Once again a " Would This Work" topic by no_8wire.

[Mr Revhead]

make up a pipe that goes under the battery into the space there.. and fit with a TRD pod filter....
thats where mines sits and works very well.

no point pissing around with twin t/bs

[Stealer Of Souls]

Just had a thought...
If you wanted to try the twin tb idea...
Then go with what I said about two separate plenums... Grind about a 1mm chunk out of the middle of your current plenum. Get a plate welded in to seal off both halves. Attach the second tb as desired and see how it goes...
I think it would be best to go for two filters. Keep the inlet tract as short as poss by duplicating the factory design on both sides of the engine bay...

[no_8wire]

I to had that thought... though it was more for turbulence reduction...

Also would the turblence(sp) be a problem with air coming from two sides?
If it was would a plate welded in to separte intakes 1-2 and 3-4 solve that?

I will go have a look if I can see what sort of air sensor my car is, if its map or AFM..If its map I will def be giving this a go...
Oh and..

As at 40% throttle originally, you have 40% air coming through (well not exactly, its a lot more complicated than that.... but for example)

If you had 2 throttles that were the same diameter as the original, at 40% throttle you'd effectively be at 80% throttle!

Which would make the car rather twitchy I would imagine.

Exactly...so at 100%throttle I would effectivly be at 200% throttle.....

[Santa'sBoostinSleigh]

I will go have a look if I can see what sort of air sensor my car is, if its map or AFM..If its map I will def be giving this a go...

one thing to be aware of - if im thinking along the lines of what you want to do (i could be wrong), you will essentially have 2 sets of filter/intake/TB's/intake plenum's (if you split the plenum down the middle)
each feeding 2 cylinders right?

would you need to take into account that you 'could' potentially have two different manifold pressures, ie one MAP sensor reading one side of the intake/2 cyliners?
or is my thinking totally wrong?

[no_8wire]

possibly...
does anyone know what this is? I assume this is a AFM?



and heres the pic of the filter in the boot...

[RomanV]

Say (for example) the AW11 has a 60mm throttle body.

This has a cross sectional area of 2827 square MM.

If you have two 60mm throttle bodies, you have 5684 square MM of throttle body area.

To get the same surface area with a single TB, you only need an 80mm throttle body!

The 80mm throttle body has a circumference of 251mm, while two 60mm throttle bodies will have a circumference of 188 x 2 = 376mm.

so you have far more surface area of piping causing drag with two throttle bodies, than one larger one.

Ideally you want as the most amount of surface area, for the least amount of circumference.

The twin throttles has a surface area/circumference ratio of 15:1
Whereas the single throttle has a 22:1 surface area/circumference ratio.
Quite a substantial difference!
It would be a shame to do all of that work, to make your car WORSE.

Not that Ive seen any reason to beleive that a single AW11 throttle body is inadequate or restrictive...
Especially on a big port engine, I would imagine you really need the air velocity into the plenum to help get some air velocity into those oversized ports.

[Ako]

The man has a point.

Just going up to a larger, single throttle body would be easier, and pose much less issues than farting about with trying to get twins working.

[no_8wire]

true...BUT as I am trying to work with what I have....twin throttles is currently looking like the way I will go...

Anybody have anyidea if that is the AFM

[Jebus]

Thre isnt an AFM in that picture.

[no_8wire]

sweet...that eletrical plug would be the air temp then?

[drftnmaz]

from what i know reguarding throtle bodys the bigger you go the less drivable it becomes and the more power you loose down low.

on a n/a eng you want to make equal length inlet runnings going to a plenum facings sideways to the thottle body of your choice.

and remeber if you were to seperate the manifold in anyway, ie to use smaller thottle bodies then remember that the eng fires 1-3-4-2 so you would want to group 1&4 and 3&2.

a good example of equal length intake runners is the late model mazda injected motors (bh chassis) they work very well and create good torque but wouldn't work the best in turbo aplication.

[Truenotch]

possibly...
does anyone know what this is? I assume this is a AFM?

Oi mang, your car is map

[no_8wire]

sweet...



so for fueling the twin throttles wouldnt cause it to run lean? That is all I care about at the moment....If it wont damage my engine I will give it a go and see what happens...

[Stealer Of Souls]

and remeber if you were to seperate the manifold in anyway, ie to use smaller thottle bodies then remember that the eng fires 1-3-4-2 so you would want to group 1&4 and 3&2

Duh. I'm such a nob... Yes... That's true... I guess (a proper???) split plenum wouldn't be that easy after all...
Well. The budget way to see if there is any value to the design is to split a standard plenum 1-2, 3-4, and if there seems some benefit. If there is then it would be best to go and make a proper one...

from what i know reguarding throtle bodys the bigger you go the less drivable it becomes and the more power you loose down low.

This makes sense. A larger throttle body will not have the same fine control of opening as a smaller one would have. But will flow more for top end.
Loss of low end power will come from the decreased intake air speed.
This makes the argument for electronic throttle control more convincing...
Small amounts of throttle = less than normal movement of butterfly.
medium throttle = normal movement of butterfly.
high throttle = more than normal movement of butterfly.

so for fueling the twin throttles wouldnt cause it to run lean? That is all I care about at the moment....If it wont damage my engine I will give it a go and see what happens...

