throttle body: how big?

[igorien2k]

i was thinking of staying N/A with my 98 1zz corolla. apart from the obvious i/h/e and cams i was thinking of purchasing an intake manifold, and chop it up in order to install a bigger TB or just ITBs by installing butterflys on the intake runners.

heres a pic of what my manifold looks like, although many of you already know:

http://www.corollaperformance.com/TechInfo/1ZZFE_1.jpg

what size TB should i install for max gain? if i do single TB, i know i dont want to go too big because that would decrease the intake velocity. what would you suggest? also, if i do ITBs would it work or are the runners way too long in order to be effective?

all suggestions welcome. and yes, i will be getting engine management to get this beast running.

[igorien2k]

anyone know maybe how to calculate velocity, volume, and cam duration in relation to performance?

[Flashmn]

I'd stay with the stock sized one. With those mods you really dont need a bigger tb.
A negative aspect of a large tb is that you lose off-idle sensitivity.

[punter]

What other mods have you done? TB won't be a restriction untill your making some serious power.

[igorien2k]

i dont have any engine mods yet, but im considering making some N/A power. probably looking at stage2 cams from MWR, titanium valve springs, alphawerks header with custom downpipe, highflow cat, custom cat-back, emanage for EMS. hoping to make 160 hp at the crank (which has been confimed as possible on a 1zz matrix with i/h/e and emanage) but maybe more if i can get some power from a bigger tb. I hear some 16V 4AG motors get a kick out of ITBs which have a total throttle body diameter of about 200mm using 45 mm trumpets. the 1zz is a high-compression motor, so i'm hoping it would have a similar effect with a larger TB, maybe with a 10 hp gain with some midrange improvement? I've actually seen photos of an MR2 1zz motor with a ~100 mm custom throttle body, but that was built for F/I so it might not be beneficial at all for N/A

[Flashmn]

Like i said in my post, it wont become a restriction quite this early. Do the other mods first and then worry about the tb, people rush into things from the wrong end. You'd only do shit to your lower end rpm band and throttle sensitivitiy going too soon to a big tb.

[igorien2k]

i was just thinking as a maximum for a 1.8L. cuz it seems like with itbs you can have a much bigger tb area then you would usually have with a single TB. why is that?

[retiredat44]

why go through all the trouble of re-inventing the wehll when you can buuy a kit already tuned for your car. You can go with an exhauast package or bump it up to a pacakge which includes a carb/with/without/new intake. Also, your engine must be in great condition with low to medium miles on it, because increasing horsepower is hard on the parts. Ber prepared to eat clutches and also make sure your brakes are either already upgraaded or upgrade those too because the corollas have very very small brakes. (personnaly, I think they made them way way too small and wear out incredibly fast under normal driving. Our front brakes are crap and wron out after only 20,000 miles each year. Which is a sick sad joke. I had a toyota truck and the brakes on that easly could go 100,000 miles. So you see you cannot just add horsepower without making the rest of the car safe.

If you just want 20 horsepower, obviously you plan to use it, but even 20 more horses will need more brakes.

[igorien2k]

a) my car is EFI
b) they dont make anything for my car - not even exhaust - all has to be custom-made or modified to fit. if you saw the pic of the manifold you would see how easy it is to modify it for itbs. intake runner lengths are ~15-25 inches with about 50mm diameter which would be good for torque if i attach butterflies on the intake runners.
c) the brakes are fine. most would say they are bigger than on hondas which are the same weight. i'm buying powerslot cryo-treated rotors and hawk pads
d) people have run 10+ lbs of boost on the stock internals. i plan to change the valve springs and cams in order to make reliable power up top
d) i have a racing clutch in my car

[Flashmn]

Itb's are quite different from a single tb setup and you cant directly compare them.
Going too big on the itb setup is also harmful. However think about it this way, with itbs one throttle body per cylinder, with a single tb you have that tb for 4 cyls, however only one is breathing through it at a particular time.
With itbs 50mm throttlebody its gonna be f:n huge, goodbye intake velocity, imagine a weber 45, the inner venturi is most likely something like 34-36...now itbs use the same principle.

Now, changing valves and valvesprings dont do shit for reliability if you dont go past redline, cams, I dont see how they affect reliability in any way. Tougher valvesprings will cause valvetrain parts and valveseats to wear out faster. Bigger cams with lots of overlap can cause shit for low end function, such as idle. And what does comparing boosted conditions and n/a high-rpm reliability have in common?

Racing clutch as in a non-sprung sinter clutch?

Just a question, have you really thought these things reading a book, or did you just take them from an import magazine?

[Pineapple]

The NA build of the 1ZZ-FE is called 2ZZ-GE.

[igorien2k]

the intake runners are 50mm each. i can choose the butterfly size. i do plan to up the redline, probably to around 7k which is the jdm mr-s redline and it looks like it can safely get there. even without valve springs its "relatively safe" because the internal components are supposed to be the same for all the 1zz-fe engines but you can never be too safe especially if the cam lift is changed. I dont plan to get such aggressive cams that my idle is ruined. i was hoping to see if using a part of the stock manifold would provide good enough resonance characteristics to help boost power. right now i'm just looking for itb length calculators that i'm hoping can guide me to see if this would actually work.

*edit* and by "racing clutch" i meant 30% stiffer than stock

[Flashmn]

I think 50mm diameter intake runners are gonna kill your low end.

30% stiffer than stock is hardly a racing clutch. Unsprung sinter clutches are racing clutches and they're hell to drive on the street.

[punter]

Originally Posted by igorien2k

I dont plan to get such aggressive cams that my idle is ruined.

Then I would seriouly doubt that the stock intake would become a big restriction.

I'd say save your time/money and look at doing things like upping the compression and a good after market computer.

[357wheelgunner]

If you are out for power, why in the world would you stick NA with the 1zz? You'll spend $3000 for a modest gain when you could have just bought a turbo kit or supercharger and been done with it.