bobgoblin

Hi, I'm new here & hope this isn't out of bounds by posting here.

I've searched as many threads as I could find concerning CAI/SRI and the VSC, TRAC, AND CEL lights before posting my questions.

I installed a Takeda CAI last week, xB ran fine for a day, lights came on. Code said MAF reading lean.

Converted to SRI, codes trip, same deal: MAF reads lean.

Cleaned MAF, no dice, still read lean.

New MAF installed. Car's better (so far). Still running SRI.

Wondering if its worth converting back to CAI.

Any input?

2008 xB. Takeda CAI/SRI the only mod so far.

TrevorS

iTrader: (1)

Just curious, how many miles on the car and what was the air filter like?

bobgoblin

Dry filter. Car has about 57k miles on it.

TrevorS

iTrader: (1)

I meant the filter condition.

In any case, the only way I'd expect an aftermarket intake to cause a CEL would be if the MAF mounts differently (further out of the air stream) than OE, or if the tubing ID at the MAF isn't the same as OE. Either would cause an unexpected reading for a given mass air flow. If the original MAF sensor works fine with the OE air box, it seems to me the Takeda is probably not a good design for our cars. But to your specific question, there's generally no huge advantage with CAI over SRI for our cars, so unless you're doing something out of the ordinary where it might really make a difference (certain racing conditions?), go with what appeals to you best. Guess I should mention there is a risk of water ingestion with a deep fender CAI unless a bypass valve is installed, not so with OE or SRI.

bobgoblin

Oh! Sorry, the filter is brand new.

The MAF went bad. I put in a new one & all is back to normal now. Still running the SRI, & I think that's what's gonna stay in there.

Thanks for the help!

ScionFred

iTrader: (1)

You're probably not losing a lot of power with a SRI (Hot Air Intake) instead of the stock CAI airbox unless you live in a hot climate. Of course no matter where you live you could gain power with a true CAI.

TrevorS

iTrader: (1)

The stock intake draws air from the engine compartment and so I question whether either an OE or SRI would better it in terms of temperature. A CAI promotes colder intake to the engine, but in practice, it's not clear the difference between SRI and CAI makes a worthwhile difference for a daily driver.

ScionFred

iTrader: (1)

You need to look at where the oem airbox draws air from vs a SRI and the performance benefits of cold air induction are crystal clear and have been for well over 50 years now. Why did you bother to run all that cold air ducting to your airbox if you didn't believe it made a worthwhile difference?

Remember that SRI dyno results are measured with the hood open and a big fan blowing cool air over the engine.

bobgoblin

I really appreciate all this spirited conversation.

Here are my observations over the last week and about 350 miles:

Midrange power is substantially more noticeable vs. the stock airbox/filter (that I removed the snorkel from). Between 40mph and 60mph I've noticed that the xB doesn't have to downshift in order to maintain speed going up hills. At highway speeds, more of the same; the power band seems to really focused around the 1.5k-3k range. All of this is with the SRI.

Economy-wise, I've seen my avg. mpg's go up from 24.1 to 26.1. This is a suspect number, though, because it is possible that the old MAF was faulty/damaged well BEFORE I installed the SRI.

Also, it sounds nice when I hit the gas.

TrevorS

iTrader: (1)

If it's such a huge difference, why have I read so many times that the practical gain between SRI and CAI is small and generally makes little to no difference for normal driving? The primary improvement comes from consistent 3" diameter piping and removal of constrictions (both SRI and CAI), not the air temperature. Why did I go to the trouble? Because I was improving my earlier CAI rendition to compete with or beat the new TRD -- an interesting and kinda fun low cost project for me ! My car is never tracked, I've little doubt an SRI would serve perfectly well.

IMO -- it's mostly a question of personal preference (ie. what tickles your fancy), whereas the air bypass need is a real drawback to CAI and adds cost to provide.

NocturnalxRS6

In my opinion CAI is the way to go, like stated earlier a RAI is just a (hot air intake). If you truly want to benifit from any CAI you can do a simple set-up like this..

ScionFred

iTrader: (1)

I've little doubt that a SRI would serve you perfectly well. So would the stock airbox. But if you want to add hp and tq cold air does that. It's very simple really. Colder air is denser and contains more oxygen atoms than hotter air. More oxygen in the combustion chamber also means more fuel which equals a bigger bang and more power.

Will you notice the difference between a SRI and CAI while putting to the grocery store? Probably not but it is real and can be measured very easily on a dyno or track.

BTW, my previous CAI pipe inlet was over a foot above the pavement. Since I don't drive through water deeper than a foot I didn't need a air-bypass and neither do 99% of CAI users. However if fording streams with your XB is your thing, don't get a CAI and if you must, add a bypass valve.

TrevorS

iTrader: (1)

I understand the theory perfectly well and I'm not denying that in performance applications it can be helpful. But for 99.99% of drivers, SRI Vs CAI won't make a practical difference. I still don't see the big deal with the stock airbox, the real problem is the snorkel -- that thing is an engine response killer and costs nothing to remove.

There are plenty of people who never expected to be in a hydrolock situation, but got their engine wrecked anyway -- call it bad luck or whatever, but it's real!

