Quote:
Originally Posted by delslo
Ok here's the conclusion I've reached:
+ reduced pumping losses from throttle position = more efficient
+ improved thermodynamic energy transfer = more efficient
- higher load to compensate for lower output = more fuel = less efficient
- lower dynamic compression = less efficient
It's a trade-off and difficult to determine which set is more significant - especially given other variables such as vehicle absolute gearing, road grade, environment, etc, etc.
Additionally, when you throw in OEM ECU parameters, everything goes out the window. Dependent on tps/revs/load/iats, etc, the ECU may or may not add or subtract timing and fuel - totally up to the OEM.
So... it may work, and it may not. Completely dependent on application.
The reason for the OP was if an OEM had done as such, I could totally get on board as they have the knowledge and resources to exhaustively test ideas more-so than enthusiasts. Not to discredit enthusiasts or things done outside the real of OEM, just always helps settle a debate easier.
other:
+ decreased warm up time
+ aids high operating (h2o) temps = more efficient
- higher risk of pre-ignition
- reduced output at all times (ever drive in traffic so bad you can't pull out unless you gun it or completely cut-off someone?)
Personally, I'd rather avoid risk of detonation and reduction of power at all times for speculative or modest gains. If anything, some sort of OEM intake to HAI valve is what I'd like to experiment with.
If it works for others, that's awesome! Thanks for the explanations. Always nice to learn new things  |
For higher load - engines tend to operate more efficiently under higher load. I remember that specifically, but I don't remember the theory of engine operation which supports it.
Driving in traffic so bad... - Don't drive during peak traffic hours, if you can avoid it. You *could* get up to 15% better fuel economy just by avoiding peak traffic hours or taking your lunch break 1/2 hour later. You'll also be less stressed, and have more time.
Example: I could leave to take my wife to school at 7 AM, and be there at 8.30AM. OTOH, I could also leave at 6.20AM, and
still only get her there at 8.30AM. Try to graph your local traffic conditions and patterns, and you'll find similar occurrences.
If you want to test with an OEM intake vs HAI, there are a few options I can think of.
One is a simple flapper valve. Open it to hot air, close it to OEM.
The second is one that I've suggested before, but it isn't as efficient as recovering exhaust heat: If you have an intake box large enough, you can insert a second heater core into it. Run it off your original heater core in series, and as your engine heats up, it heats the incoming air (once the thermostat is opened). You can't claim faster warmup with this method, and it partially cools your coolant as it heats the air. The more temperature differential there is between the intake air and the intake heater's temp, the more cooling effect the system will have on your coolant, so there is a partial trade off. The heating effect can be controlled with a coolant valve, commonly found on vehicles of Japanese origin, that don't have automatic climate control. Another option to control the heating effect is using the flapper valve method with this mod, so that you can control where the air is coming from, instead of the coolant flow through the intake heater.
While there are still other methods, those are the two most pronounced in my mind at the moment.
CFG - I wish I could answer that question about BSFC, but I can't speak to it in good conscience, because the only information that I have about BSFC is that peak torque usually coincides with it in gas engines, and peak VE is usually close to that island as well...
What this tells me about BSFC: The occurrence of the lowest BSFC per engine speed usually is at the point where, per RPM, the most torque is produced with the least losses. This could be partially shown as a function of cam profile, partially as a function of fluid dynamics, engine speed, etc.
There are still too many factors in the "system" for me to definitively say that BSFC would or wouldn't be affected by changing a given parameter.
Hope that helps. Carpal Tunnel is getting worse. LOL.