Hot air intake:How hot?
 

What kind of temps should I look for from a hot air intake? Where is the point of diminishing return as far as temperature goes? No sense in spending more money and working for "X" degrees if 2/3 "X" is enough.

Not sure but most systems will compensate for any ambient temp. Record in the US is something like 137 degrees, so 140-150 would probably be your max range.

regards
gary

depends on how far you drive; my work commute is only 12miles and I get up to 130 degrees. It's up to 100 degrees by the time the water temp gets to 195 degrees; after about 2 miles.
I've been as high as 175 degrees briefly in traffic, but leveled out to 150-160 on a 60mile drive. There were no problems. I think I read somewhere here that the engine starts acting up around 200 degrees of air intake temp.

Thanks for the feedback guys.I made one for the Regal which draws air from behind the radiator. The one I made for the Ram is drawing from around the passenger side exhaust manifold.I wondered about the radiator supplying hot enough air, guess we'll find out. I found a meat thermometer at K-mart for $16 which has a range of 32 to 530 deg.F. Time for some testing.

For carbed motors stick to coolant heat, otherwise you're likely to run into percolation issues, low pressure TBI setups might also suffer issues. MPFI and SEFI motors with injection pressures over 30 PSI or so should cope with pulling hotter air from exhaust shrouding or something.

I have seen temps of 155 or so. with the warmer temps and the better grill block, my temps have stayed around that mark or at least 150.

lovemysan (I think that is his name) has done it on his and has said that 160-180 works well. he might be a good one to talk to. I think he is also the one that said that 200 was too high. can't remember right off hand.

I got the thermometer hooked up in the Regal today.At an ambient temperature of 77 deg. F it maintained 140 deg. cruising down the road after warmed up.It went up to 157 deg. in town,but remember this is with 100% grill block. I may fab. up a pickup tube from around the exhaust manifold area to see if it changes much. I would think it would get warm sooner since It wouldn't need to warm up all of the coolant in the radiator first.Perhaps not better results,but quicker heat.

WAI....I WANT to believe!
 

Not to hijack the original intent of the thread, but is there any measurable difference in FE??

I'm a big believer in "there's no free lunch", it still takes "X" BTU's of energy to move a given mass at a certain speed, you can't fool physics.

WAI reduces air density, depending on the air temp compared to no WAI.

Air density at 200 degrees is 80% of density at 32 degrees.

Less dense air equals lower power, with less throttle restriction. It also allows fuel distribution to be better.

Last tank for me was 68.5 MPG, using operational tactics learned here. It's common knowledge that summertime FE is better than wintertime.

It probably reduces my max power from 96 to 85 HP, but I never use max power anyway.

In sustained high loads (like climbing a mountain) the much larger amount of incoming air would tend to make the air cooler so I still might have the 96 HP in that scenario. In all other cases I don't need it, since my car almost never sees more than 2500 RPM.

regards
gary

I agree with everything here, ('cept maybe "also allows fuel distribution to be better") but can one see a measurable difference in FE due to WAI?? The only real experiment I've seen is by MetroMPG here: https://www.metrompg.com/posts/wai-test.htm and his results are below the margin of error.

I can understand how a WAI would reduce warmup times, plus fuel usage would be less at idle, (less fuel to maintain Stoichiometric) but AFA I can tell, any other FE savings are the same as using less throttle.

I might try it anyway. I track my mileage with every tank and put on 40K/yr, so I may be a good candidate for experimenting....

Thanks for your quick and thoughtful reply, and good luck!

It's theoretically more thermodynamically efficient to use warm air. There's less of the energy in the gasoline going into heating the charge, and more going into expanding and making cylinder pressure. Also due to more volume of warm air being required for a given power level, it should reduce pumping losses slightly.

The reason one can use cold air setups for more power, is that you can get more air molecules in there, for an increase in volumetric efficiency, but not necessarily thermodynamic efficiency. Getting mileage gains with cold air setups is more related to "putting one over on" the ECU and managing to run slightly leaner. Can make more torque also due to great mass of air per unit volume having more momentum.

Which works best on a given engine is all down to how fuel is metered and how accurate it is. Vane airflow systems and carbs probably fare better on hot air, MAP systems can go either way, depending on where and if intake temperature is measured (Some just guess it from CTS) MAF seem happier with cold air.

I believe the same. However, in this context, there's a lot more data to consider. Even a highly efficient car is awfully wasteful; if there's X joules of energy in a gallon of gas, and it takes X joules of energy to move a given vehicle 100 miles, it might take X*7 gallons of gas to move the vehicle that far. There's frictional losses, pumping losses, and humongous amounts of waste heat; in my example it's probably more like X*50 than X*7.

All engine mods that we do here are about recovering waste and reducing loss. A WAI is supposed to do both.

Probably a CAI helps mileage by reducing pumping losses. The intake on my truck has some awful bottlenecks, and if I change my clutch fan to an E-fan I will have enough room to replace it with 4" PVC pipe.

Yes that's true, typically you're replacing a restrictive factory intake and filter with a CAI. Just sticking dryer hose to the stock airbox might not do much, though it's claimed that ram intakes done like that can cancel out the filter restriction.