Our 06 crewcab GMC has the LR4 (285hp/295tq)with an intake and magnaflow catback. This thing screams to redline in first (5500rpm) and NEVER drops off on the power. Gets 24mpg unloaded at 70mph, 16 towing 5k lbs.
I won't lie..... I want an LR4 with an LS6, HOT cam, headers, valvesprings and tune stuffed into my C4 with a T-56 and 3.45 reargears. It would makemore power than ANY engine in the C4, get better mileage and sound phenomenal.
In reply to Bobzilla:
DOOOOO EEEEETTTT!!
As a word of caution for those thinking . . ."buy LR4 + 243/799 heads = ZOMG power", you will need to mill these heads to stay at 9.5:1. Untouched heads will drop it to 9:1 (not bad for what some of us have in mind 
). You can virtually cam, tune, and header your way to 5.3 (L33) hp numbers without the added expense of heads + milling.
Remember on the 5.3 (L33, LH6 etc), they used the 4.8 flat top pistons along with the longer stroke to up the cr from 9.5:1 to 9.9:1. For the LY2, they tuned it a bit more aggressive with 9.0:1 cr.
Supposedly, GM proved that the better airflow of 243/799 heads doesn't make up for the loss of compression provided by the 706/862, so they added something extra to the LY2 to up the HP.
So that does it I know now what my next motor of choice will be. When you go forced induction on these I bet the difference between the ly2 and the lr4 becomes moot. If you are looking to stay NA the ly2 heads will be helpful in getting more hp out of it.
I think the prices of used LY2's probibly just doubbled due to this thread LOL
The other option I had considered was building a hybrid. 6.0 block (bigger bore) with a 4.8 crank and rods. Short stroke, big bore.
This would be similar to what Katech built for CTS-Vs for WC that heavily restricted after that first race.
You have to balance the bottom end since the 6.0L slugs are heavier.
Here is one of Katech's specialty engines
Katech said: Katech Performance has introduced its “Sneak Attack” LS7 5.7L engine package (KAT-A4725) for fast car fanatics who revel in hidden horsepower. Engineered to leave competitors loathing, the track-ready LS7 boasts 346 cubic-inches of displacement (4.125-inch bore; 3.268-inch stroke), spins to 7,800 rpm and pumps out 575 horsepower. “If you’re looking for high-revving power or are displacement limited our ‘Sneak Attack’ LS7 is for you,” said Caleb Newman, vice president, director aftermarket operations, Katech Performance. “It was inspired by the awesome power of the early Cadillac CTS-V factory race engine.” Newman noted that a great deal of interest has already come from Porsche, Nissan, Datsun and Factory Five GTM conversions. The potent engine package (wet or dry sump) is one of four exciting offerings in Katech Performance’s LS7 “Arsenal.” Enhancements include a Katech sleeved LS2 case, forged piston-rod assembly, forged crankshaft, LS7 cylinder heads and an LS7 derived valvetrain coupled with a Katech specified camshaft. Each ‘Sneak Attack’ LS7 is hand built by the same technicians that produce championship winning engines for all of Katech’s race programs including SCCA SPEED World Challenge, American Speed Association (ASA), International Motor Sports Association (IMSA), American Le Mans Series (ALMS) and NASCAR(r) competition. Newman added the ‘Sneak Attack’ LS7 package, while not intended for daily driving, is streetable.
All the breathing of the 4+" bore and heads + the 4.8L crank . . . It's expensive . . . but doable . . .
racinginc215 wrote: truth be known the 4.8 uses plastic connecting rods. the crank is mostly paper mache and pop cans. the blocks are made from adobe. GM used no bearings or gaskets in it and they leak worse then a LBC. My suggestion would be to post this everywhere you can think of as it's the truth. we don't people getting their hands on this horrible engine.
i don't know if you heard, but virtually everything on them is unique to the 4.8 as well. it looks the same as the rest of the engine family, but even the transmission bolt pattern is just a TINY bit different. Enough to make them impractical in any non-stock application.
In reply to belteshazzar:
Is that the truth or sarcasm?
