I was reading though the forum a little bit and i noticed a lot of words and terms i am not familiar with (im 16 btw)

- TII
- n/a

For turbos

- Spool up time
- Turbo lag?
- VE (thread about larger turbos)

 

- TII
- n/a


TII means Turbo (roman numeral)2. There was a Turbo first generation car in Japan only. America only got TurboII cars in second gen body style.

n/a means naturally aspirated. It uses no forced indiction, ie turbo, supercharger.

For turbos

- Spool up time
- Turbo lag?
- VE (thread about larger turbos)


Spool time is the amount of time it takes for a turbo to make positive manifold pressure (BOOST) as measured from idle. Some turbo's have a longer spool time, meaning that they won't make boost until 3-4K RPM. Turbo lag is the time between when you push the gas to when there is positive manifold pressure.

You can see that the two terms are similar, but spool time is usually at what RPM a turbo makes boost when accelerating from idle whereas turbo lag occurs anytime you go from a closed to open throttle situation. Some times the terms are used interchangably incorrectly.

VE is Volumetric efficiency. I am not sure how to define this correctly and coherently.

 

This is the amount of air drawn into the cylinder/chamber compared to the swept volume. So if a piston (for simplicity) sweeps 500cc (2.0L 4-cyl) and on its intake stroke only draws in 450cc of air, it's VE is (450/500) = 90%. VE varies with rpm, and the shape of the torque curve actually shows you the variation in VE. Peak torque is where VE is closest to 100%. Because in a turbocharged engine air is being pushed in, VE is actually well above 100%. It is possible for a NA engine to exceed 100% VE but it's difficult.

 

Yeah, just what I was going to say!

Getting over 100% VE in an n/a is a careful blend of intake and exhaust timing combined with the proper runner/header lengths. Companies that would like to broaden the RPM's at which this occurs, use things like variable cam timing (VTEC, Vanos, Motronic, VVTL, etc) and variable length intake runners or both.

The early term for this was Ram tuning. That's why Pontiac uses "Ram Air", for example, because this meant more power.

Clear as mud, eh? (That's Canadian for Clear as mud? I'm bilingual)

 

If you want to read up on turbo terminology, I'd highly recommend you get "Turbocharging" by Hugh McInnes or "Maximum Boost" by Corky Bell.&nbsp There is just not enough space to go typing a whole dissertation on turbo systems in here...



-Ted

 

That's just what Mazda spent the last 2 years working on. EG: RX-8 renesis