what are the differences between the LT1 block and the LS1 block?

**AaBryan** · 10-15-2007, 05:07 AM

I tired searching a little bit, but my skills are highly lacking in that area so I apologize in advance if this has already been addressed multiple times (which I would assume it has been)

My buddy is parting out his LT1 Trans Am and is to the point there he said I could basically have anything I wanted. I drive a 98 LS1 Trans Am and if the blocks are a direct swap I'm going to take his block (he's already sold the heads and cam) and start a nice little build up from there.

Basically, I'm asking if there are any reasons I shouldn't use the LT1 block, build it up, and put it in my LS1 car. Any input on the differences between the two blocks would be greatly appreciated.

**sunsetorangess** · 10-15-2007, 08:25 AM

Its not worth your time or money, If you want to start a build i would start with a better long block. ls1,ls6,lq4, Try to stay away from the lt1
J

**9T8W66** · 10-15-2007, 11:29 AM

LT1 is based off of Ed Coles original Small Block(SB) from 1955 and is a Gen II SB
The LS1 is completly differentand is a Gen III SB

**stangslayer98** · 10-15-2007, 12:14 PM

correct me if im wrong but i do recall the lt1 being an iron block with aluminum heads while the ls1 is all aluminum block/heads from a weight perspective you dont want that

**sunsetorangess** · 10-15-2007, 04:46 PM

Originally Posted by stangslayer98

correct me if im wrong but i do recall the lt1 being an iron block with aluminum heads while the ls1 is all aluminum block/heads from a weight perspective you dont want that

Your correct, The weight difference is about 100lbs, fully dressed. Also the lsx had nylon intakes and the Gen 2 motors had cast iron or alum. Not to mention the lsx motors moved up to the coil pack design while the gen 2 motors used the Dist. or opti.
J

**0rion** · 10-15-2007, 09:44 PM

LT1's also had reverse cooling.

**ATCharming** · 10-15-2007, 09:57 PM

lt1s will be heavier than ls1's due to being iron compared to ls1s being aluminum. BUT, if you plan to REALLY build it up, iron is stronger than aluminum.
ud have to make big power to have it make a difference tho, just something to consider

**C&Cbird** · 10-15-2007, 10:03 PM

The LT1 and LS1 blocks have very, very little in common. The LS1 block is actually shorter than the LT1 also.

**98ls1blackbird** · 10-16-2007, 06:20 PM

About the only thing they have in common is the bore spacing, everything else is different.

**AaBryan** · 10-16-2007, 08:48 PM

excellent info, thanks gang. I'll just let him sell the LT1 block with what's left of the car.. If anyone in South Jersey needs and LT1 block let me know