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Discussion Starter · #1 ·
It's clear that the icebox is a restriction even on mildly modified cars based off of Mikeyspec from Profunctions intake thread, but there's always a concern with IATs and SRIs so I don't think many people make the effort to change or test that setup. Kowalski 99/Mr. Kowalski posted a DIY 3.5 inch velocity stack mod to the lower intake box here on tsxclub as well as a video on youtube discussing the different configurations while playing with the setup. IATs were the same in his testing. The 3d printer files to the airhorn are linked in his video.

I used the upper half of the comptech box with the filter and swapped out the lower airbox for testing. CT lower airhorn is left in place without the reducer or elbow
With my testing IATs were a few degrees higher than the icebox with 5-10 whp gained above 6000rpm. The icebox torque gain below 3000 rpm is lost with this modification. My results are somewhat consistent to Mikey's 'long' SRI configuration

My car is a 2007 6-speed with 77k miles and the following modifications:
CT- Icebox
Serge bo header
HFC
Hondata reflash
Stock wheels/TB/RBB/Exhaust/etc.

Logging was done natively with hondata flashpro.
Please note that these WOT runs were done on a uphill on-ramp and the bump in the torque curve is where the road flattens out or dips. Because of this, I would avoid peak numbers and just focus on the shape of the curve and difference. All of these datalogs are done on the same stretch of road.

Weather conditions are noted after K (kowalski intake) or CT(comptech intake) in the run name. I could not find an input for humidity in virtual dyno.

Smoothing is set to 2.
In the first graph the temperature input for the red CT-28F run is IAT as I felt using ambient temperature amplified the difference excessively. The second red/green picture is with actual ambient temperature as the air temp input for the CT-28F run.
Similar shaped curves were compared with each other to minimize the effect of road irregularities. The green curve was done after a few WOT pulls so IATs did rise slightly.

Most of the regulars/veterans on the forum run the icebox and have a flashpro. I'd recommend disconnecting the elbow to the lower box, datalog, and see if your IATs rise too much in your use case before proceeding with this project. I think it's a worthwhile modification and will be keeping the modified box on over the icebox. Cheap HP and easily reversible/swappable back to the CT setup for CARB/DD purposes. It'd be really interesting to see if others see greater gains especially with an uncorked exhaust or RBC. I do think there's more power to be gained by opening the intake side (Mikey's final setup), but I don't have the skills to build an airbox/heatshield for the optimum short-ram, and don't want to cut up my hood for a NACA duct.
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Nice work. Soon after buying my 2008 AT I modified my intake similarly with the following differences. I installed an Ice Box, smoothed out the interior of the lower box, ran a 4 inch pipe curving into the front bumper. I modified a horn adapter and sealed it to the port next to the fog light. It's a fake port but I cut it open and added a wide hole mesh to keep the bugs out. It's a more direct flow setup.

Unfortunately I had the car tuned right after with FlashPro as I also had installed headers, HFC, cat-back exhaust, aluminum pulleys and several other minor mods that I'm forgetting at the moment. So I wasn't able to data log and compare the gains against the OEM setup. I've always wondered what tweaks to this intake would have produced. How was my bottom end affected? Where do the higher end gains start? Would a 3 inch pipe helped my lower end? Should I have cut the intake hole bigger?

I also switched from a K&N filter back to a Wix filter later for more filtration as I noticed that my synthetic oil was getting dirtier much faster. I couldn't discern any noticeable performance difference in the reduced air intake. The difference may have been minute.

I was happy with the gains overall and I've never had any moisture/water issues but I do live in Southern California so rain isn't much of an issue even though I'm lowered. Someone may have made similar intake mods but I haven't researched it. It would be interesting to see what additional gains or effects they would produce compared to OEM and other intake mods.

Once again, good work with the mods and data logging.
 

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Interesting findings..

I've had a DIY cold air intake with a K & N drop in filter for many years. Similar to the Comptech.
Sorry if I missed it, what air filter are you running?


Since the 1st Gen TSX engine bay is so sealed and so hot, I would still want that air horn out of the engine bay, making sure it is not drawing in any hot air.
But to extend that larger diameter air horn, even a few inches, thru the sheetmetal requires one to cut that hole larger.
To cut that hole larger and make the cut clean looking is not be easy.

