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dual throttlebody intake by gambler85
Started on: 06-06-2012 03:11 PM
Replies: 17 (1748 views)
Last post by: Patrick on 07-08-2014 07:13 PM
gambler85
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Report this Post06-06-2012 03:11 PM Click Here to See the Profile for gambler85Send a Private Message to gambler85Edit/Delete MessageReply w/QuoteDirect Link to This Post
I know that these intakes have been tried before but all of them that ive seen has both throttlebodies point the same direction. Has anyone made one that would have one point at the drivers side and one at the passengers side. The only thing i can think of as being an issue would be synchronizing. The two. I can deal with the throttle position and all that. I just wanted to see if its been done. It will be for a stock 2.8l
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OH10fiero
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Report this Post06-06-2012 05:20 PM Click Here to See the Profile for OH10fieroSend a Private Message to OH10fieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
The main issue is not synchronizing but measuring the incomming air correctly, the Fiero computer is not designed to read duel IAC or MAF sensors and the extra air being brought in drives the ones you have on the car nuts.
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Will
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Report this Post06-06-2012 06:29 PM Click Here to See the Profile for WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
Lol... Speak of which you know.

Fieros don't use MAF's.
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ericjon262
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Report this Post06-06-2012 07:08 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
as stated above, fieros(stock at least) don't use MAF, and most well done DTB setups route both IAC ports to a single IAC.

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Fiero84Freak
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Report this Post06-06-2012 09:34 PM Click Here to See the Profile for Fiero84FreakSend a Private Message to Fiero84FreakEdit/Delete MessageReply w/QuoteDirect Link to This Post
There is a MAP but not a MAF. One measures pressure, the other air flow. The MAP sensor can plug in anywhere on the intake plenum after the throttle body. As mentioned, no MAF so you can have as many throttle bodies as you want. Hell, if you can figure out how to mount six you can do it (and then run the accompanying tune for it, as you would have to do anyway running dual throttle bodies), but that'd be silly.

My issue is that I don't see why you would want to do it. There's no logistical advantage having them run in opposite directions, other than aesthetics which makes no sense, and honestly would likely cause more headache down the road. You would have to go about relocating other components on the passenger side of the engine compartment. Something like the TLG dual throttle body or a homemade unit with sync'd throttle bodies would be the best way to go.

Please don't take the above as offense. I just don't see why you would want to cause more headache.

Really the biggest hurdle is accounting for a new tune for the extra incoming air. Other than that just slap the MAP on there, dual up the IAC, and other little logistics and you're good to go.

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Will
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Report this Post06-07-2012 07:13 AM Click Here to See the Profile for WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
Can use a divorced IAC on a balance tube, etc.
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Report this Post06-07-2012 10:16 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
You shouldn't need a fancy IAC setup. Just run a stock-ish IAC setup on the driver side throttle body, and block off the IAC passage on the other one. The IAC system bypasses the throttle plate. It draws in air from in front of the throttle body. So there's no vacuum to equalize. And at idle, the engine doesn't draw in much air. So pulling in air from a second induction tube would be completely unnecessary.

In other words, the IAC on the second throttle body would be deleted. You only need one IAC.

You would, however, need to adjust the programming to account for the larger throttle valve. Because with 2 throttle bodies at half throttle, you'd get the same effect as one at full throttle. That may confuse the ECM.
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OH10fiero
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Report this Post06-07-2012 12:13 PM Click Here to See the Profile for OH10fieroSend a Private Message to OH10fieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sorry, meant to say Air Charge Temp sensor, which is what the Fiero got instead of a MAF.
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ericjon262
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Report this Post06-07-2012 12:36 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by OH10fiero:

Sorry, meant to say Air Charge Temp sensor, which is what the Fiero got instead of a MAF.


????? you may want to go ahead and stop now while you're ahea... just stop.

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OH10fiero
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Report this Post06-07-2012 12:44 PM Click Here to See the Profile for OH10fieroSend a Private Message to OH10fieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ericjon262:


????? you may want to go ahead and stop now while you're ahea... just stop.



Stop what? it was an honest mistake since MAF sensors are the norm and very few cars ever used the ACT sensor for data. No reason to be a dick about it.
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Report this Post06-07-2012 02:23 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
I do not like the twin throttle body intakes because you will get a false reading from the TPS. The TPS voltage reading will now be half of what it was on the single throttle body at the same air flow. This is because the flow is now distributed between the two TB's.
At half throttle with a single throttle body the TPS in theory will read 2.5Volts. However the same air flow will occur with dual throttle bodies at 1/4 throttle so you will get a 1.25V reading at 1/2 throttle . Without a completely reprogrammed chip, this will lead to fueling errors. Not an insurmountable problem but a tuning problem none the less.

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Report this Post06-07-2012 02:52 PM Click Here to See the Profile for WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by OH10fiero:

The main issue is not synchronizing but measuring the incomming air correctly, the Fiero computer is not designed to read duel IAC or MAF sensors and the extra air being brought in drives the ones you have on the car nuts.


 
quote
Originally posted by Dennis LaGrua:

I do not like the twin throttle body intakes because you will get a false reading from the TPS. The TPS voltage reading will now be half of what it was on the single throttle body at the same air flow. This is because the flow is now distributed between the two TB's.
At half throttle with a single throttle body the TPS in theory will read 2.5Volts. However the same air flow will occur with dual throttle bodies at 1/4 throttle so you will get a 1.25V reading at 1/2 throttle . Without a completely reprogrammed chip, this will lead to fueling errors. Not an insurmountable problem but a tuning problem none the less.



