Nashua_Night_Hawk

I read in Domestic Car Mag that street cars' engine would reach a Volumetric Efficiency of 85% and racing NA engines would achieve close to 100%....

So, I think with CAI and Headers we could improve the Volumetric Efficency.... this is in addition to 2-daul stage intake manifold that add some 25 lbft and 25 HP over CL-P design....

What else one can do to get close to 100% short of Boost or Nitrous?

Wires

You need to pop in a high RPM camshaft (one that develops power near the end of the power band). Gives that lumpty, lump idle.

The problem is when the piston sucks in air, it doesn't fill the cylinders fully (due to restrictions in the intake and exhaust). The high rpm cam leaves the intake and exhaust values open for a bit of time (valve overlap). The outrush of exhuast gas helps pull air into the engine to improve efficency. FYI: You can get over 100% volumetric efficiency.

Problem with the high rpm cam is 2 fold:
1) Shitty gas mileage (since you tend to suck raw fuel out into the exhaust when the overlap occurs). This screws up the ECU.
2) No low end torque or power. Shit loads of upper end power though. That's why race cars rev the engine up to the power band before the launch (or increase the converter stall speed on an auto).

The whole VTEC idea helps accomplish the best of both worlds. You get a cam that has smooth idle, and low end torque. When the RPM hits 4700 RPM, then you get the lumpier cam that gives the higher end power.

My big question is: What's the VE of the 3.2 CL-S? 90%? 95%?

Zapata

Volumetric efficency can only be measured at a specific RPM. Unless you have a variable compressoin engine 100% efficency, 100% of the time is impossible unless you are running forced induction. THis is my understanding.....

If you want to check out a cool design, do some searches on the Miller Cycle Engine.....VERY COOL .

DISRUPTV

but what abt rotary engines, aren't they very efficent supposedly?

DtEW

A very high compression ratio also helps with VE (reduction of clearance volume).

The VE of the CL-S should be very high, given that it's Helmholtz-effect "supercharged", which gives the intake charge a little more than atmospheric at peak output.