N/A 20b build

[RETed]

Originally Posted by aaron_bc

So I've been emailing back and forth with Adam from RX7Specialites in Calgary, AB about a 20b N/A build. It seems like he wants me to do a ton of extra things that I don't know if I need or not. Basically, I'm going to be building a fun street car that I will take to HPDE once in a while. What I want is a large streetported 9.7:1, balanced to 9000RPM engine. He wants me to go with new housings and says new rotors are a necessity. Do I really need all of this for a 300whp N/A build?

No.

I figured a standard 9.7:1 build with S5 rotors, a LARGE street port and balancing would be good. Should I be doing oil mods? Race bearings? Scalping the rotors? He suggested a bridge port... not sure if I want to go that extreme.

The stock bearings in the 20B (and 13B-RE Cosmo) already run better bearings.
The only upgrade would be to go FD bearings.
Not necessary if redline is set at 9k RPM's.

It is debatable about balancing the oil pick-up and districution system, since the engine is so long...
I'd go at least with an upgrade OPR and call it a day - if you're paranoid, run the FD or 100+ psi OPR, and you should be fine.

"Race bearings" are unnecessary unless you're planning to go over 9k RPM's...

Scalping rotors?
Sounds like they are trying to rip you off be charging you for expensive / unnecessary mods.

Bridge port is not really necessary...
We were able to hit 230hp at the wheels on a DynoJet with the STOCK block, STOCK intake, and a too-small air filter:
http://fc3spro.com/PROJECTS/SKY/20B/20bna01.jpg

The car could've gotten close to 250 if the air filter wasn't too small.
The stock intake is not meant for normally aspirated applications.
300 at the wheels is a realistic goal...

What do I need to build a 350whp ITB'd street ported 20b?

Aggressive street port
Short intake system
Tuned header and exhaust system
All the proper safety mods to support those power levels



-Ted