high airflow at high rpm (lack of scavenging pressure, valve float, etc.) because the intake to exhaust path is too wide open.  That's when headers and critical intake design and variable valve timing come in.

Very broadly speaking, torque and horsepower "go together," meaning you can't have high torque without high horsepower.  At least on the Otto cycle, which corresponds to most gasoline powered engines.  Different story with the Diesel cycle.

What you are probably looking for is a "design" that moves the torque peak lower in rpm or has a pretty flat torque curve starting at low rpm.

Edited October 12, 2020 by TwiceHorn

[Parliament 14296]

On 9/23/2020 at 3:01 PM, Randolph Duke said:

I finally found the answer I was looking for. Someone not only did what I have been asking about, they wrote a book on it. The short answer to my question is "just swap out the LM7 cam with a stock LS6 cam and voila!"

The SBC just never fails to amaze me.

On 9/23/2020 at 3:46 PM, Randolph Duke said:

Headers on the exhaust and a cold air intake.

Check out your intake manifold options.  Gen 3/4 intakes are true bolt ons, and you can get a cheap bump in HP just from that.  

If it doesn't have factory dual exhaust (probably doesn't) you should consider it.  Many 3/4 tons of that era did, and it's all stainless I think.  Might be as easy as cutting it out of a junkyard truck.

 

[Jkwellborn 6741]

Change your shift points. Email Black Bear Tune. I guess they’re still in business.

[Randolph Duke 4034]

4 hours ago, TwiceHorn said:

When you are accelerating, torque is a more important number, as a general proposition.  Horsepower is a top-speed, high-end thing.

"Americans buy horsepower, but drive torque."  -- Bob Lutz

Most consumer engines are designed to shift the torque curve down in rpms to the extent possible without sacrificing other things. Torque occurs because you are getting high airflow through the engine at low rpm.  It becomes difficult to sustain that high airflow at high rpm (lack of scavenging pressure, valve float, etc.) because the intake to exhaust path is too wide open.  That's when headers and critical intake design and variable valve timing come in.

Very broadly speaking, torque and horsepower "go together," meaning you can't have high torque without high horsepower.  At least on the Otto cycle, which corresponds to most gasoline powered engines.  Different story with the Diesel cycle.

What you are probably looking for is a "design" that moves the torque peak lower in rpm or has a pretty flat torque curve starting at low rpm.

When I was zipping around, trying to put numbers to my driving habits, I wasn't pushing the engine over 3,000 rpm, which on the dyno chart I was looking at, about 180hp. Obviously, I'm not pushing the engine to its limits as it is.

I want to comfortably drive around town as speeds up to 45, to have some extra kick when getting on the freeway, and better gas mileage at cruising speed. I don't really use it to tow anything, I have no real need to go over 100 mph. I just want to optimize the vehicle for my driving style and my occasional desire to be kicked back in my seat a little when jumping on the freeway. No high altitude, mostly flatland (Texas) driving.

I doubt the engine has ever been over 4,000rpm in its life, and I don't see it over 4k much ever in the future.

The wish list seems tame. I just want it looked at by someone who actually knows how to tune a GM 5.3 LM7 with a P01 ECM.

[Randolph Duke 4034]

3 hours ago, Jkwellborn said:

Change your shift points. Email Black Bear Tune. I guess they’re still in business.

I have to understand the transmission a bit better before I start changing anything. I have a two/haul switch, so I can set alternate shift points that are easy to turn on and off. First I need to get the engine settings tuned to where I want them.

[Randolph Duke 4034]

4 hours ago, Parliament said:

The SBC just never fails to amaze me.

Check out your intake manifold options.  Gen 3/4 intakes are true bolt ons, and you can get a cheap bump in HP just from that.  

If it doesn't have factory dual exhaust (probably doesn't) you should consider it.  Many 3/4 tons of that era did, and it's all stainless I think.  Might be as easy as cutting it out of a junkyard truck.

 

I'm going to stick with the stock intake manifold. From what I have gathered, the tall tubes on the stock truck intake help with low end torque. I don't know much, but I know low end torque is what I am not wanting to mess with.

The exhaust is about to get upgraded to a set of shorty headers, but nothing else until the emissions requirements expire in about three years. I only want to modify the exhaust one time if I can. That, and the idea behind this project is to have a really strong vehicle at a low cost per month. I'm going to do the engine and trans, so waiting on the exhaust until the cats can be taken off makes sense for me.

I've had the original window sticker since I bough the truck a few years ago, but I finally managed to obtain all the service records from mile 1. Full documentation of all work done. I also confirmed with the dealer that there are no outstanding recalls, or PCM/BCM software updates.

Edited October 12, 2020 by Randolph Duke

[TwiceHorn 31536]

49 minutes ago, Randolph Duke said:

I'm going to stick with the stock intake manifold. From what I have gathered, the tall tubes on the stock truck intake help with low end torque. I don't know much, but I know low end torque is what I am not wanting to mess with.