ScionFred

iTrader: (1)

I thought you'd know the theory which is why I was perplexed that you said there is no clear benefit to CAI over SRI (HAI). Now I understand that what you meant is that for 99.99% of drivers who install a performance air intake system there is no practical difference between adding say 5 hp vs adding say 10hp. They both sound and look equally cool. I guess I fall into the .01% then.


Stupid is as stupid does. I would never call blatant stupidity "bad luck".

TrevorS

iTrader: (1)

Fred, be assured I've no end of respect for you, and what you have to offer on this forum. However, I've a real problem with the "religion" aspects that sometimes materialize ! Perhaps I'm wrong, but I'm expecting somewhere between two and perhaps three HP difference between SRI and CAI under optimal circumstances. Now, that may well be the difference for the winning run on a drag strip some evening, but I question the significance for a DD driver who is simply enjoying his/her ride.

I've seen another on a different forum declare stupidity to be the explanation for being caught by hydrolock. Perhaps I'm too charitable, but it's my belief people are naturally inclined to underestimate the risks to their ride and wallet. People remain people and what's least likely is for them to take seriously a seemingly remote threat. No problem with that as long as it doesn't materialize, however, unfortunately, sometimes it does. Let's continue to be supportive of our fellows, but still point out the risks -- prevention being far less expensive than recovery !

ScionFred

iTrader: (1)

There are lots of variables to the equation but as a general rule you can expect to see a 1% improvement in tq for every 10F reduction in IAT. From my own OBD data logs comparing stock airbox to CAI to SRI I see differences in IAT ranging from 0 to 50f depending upon conditions. Assuming the best case scenerio for the CAI on a stock 160bhp 2AZ-FE engine we should see a gain of 8 ft lbs from a CAI vs a SRI. Obviously this is the best case scenerio for the CAI and under different conditions the difference is as little as 20F or +3 ft lbs. None of this is carved in stone but the theory and data are sound.

Perhaps I'm too cynical but IMO 95% of the motorists with which I share the road are compete morons. The vast majority have zero lane discipline, can't maintain a consistent speed, are distracted by their cell phones, newspapers, DVD/NAV, etc. and have zero respect for their fellow motorists. These are precisely the kind of imbeciles who drive through 2 feet of standing water with a CAI and I say F-em!

TrevorS

iTrader: (1)

Out of curiosity, I just now measured the height from the pavement to the top of my CAI inlet -- a little under 18". Given the way water rises against a pushing surface, my guess would be even a 1ft deep puddle would be very dangerous without an air bypass. Given a good rain storm, such puddles can occur and one might not even notice its presence or recognize its depth, especially at night. 'Course, if someone else happens to be operating the car, all bets are off anyway -- it's very unlikely a non-owner would (1) be aware of there being a CAI or (2) comprehend the danger if they were!

Well, given my low-to-mid torque lust (), I apparently went the right route !

TrevorS

iTrader: (1)

In light of the discussion, thought I'd take some live temperature measurements (OBDII scanner). My parked overnight ETC today was 72F, IAT 79, and aprox outside temp also 79. I drove out for lunch and with a parked idle immediately on arrival ETC was 190F, IAT 88, outside temp unchanged. About an hour later I checked the readings before starting the engine and got an ITC of 169F, IAT 97. After getting home with the engine shut off, I observed a peak IAT of 122F at roughly ETC 158. (Note: my intake pipes are insulated with aluminum foil over foam rubber and the air is taken in directly at the low left fascia vent. The only uninsulated portion being the OE airbox where the plastic itself serves as an insulator.)

It'd be interesting to see how IAT varies with vehicle speed, but the delta from exterior air appears to be about 9F at idle. I'd expect that delta to be significantly larger with uninsulated CAI piping and without direct intake of exterior air. Obviously, the larger that delta, the less temperature advantage a CAI will be able to provide over an SRI.

ScionFred

iTrader: (1)

Good points but with pretty simple solutions. If you have a CAI don't drive through 1ft deep "puddles" (personally I'd call that a flooded roadway but whatever). Don't let other people drive your car when conditions might include 1 ft deep puddles. If you can't adhere to these two points, install a bypass valve. Honestly I never felt that I needed a bypass valve with my CAI and still don't. Depending upon where one lives, who drives their car, etc., a bypass valve could be a good idea but I certainly wouldn't go as far as to say that it's a necessary component to a CAI system. Besides which many CAI systems on other cars have inlets more than 2 feet above road level.

ScionFred

iTrader: (1)

Having the ability to measure how IAT varies with vehicle speed through OBD2 data logging I can tell you that it varies a LOT! The IC placement on my turbo setup precludes me from having the true CAI that I'd like to have but what I do have is like a combo SRI/CAI. At idle my intake system functions like a SRI, sucking in heat-soaked air from under the hood. When moving at speeds say 30mph+ there is enough outside air vented into the fenderwell from the open front fascia duct to negate most of the radiated heat from the radiator, fans, engine, etc. My idle IAT delta is more like +40F but that delta is only +5F at 60mph.

IMO the bottom line is that a SRI will result in very high IAT when vehicle speeds are low but not as much at higher vehicle speeds. A CAI draws in air that hasn't been heated by the radiator, A/C condensor, engine block, etc. so idle and slow speed IAT will be much lower and remain lower at higher speeds. If you wish to talk only of 30mph + crusing IAT then perhaps the CAI IAT is only 10-20F cooler than a SRI.