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LS3 or LS7
Thread Starter
Intermediate
Joined: May 2011
Posts: 28
Likes: 0
From: Texarkana TX
LS3 or LS7
Hey guys. This is a great forum that has been created, ton of really good information. Unfortunately I am at now in need of some advise on new engine build.
I have a 2003 Z06/ls6 that had some upgrades at the time I purchased the car. 215 ET Performance heads, long tube headers, big cam (do not have grind card), underdrive pulley, dyno tune approx. 550hp at crank.
A missing chunk of #7 piston is the cause of this new engine build. After tearing down, I found 2 cracks in the cylinder wall.
My mission is to replace with something more durable. Would the ls3 or ls7 be a better choice compared to just replacing the ls6? All forged of course. I would prefer to reuse all upgraded parts listed. Does anyone know if it that is possible?
Any advice would be appreciated.
I have a 2003 Z06/ls6 that had some upgrades at the time I purchased the car. 215 ET Performance heads, long tube headers, big cam (do not have grind card), underdrive pulley, dyno tune approx. 550hp at crank.
A missing chunk of #7 piston is the cause of this new engine build. After tearing down, I found 2 cracks in the cylinder wall.
My mission is to replace with something more durable. Would the ls3 or ls7 be a better choice compared to just replacing the ls6? All forged of course. I would prefer to reuse all upgraded parts listed. Does anyone know if it that is possible?
Any advice would be appreciated.
Race Director
Joined: Jul 2007
Posts: 11,467
Likes: 8
From: 972 and 405
I've read that the LS7 has thinner cylinder walls than an LS3/2. If you're not going for a FI application I would assume the LS3 would be a better motor just for that reason. But I think people have been safe with the LS7 if you're just going to use H/C/I.
-Alex
-Alex
Le Mans Master
Joined: Apr 2001
Posts: 5,478
Likes: 718
From: Black Forest CO
I don't know about the heads so I can't answer that one. I would optimize the cam for whatever engine size you end up with. I have a forged LS7 based engine in my 02 Coupe and love it. The car is a blast to drive. I prefer the power delivery of the large cubic inches to the supercharged setup that I had before.
Tech Contributor
Joined: Jan 2007
Posts: 19,515
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From: Dyer, IN
Tech Contributor
Joined: Jan 2004
Posts: 20,030
Likes: 289
From: Wylie TX --> Less is More, except under the hood !
Because the cylinder walls on the LS7 are so close together it makes the LS3 a better choice for a blower.
LS7 would likely be the best for a NA application.
Toque
Safety Car
Joined: Jul 2010
Posts: 4,018
Likes: 388
From: Chandler AZ
How about a 454 built from a LS3 block that has been resleeved, 5000.00 block, crank, rods, pistons, +1200.00 for the LS3 block core.
Or I was reading they can do a 427 for you for 3500.00 for the short block, and 1500.00 for the LS3 block core, the 427 is not sleeved, it's small enough to not need sleeves.
http://www.erlperformance.com/gm-ls-...e-short-blocks
Or I was reading they can do a 427 for you for 3500.00 for the short block, and 1500.00 for the LS3 block core, the 427 is not sleeved, it's small enough to not need sleeves.
http://www.erlperformance.com/gm-ls-...e-short-blocks
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Melting Slicks
Joined: Nov 2009
Posts: 2,536
Likes: 15
Thats a very loaded question....but I can think of no circumstance where a 6.2 out shines a 7.0 (if the combo is built for the cubes). N/A or FI or on the jug !!
Thanks....budget goals ?? performance goals ?? cars main duty ??
Thanks....budget goals ?? performance goals ?? cars main duty ??
Tech Contributor
Joined: Jan 2007
Posts: 19,515
Likes: 1,188
From: Dyer, IN
Race Director
Joined: Jul 2007
Posts: 11,467
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From: 972 and 405
Tech Contributor
Joined: Jan 2007
Posts: 19,515
Likes: 1,188
From: Dyer, IN
Who knows.... the point is, you are regurgitating a fear discussed some 5 years ago......and has long since been proven wrong. Next time you see a guy with a c6 Zo6 supercharged, ask him how disappointed he is with 630 RWHP on a conservative tune.....
Thread Starter
Intermediate
Joined: May 2011
Posts: 28
Likes: 0
From: Texarkana TX
Car will just be a weekend driver and will see some track time also. NA I think is the best for what I'm looking for. I've heard that all ls series motors will accept the same heads and cam. If that is the case, ls7 seems to be the best choice. What difficulties will I run into with the factory wiring conversion?
Race Director
Joined: Jul 2007
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From: 972 and 405
-Alex
Le Mans Master
Joined: Jul 2007
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From: Oswego IL
Burning Brakes
Joined: Feb 2006
Posts: 1,085
Likes: 3
From: Ottawa Ontario, Canada
The new LS3 blocks (2009 & newer) are shared with the LS9 as far as I know, and are extremely strong and stiff... GM put a heckuva lot of testing into that one for support of the LS9 engine.
A forged short block with a stroker crank based on an LS3 block would be a great place to start, the 4.060 bore is good for head breathing too. Going bigger than that can start getting expensive in a hurry. I've never researched this as if I were actually going to build it, but this is my observation based on what I've read.
"LS7" and "427" sound cool, but anything starting with an LS7 block is going to be a bit more expensive. An LS3 with a 4.1" crank will get you 426 inches.
A forged short block with a stroker crank based on an LS3 block would be a great place to start, the 4.060 bore is good for head breathing too. Going bigger than that can start getting expensive in a hurry. I've never researched this as if I were actually going to build it, but this is my observation based on what I've read.
"LS7" and "427" sound cool, but anything starting with an LS7 block is going to be a bit more expensive. An LS3 with a 4.1" crank will get you 426 inches.
Drifting
Joined: Apr 2003
Posts: 1,391
Likes: 10
From: Jacksonville FL
More cubes is better, but will the parts you currently have allow you to take full advantage of the extra cubes? Not IMO.
If you buy the larger engine accepting that you'll only gain TQ you may be happy with the outcome, but it will not run like other similar CI motors.
I have had an LS7 based 440 for years now that I'm very happy with.
If you buy the larger engine accepting that you'll only gain TQ you may be happy with the outcome, but it will not run like other similar CI motors.
I have had an LS7 based 440 for years now that I'm very happy with.