Chevy 5.3 engine build

[75sv1]

I purchase a NOS Chevy LS 5.3 block off of E-Bay. It arrived yesterday. I am looking for ideas on components. I am thinking of a stock plus. Also, to upgrade the rods. Look for Hyper Eutectic pistons. This will be a built rig, XJ. I do want some sort of fuel mileage. 

I'd say my present plan:

         Scat 9000 crank if available (cast), Scat or Eagle I beam rods. I might go for H beam rods.  6.093, 6.100 or 6.125? Also, that affects the piston selection. I do see some Forged pistons from Hyper Eutectic alloy. ???  Rings molly of some brand. I did use Hastings on my two strokers. I'm looking to replace the stock cam bearings with Durabonds. King coated mains and rod bearings. 

       I want a camshaft in the 800-5,800 RPM range. So, far its Compcam. There are some others that come close and are a bit cheaper. 

With aluminum heads, is about a 10.1-10.5 CR OK on say 88 octane?  

[thecodemonk]

At 10:1 CR I’d probably want to stick with 92 octane to be safe from knock.  These questions are probably better asked on something like ls1tech forums than here if you’re looking for a lot of people with experience on the engine side specifically.

[Pete M]

don't fear the high octane.    it really isn't that much more money when you take into account the number of miles you'll be putting on it. 

[75sv1]

I did look at various web pages. Seems a lot of variations etc. Also, some of them are supercharges etc. Seems later model engines, aluminum heads, can run a higher CR. Also, Fuel injection. Still, some say higher stall speed and cam lap over. Both of those will probably ruin Fuel Milage. I might check with Comp Cams and see what they say on my intended cam. Also, longer rods are suppose to help. 

[Gojira94]

Which 5.3 block did you get? Gen III or IV? If it's Gen III, the OE LM7 rotating assembly is plenty, and has 8cc dished pistons for a SCR of 9.5:1, 87 pump gas all day long...

 

All 5.3, Gen III and IV have 3.78" bore, 3.622" stroke with a 6.098" rod. A longer rod won't get you anything unless you're doing a lot of time at high RPM, where piston speed can exceed a safe limit with a factory length (or shorter) rod. Hypereutectic pistons are just cast aluminum with silicon added for thermal stability vs expansion/ contraction of the aluminum so they keep their diameter and shape in the bore. Stock HE pistons aren't likely to encounter failure unless they see big heat spikes from too much boost or nitrous and not enough fuel. Both of of these power adders are successfully applied to factory LS rotating assemblies all the time (up to a sensible point). I wouldn't waste money on a forged rotating assembly or longer than factory rods in an engine that won't have power adders or see long stretches of high (>5800) RPMs in an XJ. Also, longer rods mean higher piston pin height and less material above the wristpin, and more expensive pistons.

 

A factory spec LM7 or Gen IV equivalent would be plenty- 280HP, 325lb ft. The LM7 truck cam is like 190* duration and .460" lift, that might make sense to bring up to the 202* - 207* / .495" - .500" range without losing any low end torque. I'd keep a wide LSA as well, no lower than 114*. LM7 heads are very decent. The 706 and 862 heads are 200cc, have a 61cc chamber, and are in large supply in every boneyard. A decent machine shop can clean them up and set them up for you. Almost everything you'd want to put this engine together could be had cheap. Perfect recipe of 'good' and 'cheap.' It doesn't need to be 'fast' (good/fast/cheap: you may choose 2) 

 

King bearings are also my preference, Hastings rings are good as well.

[Limeyjeeper]

The factory block is good for a lot of horsepower before you need to beef up the bottom end. Plenty of guys running 450+ on stock internals.

[75sv1]

This is the block I have:

99-04 4.8/5.3L Cylinder Block 1101763 | eBay

So, 2004 LS 5.3. 

[ghetdjc320]

I thought the advantage of those iron blocks was being able to handle high boost numbers on stock internals. 

[Gojira94]

3 hours ago, ghetdjc320 said:

I thought the advantage of those iron blocks was being able to handle high boost numbers on stock internals. 

 

Well, yes and no. 6 bolt mains, a lot more webbing than Gen I/II SBC for sure but with a couple of exceptions they're all powdered metal rods and HE pistons. With the pistons being the point of failure when something goes dangerously lean with a power adder. Lift a ring land and the magic smoke goes out.

 

Freiberger and Co. did a 'boost it till ya kill it' test a few years ago, thinking they were testing a 5.3 and discovered at the end, having thrown 2 dyno runs at 29psi at it, it was a LR8 4.8l. If you consider 15-17psi 'high boost' then yeah, they'll take that for quite a while with good tuning. North of 20psi and it's on borrowed time, regardless of tune/ intercooler with stock rotating assembly.

 

ANY stock Gen III/IV/V SBC will eclipse HP and TQ numbers from a stock or moderately built 4.0. and be cheaper than a 4.0 based stroker.