The exhaust is about to get upgraded to a set of shorty headers, but nothing else until the emissions requirements expire in about three years. I only want to modify the exhaust one time if I can. That, and the idea behind this project is to have a really strong vehicle at a low cost per month. I'm going to do the engine and trans, so waiting on the exhaust until the cats can be taken off makes sense for me.

I've had the original window sticker since I bough the truck a few years ago, but I finally managed to obtain all the service records from mile 1. Full documentation of all work done. I also confirmed with the dealer that there are no outstanding recalls, or PCM/BCM software updates.

Unless you run high speeds, low end torque is exactly what you want.  It's what produces "pick up" or "get up and go."  It is also useful for towing for the same reason:  it changes the velocity of your vehicle mas rapidamente.  Horsepower is more about maintaining high rpm and speed once you achieve it.

It sounds like your driving habits are mostly like everyone elses, and all you want is some grunt to get you to highway speed plus in a bit of a hurry and you have no desire to exceed say 90 or 100 mph.

That is a recipe that calls for low end torque, meaning a torque curve where a lot of your peak torque is available at something under 3000 or 2500 rpm.

Diesels have a lot of low end torque by the nature of their "air cycle," but they tend not to have much horsepower by comparison to a similarly "torqued" gasoline engine.  But that is the nature of the diesel and this is probably what you're thinking of:  tremendous grunt at very low rpm that falls off rapidly as gears and rpm climb up to street/highway speeds.  A diesel may produce half the peak horsepower (in SAE HP) compared to torque (in ft-lbs).  The lack of hp is what makes a diesel feel like it's "falling off" after that initial immense pull.

A gas engine that isn't tuned strangely is probably going to have peak HP and Torque within 10-20% of each other and the horsepower peak is going to be near the redline. The question is, where does the torque "come on."  A (non-drag) racing engine will be tuned to have HP highest at redline, and the torque curve is going to follow behind it, so probably not a lot of low-end torque.  A street oriented engine is going to want to bring the torque down to be accessible at lower rpm.  Horsepower may be diminished or occur at less than redline, but that's no big deal for you or most drivers.

Edited October 12, 2020 by TwiceHorn

[TwiceHorn 31536]

Also, headers with a stock exhaust from the headers back is often a fool's errand.  YMMV depending on the particular engine and stock exhaust, but as a general proposition, headers that feed into a single exhaust with a single muffler and cat are going to be semi-futile.

[Randolph Duke 4034]

8 minutes ago, TwiceHorn said:

Also, headers with a stock exhaust from the headers back is often a fool's errand.  YMMV depending on the particular engine and stock exhaust, but as a general proposition, headers that feed into a single exhaust with a single muffler and cat are going to be semi-futile.

Your help has been awesome. Thanks. 

Im thinking of doing the headers because they are cheap and eventually I will redo the full exhaust, so why not go ahead and do them with the idea of finishing the exhaust once the emissions requirements expire. If the muffler dies earlier l’m thinking upgrade to a 3” cat-back, nothing bigger. If I learn that money would be wasted, I’m ok staying with stock. 

Slowly but surely I’m learning my way through this project. 

[TwiceHorn 31536]

10 minutes ago, Randolph Duke said:

Your help has been awesome. Thanks. 

Im thinking of doing the headers because they are cheap and eventually I will redo the full exhaust, so why not go ahead and do them with the idea of finishing the exhaust once the emissions requirements expire. If the muffler dies earlier l’m thinking upgrade to a 3” cat-back, nothing bigger. If I learn that money would be wasted, I’m ok staying with stock. 

Slowly but surely I’m learning my way through this project. 

Fair enough. 

Back in high school, the vehicle du jour was a GM half-ton pickup with a 350 or occasionally a 400 or 454.  The "grail" was to level it and outfit said truck with headers and dual exhausts with "megaphones," the large-diameter exhaust ends that came out before the rear wheels.

Although I went to a wealthy high school, it was still common for most kids to "save up" for vehicle mods, so they did things in stages.  Sometimes headers followed by duals with the megaphones, glasspacks etc.  Those that didn't finish the exhaust found that headers didn't do much.  Some went for the duals and megaphones before headers and found that that did 80-90% of the job and came to regret the expenditure on headers.

We also collectively learned that carburetors tended to need re-jetting to a higher flow rate to maximize the advantage of headers.  You tend to kind of need to balance the intake and the exhaust.

These days, though, stock exhausts are much more optimized than they used to be, even if they still aren't straight duals.  And a lot of intake type things can be accomplished via tune without any hardware.

Just a bunch of shit knowledge i have accumulated over the years.  I love geeking out on this shit.

