4.0 throttle body specs?...

I actually like that the engine runs fine on cheap regular 87 octane gas, and already gets excellent gas mileage. So it doesn't make any sense to go through the considerable expense of tearing the engine apart to mill the head, or replace pistons, and then to be stuck with an engine that only runs on more expensive premium gas.

The throttle body only meters air, so running one with a larger bore and butterfly just makes the throttle more responsive.

 

Nitrous=more compression

 

Yeah, it does. But I'm speaking within the practical context of normal day to day driving.

Still haven't made it out to the wrecking yard (going to the dyno shop today ), but I highly suspect that the 4.0 throttle body bolt pattern is 65mm square just because so many other Toyota throttle bodies are also square.

 

Im getting 9.6cr from my searches, which leads me to say you've got lots of room for improvement there. I used to run 87octane on a 12.8cr daily driver with a conservative tune. It'll wake up the entire rpm range. It does sound like a hassle to do but like you mentioned, milling the head wouldn't be too bad. Maybe pick up a spare head at the autowreckers

 

Benefits from this?

 

Raising the compression ratio or larger throttle body?

As op said, bigger diameter(with some exceptions) will allow more air to flow at pretty much all throttle positions and should give you gains.

Raises cr will create a more compact explosion to happen in the chamber and push the pistons down harder(in a nutshell).

While one thing alone may not show drastic results, everything working together will provide great results.

 

Sorry that ^^^^ was what I was asking.