"Warm Air Intake" Apparently increases fuel efficiency?

[Duk]

it says FI not F1.

I stand corrected, but my comments still hold true.

[Cuts]

I used to have a JE camira as a daily, and since i had it for a few years i did do one or two things to improve economy.

2" mandrel bent exhaust, 1 muffler 1 resonator, no cat

twin throttles (second throttle didnt open untill over 1/2 throttle so economy and low throttle openings wasnt affected).

and lastly i had a cold air/ram intake on it.

Yes it was tried and tested i could get 800 kms to 55 litres. Picking up about 30 kms a tank over the pre cold air/ram intake.

Also i made a dodgy manometer (see pic) and had the hose just before the throttle i cant remeber exact figures but it had positive pressure pre throttle when above 80 even at wot


Dodgy manometer (water with die in it) and the intake, the pod was in there and the area behind was all sealed.


Point of this post being i did notice an improvement after the ram/cai. Weather that improvement was because the engine doesnt have to work as hard since there was positive pressure before the throttle, or simply because of the fact it only drew in cold air im not sure.

[AdrianS]

Yes it was tried and tested i could get 800 kms to 55 litres. Picking up about 30 kms a tank over the pre cold air/ram intake.

How dare you interrupt our speculations with facts ! That sort of thing will get you kicked off the internets, mark my words.

Was that economy change after all the mods, or just the CAI ?

[Cuts]

after all the mods

[oldcorollas]

Weather that improvement was because the engine doesnt have to work as hard since there was positive pressure before the throttle, or simply because of the fact it only drew in cold air im not sure.

see this doesn't exactly make sense

the engine power required is determined by stuff outside the engine.
the amount of air the engine sucks in is determined by the power required.
the vacuum in the manifold is determined the amount of air being sucked in by the engine, and the throttle is the biggest restriction (and contributor to pumping losses)..

there is almost no restriction between throttle and outside world, relative to the pressure drop between throttle and engine, ie almost no work is being done to get air from filter to the throttle...


so for the engine to "work less hard" due to the higher pressure from the CAI, it would mean that more air is going past the throttle and into the engine... which is the same as opening the throttle more.. and will use more fuel since you are getting more air into engine.

conversely, if you close throttle more, but still get the same air going into engine due to the pressure increase from the CAI... you still have the same air going in = same amount of fuel..... cold air or not.


perhaps.. as is often the case... after all these economy mods were done, you drove the car more carefully to try and increase economy... and unsurprisingly.. it did

also, making exhaust less restrictive, for a given cam overlap, will often/generally increase the amount of fresh charge being sucked through = worse economy..

[Cuts]

im not an engineer obviously im just stating what happened.

i had it for 4 years i doubt my driving style changed significantly enough in the last 6 months compared to the 3.5 years previous.

Someone get a stock camira (shudders i know) and see if they can get 800 kms to 55 litres. Since no-one in their right mind would buy a camira we will have to conclude my information is correct and move on

[AdrianS]

These articles are both from people with technology to sell, but still worth a quick read. They are talking about using variable valve timing to reduce pumping losses at part throttle.

http://www.mechadyne-int.com/vva-ref...sses-si-engine

http://www.mce-5.com/vcr_strategy/pumping_losses.htm

An engine dyno I worked on for a certain automobile manufacturer had a "motoring cycle" where the engine was spun by a big electric motor with the ignition off to measure friction / pumping losses. I don't have hard numbers any more, but the amount of throttle opening had a huge impact on the power required to spin the trusty 4AGE - think 10's of kW difference between open and closed throttle.

I'm trying to do some modelling on inlet air temp vs pumping losses : I need to know some typical figures :

Manifold vacuum / pressure at cruise
Cruise RPM
Inlet temperature
Engine Size.

Anyone got some "typical" figures for me ? If you have a mapped ECU (ms / motech / whatever) you should have the data I need.

[Cuts]

205 is typically:

-10 in/hg
2800 rpm
28 dec C
1998 cc

[oldcorollas]

These articles are both from people with technology to sell, but still worth a quick read. They are talking about using variable valve timing to reduce pumping losses at part throttle.

isn't that a standard feature of toyota engines now?

[AdrianS]

isn't that a standard feature of toyota engines now?

Yep. Everyone with VVT engines is doing it now. If I recall, some BMW's are using valve / lift variation instead of a traditional throttle butterly.

Cuts : thanks. I'm still building the model - doing some fluid dynamics research first, 'coz I'm very rusty

[AdrianS]

More technical reading here :
"Methods to improve efficiency of four stroke, spark ignition engines at part load
Osman Akin Kutlar *, Hikmet Arslan, Alper Tolga Calik
Automotive Division, Department of Mechanical Engineering, Istanbul Technical University"

http://www.energyscience.uu.nl/files...ar-ecm2005.pdf

Consider an SI engine that has 30–35% effective efficiency at WOT (full load) as a power source for a vehicle. For the same engine working at 10–20% load, which corresponds to about 50–60 km/h vehicle speed on level road, the effective efficiency will be only 10–20%.

The internet is too big - it's eating my life - so much to learn

[Big rob]

AdrianS - As already stated, pumping losses and reduced dynamic compression ratio at low loads with respect to open throttle.

However, the most efficient point correlates to the RPM range where the brake specific fuel consumption is lowest, this is always at full load due to the two reasons above.

[AdrianS]

Back to the "warm inlet air" subject - I note that none of the technical / research papers I found mentioned it, although they mention VVT, variable compression ratio, EGR, DFI and others. I'm guessing that

a) it's not "sexy" and novel enough to write a paper on,
or
b) the temperature difference is too low to have a huge effect (especially compared to EGR / VVT). 50 C vs 25 C is only 323 K vs 298 K, or 8% difference in absolute temperature. And you'd need an exhaust heat exchanger to get 50 C inlet temp at cruising speeds.

It would make a nifty project for any engineering students out there : "Effect of inlet air temperature on part-throttle fuel efficiency".
I know Toyota in Altona (VIC) have an appropriate engine dyno, with full instrumentation including fuel flow metering, computer controlled throttle & coolant temp, etc., etc. It is accurate and repeatable enough to measure small % gains, which would be near impossible to do on a chassis dyno. You could also measure power required to spin the engine at different throttle openings and RPM. The hard part would be persuading them to let you use it.

Any volunteers ?

note - I am not associated with Toyota and my opinions are all my own.
(paranoid about lawyers).

[Hiro]

It would make a nifty project for any engineering students out there : "Effect of inlet air temperature on part-throttle fuel efficiency".
I know Toyota in Altona (VIC) have an appropriate engine dyno, with full instrumentation including fuel flow metering, computer controlled throttle & coolant temp, etc., etc. It is accurate and repeatable enough to measure small % gains, which would be near impossible to do on a chassis dyno. You could also measure power required to spin the engine at different throttle openings and RPM. The hard part would be persuading them to let you use it.

Newcastle Uni have an engine dyno with most of those systems, running an early 4AFE, and have had for some time. Granted the coolant temp was controlled by a hand-valve, and fuel consumption by visually measuring level drops, but the RPM and throttle were computer-set which helps with repeatability. We used it to do some labs in Thermodynamics, as well as ripping the 4A off and chucking the CBR engine on for SAE tuning.

[AdrianS]

Newcastle uni dyno sounds perfect.