With patience and a little luck you can find a Trailblazer/Envoy/Ascender with the 5.3 and buy the whole thing for less than an LS1 would cost.

I picked up an 03 Envoy XL, pulled the LM4 and harness, parted out the rest, and made enough money to afford the LS6 cam and springs.

 

Yeah I may keep my eye open for a deal like that since I'm not in a hurry. I will say that the convenience of driving down to hawksthirdgen and literally being able to walk around their warehouse and look at hundreds of LS1's is pretty appealing. $4500 for a low mileage LS1 and T56 out of an Fbody with absolutely everything included.

I'm thinking I can sell my LT1 engine for about $500, maybe a little more if I find the right buyer. The T56 will bring in $1500-1800.

So my LS1/t56 will cost me $2000-$2500.

Do you mind me asking the details of your 5.3? Mileage and total costs?

 

I have the same engine as SgtSkid (LM4) pulled from a wrecked 04 Buick Rainier w/92k on it, gave $900 for the complete 5.3 (engine, accys, harness, etc).

Of course I cant leave things alone, so now it has 4.8 flat tops in it (~10.5:1cr) and a Tick SNS stg 1 cam (223/227 .610/.590 111+2) among other things, cant wait to get it in the car.

 

I am also looking for a replacement engine as well, since mine needs lifters and has almost 185K miles on it now (EVERYONE wants MUCH more than Hawk T.D. used replacement money to rebuild this thing, even mildly, sometimes 2.5x + more! ).

The problem I am finding is that there are NO/NONE/NADA aluminum 5.3s around here, but maybe they are easier to find in good ol' boy land?

Most on this site would then say, well just use an iron block, but they just do not understand that we road race types are trying to get as much weight off of the nose as possible, NOT add more (even if it is "only" 80-90 lbs.!), and we absolutely DO NOT NEED the strength of the heavier iron blocks for big boost, spray, yada, yada.

IF I get the money, I might just drive on down to Hawks, and let them swap a decent, lower mile, COMPLETE LS6 into my car, and still cost me less than just the rebuild on my factory LS1.

 

Dunno where "good ol' boy land" is ..... but I found mine on craigslist, it was in West Chester.

 

I picked up the Envoy for $1625 (including fuel to get it) in southern Indiana. It was a two owner with 212k on the clock. Ran great but the owner had driven it off the road and through a fence. I yanked the motor and parted the rest of it out netting about $600.

I sent it to a local shop and had them ring and bearing slap the block, install the cam, and rebuild the heads $800.
$120 for LS6 cam
$60 for LS6 springs
$??? gasket kit
$110 Melling Oil pump
$30 for LS2 timing chain
$100? for lifters - CoSpeed

I will be reusing the truck intake and bought a DBC throttle body. The nice thing about the Envoy is that the computer should be programmable for use with DBC. Otherwise I'd have to find a Savannah or Express ECU.

I am not looking for crazy HP. If I can get the 300hp to the wheels that the engine was rated for at the crank, I'll be impressed.

https://ls1tech.com/forums/generatio...questions.html

 

Given differences in displacement, one with more of it will make more torque and work less to make the same power vs. one with less of it that will always have to work harder and make torque higher in the RPM range in order to make the same kind of power at peak. Not that the 5.3 you are suggesting is a bad idea, but there are better options for the OP if he wants to be as competitive as possible and has the money.

A 5.7 with the LS6 cam and LTs will put right around the same power as the 5.3 but will smoke it in terms for torque. Remember, the 5.7 is a 350fwhp motor to begin with...so you don't have to detune it at all to reach those power goals. And that 5.3 will need more than just an LS6 cam, LTs and 243 heads to get there...thus further killing the torque.

"Detuning" a bigger displacement engine with smaller cam and smaller heads is only going to make for killer torque. A 6.2 with an LS6 Katech torquer cam (same duration, tighter LSA) and 243 heads with a 210cc runner will make killer torque down low but then fall on its face at higher RPMs (thus staying within the power limits).

