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post #1 of 3 (permalink) Old 10-09-2014, 08:17 PM Thread Starter
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Hot air intake

Decided to measure my IATs. Car was warm. I connected the efi live and went for a ride to do a log. On a 80deg day my IATs were 140city and 110hwy.
I have a K&N CAI and the IAT sensor relocated in the filter. I looked online and wanted to get a svede but they say I will have to modify my banshee hood and I am not doing this.
I decided just to upgrade the existing CAI (that was actually a Hot AI).
I cut a big hole under the filter and relocated the coolant expansion tank (05car). Then I bought Aluminum self adhesive insulation from Home depot and made a box so now the only place it gets air is the hole that I cut.
Went for a ride on that same 80deg. day and my IATs were 82 city and 80 hwy.
So I dropped 60deg of IAT just with some cutting and alluminum insulation.

Here is some pics. and yes I know it looks ugly.

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Does anyone see anything wrong with this setup besides looks?

How much power do you lose to high IATs on a NA engine?

I tried to find the answer to this and found things from 1% for every 10deg to density altitude calculators.
So how much power do you lose in percents for every 10deg and is the lost linear.
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post #2 of 3 (permalink) Old 10-10-2014, 09:45 AM
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Power loss is two-fold so I would have a hard time saying for sure. First is the warmer the air the less dense it is so less O2 per unit. That's linear. The other depends on how your IAT/Timing table is set. It pulls degrees of timing at a set temp starting at wherever. Stock it's 86* on a LS1. I'll post the table below. it doesn't pull at a linear rate with temp but in steps.

Some tables are hacked hard and they wipe out negative timing until a high temp. The problem with that is that you may experience knock when you get higher temps or if the main timing table is reduced for that then you don't have optimum timing for cooler temps. Most tables can be safely reduced a little on a stock car as they are conservative. The fuel used, compression, heads, etc all can affect timing so results may vary. A highly modded, high compression car may be more sensitive to knock too.

Your setup has the right idea. Insulating from the engine bay is crucial. Some that insulate fairly well like the kind with the lid lack in that their source of air is limited. Removing the lid results in higher trap speeds for instance by increasing their source of air. I tested intakes at the track once in looking at the issue. The K&N and LPE were worse than a stock one with a K&N drop-in. The best results with a corner intake like that was when you drilled a 4" hole below in the area ahead of the wheel. I even isolated part of the under area where the radiator blows out to prevent re-ingestion, put on a bigger cone filter and fabbed a "scoop" to channel air there when moving.

It was still a little problem as all the air blowing through the radiator rolled out under the car when stopped. The other problem I couldn't overcome was the loss due to the bend in the tube. The direction you're moving though is IMHO the best outside of an OTRCAI.

2004 Blk/Rd M6
6.3 litre LS1

Built and tuned by svede
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post #3 of 3 (permalink) Old 10-10-2014, 07:08 PM Thread Starter
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I just looked at my table and it starts pulling timming at 104. The stock tune is really conservative because I rarely have any knock and the best gas I can get here is 91.

I also isolated the radiator area so its really getting air only from the hole that I drilled.

I am really curious about the power loss due to high IATs though.
Everyone is talking about CAIs, heat soak, pulling timming etc. And I think I found the answer. Someone please correct me if it is not right.

Lets say before I modded the intake on a 80deg day my IAT was 140. And my car has 500whp.
From Viper forum 1% for 10deg: So I am losing 30whp.
From a density altitude calc :It says that I am losing the same 30whp. and that you are making 100% of your power at 50deg.
From Ideal gas law : the difference is 6.66%

So 3 sources are showing the same. You are losing about 1% power for every 10degF of IAT.
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