[TwiceHorn 31536]

An addendum on the low-end torque thing.  I have driven mostly V8s (two pushrod, one DOHC), an NA four banger, a V8 like modern DI V6, and most recently a 2.0 turbo four.

The turbo has a peak torque 10 percent higher than peak hp and it comes up 90% at 2000 rpm and peak at 3000.  Because it has decent horsepower, it keeps pulling up to 100 plus, but you can feel it running out of breath compared to the 30% higher hp (and lower torque) V6. But the V6 had a high torque peak. 

For around-town enthusiastic driving that doesn't involve high speeds (over 90-100), just some fun acceleration, it may be the most fun engine I have ever driven.  That type of torque/hp and low-end availability is a characteristic of turbocharged engines, which I had avoided out of reliability fear (justified 20 years ago, not so much today).

But the hype is real.  Really real.  Low end torque is where it's at for most people, when it's combined with decent horsepower and rpm (the things a lot of diesels lack).

Edited October 12, 2020 by TwiceHorn

[MagicSoccerSpray 1732]

7 hours ago, Randolph Duke said:

The project is progressing. I'm wondering about how tuning might factor into the project. For some time, I have been wondering why our phones and computers need software updates, but not our car ECMs. Well, I found the following that helps any GM car owner check software upgrades that are needed but may not have been applied to your vehicle:

Most of the progress I have made on the project has involved defining my wants, needs and expectations for the output of the engine. First, drove to a "proper place" (for me, a feeder street) and from a dead stop, dropped it down into 1st, and romped on it, when I hit what I thought was an aggressive push of the engine, I shifted into 2nd and noted the RPMs. Same for 2nd to 3rd. Winding it out in 3rd had me flying on the freeway, so the 3/4 shift point can be thought out later.

With the RPM info, I googled the dyno chart on the engine and found out how many HP I was drawing from the engine at what I thought was the aggressive end of my driving style. Well, it turns out that number ain't that high. I was flying around at about 3k rpm which is about 200 HP. About as much as a Miata puts out.

So, if the engine is capable of 285HP stock, I need to some more research to learn how tuning might affect the rebuild decisions. Clearly I want power in the lower end of the power band, and I'm willing to give up top end (the engine has never been over 4k in its life). I also want gas mileage for between 2k and 2.5k in 4th gear (70-90 mph with no load).

Upgraded the transmission cooler core to 20,000 (from stock), planning the transmission rebuild to a 4L65E.

On to the tune. Any thoughts/ comments/ suggestions would be appreciated.

 

Good to see you're finding out the LS is already set up well for what you're asking of it, and should be able to deliver with just a "torker"/"RV" cam and tune. HP Tuners is the software most often used to adjust GM engine management, otherwise any good dyno shop should be able to adjust your PCM to suit. Please keep the thread informed, as I plan on a cam/exhaust/tune eventually too.

5 minutes ago, TwiceHorn said:

But the hype is real.  Really real.  Low end torque is where it's at for most people, when it's combined with decent horsepower and rpm (the things a lot of diesels lack).

 

True. Drive for show, putt for dough... Torque is where it's at.

[Jkwellborn 6741]

I have to understand the transmission a bit better before I start changing anything. I have a two/haul switch, so I can set alternate shift points that are easy to turn on and off. First I need to get the engine settings tuned to where I want them.

Black Bear used to send a data logger that would track how you drove. They would take some of the torque management out of the transmission to make it shift a little harder.

[TwiceHorn 31536]

4 hours ago, Randolph Duke said:

Your help has been awesome. Thanks. 

Im thinking of doing the headers because they are cheap and eventually I will redo the full exhaust, so why not go ahead and do them with the idea of finishing the exhaust once the emissions requirements expire. If the muffler dies earlier l’m thinking upgrade to a 3” cat-back, nothing bigger. If I learn that money would be wasted, I’m ok staying with stock. 

Slowly but surely I’m learning my way through this project. 

Also if you are doing an engine-out rebuild that makes installing headers pretty convenient.  Most, but not all, header installation is an engine up or out proposition.  Back in the day, the install was about as expensive as the headers themselves.  So might make sense to do it for "future reference" when you are emissions-inspection free.

[Randolph Duke 4034]

I'm very reluctantly realizing the first thing I need to do is go back to the basics and get the truck tuned properly, then build/ rebuild from there. As much as I hate to do it, I'm going to have to learn something about tuning software.

Tuning software and the associated sensor, etc looks to be about $600, +$100 per vehicle (after the first). Some functionality (clearing engine codes, capturing engine performance details) can be applied to all OBDII vehicles. For the sake of this project, I'm just going to count the $100 vehicle license fee to the overall cost of getting the truck into good repair.

This guy seems to be a good place to learn the basics of tuning a vehicle. (Yes, there are a number of adjustments the factory makes in the name of either safety or increased "user-friendliness" that can be dialed out that will increase both performance and fuel mileage.)