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so...effective at cooling underhood temps but ineffective with cooler air to intake?
yeap. there's two arguments;
1. hood vents/spacers cool underhood temps. CONFIRMED.
2. hood vents/spacers cool intake temps. UNCONFIRMED. i think the location of the hood vent makes a big difference. that's prolly why the OPs test came out the way it did.
 

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i bet if there was a vent in the front or just more open areas in the front of the car for air the intake temps would be cooler...spacers/venting in the back just lets the heat out

i have no idea how you could get more air through the front but i think if you want more air to the intake get a scoop or get brake duct lines but route them to your filter
 

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Discussion Starter · #84 ·
Just got an CAI put in my car. Now THAT is effective at getting colder air. So much nicer not to have to worry about heat soak. I'm in SD though.

Meanwhile, I haven't tested this, but I'm guessing that the only way to make a true difference is to double stack those spacers. I don't doubt that an open hood would result in lower temps, it's just that one spacer is a negligible difference. For me though, the extra drag and extra risk to my engine wasn't really worth it. That being said, there's the dangers that go with a cai too! but luckily, I'm in SD and the weather's not too bad here.
 

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Just got an CAI put in my car. Now THAT is effective at getting colder air. So much nicer not to have to worry about heat soak. I'm in SD though.
Not sure what you are trying to say. Heatsoak isn't the temprature of the air being injested by an induction system but engine bay components absorbing and conducting heat that is being generated by the engine.
 

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Discussion Starter · #87 ·
oh really? I always understood it as the engine sucking in hot air. So why do people always talk about heatsoak as a negative for only short ram intakes?
 

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short ram intakes are more affected by things being hot in the engine bay because all the conductive stuff that has the "heatsoak" will heat the air in the engine bay which would cause hotter intake temps for SRI...but if you are moving there is cool air being blown through the engine bay so it isnt bad
 

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Discussion Starter · #90 ·
short ram intakes are more affected by things being hot in the engine bay because all the conductive stuff that has the "heatsoak" will heat the air in the engine bay which would cause hotter intake temps for SRI...but if you are moving there is cool air being blown through the engine bay so it isnt bad
yeah that's what I thought too, but the guy above is saying it doesn't have to do with intake air temp. I definitely notice the heat soak after sitting a bit. Actually I notice it period because CAI still takes in a lot colder air. I put my CAI in and it's usually 10 degrees above ambient versus sri which is about 20+ above ambient and harder to get down than cai after idling.
 

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just because you have a CAI doesnt mean you dont have heatsoak...you have heatsoak but your intake temps are not affected because the air in a CAI is being drawn from somewhere outside the engine bay

all heatsoak is is when the parts in the engine bay get hot...very simply put

a short ram will take in hotter air if the engine bay is hot (heatsoak) and the car is not moving
 

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Heatsoak affects metal intakes easily, hence why some of the plastic ones "claim" they run colder.

And when opening the back of the hood, it may create a vacuum yes, HOWEVER, the factory airflow is disturbed, now I am no expert, but I believe there is a reason they use seals in spots when the hood is closed, to make sure the airflow is directed correctly. This may be why someone experienced slightly higher temps with spacers in.

BTW, if you haven't noticed, the cold air and short ram on these cars don't make a HUGE diff in air temp, as the short ram is on the back, which is directly open to the ground. I didn't experience any diff during driving in hot or cold, except during extreme cold, when you can always tell a difference. I did however, get a wet filter during hard driving rain and highway driving with a cold air, during vtec engagement, the check engine light flashed and power dropped drastically, and it only did it during rain.
I switched back to a short ram instantly.
 

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Discussion Starter · #94 ·
so you're saying heatsoak is the stuff in the engine bay actually getting hotter, but how much does that affect the car's performance? I'm guessing, practically speaking, people are only concerned with heatsoak in how it affects ingested air since a hotter engine doesn't seem like it'd be as bad as hot IAT. In which case, it is a problem more relevant to SRIs than CAI since CAI are farther away from the build up of hot air.
 

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Discussion Starter · #95 · (Edited)
Heatsoak affects metal intakes easily, hence why some of the plastic ones "claim" they run colder.

And when opening the back of the hood, it may create a vacuum yes, HOWEVER, the factory airflow is disturbed, now I am no expert, but I believe there is a reason they use seals in spots when the hood is closed, to make sure the airflow is directed correctly. This may be why someone experienced slightly higher temps with spacers in.

BTW, if you haven't noticed, the cold air and short ram on these cars don't make a HUGE diff in air temp, as the short ram is on the back, which is directly open to the ground. I didn't experience any diff during driving in hot or cold, except during extreme cold, when you can always tell a difference. I did however, get a wet filter during hard driving rain and highway driving with a cold air, during vtec engagement, the check engine light flashed and power dropped drastically, and it only did it during rain.
I switched back to a short ram instantly.
I noticed a huge difference in IAT and the rise/fall of IAT switching between SRI and CAI. Without a doubt I made more power CONSISTENTLY with the CAI. Driving on the freeway out in 67F temperature with the SRI I could only get the IAT down to 88-91. With a CAI I could easily get it down into the low 70s (another San Diegan can attest to these lower temps on his own Si). What's more, being at idle didn't raise the temperatures as fast and definitely lowered faster after a little driving. Sitting at idle with a SRI I could easily get the temps up into 115-120+ just by driving in the city. With the CAI, you're hovering around 100 more often.

The reason I made the switch despite being one of the most paranoid guys in the world (I got sri solely because of fear of hydrolock; I hate how loud it is) was because I was so sick of the heatsoak (speaking practically of how it affects my IAT). I could only get the car to have that awesome pull for the first 10 minutes of driving or 30 seconds after a long haul on the freeway before it lost a bunch of power. I never thought it'd be that big of a difference since so much air is coming in so fast, but it does!
 

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Either way, the only real test is a timed run at a drag strip, the butt dyno is not as accurate as you think,
I like the intake temp measurement, good call on that one. I still would have an SRI over the cold air... lose more low end with a cold air anyway in my butt dyno's opinion.
 

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The biggest thing I think people are forgetting is that temperatures under the hood are not uniform,at idle and definitely while the car is moving.SRI are more prone to suck up air with or without hood spacer because while there is not as many places for hot air to escape W/O spacers, there is bound to be more turbulence and mixing(with spacers) of what could be cooler air with warmer air due to this turbulence in the engine bay.this mixing raises the overall temp of the air in the vicinty of the filter on a SRI.Which is why CAI are less likely to experience this.Also.CAI are a little less likely to heatsaok due to the fact that they are constantly drawing in cooler air than what exists in the engine bay,which helps to cool the metal of the intake tube from the inside out.
 

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Discussion Starter · #99 ·
Well, I do believe import tuner did a legitimate test with their miata hood spacers, but I'm under the impression that it all depends on the design of the car and how high you're actually willing to put raise your hood. In the end, I live in SD so I'm happy to use my CAI for now and not worry about the spacers.
 

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As it refers to intakes, "heat soak" has nothing to do with whether an intake is a short-ram or a cold-air. When an engine is running and the short-ram draws in warm engine bay air, this in not "heat soak". This is simply running with increased intake air temps. CAI's and short-rams are equally susceptible to "heat soak".
It does have to do with being a short-air or cold-air, while else would it affect those and not the regular stock intake? The increased air temps is due to the heat transference, either through the filter element or through the metal piping.
 
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