I am thinking about building an aluminum LS2 4.0" bore stroker myself. I want to use either a 3.9" or 4.0" crank, giving me either (roughly) a 392 or a 402. I know the 4.0" stroke will get me more cubes. Is there any benefit to the 3.9" stroke over the 4.0" stroke?

Is the 3.9" easier to assemble?

I think the rod angles are less severe on the 3.9 stroke - does that mean it will not burn oil like a 4.0?

Anything else to consider?

 

The problems I read with the 4" crank is that with a 6.125" rod in a GM
production block it pulls part of the piston out of the bottom of the sleeve.
This tends to scuff the skirts, flutter the rings, and generally use oil. I was
recently considering either building a .020" over LS2 block for 368 cubes or
putting a 3.9" crank in my LS1 block for 374 inches. I found the K1 crank,
Callies Compstar 6.25" long rods, and a short 1.053" piston from Arias that
would have a bettter rod to stroke ratio and not pull the piston out ABDC.
An LS2 block at 4.005" with a 3.9 crank would make a nice 393 but trying to
find a piston with the short compression height is difficult. IIRC Arias or JE
had a 1.105 or 1.11 CH for a 4.005" which could work with the 3.9 crank and
a 6.20" rod but you'll need a .060" cometic gasket as the piston will be out of
the deck by almost .020".

 

Wiseco makes a 1.05 CH pistons and you can make them work with a longer rod

 

Thanks for the info guys. It seems like a lot of trouble to get less cubes.

I can see that the 4" stroke 402's are pretty popular. Do most of these engines burn oil just by design? I've searched and seen threads that seem to go either way... mostly towards the engines burning oil.

 

Wiseco and other piston manufacturers recognize the issues with LS motors and short sleeves so they have developed pistons to combat that issue. Many of 402's are running around without issue so I don't see why you just can't order you up a rotating assembly and roll with it. Now a 4.100 or 4.125 crank that's a different story.

If you planned on running boost, then I would tell you 3.9 crank all day long to get a better piston in the bore.

 

My car is at Cartek in NJ now & I'm picking it up next week.. they did the following to my 05 LS2 with an (A4) transmission, and 2800 converter with 3.15 rear end gears...

Callies 4" forged crank

Manley forged connecting rods

Wisceo pistons

Melling oil pump

Kooks long tube headers

FAST 102 ported Intake

Ported & polished 243 heads

42 lb injectors

dual valve springs with titanium retainers

Cartek 3x competition cam (I Don't know the specks) I asked that it not be TOO aggressive as I'll be driving it at home with the wife, & its a 100 mile drive to Englishtown or Atco tracks..



Late next week (Dec 18 - 20) I should have put about 300 miles on it and it will go back for a dyno tune... Would I be expecting 500 hp unreasonable ??

 

Wow - I was also considering a 3.905" bore 373, but I came across this LS2 block and I think that's what I'm going with.

Also, Race-Tec, which I believe is owned by a former owner of JE, has a bunch of good value-oriented pistons that are supposed to be of excellent quality. There's also a reseller out there that will refinish the top of the piston to any height you want at no charge!! That might be the way to get the piston to come out of the hole .007 or whatever it's supposed to be.

No boost for me. I have a stock take-off TVS1900 from a Cadillac CTS-V that doesn't clear my hood, so I'm going to scrap that idea and build a stroker instead. My car is heavy at 3,900 lbs and has very shallow gears (2.48 1st gear and 2.88 rear gear) so I could use a little extra stroke!

I don't want to beat this to death, but what features am I looking for WRT an improved stroker piston? Wiseco makes good stuff but there are other lower cost options out there and I'd like to know if they have the improved design attributes.