Modern 5.7 Hemi Stroker kits let you change your compression ratio at a little extra cost. Some of them even give you that elusive extra 0.5 to 1 point more with high octane fuel, and if you keep the engine temp down around 200oF adding some water/methanol injection, you might just nose ahead of the competition.
Let’s take a look at some of the 5.7 Hemi Stroker kits on the market today.
The GM LS is a power for value kit; it’s a tough and potent engine that is based on old 5.3L engine blocks. What GM does, is add a large turbo and camshaft that delivers 1,000 horsepower. Consider the GM LSX or even the World Products’ Warhawk tall-deck block. If you add a 4.250˝-stroke crank, you end up getting a massive 511cid.
With this in mind, consider that these engines do have their limitations and you need to pull back to get the best performance. As such, it’s best not to add anything larger than a 4.000˝ Stroker crank in a stock block. These blocks come with a typical 9.230˝-tall deck and have poor piston stability at the bore bottom. As such, a 4.000˝stroke will give you a 408 cid motor with a 4.030˝ bore, or, you can get a 383 cid with a 3.902˝ bore.
If you use an LS3 block, then a 4.000˝ arm will provide up to 416 cid, and for an LS7 you will get 427 cid. Based on experience, anything over 454 cid is not recommended since they have very short life spans.
If you are looking for a budget-friendly option, and want to reach 408 cid, consider starting with an LQ9 or LQ4, these iron truck 6.0L engines can be bored to 4.030˝ then you can install any 4.000˝ Stroker crank kit. This will give you a high compression 408 cid engine, and if you combine it with an LS7 head or equivalent, you will reach 650hp and 550 ft.-lbs. of normally aspirated torque.
Other options, instead of old iron blocks, are taking an aftermarket LS engine such as a Dart Aluminum or Iron block. Another option is the Racing Head Service’s (RHS) LS Race Block which is cast out of A357-T6 aluminum and comes with press-in spun cast-iron liners. These liners are available in two bore sizes 4.125˝ and 4.165˝. This model has a raised cam position that can take up to a 60mm cam core. It also has a relocated oil galley that gives room for a 4.600˝ stroke crankshaft, and the oil galley directs oil to the main bearings first. You can get two different deck heights, the standard 9.240˝ and their tall model of 9.750˝.
Another option is back to the World Products’ Warhawk LS Race Block that is cast out of 357-T6 aluminum. This model comes with rugged 1045 steel cross-bolted main caps that are retained with huge 7/16˝ main studs and cross-bolts. The Warhawk also brings you two-deck height options, their tall 9.800” and their standard 9.240˝deck. With these two models come two bore sizes 4.000˝ and 4.125˝, this gives you room to clear a 4.500” stroke crank.
Now let’s take a look at the Mopar Gen III Hemi made by FCA (formerly Chrysler). The Gen III Hemi comes with exceptional-flowing heads and a solid block design that takes a larger rotating assembly easily with no need for machine clearance or grinding. There are three versions produced available for trucks and passenger cars. One of these is the 5.7L which has a 3.918˝ bore and 3.578˝ stroke. What you need to take heed of is that the Gen III Hemi cranks come with a pre-2008 reductor ring that has 32 teeth. You do not want to start building up a stroked engine with an incorrect reluctor ring. The most popular Mopar kit gives you a 4.050” Stroker crank that builds up to a 392 cid engine out of a 5.7L model.
There is no limit to the number of options available on the market today. I have only briefly outlined a few of them, but these are the tip of the iceberg, the best tip mind you.