Need help with my 5.3
01-29-2015, 10:21 PM
#1
Teching In
Thread Starter
Need help with my 5.3 I just recently bought a 5.3 LS out of a 2000 Tahoe with 66k miles. I'm going to drop it in a 1981 Chevy Malibu. I'm wanting to add some bolt on parts that'll help with HP and performance. I'm trying to go the economic route for now. I'll be rebuilding and getting high performance parts in about 2-3 years. Any ideas, thoughts or opinions are greatly appreciated. 
01-30-2015, 03:23 PM
#2
Camshaft. The biggest bang-for-buck upgrade, by far. Get yourself an LS6 camshaft with springs to match. You can leave everything else stock and pick up quite a bit of power across the board, while retaining OEM-grade reliability.
01-31-2015, 07:20 PM
#5
Cam is a good idea. You've got a truck motor with a truck cam. LS1 cam is a good budget route. I've got one too if needed. 
See this article for stock GM cams in 5.3. I feel like I've posted it ten times but it's good info. The numbers are at the crank and not wheels and with long tube headers and a tune(well aftermarket EFI really but you could get same results with a tune).
http://www.hotrod.com/how-to/engine/...st-comparison/
The pre-2005-ish truck intakes aren't terrible but leave a lot to be desired above 5K RPM. It's fairly cheap to upgrade to a later-model factory truck intake and gain across the the entire RPM range. That is of you have the hood clearance for the truck intake. Have you determined that?
LS1 heads will have a bigger intake valve than the early LM7 heads but also larger combustion chamber hurting compression. So that's a cheap swap if you mill the heads to gain compression back. Or you can get some cheap used LS1 valves and pay a machine shop to open up the seat on yours to handle the 2" valve and mill your heads and get to ~10:1 with a 2" intake valve and you're doing pretty well for minimal cash. Do you have 862s or what?
See this article for stock GM cams in 5.3. I feel like I've posted it ten times but it's good info. The numbers are at the crank and not wheels and with long tube headers and a tune(well aftermarket EFI really but you could get same results with a tune).
http://www.hotrod.com/how-to/engine/...st-comparison/
The pre-2005-ish truck intakes aren't terrible but leave a lot to be desired above 5K RPM. It's fairly cheap to upgrade to a later-model factory truck intake and gain across the the entire RPM range. That is of you have the hood clearance for the truck intake. Have you determined that?
LS1 heads will have a bigger intake valve than the early LM7 heads but also larger combustion chamber hurting compression. So that's a cheap swap if you mill the heads to gain compression back. Or you can get some cheap used LS1 valves and pay a machine shop to open up the seat on yours to handle the 2" valve and mill your heads and get to ~10:1 with a 2" intake valve and you're doing pretty well for minimal cash. Do you have 862s or what?
02-01-2015, 02:53 PM
#6
Teching In
Thread Starter
Yeah I have stock 862s but I'm wanting to upgrade to 243s but I was told the mounting holes are different since they're car heads. Does anyone know if this is true or not? 
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02-02-2015, 09:14 AM
#8
Right. 243s bolt right up. Your LM7 has dished pistons and need a small combustion chamber though so you would likely want to mill the 243s a little. They have a small chamber already bit not quite as small as the 862.
See here for some good head info:
https://ls1tech.com/forums/new-ls1-o...casting-s.html
Keep in mind the original 243s came on C5 Corvette ZO6 models and had hollow intake valves and sodium-filled exhaust valves(lighter valvetrain) Outside of those, 243s are all the same with standard factory valves.
Your 862s share the same dimensions as the 706. IIRC different casting process/supplier. Some 706s had cracking issues so feel good about getting the 862s. With the small chamber and same basic port as LS1 heads, these are the heads that were referred to as "5.3" heads in some worked versions like the seemingly famous PRC 2.5 5.3 heads.
See here for some good head info:
https://ls1tech.com/forums/new-ls1-o...casting-s.html
Keep in mind the original 243s came on C5 Corvette ZO6 models and had hollow intake valves and sodium-filled exhaust valves(lighter valvetrain) Outside of those, 243s are all the same with standard factory valves.
