1ZZ throttle body = 1.8L CAI?

[CrankyOldMan]

I'm tinkering with a custom intake setup that will use the 1ZZ throttle body. It occurred to me that the larger diameter TB would be better suited to a CAI/SRI with a matching diameter/adapter. The K&N intake for the 1.8L yaris (part 69-8615TS) has a 2-5/8" ID at the TB, but the "normal" intake for the 1.5L has only a 2-1/4" ID. From what I've found in other threads here, the OD of the stock TB is 2-1/4". Has anyone measured the OD of a 1ZZ?

My question then is: will the intake for the 1.8L mount up correctly in a stock 1.5L engine bay? The instruction sheet makes it look like it would, but I'd rather have confirmation before dropping $300 on the kit.

Oh, and sorry for all the acronyms. Trying to keep it brief.

[Lil Abner]

I think you're overlooking one key aspect: our MAFS won't like a larger diameter intake pipe. If you put our MAFS in a larger pipe, you'll get a CEL, and the engine won't run smooth. I don't know if there's a way to "trick" the MAFS into thinking it's in a smaller pipe or not.

Side note, are you planning on getting more power and keeping good gas mileage with this? I keep reading, and haven't found a solid answer if the large throttle body will hurt my 45mpg.

[Bluevitz-rs]

Cranky, it won't work unless you're running a piggy back to correct the MAF reading. You'll be running lean with a larger intake pipe.

[CrankyOldMan]

Cranky, it won't work unless you're running a piggy back to correct the MAF reading. You'll be running lean with a larger intake pipe.

Hmm, now I'm confused. What's the point of using a larger throttle body with the stock intake then? Can the stock tubes take advantage of a wider throttle opening without dramatically altering the air flow volume? I'm not opposed to running a piggyback, but wasn't planning on adding one prior to going FI.

[Bluevitz-rs]

problem with running larger pipe is that air velocity slows down across the MAF due to more available surface area for the air to travel. The MAF then translates this into less air going into the motor --> which leads to less fuel injected. When in reality MORE air IS going into the motor. So unless you're correcting those misread values, your motor will run lean.

[Bluevitz-rs]

Area of a 2.25" pipe --> 7.0686"

Area of a 2.625" pipe --> 8.2467"

∏D=Area

So that's roughy 16% more surface area. If you corrected the fuelling by approximately that much you should be alright.

[CrankyOldMan]

∏D=Area

∏D = circumference
I get what you meant though. =)

A = pi * r^2

2.625" = 5.41 in^2
2.25" = 3.98 in^2

which is actually a 36% increase in cross-sectional area.

As far as the air velocity slowing down, that's because the displacement of the engine can only "suck in" so much air per stroke? I was thinking of it in terms of the air blowing into the larger filter and tube, but I guess that doesn't matter if the valves aren't open.

So assuming that I get a piggyback and correct the A/F ratio, does the engine actually get more air/fuel per stroke?

[samuraivince]

what if you use a larger tube then bottle neck it? i mean putting the MAF sensor in the smaller part of the tube.....would that work? i've wanted to do that same mod, but knew it might not work out

[Stove]

2.25" = 57.15mm. The smallest diameter in the intake system is still the throttle body. A 1zz TB has a 55mm bore. As long as your intake is larger than that you wont have a problem. The smaller bore of the TB will limit the amount of air that can pass freely through the intake system.

I believe that the 1NZ intake is actually 60mm not 2.25". 60mm = 2.362"

[thebarber]

do like me

run a 2.5" tube before the maf and 2.25" from the maf to the tb

speeds the air up at the maf since 2.5" of air has to go to 2.25" then down to 1.75 at the tb

i don't know if it does anything, but i dyno'd 106whp and 107 wtq with just an intake and my resonator-back exhaust (which by the way, is for sale)

[samuraivince]

interesting.....so doing a 3" pipe from the air filter to the MAF size pip wont give you much gains?

[CrankyOldMan]

I just looked over the installation instructions again and the 1.8L intake from K&N (for the Scion xD) still uses the stock MAF section, but that would still cause the same problem, since I'm sure the xD has a larger intake diameter. Crap.

[samuraivince]

could we use the MAF from a Toyota Celica, then make the pipe bigger?

[CrankyOldMan]

could we use the MAF from a Toyota Celica, then make the pipe bigger?

I'm gonna guess no, since it's the ECU that decides what to do with the MAF data. Perhaps CTScott knows what the output from the MAF is? (I.e. voltage or PWM).

[WeeYari]

could we use the MAF from a Toyota Celica, then make the pipe bigger?

If only things were that easy. The issue is really the ECU. It is in control of adjusting the fuel based on air flow. This is why a piggyback is being discussed. You need to fool the ECU.

CTScott has spent some time on trying to figure out if/how the ECU fuel map could be remapped. No success.

[samuraivince]

hmmmmm, there has gotta be some little trick to it that wont make the engine run too lean. i was also toying around with the idea of dual air intakes, by spliting the intake with a Y pipe and putting 2 cone filters, then running flexible tubeing from behind the fog light area, or cutting a retangle in my bumper right in from of the original intake and removing tis little rubber piece thats part of the radiator frame (kinda like what you can do on the Nissan 350's) but that would just be to push more air to the filter(s)

[thebarber]

post up when you blow up your engine, vince

[samuraivince]

lol, will do if it comes to that. but i like to do my homework before messing up my "baby".......and all i wanna do is give the "black dragon" some extra zip

[Reactor]

ECU will learn by how much to offset MAF sensor readings that are affected by different intake runner diameter. The Long Term Fuel Trim value will eventually be in the plus territory since ECU will assume that MAF does not measure as much air as is actually entering the motor.

[Bluevitz-rs]

So you have data to back up your claim?

[Reactor]

Scangauge can display LTFT value. I have one and clearly saw difference between running stock intake and AEM (i have 2006 xB)
AEM intake is slightly smaller diameter than stock runner which makes the MAF readings be higher than what they should be. So my ECU learned to run -5 to -7 Long Term Fuel Trim once it's off idle. With stock intake before it usually ran between +2 and 0.