For even more cooler air into the engine, you should bypass the throttle body coolant lines, if you haven't already.
Super easy to do on the TSX with zero downsides, even in the Canada winter where I live.

But the intake manifold gets super hot. I've seen folks install the insulating gaskets between the 2 halves of the intake manifold and between the base and the cylinder head.
Minimal improvement. One really has to somehow modify the intake manifold base so coolant doesn't flow thru it.

Another easy mod, if you haven't already is an underdrive crank pulley.
I've had a RSX-S OEM underdrive crank pulley on our TSX for over 10 years, zero downsides.
You can feel the difference revving thru the gears on a manual trans.
If I were to do it again, I would find an even smaller diameter crank pulley.
 

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Very good suggestions by CalgaryTSX. You can also add other underdrive pulleys (power steering) but I would recommend staying away from alternator underdrive pulleys. They can cause serious charging and power drop issues for both OEM electrical systems and those with aftermarket stereos and other high load electrical components. It caused all kinds of havoc for me and that's probably why they are not common anymore.
 

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I kept my stock power steering and alternator pulleys.
While aftermarket shiny aluminum pulleys for those look nice, zero power gains.

Another low cost suggestion for OP @lnlds would be to remove both exhaust resonators.
Even with his high flow cat, the car will gain just a bit of sound.
Low cost, zero HP gain but lose some useless weight!
 

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Discussion Starter · #6 · (Edited)
I'm using the comptech filter that came with the CT icebox for both setups

The original developer of this specific setup for the lower airbox reported loss of power when extending the airhorn out of the engine bay, and also cited this video
(timestamped for convenience) by gears and gasoline finding 8 whp with a SRI velocity stack. They lost power when ducting it down to the standard cai area.

For the street this setup should be good for my use case. When I eventually track this car if IATs go crazy I'll just swap back the standard lower airbox. I don't plan on tracking this car for quite some time, so I'm hoping the other regular track guys can chime in with some data if they're interested in doing this modification.



As far as the exhaust, I really don't want to add any extra noise I have a yonaka 2.5 inch stainless steel catback sitting on the shelf, but I'm leaning towards avoiding doing anything that increased noise or attracts attention. Lightweight wheels will be done at some point for the car.

I've never looked into pulleys for a number of reasons. Crank pulley bolt seems like a pain to get undone and I'm still uncomfortable with any potential with harmonics/dampening even if there's not much evidence behind it.

I know there's something wrong with my logic but wouldn't a smaller crank pulley increase the amount of force needed to turn the accessories and overdrive the accessories? Think keeping the car in 6th gear all the time versus keeping it in 1st or a smaller supercharger pulley creating more boost.
 

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Underdrive crank pulleys are worth researching.

I've had one on my 5.0L Fox Mustang for 20 years.
I think the 5.0L Fox platform is where the development for underdrive crank pulleys started...


I've been looking for one for our lame Honda HRV which has the Civic R1.8L engine, but no one makes one...
 
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You don't have to use a smaller crank pulley. You can just go with a lighter crank pulley (same diameter). Remember that a smaller crank pulley is usually slightly smaller so the overall effect is minimal if any on your accessories. If you greatly increased the weight on your accessories then that would have a bigger affect on how hard your car would have to work to drive them but you are not changing the weight of your accessories.

As far as overdriving/underdriving your accessories that is a bit more involving because it depends on various factors and is definitely worth researching as CalgaryTSX has mentioned. The size of the pulley used on your actual accessories definitely has an effect and can cause serious issues to things like your alternator and power steering performance. Definitely research.
 

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That video hints to possible gains that I also suspected when I ported my intake into a cutout on the front bumper, allowing air to be rammed in for more input. This is opposed to just directing the air intake down into the restricted space behind the front bumper. I'm curious as to how wide the improved area under the curve is. And how low in the power band do your gains start. It would be an interesting experiment.
 

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Hi man, I was scroling on google search and saw this 😄.
Thanks for doing this mod and testing it on your car.
If you do it on stock box car would start flaying with that mod.

I can send you secon (upper v.s file) to fit it and test it.
Also would be cool if you ported your tb like I have.
 

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Also dont know if I told you or someone else... When we did this modification we didnt get any gain after that mod and after driving it for cupple of days cars started dropping times. 100-200 kmh was almost 2 seconds reduced.
So you can test it again after week of driving and see if there is any difference.