I don't know why people seriously think anyone would seriously try to use a dual throttle intake with a factory tune. Seriously.

[This message has been edited by Will (edited 06-07-2012).]

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Will
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Report this Post06-07-2012 02:55 PM Click Here to See the Profile for WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post

Will

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Member since Jun 2000
 
quote
Originally posted by Dennis LaGrua:

I do not like the twin throttle body intakes because you will get a false reading from the TPS. The TPS voltage reading will now be half of what it was on the single throttle body at the same air flow. This is because the flow is now distributed between the two TB's.
At half throttle with a single throttle body the TPS in theory will read 2.5Volts. However the same air flow will occur with dual throttle bodies at 1/4 throttle so you will get a 1.25V reading at 1/2 throttle . Without a completely reprogrammed chip, this will lead to fueling errors. Not an insurmountable problem but a tuning problem none the less.



I guess it's a good thing that the Fiero computer judges load via the MAP sensor and not the TPS...
The differing relationship between MAP and throttle position may screw up when the ECM enters PE fueling and may screw up AE/DE;

Really... Like I said above... don't use without a retune.
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ericjon262
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Report this Post06-07-2012 06:02 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by OH10fiero:


Stop what? it was an honest mistake since MAF sensors are the norm and very few cars ever used the ACT sensor for data. No reason to be a dick about it.


an air charge temp sensor, or as it's more commonly known, an intake air temp, does not do the majority of fuel or spark control, that's what a MAP sensor is for.

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Slowbuild
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Report this Post06-08-2012 12:39 AM Click Here to See the Profile for SlowbuildSend a Private Message to SlowbuildEdit/Delete MessageReply w/QuoteDirect Link to This Post
I built one:

http://www.westcoastfieros....?TID=1625&PN=1&TPN=2

It starts near the bottom and goes on for pages...sorry...

I'm custom tuning $59 for adding a turbo. The intake was to try to maximize the turbo's potential on my 3.4pr. Better flow before = better flow after.

Anyway, I ran the dual TB nat. asp. for a while...it really woke up the 3.4 after I added some fuel and timing; I still want more, thus the turbo. The manifold alone extended the rpm range about 1k, and I didn't notice any loss in the bottom end.

I used a single IAC and ran a healthy size crossover. I have toyed with inverteing the TB and reversing the actuation of the throttle plate (Bottom towards the rear, not the front). It could work. As it worked out I mounted the tps on the other TB. On the non IAC TB I filled the IAC port with epoxy. I scrapped the hot water feed to the manifold.

A very stiff linkage is required between the two Tbs. When the tubo is done I will revisit this issue. It's not too bad, but for really good synch it's necessary.

One of the best things about this manifold is the access to the injectors, adj. fuel pres. reg., etc. It makes it a breeze to do things which are impossible on a standard manifold equipped car.

Chay
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Will
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Report this Post06-08-2012 08:02 AM Click Here to See the Profile for WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
Dagonnit... you're making me want to finish the bolt-on dual plenum arrangement I was building for my Formula a couple of years ago.

[This message has been edited by Will (edited 06-08-2012).]

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gambler85
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Report this Post06-08-2012 09:33 AM Click Here to See the Profile for gambler85Send a Private Message to gambler85Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thank you input the input guys. The reason i want to run one off each side is to make the filters sit in both side scoops. I also know i am going to need a retune. Im thinking about running my ms2 on this car anyhow.
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Patrick
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Report this Post07-08-2014 07:13 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
Perhaps I'll eventually start my own thread on this if it's a viable idea, but this thread has some relevant info in it, so...

From what I understand, the Fiero's stock intake has quite a restriction in the neck. The engine therefore runs out of steam at high RPMs. I use my 5-spd '88 Formula to autocross, so I'd like a few extra ponies without having to entertain an engine swap.

Various methods have been employed to deal with this flow restriction issue, such as enlarging the neck of the intake. I'm not interested in going that route.

I've relocated my battery to the front, and the old battery location is all cleaned out. Something needs to go there.

I'm interested in a installing a secondary throttle body, but one that's only employed for wide open throttle (WOT).

I'm not interested in having same-sized dual throttle bodies that are synched together. I feel that this complicates proper tuning. With my idea, the secondary throttle body (smaller in size/CFM) would be mounted over on the passenger side of the intake and wouldn't start to open at all until perhaps 3/4 full throttle. There's probably a "best" time for it to begin to open, and that's hopefully what can be determined here.

A few questions then.

1) With a stock (and/or mildly tweaked) 2.8, what flow/CFM is required at WOT?

2) And what does the stock throttle body/intake supply?

This info would allow me to choose an appropriate sized secondary throttle body or valve of sort sort. (Suggestions of what to use are welcome.)

3) I've heard that at some point, the ECM just basically dumps gas at WOT. When exactly does that occur...

4) And perhaps more importantly, what determines when the ECM dumps gas at WOT?

This info would allow me to hopefully configure when the secondary throttle body/valve should best be opened.

Feedback would be much appreciated.

[This message has been edited by Patrick (edited 12-01-2014).]

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