davidhouston23

Long story short my LS1 blew. Everything from the heads and up is fine, the block has a few holes, which is why i'm making this thread.

Anyways, I'm on a budget and my Trans Am is my only car. I'm wondering if I were to buy a 5.3L short block, could I just bolt my LS1 stuff on it, put it in the car, and go? It's an auto transmission. Would the wiring harness be the same? Would I need to do something with my computer?

Sorry if this is a dumb question. I'm mechanically inclined, though I don't know much about engine swapping, etc. I searched and couldn't find anything, so any help would be greatly appreciated.

Thanks.

blackLS1m6

iTrader: (14)

Yes, you can run a 5.3 short block. You can bolt up your LS1 top-end parts, oil pan, etc. As far as the wiring harness goes just use your sensors from your LS1. Make sure you check out your LS1 parts out before reusing them, check to see if you bent any valves,broken valve springs, metal shrapnel in the intake, etc. Clean everything throughly like the oil pick-up tube and anything you are reusing of the LS1. Your computer should be recalibrated, VE table, engine displacement, etc. But it might run ok not sure. Maybe someone else who has done this will fill in. Good luck!

GMCtrk

iTrader: (23)

You're going to lose compression bigtime with those LS1 heads. 5.3 is 9.5:1 with 59cc heads.

But, it will work, you'll be down about 75hp from your LS1.

1FastBrick

iTrader: (16)

This is actually becoming very common as a cheap replacement alternative. The only difference with the 5.3L block Vs. LS1 is that its Iron and has a smaller cylinder bore. As far as the sensors go I believe only the oil pressure sensor on the LS1 is different. It is shorter then the one on the Trucks 5.3L . The crank and cam sensor should be the same as they use the same 24x reluctor wheel and the general cam design is the same.

blackLS1m6

iTrader: (14)

Yeah compression would probably be around 8.75:1 roughly. Might want to use the 5.3 heads or mill your ls1 heads to keep compression up.

1FastBrick

iTrader: (16)

Compersion loss yes!

GMCtrk, You sure about that??? I thought the 5.3L were rated at roughly 9.5:1 or 9.6:1 from the factory.

I know the stock 5.3L heads have a 61cc combustion chamber not 59cc

davidhouston23

Well if I can find a good enough deal I might buy an aftermarket cam for the 5.3. If I used the 5.3 heads would I still be down 75HP?

Thanks for the help btw, really brightened up my day!

1FastBrick

iTrader: (16)

I believe its more like 15hp by putting the LS1 heads on a 5.3L

InchUp

iTrader: (2)

From 1999 to 2007, the 5.3L has been 9.5:1 in the trucks. In 2007, it bumped to 9.9:1. Today's 5.3L trucks are still 9.9:1.

5.3L heads are actually 61.15cc.

Stock LS1's are in the 310-315hp range from the factory. Most 5.3L's are in the 285-290hp range.
75hp loss might be a bit steep.

davidhouston23

So.. I take it running LS1 heads on the 5.3 is probably not a good idea. I guess the stock 5.3L heads are pretty good eh?

1FastBrick

iTrader: (16)

Average stock 5.3L is rated close to 300 hp at the fly wheel. I think it was 285 from the first year up to like 315 in the later years say like 05-06. the aluminum 5.3L L33 option I believe was 330

davidhouston23

Eh, not that bad I suppose. Do you know anyone that offers a rebuild kit or something of that nature for the 5.3L? New gaskets and such?

1FastBrick

iTrader: (16)

Depending on the Castings... The newer 799 and 243 castings are different obviously...

LOL... J/P

InchUp

iTrader: (2)

More or less, 5.3L heads are LS1 heads with smaller valves for the smaller 5.3L bore. They flow about the same when on the same size bore until the upper RPM's where the LS1 heads start to pull away very slightly.

InchUp

iTrader: (2)

Texas Speed. Browse their gaskets link under the Corvette LS1 motor section.

1FastBrick

iTrader: (16)

Oh so true...

1FastBrick

iTrader: (16)

http://www.performancetrucks.net/for...d.php?t=428941
Here's the Gm part numbers

InchUp

iTrader: (2)

Nice work. Bookmarked. Thanks.

1FastBrick

iTrader: (16)

It's top secret so Pass it along... trever1t and Low LQ4 did one too but I personally think its harder to read.

In case you need other Gm Part numbers its here...
http://www.performancetrucks.net/for...d.php?t=429595

the_merv

iTrader: (88)

You are going to have to drill and tap the Iron Block for the Alternator Bracket.