LT1? LS1? What is it?
Supreme Member
Joined: Apr 2000
Posts: 1,338
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From: Chander, Arizona USA
Car: 2006 Silverado 1500
Engine: 5.3L
Transmission: 4L60E
LS1 is considered a gen III small block, but there isn't really much in common with the LT1 gen II small block. the LS1 is a 346 cubic inch 5.7 liter aluminum block/aluminum heads engine with 6 bolt main caps 1.7 ratio roller rockers, composite intake that doesn't seal to anything but the intake part of the heads, etc. many advances and is a completely different engine than the gen II. the gen II is the LT1 which is alot like the older 5.7 liter 350 cubic inch engines and comes with 2 and 4 bolt mains depending on y body, f body, or b body, and comes with aluminum heads also depending. the y body got 4 bolt mains and aluminum heads, the f body got a 2 bolt main block with aluminum heads, and the b body got cast iron heads with 2 bolt block. the intake on the LT1 seals to the lifter valley and intake side of the heads causing it to be heated by the lifter valley oil and leak every 30k or so. the LT1 has stamped steel rocker arms with a 1.5 to one ratio.
as for parts on them, the water pump on the LS1 is belt driven and the LT1 is cam driven. the LT1 has a distrubutor called opti-spark also driven off the cam and the LS1 uses individual coils fired by the pcm.the firing order on them is different as well as the port configuration. the LS1 is ieieieie and the LT1 is ieieeiei. this pretty well covers the basics.
as for parts on them, the water pump on the LS1 is belt driven and the LT1 is cam driven. the LT1 has a distrubutor called opti-spark also driven off the cam and the LS1 uses individual coils fired by the pcm.the firing order on them is different as well as the port configuration. the LS1 is ieieieie and the LT1 is ieieeiei. this pretty well covers the basics.