[ghetdjc320]

28 minutes ago, Gojira94 said:

ANY stock Gen III/IV/V SBC will eclipse HP and TQ numbers from a stock or moderately built 4.0. and be cheaper than a 4.0 based stroker.

True, just a lot more expensive to swap 

[Gojira94]

37 minutes ago, ghetdjc320 said:

True, just a lot more expensive to swap 

 

Agree. I almost feel like the OP is at a disadvantage with a bare block. Easier to get a complete engine with harness and electrical for <1k and swap that in.

[DirtyComanche]

1 hour ago, Gojira94 said:

 

Agree. I almost feel like the OP is at a disadvantage with a bare block. Easier to get a complete engine with harness and electrical for <1k and swap that in.

Absolutely.

 

I bought a whole truck for $1200, sold the doors for $400, hood for $200, tires for $300, seats for $200, grill and headlights for $150, taillights for $50, tailgate for $150, tcase for $250, kept the engine/trans/wiring/ECU and scrapped the rest.  Granted I have a trailer and had some time/space to blow the truck apart to do that, but it at least netted me a complete engine/trans for negative cost.  I could have made a lot more on the part out if I was willing to wait longer too.

[thecodemonk]

1 hour ago, Gojira94 said:

 

Agree. I almost feel like the OP is at a disadvantage with a bare block. Easier to get a complete engine with harness and electrical for <1k and swap that in.

 

100% this.  MCM had an episode that talks about that too...way easier if you have a whole vehicle to work with and see where everything was and goes and can more easily identify what's going on where, even in a case where you're going from one vehicle to a different one.

[75sv1]

14 hours ago, thecodemonk said:

 

100% this.  MCM had an episode that talks about that too...way easier if you have a whole vehicle to work with and see where everything was and goes and can more easily identify what's going on where, even in a case where you're going from one vehicle to a different one.

And don't have a neighbor who calls the County Zoning Bord if you have a vehicle that doesn't run, etc. OK, the 4 Saab Sonnets were a bit much.  

[75sv1]

I did do some searching. The stock LS1 5.3 had 9.5 to 10.0 CR. There were some of the motors that had Hypereutectic pistons. I believe the 99-up Jeep 4.0Ls have hypereutectic pistons with a coated skirt. As I know it, Hypereutectic pistons were developed in 1936 By Karl Smidt. They were used in the Daimler-Benz BD 605. It did have direct injection and was Supercharge. Used in the Me-109. Basically, a higher percentage of silicon say 13% is achieved.  

[ghetdjc320]

A true LS1 is a 5.7 aluminum block engine. Many an engine are called “LS” but most are not true “LS” part numbers. 
 

I know this is not relevant to your build so apologies but I’ve seen many people here on forums recently throw around the idea of a cheap LS1/3/6 swap. I can tell you my late LS1 cost more than most think an entire swap costs. Ok done with the rant 

[schardein]

I understand the addiction to horsepower, I've done my fair share of hot rodding in the past.  These days, I'm very happy to pick the engine that makes the horsepower I want and swap it in, in basically stock form.  I bought a 2004 LM7 iron block 5.3 back in 2016 for my CJ7.  Other than a aggressive speed density tune (which the tuner said requires 91 octane fuel) and a set of headers, it's stock.  Probably makes 300-330hp and puts a smile on my face every time I drive it.  I'm not afraid of freeing the horses every once in a while, and it's held up fine.  If it ever quits, I'll grab another 5.3 out of the junkyard and slap it in over a weekend.  Once the swap is sorted out, replacing the engine itself is a cake walk.  

[75sv1]

13 hours ago, ghetdjc320 said:

A true LS1 is a 5.7 aluminum block engine. Many an engine are called “LS” but most are not true “LS” part numbers. 
 

I know this is not relevant to your build so apologies but I’ve seen many people here on forums recently throw around the idea of a cheap LS1/3/6 swap. I can tell you my late LS1 cost more than most think an entire swap costs. Ok done with the rant 

Actually, in some sense it is what I am dealing with. There is a whole family of 'LS' motors. So, how the different parts interchange etc. and performance numbers, and specs. etc. I did see the specs for a later 5.3 with 10.5 CR. And anther spec for say a 6.0L with 11.0 CR. The later ones had AFM and variable cam timing. Also, the term "pump gas'. Is pump gas 87, 88, 89, 91 ,92, 93 octane ? And that is a big difference in price per gallon. Also, factor in E85. 

         I will note that yes a stock 5.3 is putting out 270-320 HP and them more than that for torque. In an XJ or MJ frame, that's a lot. Its plenty for most street rods. And would do me fine. I am not looking for a 400-500 hp motor. Just, something say stock plus and a bit of an upgrade in components. Most of the aftermarket is geared to Hot rod street racers. Cams 1500-6500 RMP or 2500-7500 RPM and up. A few in the lower Truck RMPs.