5.3 LM7 - yay or nay?

[NC_John]

I'm checking out a 2001 5.3 LM7 tomorrow. 80K miles, still in truck, running.

I'm looking to build something (eventually up to) 400 or so HP. Maybe boost it later. Since I am swapping this into my '70, I'll have too much money in the swap right now to do much performance-wise immediately so a lot of the performance stuff will be added later.

I know the 2005 and later LS's have a few upgrades but if this one looks good, is complete and the price is right, is there any reason why I wouldn't want it?

I'm trying to research this as much as possible but its information overload and all the different LS configurations make it really confusing.

thanks

[tinydb84]

I have a 2003 LM7 that is in my 75. Not running yet. I am either going to boost it or port the heads and change out the pistons to give it a bit more power.

The newer engines have better rods and there are some other 5.3's with better heads but all and all I haven't heard of anyone being disappointed with their LM7's.

[NC_John]

Originally Posted by tinydb84

I have a 2003 LM7 that is in my 75. Not running yet. I am either going to boost it or port the heads and change out the pistons to give it a bit more power.

The newer engines have better rods and there are some other 5.3's with better heads but all and all I haven't heard of anyone being disappointed with their LM7's.

I knew about the rods, but those will end up getting changed eventually anyway, especially if I go stroker.

thanks for the input

[clinebarger]

5.3L's are great reliable engines. For a N/A performance build.....Go 6.0L, 4.00" bore engines are way easier to get 400hp out of compared to a 3.78" bore 5.3L/4.8L.

If you Boost it.....The bore size is not near as crippling, Just keep in mind that there is more too it than a cheap Turbo & some piping.....A good fuel system can easily run over a grand.

As for Later engines being better than Early ones......I had a stock bottom end '98 LS1 topped with a Magnacharger MP1900 in a '50 Studebaker Pick-up, I beat the snot out of the motor for years at 15 psi (Smaller Pulley) & could not break it!! The 2 most important things I did was the Fuel System (Aeromotive A1000 pump, 43# Injectors, #8 Lines) & a GOOD Tune!

[NC_John]

Originally Posted by clinebarger

5.3L's are great reliable engines. For a N/A performance build.....Go 6.0L, 4.00" bore engines are way easier to get 400hp out of compared to a 3.78" bore 5.3L/4.8L.

If you Boost it.....The bore size is not near as crippling, Just keep in mind that there is more too it than a cheap Turbo & some piping.....A good fuel system can easily run over a grand.

As for Later engines being better than Early ones......I had a stock bottom end '98 LS1 topped with a Magnacharger MP1900 in a '50 Studebaker Pick-up, I beat the snot out of the motor for years at 15 psi (Smaller Pulley) & could not break it!! The 2 most important things I did was the Fuel System (Aeromotive A1000 pump, 43# Injectors, #8 Lines) & a GOOD Tune!

I've got to spend a LOT more money around here to get into a 6.0 that doesn't have 300K on the clock compared to a 5.3.

The one I looked at today was a bust. It was not the original engine in the truck, the seller said HE was told it was only 80K. It looked pretty greasy for only 80K. The truck originally had a 4.8 and the seller couldn't prove it was replaced with a 5.3 (4.8's are fine but worth a lot less). The final nail was I was told it was running. When I got there he told me that he sold the gas tank and I couldn't hear it run. I walked. Too many inconsistencies.

[Heavymetl]

Just went to the track on Thursday, my buddies tuned Lm7 swapped Chevelle ran 13.61@98mph, bone stock with headers.

Not bad for a full weight 1970 Chevelle with 3.90 gears on Drag Radials. A set of headers and a tune does wonders for those things. Not 400hp, but not a total slug either.

[Advanced Design]

I remember when that article came out ..... and the surprise ending was very interesting.

[mongocanfly]

Ive got a bone stock LQ9 6.0 with headers in mine..on the dyno it put out 346hp..they said they could turn it up more if I wanted but decided to just leave it there..they said a cam and head swap would take it over 400 easily.. I gave around 1600 3 years ago for the complete 6.0 engine but I know their higher now..but I can still buy complete 5.3s all day for around 800 locally

[NC_John]

Originally Posted by mongocanfly

Ive got a bone stock LQ9 6.0 with headers in mine..on the dyno it put out 346hp..they said they could turn it up more if I wanted but decided to just leave it there..they said a cam and head swap would take it over 400 easily.. I gave around 1600 3 years ago for the complete 6.0 engine but I know their higher now..but I can still buy complete 5.3s all day for around 800 locally

That sounds like a nice little power plant. 5.3's around here for that money have 200-400K miles.

[Zoomad75]

Worth it. I'm now into the tuning stages on my LM7 swap. Night and day difference to carb'd 350's. It starts with one twist of the key, runs right up to redline without hesitation and beginning to get decent fuel mileage for something shaped like a barn with 35" tires twisted by 4.10 gears. I'm up to 12.12 mpg right now and I haven't hooked up the wiriing for the TCC yet in the trans so it should go up a little more. Still, I'm wanting more mpg, but it's going to be tight to tune it in. Time will tell.