I was talking to a fellow GRMer just this week about that twin turbo 4.8, I might have to change my plans for the LS7 and go this route.
belteshazzar wrote:racinginc215 wrote: truth be known the 4.8 uses plastic connecting rods. the crank is mostly paper mache and pop cans. the blocks are made from adobe. GM used no bearings or gaskets in it and they leak worse then a LBC. My suggestion would be to post this everywhere you can think of as it's the truth. we don't people getting their hands on this horrible engine.i don't know if you heard, but virtually everything on them is unique to the 4.8 as well. it looks the same as the rest of the engine family, but even the transmission bolt pattern is just a TINY bit different. Enough to make them impractical in any non-stock application.
the bellhousing isn't different. they bolt up to the same trans that the 5.3 uses. it's ever so slightly different than an old school small or big block, but that's only because of the lack of alignment dowels, metric fasteners, the elimination of one bellhousing bolt, and a deeper offset from the crank flange than an old school V8. externally, they are identical to a 5.3. unless you start looking at casting numbers, that is.. you could even tell the poor soul that you just beat in a heads up race that it's a 6.0 so they don't feel so bad.
if you really want to mess with people, get the GM front mount distributor kit that uses a Ford distributor and put a carbureted intake on it.. some people would think you have a weird Ford 302..
So where is the best place to find a complete engine and what turbos are recommended
go to www.car-part.com and look up a mid 00's Chevy SIlverado engine..
^ This!!!
Also take a peak on eBay . . .the same vendor may have it cheaper there . . . That's how I found mine.
A single MPT70 should make LS7 numbers . . .
I am just amassed that this motor makes virtually the same hp in stock form as the 5.3.
Does the 4.8 respond as well to a cam as the 5.3 LM7?
Yup . . . HP numbers would be close, torque would be lower of course . . .
Remember the LR4 and LM7 have the same heads, same camshaft, same compression ratio and same bore.
Now if only they made an aluminum block version of this. Are the bearing journals the same as the 5.3? I have seen LM4 blocks on Ebay for really cheep. I know at that point it would probably be best to build a 5.3 but I can see getting a 4.8 on the cheep add a LM4 block stir and you have a light high revving v8 that takes boost well. Add a Miata and I can see that halling the mail quite nicely.
SyntheticBlinkerFluid wrote: In reply to belteshazzar: Is that the truth or sarcasm?
sarcasm
dean1484 wrote: Now if only they made an aluminum block version of this. Are the bearing journals the same as the 5.3? I have seen LM4 blocks on Ebay for really cheep. I know at that point it would probably be best to build a 5.3 but I can see getting a 4.8 on the cheep add a LM4 block stir and you have a light high revving v8 that takes boost well. Add a Miata and I can see that halling the mail quite nicely.
Wait. Think this can be done on a chalenge budjet? I could see a chalenge winner with this combo. Add boost and .. . ..
I am doing it again. Having a conversation with my self.
And Then I go and find this. Put a 4.8 in it add boost and for cheep you would have a really nice car.
http://boston.craigslist.org/gbs/cto/2518762206.html
belteshazzar wrote:SyntheticBlinkerFluid wrote: In reply to belteshazzar: Is that the truth or sarcasm?sarcasm
There needs to be a sarcasm font. 
dean1484 wrote: And Then I go and find this. Put a 4.8 in it add boost and for cheep you would have a really nice car. http://boston.craigslist.org/gbs/cto/2518762206.html
Holy Crap!!!
dean1484 wrote: And Then I go and find this. Put a 4.8 in it add boost and for cheep you would have a really nice car. http://boston.craigslist.org/gbs/cto/2518762206.html
Oooooohohohohohohoh Billy, that's a thought...
dean1484 wrote: Now if only they made an aluminum block version of this. Are the bearing journals the same as the 5.3? I have seen LM4 blocks on Ebay for really cheep. I know at that point it would probably be best to build a 5.3 but I can see getting a 4.8 on the cheep add a LM4 block stir and you have a light high revving v8 that takes boost well. Add a Miata and I can see that halling the mail quite nicely.
Yes 4.8 guts will work in any aluminum 5.3 . . .
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