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1991 Celica GTS
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Discussion Starter #1
True or false. Then please explain.
If I want to further increase the amount of air entering my motor, one option is getting a bigger throttle body, right? Well if I did that would definetely call for bigger injectors, right? If so far I am right, what else besides a stock tb would fit on my 5sfe, or soon to be 5sfte?
 

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1990 Celica GTS
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Every cylinder will hold 2.2/4=0.55L of air/fuel mixture without force induction. So on a NA engine you don't need too big TB cause the engine can draw only so much air.
Basically get it as big as the intake pipe for turbo to remove bottle neck.
You'll need to P&P the head and manifold to get any gain from a bigger TB.
 

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On the injector side of things, don't worry, your stock injectors are barely working at 65-70% of it's capacity at best, you still got the remaining 30% for extra fuel you may need and that shoudl cover any work on the TB or a P&P job. F/I is another game
 

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Pineapple said:
Every cylinder will hold 2.2/4=0.55L of air/fuel mixture without force induction. So on a NA engine you don't need too big TB cause the engine can draw only so much air.
Basically get it as big as the intake pipe for turbo to remove bottle neck.
You'll need to P&P the head and manifold to get any gain from a bigger TB.
perfect solution!!
 

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Just to let ya know, injectors are rated at 80% or maybe it's 85% duty cycle.. So when sizing an injector you do not want to pick an injector that will need to work more than 85% duty cycle or it will go bye bye.

As for wanting a larger throttle body.. you can go as large as you want.. Like it was said above, the engine will only draw as much as it can possibly take it on the intake stroke. An engine is just a large air pump.. so you can have a throttle that measures 50" in diameter for all it matters.. it will still only take in as much as it can possibly draw in.

However, having a larger throttle body will allow air to enter more freely and quicker, and the gains can be substantial in some cases.

As for forced induction.. it really doesn't matter. Like it was said above, match the throttle size to turbo outlet size.... If you want to smooth up the throttle body or the intake manifold that is your option. Easiest way in my opinion is just to sand blast everything with a very fine grain, that will get a pretty damn smooth surface. Best do dissamble everything and use this methode on the inside of the manifold and you can probably polish the throttle body by hand pretty easily.

But you really don't need to get to picky with throttle sizing in a turbo application. Have you considered putting a G head on.. from the 3S-GE? If I was you.. I would get a 3S-GTE head.. take the turbo components as well, the engine harness and ECU too.. put the G head down install the stock turbo compenents and the engine harness with the ECU.. that will be a pretty easy conversion and be better than your current F head. Plus all you will need to do is change your fuel pump to the 3SGTE pump or equivelant aftermarket pump.. use the 3SGTE injectors, that way you won't need any aftermarket fuel controller.
 

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1991 Celica GTS
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125 Posts
Discussion Starter #6
ok, so what other tb , besides the stock will mount?
 

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1991 Celica GTS
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Discussion Starter #8
sleepr said:
make a 1 off intake man. so you can put any tb you want on there:rolleyes:
ignorant to what you said, I need layman's terms on that one.
 

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1991 Celica GTS
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Discussion Starter #10
thanx, is there an adapter premade or is this a fab jop?
 

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1990 Celica GTS
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A cut and weld job. Cut the mounting plate off, weld another one on to fit the TB you want. Then you need to make sure you can use the throttle position sensor with stock ECU or go stand alone.
Another thing is the 5S-FE got an Idle Control Valve on TB to control idle speed. Removing it will for sure require full stand alone ECU to get the engine to idle.
 
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