Me personally I'd rather have a 6.2 making 345rwhp peak but make 400rwtq from 3000rpm to redline rather than a 5.3 making 345rwhp peak but only make 350rwtq peak.

 

I think I've decided. I've found some bone stock LS6 dyno graphs and I really like how it looks. Tons of low end torque and pulls hard all the way though 6000.

I know I'll be paying a premium for the LS1 from hawksthirdgen, but being able to drive an hour and a half away and look and hundreds of LS1's and T56 and pick out what I think is the best one is pretty nice. And it'll have absolutely everything I need.

I think an LS1 with ls6 cam/springs, manifold, and long tubes will get me close enough to my target.

I just need to figure out what kind of peak hp I will have if the rules require an average hp of 345.

 

So after looking some stock LS6 graphs, the hp curve near peak is so flat that average hp is close to peak. So I'm going to need 350 peak.

As long as I keep the stock LS1 heads, but use the ls6 cam and manifold, it should be pretty close, right? Will I need LT's or just use stock manifolds?

 

It will be close, but I would still do the LTs and then take away timing up to if you want to even out the power gains there so that you don't overshoot your goal. Or do one of those 112 LSA LS6 cams to pull power earlier.

 

For road race I would always choose the larger displacement engine. Torque wins, and keeping the revs down helps LS motors live on the road course. When you start to wind these motors out with the stock wet sumps, they don't last long.

 

Why's that? What would you call normal shift points? I only plan to run it to 6500 or so it I need it for s straight to keep me from shifting to 5th.

 

How often (# of times a season) does NASA put you on the mobile dyno??

 

I'm not sure.

 

LS motors pool a ton of oil in the heads, the oiling system stock is less than ideal for road racing. I'm sure you're going to add the improved racing goodies when you swap the motor, it should be considered mandatory. I would also consider a Melling pump - according to data from improved racing, they cavitate less at high rpm then a stock pump. In general, the less rpm the happier the motor. I wouldn't be worried running to 6500 on a straight to avoid shifting to fifth. I do the same and my motor doesn't complain. I do keep shift points around 6000 normally but stretch it at certain tracks to avoid a shift.

Depends on how well you run. Run up front, expect it.

 

It's not that there's a limit on shift points, but keeping it at 5500+ rpm all the time is going to be a helluva lot harder on the valvetrain and suffer more oiling problems than if you keep the engine at 4000rpm because you have more torque.

 

The guys in the autox/roadracing section on Corvetteforum love the reliability of the LS6 especially over the newer LS2/3/7. A stock LS6 would make a great choice, I would look into the Improved racing baffle kit if you're running a stock pan.

Another option maybe a 5.3 with a CamMotion truck drop in cam. The tq curves look very strong, granted I think I've only read of them running through automatics, they are also designed to be easy on springs.

 

I road race a E36 M3 with an LS6 swap, I highly recommend getting the oil pan baffle especially if the tracks you are visiting have left hand sweepers. Also, a large oil cooler and 15w-50 M1 oil (cheap and effective).

My LS6 is fairly stock, has home made intake and long tubes, made 365whp but the kicker is the table top torque curve peaking at 407lb-ft!

 

AGREED!

BUT, try finding one in decent shape, with lower miles in certain areas of the country (maybe EVERYWHERE at this point) due to the damned swappers and drifters snatching them up before they're even on the market. (Sorry, Inflame, NOT directed at you personally. )
(It's almost as if they have some kind of 'sniper app' for this, like on ebay or something. )

 

Haha, I actually got VERY lucky with mine. It was advertised as a LS1 on craigslist, after close inspection and running the #'s, it was actually an LS6! Lucky me huh

Also, I did everything possible (so far) for oil control.

-Drilled oil filter inlet or outlet, casting flash partially blocks this area, quick drill opens ti up.
-Drilled lifter trays
-Improved racing oil pan baffle
-Improved racing crank scrapper

What I wish I did was drill the heads for thicker push rods and the oil drain passages, so as much oil as possible leaves the head. The push rods would have smaller oil orifices too.

That's next winter after getting the heads CNC'd.