Is it worth it to do? I'd say yes. It's not a budget kind of project to tackle though. You can do it on the cheap, like buying a boneyard engine but you'll have to spend money where it counts. I know lots do the stock harness, but the best money spent on the swap is getting a GOOD stand alone harness to run with the stock ECM. Howell has some great stuff in this department and they don't break the bank. Mine is a Howell harness. Nothing will make you want to tear your hair out faster than the LS sitting in the engine bay and you can't make it crank because of some wire you forgot to clip or clipped the wrong one. The Howell guys can do the base tune and elminate garbage like the passlock security BS and torque management.

It's not a cheap replacment for a good running small block. But if you want to modernize your ride and get better driveability, it's one hell of a way to do it.

[LeesTruk]

I'm running a set-up similar to what Cline describes (5.3L w/Brian Tooley stg.1 cam and I6 Trail Blazer torque convertor(2200-2600 stall)) in my '80 C10. What a great combo. The truck will putt around town comfortably, fly when you get "stupid" with the gas pedal, and give 19mpg (hiway) @70-75mph. It's like having the best of all worlds in one package. Yes, it does come at a greater cost than the sbc swap, but there is no comparison on the final outcome. And yes, just as Cline says, it will put a smile on your face =>

[Heavymetl]

Originally Posted by Zoomad75

Worth it. I'm now into the tuning stages on my LM7 swap. Night and day difference to carb'd 350's. It starts with one twist of the key, runs right up to redline without hesitation and beginning to get decent fuel mileage for something shaped like a barn with 35" tires twisted by 4.10 gears. I'm up to 12.12 mpg right now and I haven't hooked up the wiriing for the TCC yet in the trans so it should go up a little more. Still, I'm wanting more mpg, but it's going to be tight to tune it in. Time will tell.

Is it worth it to do? I'd say yes. It's not a budget kind of project to tackle though. You can do it on the cheap, like buying a boneyard engine but you'll have to spend money where it counts. I know lots do the stock harness, but the best money spent on the swap is getting a GOOD stand alone harness to run with the stock ECM. Howell has some great stuff in this department and they don't break the bank. Mine is a Howell harness. Nothing will make you want to tear your hair out faster than the LS sitting in the engine bay and you can't make it crank because of some wire you forgot to clip or clipped the wrong one. The Howell guys can do the base tune and elminate garbage like the passlock security BS and torque management.

It's not a cheap replacment for a good running small block. But if you want to modernize your ride and get better driveability, it's one hell of a way to do it.

Most tuners set up the engine to run "closed loop", so it's using feedback from the O2 sensors to run at Lambda 1 (14.7 AFR gas) at cruise. Because of that, there's really not much to tune into an engine for better fuel mileage. That being said, it is possible to set one up "Open Loop" and dial in a lean cruise condition during low-load situations. But that's really splitting hairs for a vehicle that more for fun than squeaking out every bit of mileage daily driving a commute.

[NC_John]

I'm checking out another 5.3 this afternoon. Leaned towards a 6.0 for a bit (and would still like one) but the price is good on this one so if everything else looks good I'll pull the trigger.

There's actually no question as to whether or not I want to go LS. I've owned several LS's... They were just always in the original (late model) vehicle. In fact, there is a '15 5.3 under the hood of a Tahoe in the driveway but my wife won't let me have it. They are great engines.

The real question was go after a garden variety LM7 or try to hold out for something a little sexier? Just like the LWB vs SWB dilemma during the original purchase of the truck.....I guess I'll know what I want when I see it.

[Cjcolbyjack]

Look for a place like lonstaronlineauctions. That have auctions for your local impound. Public auction. I just picked up a 2000 escalade 6.0 awd for $700 total price. 170k. It was rolled. The guys that look at those auctions are looking for cars to fix. Not the ones completely trashed. I also just picked up a 05 awd Lincoln aviator with 100k for 1100. I'm gonna set my 54 right on top and be done.

[Cjcolbyjack]

This should answer all your questions
http://www.stevesnovasite.com/forums...d.php?t=115983

[NC_John]

Originally Posted by Cjcolbyjack

Look for a place like lonstaronlineauctions. That have auctions for your local impound. Public auction. I just picked up a 2000 escalade 6.0 awd for $700 total price. 170k. It was rolled. The guys that look at those auctions are looking for cars to fix. Not the ones completely trashed. I also just picked up a 05 awd Lincoln aviator with 100k for 1100. I'm gonna set my 54 right on top and be done.

I wasn't able to find anything like that over here in the tarheel. Everything ended up linking back to copart (who seems to have a monopoly on all the salvage stuff around here).

I found a bunch of viable engines just out of state on CL and am going back and forth getting pictures and info from the sellers.