HTX

iTrader: (1)

This question is based off of a topic in another thread, and i thought it would be more accurately discussed here.

I made the comment that the LS7 was far superior in every way to the LS3. It seems that i may have made a misinformed comment. A few people argued that the LS3 has more potential and responds to mods better. They also said that the LS7 was more fragile and couldnt hold to power adders as well as the LS3 could.

I can see how the LS3 could hold to FI better due to thicker walls, however in a N/A or NO2 application i dont see how an LS3 can outperform an LS7.

Anyone care to shine some light on this topic?

NemeSS

iTrader: (127)

LS7 comes with CNC ported heads from factory, dry sump oiling system, extraordinary rotating assembly. and the cylinders are correct length for the stroke of the crankshaft used, larger bore cylinder case. all abvious.

the LS3 does not come with any of those features. its just another service engine. very similar to the 6.2 L92 engine.
N/A mod for mod, the LS7 will prove superior.

Forced induction has too many variables to accurately determine which application will hold better capacity for PSI and or chemical assistance from
N2O. Its subjective.

Johnnystock

iTrader: (6)

I think its true that the LS7 walls are more fragile than LS3. Other than that, LS7 all the way. LS3 is just cheaper.

COPO9560

The LS7 has the larger bore allowing LS7 type heads. Believe you would have to sleeve a LS3 block to get 4.125 bore. LS3 can be dry sleeved to this bore where LS1 would have to get wet ones, which appear would be stronger in long run.

I would think a you could gain hp over stock easier with LS3 as LS7 has all the good parts to start with. LS7 starts at 505 hp without headers and might be a little conservative.

As for FI, the new LS9 went back to smaller bore & stroke. Suspect if the LS7 block would have worked they would have used it.

trumperZ06

The mod shops are easily getting ~ 560/590 rwhp with the LS7.

The magical 600+ rwhp requires a very exotic cam which messes up the "street manners".

Corvette looked at using the LS7 block for the ZR1...

But due to the thin walls and GM providing a 100,000 mile warranty, they went to the LS9 (modified LS3) block.

Robin L

The LS7 block is as good or better than the other OEM blocks. One guy split a cylinder wall and suddenly everone thinks they are junk.

The sleeve guys hate them because they can't make them larger.

Many shops PREFER the LS7 block for their big cubic inch engines. Lingenfelter uses them in their 1000+ horsepwer turbo builds.

It's true that you can get a longer sleeve installed in a LS2/LS3 and have more skirt support for those strokes over 4.125".

The LS engines already have decent compression ratio I have heard of guys wanting to put Pro Chargers on their LS7s and expect huge gains. With an engine as refined as the LS7 your not going to see the kind of increase in power that other engines will deliver.

Mike Copelands LS7 with more compression and a different cam made 700 horsepower at the crank. He from the truck on the Hot Rod Power tour!

The only thing to watch is the Ti rods. Once you get much over 700 horsepower you need to step up in my opinion.

And it won't leak past the sleeves either

Robin

HTX

iTrader: (1)

I understand that the LS9 has nozzles that squirt oil on the bottom of the piston to ensure that the cylinder is lubricated at higher rpms. Does the LS7 have these "squiters" as well?

rsz288

Ditto ^^^. Plenty of people split regular LS1/6/6.2L sleeves and blocks too and no one says they are weak. Anything will break when abused enough. If the LS7 sleeve setup didnt meet GM durability objectives (100,000 miles 7k redline), which always seem very conservative, they would come from the factory stronger. If GM meets S/C power objectives with a 6.2L block, why not. Arguably lower cost than an LS7 configuration, and can be marketed to the green lobby as a reduction in engine size.

Pure and simple, only an LS7 is an authentic "427" LS as well. Its a "magic" number!


LS7 doesnt have the "squirters". The oil jets are to take heat out of the underside of the piston crown/piston to help maintain piston strength in that area on the S/C engines (source GM).

LSX350Z

An LS9 is by no means an LS3!

Hans Grüber

iTrader: (2)

What do you mean?

But when one considers the price, $14 000 for the 505hp LS7 and $6300 for an 436hp LS3. One could make a good argument that the LS3 has much more bang for your buck.

sdbrown84

iTrader: (22)

Per dollar for horsepower yes. However you cannot argue that matching the correct stroke with the respective bore will always yield better power throughout the band than say taking an LS3 and stroking it to make a 427 displacement.

S10xGN

iTrader: (11)

Robin,

I've not heard that before, care to elaborate?

Robin L

The guys who I deal with are very conservitive on the numbers. The Stock rod has a split bushing in the pin end. Once that is replaced with a solid bushing the rods hold up very well. They have not failed any but it is better to be conservitive.

My opinions......FWIW


Robin

S10xGN

iTrader: (11)

Thanks, I'll keep that in mind...