View Single Post
Old 02-07-2018, 10:22 PM   #13
bobxyz
Board Member
 
bobxyz's Avatar
 
Join Date: Aug 2014
Location: Boulder, Colorado
Default

Quote:
Originally Posted by vwbusman66 View Post
So, in research, I have discovered the concept (and reality) that a bigger turbo producing the same PSI (let's say 1 bar/14.5 PSI for argument's sake) is actually flowing a larger volume of air.
A better description would be: A more efficient turbo producing the same PSI (1bar) is actually flowing a larger mass of air.

Power is mainly proportional to mass of air in the cylinder. Higher temperature air is less dense (e.g. hot air balloon) and has less mass. A lower efficiency turbo will heat the air more, while a higher efficiency turbo (at a given boost point) heats the air less. Less heat means denser air, means more power.

No matter what, compressing air increases the temperature, more so with an inefficient turbo. Hence improving the intercooler reduces the air temperature. Lower temperature air means denser, means more mass, means more power.

Quote:
Originally Posted by vwbusman66 View Post
Does this mean that if I'm running a b230ft with a 13c at 1 bar and I replace said 13c with a 15g at the same 1bar, I will need more fuel to maintain a stable/safe AFR?
At 1bar, a 15g is more efficient than a 13c - the rise in boosted air temp at 1bar with a 15g will be less than a 13c. Thus lower temp 15g air means denser air, means more mass, means more power, and needs more fuel at full boost. The MAF - Mass Air Flow meter measure air mass, not CFM (it has temperature compensation built in) and will automatically adjust the fuel flow to match if the injectors can keep up.
__________________
'85 245glt aw71 k-jet -> lh2.4
bobxyz is offline   Reply With Quote