Rebuild time, which motor/porting to pick?
 

I have a strong running s5 13bt with coolant seal fun. Running standalone and a bunch of other supporting mods.

I'm looking at at either

• Rebuilding the 13bt, street or half/bridge and some dowels.
  
• 13b-rew, street or h/b (more then likley street due to extra cst of rew keg)
  
• 13b-re (easier to swap in then 13b-rew. Plug and play really since it uses an s5 style CAS.

Wondering if its really worth it to go to another generation motor for the extra 1krpm redline and downling or if I can just have my 13bt rebuilt to those specs for the same or less then it would cost to find another swap.

Hoping to build a ~400hp motor with the same throttle response I have now (stock s5turbo/motor with a tune etc) I like the instant throttle/boost response :)

if you have an s5 you're all good. you most likely have the stronger irons. Remember that money you spend on engine internals could be spent on a quality turbo system. Don't overbuild one and cheap out on the other. You can buy an omfg ball bearing billet blah blah turbo but have junk rotor housings. Or you can spend a ton of money on internals you don't really need and have a crap turbo manifold. You have to budget wisely. I would not dowel pin this engine, not for your goals. Get a good turbo and manifold and skip porting altogether.

the higher redline you speak of isn't really due to many internal changes between the s5 and later engines except for a few minor things. The FD service highlights document available in the 3rd gen sticky thread explains the differences in engine internals. You can tach an s4 or s5 engine over 8000rpm easily, but that doesn't mean it will make power there.

Stock ports. T3 hotside turbo with twin scroll housing and divided manifold. You can't have big ports, power continuing to increase past 6500-7000rpm, and torque at 2000rpm. Stock ports are very underrated. Would you put long duration/big lift cam(s) on a turbo piston engine and then expect low end?

Thanks for the post :D

I was reading about how the doweling isnt really necessary if i stick around 400hp.

I was planing on having a devided t4 manifold an a s362 (borg warner equivalent to a gt35r sorta) Was going to pick a hotside a/r depending on the porting.

I realize that with porting you change the power band and lose low end. But from what I can tell the car makes crap all below 3000rpm (well, more then an n/a :P)

If you decide to port, leave the closing edge alone, and just street port it to have an earlier opening. You will get the better low-end torque that you're after without altering where in the RPM band the engine makes its power.

:nod: :icon_tup: Listen to the guy, he speaks the truth. For the majority of rotary guys out there, when it comes to ports, less is more. :)