2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Is a cold air box required with a cone filter for N/A?

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Old Aug 11, 2003 | 01:41 PM
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2nub_2stupid's Avatar
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Is a cold air box required with a cone filter for N/A?

Just wondering, but do i really need a cold air box if i install a cone filter into my 87 n/a??

what would happen if i don't?
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Old Aug 11, 2003 | 02:13 PM
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You'll just be sucking in hot engine air, I've been running a cone K&N for a couple months now without a cold air box and it still runs like a raped ape. Ran a 9.8 in the 1/8th with just a downpipe and the air filter. N/A
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Old Aug 11, 2003 | 02:41 PM
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It's really not required, but it is recommended. Your engine should operate just fine, but you're not getting the maximum benefits of the intake modification. Allowing the engine to breathe the hot air from the engine bay will just cancel any benefit you made have had from having a cone filter in the first place. Ideally, the air filter should be completely isolated from the engine bay's heat and a cold air box is just one way to do it.
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Old Aug 11, 2003 | 06:13 PM
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Atomica, I think you forgot to do some advertising here. (He built an awesome cold air box and is selling the plans for those of you who don't know.)
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Old Aug 11, 2003 | 06:39 PM
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I have monitored the intake air temperatures of a similar setup, and have noticed that while there is a lot of heat getting sucked into the engine at idle, around 30mph the intake temperature becomes closer to ambient because of the higher airflow through the engine bay. Of course, it depends exactly where you place the air filter, but it is difficult to tell what is a good spot unless you have an intake air temperature sensor. If you get too tricky with the plumbing, then you get a pressure drop (aka a restriction), which isn't good, either. A cold air intake would be better than a cone filter and AFM adapter, but it is not necessary.
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Old Aug 11, 2003 | 09:11 PM
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how much of a difference would it be with like a top to the air box, would it like trap more cold air in? or does the hood do the job?
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Old Aug 11, 2003 | 09:15 PM
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Just wondering but do you guys know what the size of your cone filter is like dimensions if possible.

cause stupid ppl at the parts shop said that i need like specific dimensions for them to find.
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Old Aug 12, 2003 | 01:21 AM
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Originally posted by Evil Aviator
I have monitored the intake air temperatures of a similar setup, and have noticed that while there is a lot of heat getting sucked into the engine at idle, around 30mph the intake temperature becomes closer to ambient because of the higher airflow through the engine bay.
It's this low-speed problem that people don't consider. If you sit at the lights for a minute and then gun it from the green, the highly loaded engine is sucking in extremely hot air from the heat-soaked engine bay. This is the perfect condition for detonation.

Same deal at the drags. How hot is your engine bay after lining up for ten minutes? Then you give it full load for quarter of a mile!

It doesn't matter if you've got an NA or a turbo, you should always try to keep intake temps as low as possible.
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Old Aug 12, 2003 | 08:12 AM
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Originally posted by NZConvertible
It doesn't matter if you've got an NA or a turbo, you should always try to keep intake temps as low as possible.
True, but a stock engine in good shape will run just fine with a cone filter on the AFM. I drove my slightly modded 88 TII with an HKS intake and 87 octane in 100F+ weather at sea level with no detonation problems.
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