I could use your guys' help with some hard to find information. My brain hurts a little from trying to dig it up myself.

I'm curious if anyone has logged intake air temperatures inside the manifold. Specifically trying to determine the amount of heat the manifold is adding to the air intake temperature.

In other words, what is the air temp right before going into the engine vs. air temp after the intercooler.

Realistically it doesn't matter if the car is N/A or F/I, but since I'm going to apply the findings to compressor maps and manifold choice / design, I thought I would post it here in the F/I section.

Kinetics website is comparing the air temperatures inside the stock manifold vs. the Velocity manifold.
This is probable at idle with lower air speeds, but what about 3K+ rpms where the air is really starting to move? Does the temperature of the manifold itself have a big impact on intake air temps?

 

the temp difference between the maf sensor where intake temps are taken and going into the engine are essentially nil, mayby a single degree at most. kinetix puts up a chart like that as a marketing ploy knowing full well people will see the temp differences due to being slightly larger and standing out on the background. however most people look right over the time due to being slightly smaller and being closer to the background color making it harder to see.

you notice that after 5 minutes even with aluminum which is a far far better conductor of heat then air(one of the reasons heatshields have an airgap) it only reachs a little more then half the temp of the source. air in the intake only is in contact with the intake manifold for less then a second to a few seconds meaning that there is very little tempature change.

then after that the downside of stainless is while it may take longer to convect the heat initially it will take longer to loose the heatsoak as well.

mind you this is just off the top of my head but if you really are curious the math is out there for it to get a rough general idea but alot of work(the math) for not much benefit

 

+1 on the above, although I'm not too sure about the 2nd part since the thickness of the Kinetix manifold is a lot thinner than the stock plenum.

 

Unless air spends 5 minutes in the plenum before entering the combustion chamber that chart is useless. In real life it's milliseconds and the delta temp is pretty much zero.

 

but heres the other part to that marketing ploy, you immediately went to comparing stock aluminum to kinetix stainless, but nothing there indicates that =P it is simply comparing two materials with no mention of thickness.

its a pretty common thing with marketing and web development.

 

Very true -- good point.

 

I agree with you guys about the marketing ploy stuff. I think that if there were any real numbers showing lower intake temps, those would have been posted.

I would debate that delta t is close to zero though.

For the sake of discussion let's ignore comparing manifolds at this point.

It would seem that just like an intercooler, a very hot manifold would act as a heat exchanger.

Even a small intercooler is capable of drastically changing air temperatures. Obviously larger is better, but the difference between NO intercooler and a small intercooler is dramatic. Our complex manifolds have a substantial amount of metal and surface area to transfer that heat to the incoming air. I image that our manifolds get too hot to touch like most.

There may be something to this, but it's probably negligible, like wrapping your intake piping with heat wrap.

You guys are probably right and I'm just over thinking this one.

 

heres the difference though with the intake your looking at about half a cubic foot of surface area for heat transfer in a hot engine bay. with a intercooler, even a small one your looking at about a cubic meter of surface area some of the larger ones a few cubic meters due to the amount of fins and fin density. on top of that you have a much cooler ambient air being forced through it vs a static airflow with the manifold which is where the temp changes come from. atomizing fuel in the intake(even gas) will absorb far more then changing materials will help. just take a look at the airgap intakes for old school small blocks, to manifolds of the same design provide next to no change most of the gains seen are from removing the air flow from coolant(since the non air gap manifolds subject the intake air to coolant flowing around it.)

 

That's a huge difference in surface area.

Thanks for taking the time, I can go find something else to needlessly worry about now.



Oh, so back to my math. What kind of temperatures could I expect after intercooler? +6-9 degrees above ambient temps?

Large Bar and Plate design.

 

depends on efficiency, amount of boost, ambient temp. i know on my bp kit at 20 psi i see about 90-100 degrees post intercooler on the highway on a 85 degree day. the hotter the temps the more it will cool but it wont be as cool as a lower boost level. for instance i see 90-100 with 20 psi, but if i crank it up to 30 the outlet of the compressor will probably be around 60-70 degrees higher but inlet air temp will likely be around 120. more total cooling but the temp is higher hopefully that explains it for you.