Bill71

I need to get started on an engine for my 71 Camaro. Car will be a dedicated track car with a little street driving. I want as much power as possible but still have some reasonable durability. I am looking for a powerband of 3500-7200. I want to use the Trick Flow Gen X 255 heads. My thinking is the short stroke will be happier at this rpm but don't want to be looking for more power after the engine is built. I know the LS3 block was not designed for a 4" stroke like the LS7 but the 418 seems to be very popular. Any advice on which size engine as well as parts recommendations is appreciated.

Other specs: T56, Edelbrock single plain, 4150 TB, Holley HP ECU, rear gear tbd.

newschool72

iTrader: (12)

418 spun to 7K will most likely be quicker than a 376 to 7500. I would go with the stroker for the added torque. Built a little milder with forged quality parts should mean a longer life too.

1989GTA

With your criteria I would go with the 418 hands down. More power and the realiability will be there.

Bill71

Ughh! I just realized I did not clarify that track meant road race track. Lots of time spent at high rpm. Does that change any of the responses? Thanks for the input.

MertezWS6

iTrader: (8)

418 FTW! love the torque and 500+ at 3500 RPM'S...comes on violently

Ari G

iTrader: (25)

With the 255 heads you want a bigger cid motor then a stock LS3 as your rpm are not real high to use them up

With the durability that would be your valvetrain and camlobe selection mostly but a .866 piston pin(custom pistons) would help you if you go with the 4" or 4.125" stroke as the piston will not stick out as much

Bill71

I'm a little confused by the comment. If I am correct the 255 head is actaully a smaller port than the factory LS3 head so why would it not work for 376 cubic inches?

Ari G

iTrader: (25)

They will work fine either way but the bigger motor will put a higer pressure demand on them and that is good for your lower rpm range and throttle response

FLYZNTN

You could go with a 3.9" stroke or a 3.825" stroke.

4.08 x 4 = 418.369
4.08 x 3.9 = 407.910
4.08 x 3.825 = 400.066

Callies makes a 3.9 in a magnum that is a very good crank.

Just a thought....

Also, if you are going with the TFS 255 you may want to consider going to a lighter valve if you are turning high RPM for extended periods of time.

Bill71

Agreed. Hollow stem with titanium retainers are what I plan to use.