Your 862s share the same dimensions as the 706. IIRC different casting process/supplier. Some 706s had cracking issues so feel good about getting the 862s. With the small chamber and same basic port as LS1 heads, these are the heads that were referred to as "5.3" heads in some worked versions like the seemingly famous PRC 2.5 5.3 heads.
02-04-2015, 07:20 AM
#9
Teching In
Thread Starter
Ok thanks guys. I'll probably get 243s and have them milled. And will me going with a LS6 cam and springs be a better route to go instead of the LS1 combo? I have a car and truck intake that came with the motor.which one of those should I use? Sorry for all the questions, I'm new to the LS world.
02-04-2015, 08:34 PM
#10
Occurs to me the LS1 cam would be a better match for the stock heads and LS6 better with 243s and stall and gears and turn higher RPMs. LS1 would be more forgiving and make more power right off idle IMO.
Which car and which truck intake? Do you have the hood clearance for a truck intake? If yes, then the late truck intake is great and cheap. If not, the LS6 intake flows significantly better than the LS1 intake and will run you about $350 used. The late truck intake I found brand new on Amazon for a hundred bucks. The later intakes do need a 4-bolt throttle body or adapter($50).
Which car and which truck intake? Do you have the hood clearance for a truck intake? If yes, then the late truck intake is great and cheap. If not, the LS6 intake flows significantly better than the LS1 intake and will run you about $350 used. The late truck intake I found brand new on Amazon for a hundred bucks. The later intakes do need a 4-bolt throttle body or adapter($50).
Last edited by Mercier; 02-04-2015 at 08:39 PM.
02-07-2015, 04:49 PM
#15
I can't quite tell from that pic on my phone but check this link and you can likely tell:
http://www.thedetailzone.com/LS6%20Intake.htm
LS6 definitely worth running. LS1 or that truck intake will run OK but you'd be leaving 10-15HP on the table at higher RPMs I think.
http://www.thedetailzone.com/LS6%20Intake.htm
LS6 definitely worth running. LS1 or that truck intake will run OK but you'd be leaving 10-15HP on the table at higher RPMs I think.
02-09-2015, 07:08 AM
#16
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Thread Starter
I got a chance to look at the intake and it seems I got lucky and have an LS6 intake. Just need to clean it up. Thanks for all your imput guys it is very helpful. Anyone happen to have a wire harness, Ecu and computer for sale? Or know someone that does for my year and model of my engine? I'm going with the 4L60 by the way.
02-09-2015, 07:36 AM
#17
What is your cam choice OP. If you were getting an LS1 cam for like $50 that would be a no brainer. However the LS6 cams still command $150 and at that point, I would not be opposed to buying a used aftermarket cam with much better features. On the flip side, if you have no intention of running a stall in your 4l60e then the LS6 is still viable.
02-12-2015, 06:30 PM
#19
LS6 valve springs are $60 new all day long. That puts the cam at $240. Not a terrible deal but at that price it's worth spending a little more and getting the "right" cam. Custom cam is ~$400 but you could also find a used LS6 for less if you are patient. I've got 2000 LS1 cam, valve springs, retainers, pushrods(all from 40K mile Corvette) you can have for $75+shipping if you wanna do it cheap now. Then you can buy a custom cam later. I've also got a set of new LS6/LS2(same part# now at GM) valve springs. $100 + shipping if you want the LS1 cam and the LS6 valve springs. $115 + shipping and you can have it all.
Stall is not my territory so hopefully the others can help. I like clutches.
Stall is not my territory so hopefully the others can help. I like clutches.
02-12-2015, 10:15 PM
#20
Or I just ten minutes ago pulled the stock cam, oil pump, front cover, timing set off my 50K mile LS2..that's almost a LS6 cam. We could work a deal on that too. You would need a cheap extension harness and a front cam sensor.
No hard sell here; just parts sitting needing a good home.
No hard sell here; just parts sitting needing a good home.