Don't know. I guess the assumption that the manifold pressure/vacuum would be the same in each half of the intake wouldn't be too far off...
It's a little risky. For 100% reliability you'd need two MAP sensors that interface individually with the grouped cylinders. This is the only way to truly ensure that everything is under control..
But in my personal opinion, I'd just assume that each half of the intake has the same pressure. I reckon it'd be okay.

[RomanV]

Small amounts of throttle = less than normal movement of butterfly.
medium throttle = normal movement of butterfly.
high throttle = more than normal movement of butterfly.

Hmmm, non linear throttle control?

You could do this simply with an oval shaped pulley that the throttle cable attaches to, instead of a round one.

Without the scariness of having a computer controlling your go pedal!

[RomanV]

Loss of low end power will come from the decreased intake air speed.

Correct. But shutting the throttles more to create more vacuum will not increase air speed by the same amount... The engine is still consuming approx. the same amount of air, but there is a larger volume of air in between the throttle(s) and the head. So air velocity and throttle response will decrease, regardless of what you do. It'll be like driving a laggy turbo car... That never comes on boost!

so for fueling the twin throttles wouldnt cause it to run lean? That is all I care about at the moment....If it wont damage my engine I will give it a go and see what happens...

Don't know. I guess the assumption that the manifold pressure/vacuum would be the same in each half of the intake wouldn't be too far off...
It's a little risky. For 100% reliability you'd need two MAP sensors that interface individually with the grouped cylinders. This is the only way to truly ensure that everything is under control..
But in my personal opinion, I'd just assume that each half of the intake has the same pressure. I reckon it'd be okay.

Generally when people run quad throttles, they take a vaccuum hose from behind each throttle, which leads to a single 'plenum'. The map sensor attaches to this.
Otherwise the vaccuum pressure jumps around too much, from reading the pressure from only 1 or 2 cylinders. (courtesy of being so close to the opening and closing valves)

No8Wire, there is no way that anyone can garauntee you that it wont run lean. It will completely depend on how you proceed.

I still think its a crazy and pointless idea, but good luck anyway I'll be interested to see how this turns out, even if I am a skeptic.

Although I think that for all the trouble you are going to, you may as well look at getting some quad throttles adapted instead, which would be much cooler.

[Mr Revhead]

yeah to be honest id be suprised if you saw any gain at all.....

go the quads.....

[barryogen]

I to had that thought... though it was more for turbulence reduction...

Also would the turblence(sp) be a problem with air coming from two sides?
If it was would a plate welded in to separte intakes 1-2 and 3-4 solve that?

I will go have a look if I can see what sort of air sensor my car is, if its map or AFM..If its map I will def be giving this a go...
Oh and..

As at 40% throttle originally, you have 40% air coming through (well not exactly, its a lot more complicated than that.... but for example)

If you had 2 throttles that were the same diameter as the original, at 40% throttle you'd effectively be at 80% throttle!

Which would make the car rather twitchy I would imagine.

Exactly...so at 100%throttle I would effectivly be at 200% throttle.....

well, kinda, I mean you would only hit whatever limit your injectors have, but getting much above 100% throttle(meaning 100% of normal throttle) you would probably just flood the engine, and confuse your ECU.

[barryogen]

The man has a point.

Just going up to a larger, single throttle body would be easier, and pose much less issues than farting about with trying to get twins working.

Going to a larger one doesn't necessarily make it better either, you have a higher potential flow, but the air speed is lower, not sure how much difference it would make, but it would certainly make some. larger area would also f*ck with MAP(larger area using same amount of air would make a lower MAP).

[Stealer Of Souls]

Small amounts of throttle = less than normal movement of butterfly.
medium throttle = normal movement of butterfly.
high throttle = more than normal movement of butterfly.

Hmmm, non linear throttle control?
You could do this simply with an oval shaped pulley that the throttle cable attaches to, instead of a round one.
Without the scariness of having a computer controlling your go pedal!

Actually. Considering how it all goes together, it's almost like linearising the throttle...
The only thing I see about an oval shaped pulley is the uneven pedal force that'd be needed. You'd have to push the pedal harder to get the first bit of movement, and it'd get easier to push. Possibly an issue with cable length too...
Computers aren't that scary. A lot of modern cars are getting fly-by-wire throttles now. Makes for wicked cruise control.

Generally when people run quad throttles, they take a vaccuum hose from behind each throttle, which leads to a single 'plenum'. The map sensor attaches to this.
Otherwise the vaccuum pressure jumps around too much, from reading the pressure from only 1 or 2 cylinders. (courtesy of being so close to the opening and closing valves)

Ah. Well. There's the solution to that problem...

I still think its a crazy and pointless idea, but good luck anyway I'll be interested to see how this turns out, even if I am a skeptic.

I too think that this idea will probably turn out to be a flop, especially on a stock NA. But as always, the proof is in the pudding. Who knows. He could be on the verge of the next big mods craze.
I say give it a go. Intakes are complex items and I for one don't know enough to give a 99.999% definite answer. If it doesn't work, well then we now all no the exact answer. And if it does work, we'll all come asking to see your design.