Difference Between Similar Terms and Objects

Differences Between LS1 and LT1

LS1 vs LT1

The LS1 and LT1 are two GM engines that are very popular among enthusiasts. The LS1 engine is the newer design that replaced the older LT1 engines. The main difference between the LS1 and LT1 engines is the material used in the block. LT1 engines were made out of cast iron while the LS1 engine blocks were made out of aluminum, except those made for trucks, which are still made out of cast iron for optimal strength and durability.

The change in metal used has distinct effects on how the engines perform. The LS1 engines are much lighter compared to the LT1 engines, and in vehicles, reducing the weight always relates to better performance. The aluminum block of the LS1 engine is also much better in dissipating heat compared to the cast iron block of the LT1. This lets the engine achieve a higher compression without worrying about overheating the engine due to excessive heat. Because of this and a variety of other factors, the LS1 engines produce more power than LT1 engines. The LT1 engines produced prior to the release of the LS1 engines were rated at 260 hp, while the LS1 engine debuted at 345 hp and gradually increased over the years.

Another major difference between the LS1 and LT1 engines was the way they were controlled. LT1 engines were based on old systems that were carbureted and used a distributor to control the firing sequence. On the other hand, the LS1 dumped this style in lieu of a distributorless system. Instead, the LS1 is an EFI engine that uses the ECU to control the firing order as well as the mix of air to fuel. The LS1 engines are much easier to tune because you only need to input values in the computer rather than manually manipulating the values. LS1 engines are also more fuel efficient since they will reduce the amount of fuel being fed into the engines when there is not enough air to burn it. In the LT1, the amount of fuel being fed stayed approximately the same, and some of it will not be burned and is therefore wasted.


  1. LT1 engines have a cast iron block while the LS1 engines have an aluminum block.
  2. LS1 engines are lighter than LT1 engines.
  3. LS1 engines have better heat dissipation than LT1 engines.
  4. LS1 engines produce more power than LT1 engines.
  5. LS1 engines are distributorless system while LT1 engines are not.

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  1. There is so many things in this article that need corrected. While the LS1 did dissipate heat better, the LT1 had a unique feature the LS did not, and that was reverse flow cooling which cooled the heads first, then the block. Most systems cool the block, then the heads. That unique feature allowed the LT1 to run 10.4:1 compression and reduced detonation. This also allowed these engines to run compressions as high as 12:1 on 93 pump gas. As comparison, a factory LS1 runs 10:1 compression. LT1s also were making 330 HP by the end of their run, not 260. The LS1 deputed at 305 and topped at 345 HP in stock form. The LT1 also was NOT carbureted. They were sequentially fuel injected (except 93 which used batch fire injection), but none the less they used 8 injectors and a computer to run, just like the LS engine. The LT engines also only partialy used a distributor. The Opti-spark, while infamous for reliabity, was an extremely high end piece for the 90s and allowed extremely accurate ingition timing. It was driven off the cam like an old school dizzy but sent a reference signal to the ECM to ignite the plugs. The LS1 makes more power because of better flowing heads/intake and the revised firing order and a longer production run allowing a better aftermarket. Either way though, both engines are stout and can be made to make big power.

  2. You fail to inform people that these two engines do not look at all the same and they have few if any interchangeable parts. One of the biggest problems I saw with my LT1 was the location of the distributor…..right under the water pump.

  3. This author appears to be comparing the old school generation 1 LT-1 to the more advanced LS1. It does NOT compare the generation 2 LT1 to the LS1.

    • ha, I have a zz4 chevy crate don’t rem. year it has 350 hp 400 tf dist in rear of engine is this a ls or lt ? what year?

      • It is neither. It is, for all intents and purposes, a Gen 1 small block Chevy.

        As far as year, it’s a crate engine, so it doesn’t really have a year but parts from 1955-03 will fit it. Keep in mind that anything ’87 and newer was fuel injected, but some parts still swap.

  4. I have a 96 Z28 with an lt1. I am having issues with starters, I will be replacing my third starter, not sure why they keep failing, any ideas ?

    • Are you sure it’s the starter? There are other parts in the electrical system that can cause a starter motor to appear bad. Relays, bad connections (especially grounds) can all have an effect. Make sure none of the teeth on the flexplate/flywheel are broke. Make sure the mounting surface for the starter on the block is clean, this is where the starter grounds. Make sure the battery is good condition with clean, tight terminals.

      • For MY fourth replacement I finally cleaned mounting surface (It looked clean but had an insulating build up) Good ground equals full current flow.Problem solved.

  5. Every time I read about Lt & Ls l learn something

  6. I have a 2000 s10 2. 2l and want a v8. What one should I use? This is my first Chevy. Looking for any info. Thanks

    • Put the ls1 in there. They are the most popular
      350 LS1 5.7 liter V8 take the one out of a truck because you want the ls1 that has a cast iron block so you can load a thousand hp and not worry about blowing the motor.
      Or put LS2 in it they literally fit in anything and it’s got 400 hp and 400 lbs ft. Torque. It’s a fucking beast

  7. Like to know more about Lt1s I just purchased a 94 camaro body’s good and I think it’s all stock it has 130000 miles on it like to hear some feed back don’t know how hard it was run

  8. Good afternoon guys,

    I have a 96 Impala AS with 2nd Generation LT1. I’m looking to swap to a LS1 or 3.
    Anyone do this

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