LS3 and LS7

[Skylane765]

Why does the LS7 have 500 hp but the LS3 crate engine has 535?

[HDRDTD]

The LS3 crate engine from Chevrolet is rated at 430hp
http://www.chevrolet.com/performance...gines/ls3.html

I would imagine many suppliers offer some kind of LS3 crate engine configured their way.

[Skylane765]

Ok, so others like Summit that sell the LS3 are doing something to increase the HP? They are not direct from GM.

[gen=5]

ls7 is rated with all the a/c ps etc...as it sits in the car..the crate ls3 is rated with just the motor on a stand.It could have a different cam depending on the crate part #...the circle track Ls3 has different cam,and carb intake. you know how when you add headers to your car it gains power etc... well if the ls7 was put on dyno with just headers it would have close to 600 hp if not a little over...all of those accessories/exhaust makes a big difference..also crate motors tend to be rated differently when compared to the same motor in a car...crated motors are gross rated normally and a cars power out put is rated by SAE standard's..
back in the old days everything was gross rated,then they installed the motor in the cars and still rated the motor in the car with 400hp when the real output as it sat in the car might of been as low as 325 or 350hp...depending on the accessories,and the exhuast system...crate motors tend to be rated with only headers or even a tune as well...it helps with sales and shows what the motor really makes.
If all motors came maxed out installed,there would not be much need for as many aftermarket parts thats for sure,lol..

[gen=5]

Not completely true the GM PART NUMBER 19301360 is a ls3 rated at 525 and its a GM motor gross rated,the 430 is rated as a replacement for the ls3 in the gen5 GM has a couple different LS3 crate motors...based on what GM states in there parts catalog is the only change on the 525 is the camshaft...95hp is a lot for just a cam...like i said its mainly due to having no accessories and being gross rated..

[HDRDTD]

Originally Posted by Skylane765

Ok, so others like Summit that sell the LS3 are doing something to increase the HP? They are not direct from GM.

Correct.

[SSCorbo]

Originally Posted by Skylane765

Why does the LS7 have 500 hp but the LS3 crate engine has 535?

GM I believe sells variations of the LS3 through gmcrateenginedepot and there performance parts. The three variations are the stock 430, 475 and 525 I believe. Basically just cam upgrades I believe, Plus the LS7 is of course underrated. My buddies bone stock LS7 put down 478 to the wheels on a mustang dyno

[hognutz]

Originally Posted by Skylane765

Ok, so others like Summit that sell the LS3 are doing something to increase the HP? They are not direct from GM.

those LS3 motors have revised camshafts. they still come directly from GMPP but they are not a factory instlled LS3.

I still think an LS7 could win the race. the LS7 has a broad power delivery that is pretty crazy for a stock motor. it also has 700 more rpm to play with.

to put it plainly my Z06 felt more than 70hp more than Z51 vette. just smooth power everywhere.

If I were building a hotrod though the price of the 525hp ls3 would make me buy it and just gear the car accordinly.

[Scott@Bjorn3D]

Actually the 525 version has cam and head work.

[jessrayo]

Originally Posted by hognutz

If I were building a hotrod though the price of the 525hp ls3 would make me buy it and just gear the car accordinly.

The actual peak HP may be better but the larger displacement is going to make a lot more torque and overall be easier to drive fast because it will have a much wider band of useable power. I love the 427 with a blower on it.

[hognutz]

Originally Posted by jessrayo

The actual peak HP may be better but the larger displacement is going to make a lot more torque and overall be easier to drive fast because it will have a much wider band of useable power. I love the 427 with a blower on it.

I like the 427 better too but If I were building a project car I would still get that LS3 based on overall project cost.

if I were more well off I would do something like you did for sure. every time I have built a car I have went like 10k over budget so I would just save some of that up front ha ha.

the cost of the 525hp crate is pretty good. I have built old school small blocks that cost that and proabalby had worse road manners and no more power.