I am looking for some advice on an LS stroker engine build. My primary question is in regard to which block and/or pistons I need to achieve my objectives. I have seen a couple of articles in the car mags discussing concerns with inadequate cylinder length to accommodate 4” or 4.1” stroke and still be daily driver durable and/or have good oil control. I have also seen some articles on piston designs that hint at solving this problem, but don’t seem to come right out and actually state that. I need more guidance from some experienced builders/users of these engines.

My objectives for the engine are as follows…

* To allow me to obtain engine build experience with the LS series engine (no crate engines).

* To be SCCA Solo 2 Street Modified class compatible (this means a production engine block is a must)

* To improve weight distribution of my car (‘96 Camaro) - this means an aluminum engine block.

* To utilize forced induction (inter cooled centrifugal)

* To be 400 ci or more displacement would be preferred (would be willing to trade it off if it helped make forced induction work better)

* The engine will be a daily driver (about 8k miles/year)

* I would like to get 5 years of hard usage between freshenings

The car will be autocrossed and drag raced at least once a month w/ a couple track days per season (street raced whenever possible).

With this in mind, can I build a 402 w/ an LS2 block or 414 w/ an LS3 block or do I really need to start w/ an LS7 block for the longer cylinder length? If the LS7 is really needed, can it accommodate a 4.1” stroke or should I just stay at 4” w/ that block? Are there piston designs that compensate for the short cylinder length and long stroke appropriately?

Thanks in advance for your advice.

 

First off, you'll NEVER want to build an undersquared motor (bore smaller than the stroke) because they compromise durability and high-end power.

I'd look into the squared 4.0" x 4.0" LS2 402 or the oversquared 4.065" x 4.0" 414 LS3 (optimal).

If cost is a concern, you may want to go the LS2 route over the LS3/LS7/L92 route of the LS3. I had a 408ci LQ9 and I've yet to see many rectangle-headed LS3/L92 builds make the power that my motor did with ported LS6 castings. You REALLY need to know what you're doing to design a rectangle port setup of the Gen IV motors due to the huge intake runners of those heads. Cam choice is CRTICAL for those motors.

Mike

 

It really comes down to how much power you want to make. You can make 500 rwhp with a stock block and a blower pretty easily. So the question is how fast do you want to go. I am in my 3rd year of 450 to the wheels NA and about 20,000 miles with no issues. The more power and more power adders, the more it will affect your reliability. So start with a horsepower goal, then reverse engineer.

-Geoff