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Where to start? 5.3 iron block build

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Old 11-22-2018, 06:07 PM
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Default Where to start? 5.3 iron block build

Toying with the idea of using the 2009 Iron 5.3 block that I purchased as a mockup block for my 96 impala and putting it in my 70 challenger. It's sacrilege, sure, but the procharged 340 setup I built has been nothing but trouble and I have been dying to try my hand at a big power turbo LS build.

As mentioned, I have the bare 5.3 iron block and a bare set of 862 heads and I have been doing a lot of research but I'm stuck on where to even begin. I would love to build something 800+ rwhp capable . The car mostly gets cruised lightly, will occasional track use. What I'm saying is, I don't want a TOTAL time bomb but since it's not like I'm out flogging it every weekend I'm willing to take some chances to keep budget friendly.

Been doing a lot of research and I'm just hung up on one thing. I'm wondering if it is even worth keeping this block/heads for a "budget build" since I don't have ANY of the internals. The block I have probably needs to be cleaned up a bit, at least a hone and maybe a slight overbore/deck milling for some surface rust. I mean I know I could build one hell of a motor if I went stock crank with Compstar rods and Weisco pistons, but adding the cost up of buying new everything else I'd need to assemble the motor and I'm into the price range of buying something like a TSP long block (which isn't what I want to do, nor is it the price range I want to be in).

Guess I'm just looking to see if any of you budget builder experts recommend keeping the bare block and heads or if I should just sell it all and find myself a complete motor to work with? I'm almost thinking for a budget build it's just not worth keeping it, but I'll let you guys tell me whether you think there can be some compromise between a tight budget and a stout motor when starting from scratch like this. Right now I'm just not seeing it.
Old 11-22-2018, 06:17 PM
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Originally Posted by kris396ss
Toying with the idea of using the 2009 Iron 5.3 block that I purchased as a mockup block for my 96 impala and putting it in my 70 challenger. It's sacrilege, sure, but the procharged 340 setup I built has been nothing but trouble and I have been dying to try my hand at a big power turbo LS build.

As mentioned, I have the bare 5.3 iron block and a bare set of 862 heads and I have been doing a lot of research but I'm stuck on where to even begin. I would love to build something 800+ rwhp capable . The car mostly gets cruised lightly, will occasional track use. What I'm saying is, I don't want a TOTAL time bomb but since it's not like I'm out flogging it every weekend I'm willing to take some chances to keep budget friendly.

Been doing a lot of research and I'm just hung up on one thing. I'm wondering if it is even worth keeping this block/heads for a "budget build" since I don't have ANY of the internals. The block I have probably needs to be cleaned up a bit, at least a hone and maybe a slight overbore/deck milling for some surface rust. I mean I know I could build one hell of a motor if I went stock crank with Compstar rods and Weisco pistons, but adding the cost up of buying new everything else I'd need to assemble the motor and I'm into the price range of buying something like a TSP long block (which isn't what I want to do, nor is it the price range I want to be in).

Guess I'm just looking to see if any of you budget builder experts recommend keeping the bare block and heads or if I should just sell it all and find myself a complete motor to work with? I'm almost thinking for a budget build it's just not worth keeping it, but I'll let you guys tell me whether you think there can be some compromise between a tight budget and a stout motor when starting from scratch like this. Right now I'm just not seeing it.
Yea depending on where you are, its definitely gonna be easier and more budget friendly to just pickup a motor from a junkyard. Around NY wreckers sell 5.3’s for anywhere from 500-1500 depending on mileage. I actually bought my Lm7 as a longblock off craigslist for 300 bucks, minus valve covers, sensors, and accessories, but with only 89k. So if you’re really trying to keep it budget friendly, I would look for a complete motor.
Old 11-22-2018, 06:31 PM
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Originally Posted by Mgg4591


Yea depending on where you are, its definitely gonna be easier and more budget friendly to just pickup a motor from a junkyard. Around NY wreckers sell 5.3’s for anywhere from 500-1500 depending on mileage. I actually bought my Lm7 as a longblock off craigslist for 300 bucks, minus valve covers, sensors, and accessories, but with only 89k. So if you’re really trying to keep it budget friendly, I would look for a complete motor.


Cool, thanks! Yea I paid about 300 for my block and heads and got kinda upset when I saw a few complete motors pop up locally for not a whole hell of a lot more. At the time though it was easier just to get a bare block and heads as that was all I needed for mockup.

It just seems like there are too many small parts that will nickel and dime me (valve covers, timing cover, rear cover, valves, sensors etc...). I estimated the cost of machine work, aftermarket rods/pistons, a stock crank, balancing, new oil pump and new timing chain ending up almost in the $3000 range. With the whole top end I'd probably be dumping upwards of 5K.

Meanwhile I see guys making 750+ WHP with like $1500 in studs, ls9 gaskets, Lil Jon or BTR cam/valvetrain and everything else stock. There doesn't seem to be an in between, once you start upgrading rods/pistons it gets costly and you'll want to spend more to protect your investment. If I'm using mostly stock parts it doesn't seem to make sense to start with a bare block.
Old 11-22-2018, 06:48 PM
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Originally Posted by kris396ss
Cool, thanks! Yea I paid about 300 for my block and heads and got kinda upset when I saw a few complete motors pop up locally for not a whole hell of a lot more. At the time though it was easier just to get a bare block and heads as that was all I needed for mockup.