Regarding long pipe intakes like tradicional behind the bumper cai they always lose vs shorter intake setup on k24 and it is always 5-10hp range like in this video.
Also humble performance did the same test with same outcome.

My car is now taken apart for bracing installation but I plan to install new air ducting from grill that will be more suitable for people who don't want to run channel from / next to the fog light.
 

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^^ That's a classis chassis dyno operator error or cheating. :)

A short ram air intake will always make more power on a chassis dyno, with the hood up.
But that's not reality, especially with the super hot and sealed TSX engine bay.
For a true comparison, you need to dyno with the hood closed.

With the hood up, the short ram intake is drawing in nice cold air. With the hood down, not so much...

You can see that the hood open or closed will have minimal impact on a chassis dyno with a cold air intake drawing air from outside the engine bay.
 

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it is not super hot or sealed, just log your device and see for your self. On my setup there is like 2 celsius difference at the worst with channel open vs closed I did 2 tests proving that.
When I extend pipe behind the bumper my car goes slower so yeah it is loosing power.

long intake is always loosing power vs short one.
 

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I do monitor intake air temps on our TSX using a Scangauge.
The original air intake temps on the TSX are incredibly high due to the OEM hot air intake and the throttle body coolant heater lines.
The engine bay in the TSX is incredibly sealed. You can see all the rubber seals at the leading edge of the hood, down the sides and the trailing edge of the hood, the sealed up rad support and the plastic lower engine cover.
Go for a drive in your TSX and then touch anything in the engine bay.

If I drive thru the rain in our TSX, the engine bay is dry. Unlike our HRV, our Dodge truck or my Mustang.


long intake is always loosing power vs short one.
It's not that simple. There are numerous things going on here...

Length of the intake pipe.
Size and flow of the air filter.
Quantity of air (restriction).
Temperature of incoming air.
Ram air affect, if any.
 

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It's understood that running the intake into the restricted area behind the bumper has not shown to be beneficial, especially on the low end. I don't think there's any more left of that dead horse to beat. What I've mentioned and found to be beneficial is porting a smooth airflow through the front bumper to get a rammed effect. Along with that go other considerations like modifying your air/fuel mixture. It has to be done with other complimenting mods. I just didn't do any data logging to see how to optimize a smooth, rammed air setup.

And of course widening the intake diameter through the piping and intake to the air box has an effect. The width needs to be studied to see where it's beneficial in the power band and where it's a detriment (low rpms?).

I did find it slightly beneficial to use a less restrictive air cleaner (foam and K&N) but it was minute and it contaminated my oil much faster. I chose to go back to an oem type (Wix) for better maintenance.
 

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Discussion Starter · #16 ·
Kowalski 999: I haven't done an upper airbox mod since I have the CT intake lid which is a product available in North America. It's very similar to what you've done with the larger upper velocity stack,smoothed out box, and larger volume box. Fuel economy has also increased for me (1-3 miles per gallon). Thanks again for posting the 3d printer files, and the videos. I originally had the same concerns as other posters in this thread with IATs, but since you addressed in the video I felt comfortable taking the time to play around with this intake setup.

Litespeed08: The oem narrow diameter piping airbox does have an advantage below 3000 rpms over this mod and other aftermarket tube style intakes. I definitely can't lug the engine in the low RPMS as much as I could with the OEM lower airbox in place. The gains up top with this modification are worth it IMO, the car 'feels' more rev happy like a honda and less like a small v6 that runs out of breath up top. If I plan on sitting in traffic and encountering lots of stop-signs and traffic lights I'll swap back the oem lower airbox

CalgaryTSX: Of course I still have to do more datalogging when it gets much warmer, but as it sits I can't recommend this modification enough for those with a stock intake or CT-icebox.
 

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Thank you for giving it a go 👍

Was fixing bumper today and puting on ats lip so I tested iat with channel open and removed+ hole was blocked off.
Outside temp 19c
With channel iat 22c
Removed channel and blocked off hole iat was jumping 25 - 26c.

When I tested it during the winter it was smaller difference.

I will make new ducting that goes from front grill and test it in couple days.
 

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Discussion Starter · #18 ·
Playing around with the Virtual Dyno temperature input, every 8 degrees F or about 4 degrees Celsius is worth about 2 whp according to whatever formula they use.

If the fog light duct works well at decreasing IAT, how come you're building the hood duct/channel?
 
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