1,200 hp 4.8!!!!

[SactoJim]

Anybody see this article in the new Hot Rod? They took what they thought was a well worn 5.3, did a mild port/polish and installed 2" intake valves on the stock heads, diff rings, put a good cam in it and a FAST intake. Made like 470hp NA and then they put a intercooled 2-turbo system on it and cranked it up to like 27lbs boost! They were running the motor up to 7k RPM's which got them scratching their heads, only later to find out why.

What they wanted to do was see what it would take to grenade a stock bottom end LS motor. At the end of the day, they claim they did something like 60 - 1000hp runs before the ignition gave up. They didn't hurt the motor.

They later took the motor apart only to discover it was a 4.8!

These LS motors are the chit!!!!

[C-10 simplex]

That's pretty good if confirmed.

As you probably know, the lsx blocks are rated to at least 1500hp for only about $2200!

[sav300]

Just read that article today and I would say that making 4+ HP per cubic inch is pretty darn good!!! May not last that long at that HP, but like they said detune it to about 600-800 and your sitting pretty good for a basically stock engine. I can tell you that my next project won't be a carbureted SB, it'll be an LS base!

[fastwillie 696969]

machine tolerance does wonders

[ratrod67]

I am putting over 500 to the ground in my daily driver 2001 extended cab with a 4.8. Has heads, cam, stall, 373 gears and NOS. LS motors are super reliable with decent power IMO.

[eagleuh1]

Shhhhhh. Keep this quiet. We don't want everyone having one. Thats good to know they can handle that, in case I inherit some turbo money.. In my case it would have to be supercharger money.

[dajn]

I bought a 2000 suburban from a coworker with 280000 miles on it. The 5.3 just finally gave out and this guy could not possibly have treated it any worse. to the rug constantly and basically never changed oil. very good engine. the used 5.3 I put in it will last me forever the way I treat it. also gets no worse then 16mpg with my setup. best part is, the used motor I got was only six hundred dollars and I guarentee at least 200000 more miles out of it.

[Fitz]

Originally Posted by SactoJim

Anybody see this article in the new Hot Rod? They took what they thought was a well worn 5.3, did a mild port/polish and installed 2" intake valves on the stock heads, diff rings, put a good cam in it and a FAST intake. Made like 470hp NA and then they put a intercooled 2-turbo system on it and cranked it up to like 27lbs boost! They were running the motor up to 7k RPM's which got them scratching their heads, only later to find out why.

They later took the motor apart only to discover it was a 4.8!

These LS motors are the chit!!!!

To run that much boost the compression ratio needs to drop down to about 8:1. Unless they were all comatose they would have noticed the difference in stroke for the 4.8 vs the 5.3 when they changed pistons/rods for the turbo set-up.

[406 Q-ship]

Originally Posted by Fitz

To run that much boost the compression ratio needs to drop down to about 8:1. Unless they were all comatose they would have noticed the difference in stroke for the 4.8 vs the 5.3 when they changed pistons/rods for the turbo set-up.

They did not change anything in the short block for pieces, they opened up the top ring end gap. Hot Rod even used the original top ring just opened the gap on a ring file. The jist of the article was to find the weak point in an LS series engine not to see what power they could get, so the engine was not built to handle the pressure. Hell the little 4.8 made 451 HP/ 380 lb/ft with just the worked heads and a cam. It was a thrash to destruction article that never granaded. The LS series is one of the greatest engines ever.

[Fitz]

Originally Posted by 406 Q-ship

They did not change anything in the short block for pieces, they opened up the top ring end gap. Hot Rod even used the original top ring just opened the gap on a ring file. The jist of the article was to find the weak point in an LS series engine not to see what power they could get, so the engine was not built to handle the pressure. Hell the little 4.8 made 451 HP/ 380 lb/ft with just the worked heads and a cam. It was a thrash to destruction article that never granaded. The LS series is one of the greatest engines ever.

LMAO!!! That would yield a dynamic compression ratio of 26:1 @27 LBS of boost. NO WAY!

[406 Q-ship]

Originally Posted by Fitz

LMAO!!! That would yield a dynamic compression ratio of 26:1 @27 LBS of boost. NO WAY!

That writer should have looked like Calvin in your avatar!

They only got it to 26 PSI, at 27 psi (they tried) the ignition just could not light the fire.......suprise suprise.

[Fitz]

Originally Posted by 406 Q-ship

That writer should have looked like Calvin in your avatar!

They only got it to 26 PSI, at 27 psi (they tried) the ignition just could not light the fire.......suprise suprise.

Or perhaps he got more help than he could stand from the "Editorial Staff." In any event the article has a flaw or two!

[bluex]

They did use 118 octane race gas. I guess that helped a little?

I kinda doubt it too, but who knows.....
Posted via Mobile Device

[BlazinC5]

I dunno. Aside from the astronomical compretion ratio that was mentioned. What gets me, is that they took this motor apart, reasembled it, then ran it only to THEN discover it was 4.8 and that's way it was able to run so hard? Am I mistaken that the block would not have the displacment stamped or cast into the block like all other blocks? I don't know of anyone that wouldn't look to see what they had somewhere in the proccess.
I think the article smells like 3 day old Flounder, Cause sumthin is definitly fishy with it. Just my 2 cents.

[classic70]

The 4.8 and 5.3 use the same block, they have 4.8 and 5.3 cast into the block.

[Fitz]

Originally Posted by classic70

The 4.8 and 5.3 use the same block, they have 4.8 and 5.3 cast into the block.

They also have the same cylinder bore but the 5.3 is stroked 9 mm. I think this article is BS. To prevent detonation they needed to change a lot of stuff including the fuel and program to run 27 inches of boost.

[406 Q-ship]

Originally Posted by Fitz

They also have the same cylinder bore but the 5.3 is stroked 9 mm. I think this article is BS. To prevent detonation they needed to change a lot of stuff including the fuel and program to run 27 inches of boost.

It was was on 118 race fuel and a custom tune. It was a stock short block only (block, pistons, rings, rods, crank, bearings), they were just trying to blow it up and it did not let go, the writer is NOT saying that you can bolt on two ebay turbos on a stock 4.8 to achieve 1,200 reliable horsepower. At 26 PSI the headgaskets would never hold up.

[jb1016]

Originally Posted by 406 Q-ship

It was was on 118 race fuel and a custom tune. It was a stock short block only (block, pistons, rings, rods, crank, bearings), they were just trying to blow it up and it did not let go, the writer is NOT saying that you can bolt on two ebay turbos on a stock 4.8 to achieve 1,200 reliable horsepower. At 26 PSI the headgaskets would never hold up.

Agreed -- the whole point of the story was that they were trying to make the thing cry uncle, and it never did -- they just ran out of time on the dyno. Amazing.

[breeze85cten]

I have a 2004 4.8l LS with about 100k, cam, slightly ported heads, LT Headers, awesome tuner and pushing 7k rpm and best run on dyno was 305 rwhp. This is with all stock internals and a LS1 intake (mainly for looks cause it doesnt help with power). I always hit the rev limit and it is solid everytime! Oh yeah it is in my 1985 c10. LOVE LS!!!! Dependable power all the time. Now I need twin turbos!!

[breeze85cten]

Here is some more before and after I tore it apart.

[NONHOG]

Originally Posted by breeze85cten

Here is some more before and after I tore it apart.

That second pic. Wow looks sharp. Lots of elbow grease involved!