It just seems like there are too many small parts that will nickel and dime me (valve covers, timing cover, rear cover, valves, sensors etc...). I estimated the cost of machine work, aftermarket rods/pistons, a stock crank, balancing, new oil pump and new timing chain ending up almost in the $3000 range. With the whole top end I'd probably be dumping upwards of 5K.

Meanwhile I see guys making 750+ WHP with like $1500 in studs, ls9 gaskets, Lil Jon or BTR cam/valvetrain and everything else stock. There doesn't seem to be an in between, once you start upgrading rods/pistons it gets costly and you'll want to spend more to protect your investment. If I'm using mostly stock parts it doesn't seem to make sense to start with a bare block.
Oh yea these junkyard 5.3’s are fine with boost the way they are. My car has an Lm7 from an 03 silverado. I did the usual head gaskets, head studs, lifters, pushrods, and rocker trunion upgrade. I just broke 10’s on my second track day with the Lsa blower. It also has stock 799 truck heads and a turbo cam.
Old 11-22-2018, 07:15 PM
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Originally Posted by Mgg4591


Oh yea these junkyard 5.3’s are fine with boost the way they are. My car has an Lm7 from an 03 silverado. I did the usual head gaskets, head studs, lifters, pushrods, and rocker trunion upgrade. I just broke 10’s on my second track day with the Lsa blower. It also has stock 799 truck heads and a turbo cam.

That's what I like about it, so simple yet so effective! It's a tough decision to make because I recently had a fully forged 340 built for my challenger and spent a ton of time building my own custom procharger setup from scratch. The setup is totally bad ***, but in short old mopars are just a pain in the ***. So many mix and match parts, I think I'm sucking oil from the oil galley from incorrect manifold/head angle, the pushrod angles are atrocious, the FITECH 1200 has been nothing but trouble on E85. even if I were to get all the engine issues ironed out I'm still left with a setup that has questionable durability. Those 340 blocks are strong for the day but known to split at 600FWHP. Even with MLS gaskets and studs I don't know how far I can push the heads before they push water.

I feel like I can build a much faster 5.3 for the cost of selling all the mopar stuff. Back it with a TH400 and shoot for deep 9's. Messing with turbos would be new to me but at least the engine would be relatively simple. Not like a hundred people haven't already done what I'm looking to do before.

You guys can ban me but this would probably only be temporary. I'd love to save for a while and do a hellcat swap at some point some years down the road.
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Last edited by kris396ss; 11-22-2018 at 07:21 PM.
Old 11-22-2018, 07:37 PM
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you can put budget forged pistons and rods in for not huge money. other than that good springs installed and shimmed to the correct height, proper rocker geometry and PR length and you dont need anything extraordinarily fancy to hit 750 wheel.

On a 5.3 I'd like to try a small back wheel s480, divided to the flange and a 216/220 .600 lift 114 cam and see if I can spool it fast (well controllably fast)
Old 11-23-2018, 12:26 AM
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Soooooo..... what rods and which pistons? Are Scat rods strong enough?

Would Wiseco forged flat tops be good in a case like this?

Seems like better rods and pistons in a 5.3 would be good insurance for hitting 750 at the wheels, and I have a spare 5.3

What are the top budget choices for better pistons and rods on a 5.3 ?
Old 11-23-2018, 09:47 AM
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well you have two ways to go, stock length rod or 6.125 rod so nail that down first, then choose a piston.

there are a lot of options out there. I have used the scat I beam rods in SBC nitrous applications. I like them.
Old 11-23-2018, 10:12 AM
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I went with the herd (swapping to a 5.3) after staying faithful to my original LT1 (stock > N2O > heads/cam/N2O > Solid Roller stroker/N2O > Turbo) in 2014. Like most, I'd read you could find a boneyard dropout, pan to intake, for $500 to $600. I bought one from a 150K or so '02 Silverado. The plan was to just clean up the stock stuff, end gap the rings for boost and bolt her in. While he had it down, I thought, "Hey, I should as for the ARP rod bolts". I called him and asked for that. He countered, "Well, yeah I can do that but by the time I resized the rods, balanced them, etc, for the parts and labor, you could have new set of Callies Compstar rods". I *think* they were $5xx 'ish then. So I sighed and said okay. Then as he was cleaning up the pistons, he said, "You know, I could get some forged wiseco pistons for $5xx or so?". I agreed to that too. Lol.. by the time he was done with me, everything but the block and crank had been replaced. But, I've ran up to 29.x PSI on my PT7675 turbo and it just screams. Haven't bent a rod, cracked a piston/ring yet. I *have* destroyed my hybrid Ford 8.8 (broke the torque arm mount off the differential) and killed my race prepped TH350 but the engine? Strong as an anvil.

Lots of folks have just cleaned up their stock 4.8/5.3 , put a good turbo cam/springs/trunions, proper injectors, opened the ring gaps appropriately, ARP (or Chinese equivalent) studs, added their turbo(s) of choice and made astounding power(the tune is all so important here). There's a video of a guy taking an otherwise tired (200,000 mile plus) 4.8, doing the aforementioned small upgrades and making over 900rwhp. Stock pistons, rods, crank and heads. Unbelievable.... After decades of making engines that were just barely able to withstand 500 crank hp without extensive block work(splayed 4 bolt mains, etc) and all forged componentry, GM decided to 'over engineer' the 4.8/5.3 to hold incredible overloads on stock parts. THANK YOU GM!

4.8 motor


Last edited by mightyquickz28; 11-23-2018 at 10:19 AM.




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