VCman123

I recently installed a Comptech Icebox intake on my 2006 MT TSX. While I definitely noticed power gains at higher RPMs, it does seem that there is slightly less power from the standstill. I do not think this is necessarily bad, as I now am apt to spin the tires less when starting on a hill (MT in San Francisco is tough). Everything else about the car is stock (header and reflash are next in line).

I have seen people reference this low end power loss issue in other posts, but I am curious if someone can offer a more scientific explanation about why this occurs? Will adding a new header fix the issue?

Thanks.

Audioserf

I have an Injen CAI which has similar effects (loss of low-end torque, more power higher in the powerband). It may be a symptom of all intakes.

clee109

it's typical of all intakes to do that. however; the ice box looses the least amount compared to injen and aem. Adding headers is always a great mod and may help a bit, basically with intake you have just allowed the engine to take in air easier, however it can't pass it easier and can sometimes lead to that power loss, headers allow the engine to exhale better and exhaust and RT cat can really help. Be sure to search the forum and you'll find all the info you need

TinkySD

Look at dynos of WOT the icebox actually retains nearly all the stock torque under 3k and in some areas has more than stock.(and obviously some areas where there is less) Tthe torque loss pales in comparison to the major hit CAI designs take under 3k RPMS.

However, my own personal theory, after trying some different intakes is that the effect on less than WOT is pronounced. In my experience any intake on the TSX causes less power at partial throttle openings lower in the RPM range.

Of course that would be near impossible to quantify as dynos have to be run at WOT to be repeatable.

xjohnkdoex

iTrader: (2)

could this be attributable to a bad seal w/ the box? are you using the comptech filter included, k&n (w/ or without weather seal), etc...?

Audioserf

I'm using the filter which came with the Injen. It's a cone filter. All the seals are on right. It's not just me, others report a low end torque loss with Injen as well. I'm not worried about it.

xjohnkdoex

iTrader: (2)

my bad, i meant to quote the original poster.

VCman123

I am using the Comptech filter, and the fitting appears snug.

jlukja

Here is the dyno from Comptech's website: http://www.comptechusa.com/store/med...tsx_icebox.pdf

If you look at the data on the left hand side you'll see that the horsepower is within 1 or 2 HP in the low rpms. You get more of a benefit as the revs go up. I didn't notice any loss of power in the low rpms when I installed mine though a difference of 1 hp is hardly noticeable among the other variables.

xjohnkdoex

iTrader: (2)

gonna try and install mine this weekend. looking forward to it!

acn684

didn't notice any low end loss either, if anythign my low end is much peppier.

Black_6spd

At first I did encounter a considerable power drop at low RPMs when I installed the Injen CAI. This was accompanied with throttle lag.

As I did more aggressive driving, the problem went away after a few hard runs. It might be due to the ECU "learning" the new airflow.

bluexcrush

the scientific explanation for the loss in low end power is due to the length of the pipe and how far the air has to travel to reach the engine... On CAIs the pipe is longer since it has to reach the bottom of the car to suck in cold air, therefore it takes longer for the air to travel from the beginning of the pipe into the engine, therefore when you gas the car, it takes a bit longer for the car to respond.

CrazyCool[O]

iTrader: (1)

Wow you guys are smart! So....better engine reponse with SRI?

JTso

iTrader: (2)

All this talk about low end loss is comparing to the stock intake system after the modification. right? So, isn't the stock intake system longer, narrower, and more restrictive than any of the CAI or SRI? Just think about it.

bluexcrush

the SRI will produce a better engine response, but won't produce as much gains at higher rpms.

I believe that the CAI is longer than the stock intake system.

bluexcrush

so therefore, the SRI is useless imo.

JTso

iTrader: (2)

Nope, the stock intake goes down behind the front bumper and back inside the engine compartment. The inlet is right in front of the battery behind the radiator. Below is all the components of the stock intake system.

SoCaliTrojan

The length of the intake doesn't matter as much. The time it takes from the air to travel from the filter to the engine is irrelevant since there should be air inside the intake already (unless the intake magically keeps a vacuum until you hit the gas). Sure, a CAI will have more air in-between the engine and filter, but once you get going, it shouldn't have much of a difference in air flow with a SRI (since the filters are the same). Sure, there will be a momentary vacuum pulse which has to travel from filter to the engine (which will let the SRI respond quicker), but once the air from the filter reaches the engine, the two should perform similar (if they had the same air temperature).

The reason why there is a CAI and SRI model is so that the CAI can get colder air, which is more dense.

My accord has a SRI...I noticed a big loss of low-end power. I have to put alot of throttle to get up to speed. The high-end power is noticeable though. Basically an intake shifts the power from the lower end to the mid and high end.

JTso

iTrader: (2)

Actually, the length of the intake matters a lot in addition to air density, but it's not something most people think about when upgrading.

The two Honda intake design diagrams below illustrate the effect of intake length and air path. It also indicates how the power band is affected. Honda has been using this design for many years including some of the current models.

vidgamer

My old Honda Prelude had two places where it switched from longer to shorter paths -- one in the resonator, and the 2nd in the intake runners. However, the part in the resonator didn't just create a shorter path, it was opening a restriction. So it was actually restricting airflow, I guess you could say, at lower rpms! (To create a higher velocity for the lower amount of air needed?)

junktionfet

As JTso pointed out, the length is pivotal.

I think the misunderstanding is that some of you are looking at this issue from the "inertia" perspective only... i.e., a bunch of nearly stagnant air has to get moving over a long distance, and that must be bad, etc.

However there is no mention of the "momentum" perspective. Once the inertia has been overcome, the momentum of the air in the system can be impressive, and it can help boost the engine's breathing ability somewhat.

Not only that, but the relatively narrow design of the stock system ensures that the air inside is never fully stagnant--so the hardest part of overcoming inertia isn't even a worry.

The stock system is undoubtedly tuned to optimize this "momentum" effect over a broad range at low RPM. Aftermarket intakes generally emphasize the effect at higher RPM. Barring any net gains from an aftermarket system, you are simply moving power from one place in the spectrum to another place.

As my tests have pointed out, there is no "restriction" in the stock intake system. It breathes perfectly no matter what (no pressure drop in the airbox). So any net gains from an aftermarket system must be largely due to intake air temperature and higher peak "momentum" from reduced turbulence inside the tubing, etc.