JustAZ06

So, unfortunately, my ls7 dropped a valve (like many others) causing catastrophic engine failure and now in the market for a new motor. It's between the ls7 and the lsx 454. Whichever way I go is going to be expensive so whichever motor I decide on will remain stock so I can maintain the warranty that they come with.

That said the lsx 454 will yield 580hp /600tq (fuel injected, crank hp) but is a bit heavier and doesn't revv out to 7k rpm.

The ls7 is obviously lighter and has a bit more rpms. 505hp/470tq.

Stock for stock which engine do you think would yield better performance, mostly street racing?

I know what the initial answer at first glance is but both have some pros and cons that may even the playing field more than I may realize.

Here is a link to the page I'm looking at, hit LS motors and scroll down to the ls7 and 454. Gm has a dyno sheet of both engines as well... thanks for your advice. http://m.chevrolet.com/performance/crate-engines.html#.VS6FZsnD_qC

blackandgold

iTrader: (2)

Iron or Aluminum 454?

JustAZ06

Iron block 454. From what I can gather it's roughly 100lbs more than the ls7.

blackandgold

iTrader: (2)

Per the weight of blocks thread, it looks like you'll be penalized ~120lbs for the 454 block. I'm not sure if the heads/accessories are any different. I'd stick with the LS7, adding that much weight to the nose of your car would negatively impact handling. Plus I'm guessing replacing an LS7 with a new one is easier than swapping in a 454.

JustAZ06

Ls7 is 11.5k for a long block and the lsx 454 is 9.5k. So even being down on power you think the ls7 would still be a quicker motor?

gnx7

iTrader: (28)

If this isn't covered under warranty....

Call RED or ERL to resleeve a 5.3 and then either buy some used LS7 heads and have them redone from the Corvette forums... or bite the bullet and get some TFS LS7 heads or go cathedral port AFR/TFS etc.

Max out your compression for the fuel you will use.

Never buy a crate motor if you have a functional brain! If the warranty is there.... work with a dealership that will allow you to port the heads/do a cam and live it up!

blackandgold

iTrader: (2)

This is a fair point. For 10k you can have a lot more power from a resleeved block.

One Bad Duramax

just call steve at red i had him do my ls7 win in fast work honest price