I've been planning to build a 408 Stroker with an LQ4 for my 3/4 ton truck. I'm now thinking about a 4.100" or even 4.125" stroke since I won't be running it over about 5,500 RPM's and I mainly want torque over HP. I've done several searches and I'm not having much luck. Here are my questions:

What kind of problems do you think that I would have with durability?

Where could I find off the shelf pistons (4.030") with a compression height of about 1.050" to use with 6.125" rods? I want about -15 to -30 dish for an 87 octane engine.

Thanks,

Steve

 

When looking at the 4.100" Eagle crank, it's price makes it the clear choice against the competitors highly priced 4.125". The Eagle is gunna be a clear $1200 cheaper. $1200 for .025" just dosen't seem "cost effective" to me, espeacially since the motor is not going to go over 6k. If built correctly, you should have no problems with durability. The rod/stroke ratio is better than the 382 LS1 motors being built, and they last a very long time. I doubt anyone stocks the piston on the shelf, but having one made isn't that expensive. Wiesco's are very cost effective when it comes to custom pistons. I'm sure some of the companies may have that piston on file, and all they would have to do is cut it. May not even cost you any more.

 

Thanks Beast96Z

 

Consult your piston guy before you buy the crank. If you need a 30cc dish you may have trouble packing all that into a 1.050 pin height and keeping a acceptable crown thickness. He will need to know what your small end rod thickness is above the pin for calculations.
The cylinder length is also on the short side for that crank(it's pretty short at 4 inch).

Kurt

 

Kurt,
Thanks for your insight and experience. I've decided to stick with the 408 and the 4.000" stroke with Mahle Pistons. I ran the simulation on DynoSim and the 408 is actually more efficient with the same cam (see below). The mechanical efficiency of the 408 is greater (piston speed, pumping losses, etc.). It's a case of less being more at the end of the day.

The reason that I was enticed by the 4.125" stroke is that someone is selling a used Lunati on eBay http://cgi.ebay.com/ebaymotors/ws/eB...3ARTQ%3AUS%3A1 with a starting price of $800. Today, the seller has added stock 5.7 L bore pistons that are very light (BORE: 3.899", Average weight - 362 g). Since the bob weights have been drilled for these light weight pistons, the crank will also need Mallory metal. This might be a good deal for someone, but not for me with a significantly heavier reciprocating mass.

All my best,
Steve