5.3 engine
 

I just acquired a 04 Trail blazer with the 5.3 engine. Has 151,000 miles, runs decent, 4 wheel drive. Has a blown right hand exhaust gasket. Thinking of maybe putting drivetrain in my 69 stepwise. Does anyone know what horsepower this thing has? I like the idea of the fuel injection and maybe gas mileage of the overdrive. It may have a 700-R4, but not sure. It's almost to nice of a car to part out, it's loaded up, but I have no use for it. What do you think, what do I need besides drivetrain and computer?

Re: 5.3 engine
 

Im going through the process of putting an 04 5.3 from a tahoe and a 4l80e into a 69 right now. There is a ton of good info on this site on fuel systems, motor mounts, ways to make gauges work with ls, etc. Here is a good link:

http://67-72chevytrucks.com/vboard/s...d.php?t=456787

The 04 5.3 is rated to 295 fwhp stock I believe. Have read on a bunch of guys getting to around 380 with just a cam and headers though.

Re: 5.3 engine
 

It should have a 4x4 4L60E. You’ll need to swap to a 2wd tailshaft.
I don’t know the stock ratings, but the 5.3 in my Tahoe does ok and it’s a heavy vehicle.
You’ll want to get the engine harness, the gas pedal, the TAC module, all the accessories and the hoses too.
The only hard thing to get working is your mechanical speedometer. I think someone makes a tail housing with both a VSS and a cable drive.
I’m starting a 6.0/TKO swap into my 68 now, so I’ve been looking for the same info. It’s out there. The LS1 tech message board has some good info too.

Re: 5.3 engine
 

My '01 5.3 has towed a 65 Impala across the country multiple times. The transmission eventually couldn't hack it, but the engine has never been apart - 280k mi and counting.

Re: 5.3 engine
 

blown exhaust gasket may be from exhaust manifold bolts...for several yrs they were prone to having broken bolts..i had 4 broke on my LQ9..
2004 5.3 will be around 295hp
it wont be a 700r4...like stated above..tailshaft swap or another trans

Re: 5.3 engine
 

Engine mounts
Modified Harness (modify it yourself, send it out, or pick up a pre-made one... your choice)
the PCM will need to be flashed to get rid of anti-theft and a couple of O2 sensors
Your exhaust manifolds, I believe, will fit between the frame rails so you're good to go there (vs. truck ones, which don't fit without trimming)
Grab some of the exhaust - specifically the Y pipe so you can customize it to your needs
As others have said, the gas pedal, TAC module, and all associated wiring
There's someone here on the forum that makes an adapter bracket to bolt the DBW pedal in to your truck
Your driveshaft will have to be modified or replaced, most likely
Yes - a 2WD trans or convert your 4WD 4L60E to 2WD
You may have to make some modifications to your in-cab fuel tank - not sure exactly what people are doing with the 67-72's. On my 80 I am replacing the entire fuel system with a tank and sender from an FI Squarebody, using the pump from a later model Silverado, a corvette fuel regulator/filter, and either braided or nylon quick connect lines (haven't committed yet)
A speedometer can be tricky - I work in IT so I'm doing an OBDII driven digital dash (cheap android tablet and an app, plus customization to make it do what I want)

Re: 5.3 engine
 

Pretty sure stock is 345 hp.

Upgraded cam and valvesprings is good for another 40 or so, the heads are definitely not a limiting factor.

Re: 5.3 engine
 

You will definitely need to swap the oil pan. The trailblazer oil pan has the front axle going through it.

Re: 5.3 engine
 

5.3L is a LM4 has 4L60E trans

Horsepower (hp / kw @ rpm) 290 / 216 @ 5200
Torque (lb-ft / Nm @ rpm) 325 / 441 @ 4000

Re: 5.3 engine
 

This is the list I'm using for finding a cheap replacement cam in my 5.3.

https://www.hotrod.com/articles/ls-cam-test-comparison/

Re: 5.3 engine
 

As long as you didn't pay more than $3500 and the powertrain is in decent condition, I would keep it and use the vehicle as a donor. If you paid more than that, you'll have to do a bunch of parting out to get a good value because you can get a 5.3/4L60E dropout with that mileage or less for $3000 on from a few places.

From a convenience standpoint, it's a great vehicle to use as a donor. You have all of the parts you need and it's a complete vehicle. You could take out the engine and trans, change out the tailshaft, give the engine a tuneup, clean it up, or do any bolt on mods. You'll need the engine, trans, PCM, engine harness, air box and plenum, gas pedal, TAC module, TAC module harness, and battery cables.

While it's out of the vehicle, it's best to do the following:
-Clean everything
-Spark plugs
-Plug wires
-Replace knock sensors and harness
-Replace intake manifold gaskets
-Bolt on headers or camaro manifolds with new gaskets (and remove any broken manifold bolts)
-New water pump
-New power steering pump
-New idler pulley
-New tensioner pulley
-New serp belt

Re: 5.3 engine
 

I own a V8 trailblazer platform and let me add my input. I’m unsure if 04 has a TAC module, I know for a fact 05 and up doesn’t use a tac but a different throttle pedal than Fullsize trucks so if you can’t find a tac module then that’s why. The exhaust manifolds like stated are direct swap for our trucks. You’ll save about 80 lbs because the trailblazer has an LM4 which is an all aluminum version of the LM7. As mentioned the oil pan is a front sump so will need to be swapped but the kicker is the ac compressor bracket bolts to the oil pan also. So you’ll need this adapter or keep in mind LS3 Camaro accessories have the same spacing so maybe something to look into. Engine mounts/isolators on the trailblazer can be used if you make custom frame stands which will also help to keep the compressor in the stock lower position. The catalytic converters are in the Y-pipe so either plan on cutting the flanges off and building exhaust. LS plug wires rarely go bad and used originals are typically better than new aftermarkets. No reason to touch knock sensors or intake gaskets which are actually molded seals. And as easy as all the accessories are to get to if they’re not bad don’t spend the money. LS parts last a long time and a lot easier to replace in truck than SBC items