I have been working on a dual TB intake for my 3.4 pushrod engine for a couple weeks (an hour or two a couple nights a week). It is close to finished. I hope to be mounting it on my fiero in a couple more weeks. I have a write up and pics of what I have done on my webpage.
------------------ Martin D. White 86.5 GT 3.4 pushrod (dual TB intake in the works) on 88 cradle (2.5" coilovers), gt-40 style hood vent, recessed lights, GA brakes on held drop spindles. 2610 lbs and on diet...
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12:32 AM
PFF
System Bot
yellowfieroarri Member
Posts: 619 From: Sorø, Denmark Registered: Mar 2002
Looks great (well not appearence wise but you know what I mean)! I remember hearing as much as a 30 horse (don't quote me on this) from a setup like this. I have been wanting to do something like this for a while but I haven't gotten around to it. I guess all I would have to acquire would be an extra tb, scrap metal, and a middle intake (so I could drive my car while I did it).
I can't wait to hear Dyno #'s.
Kevin
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01:50 AM
Borgio Member
Posts: 221 From: Kokomo, Indiana, USA Registered: Oct 2001
Geez, I just complimented you in another thread, before I had read this one and looked at the new page on your site. I'm sorry, but I have to do it again. Nice site, nice write-up! Keep modding and keep that site updated!
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02:11 AM
Dennis LaGrua Member
Posts: 15139 From: Hillsborough, NJ U.S.A. Registered: May 2000
Your dual throttle body looks like great fab work but I believe that you must give thought to the engine management and sensor inputs. Since both throttle bodies open together equally; the ECM would be happy with a single TPS signal from one of them. However, the problem as I see it is with the IAC. Both banks of cylinders will need to draw air from each throttle body to idle properly. How do you intend to control the idle? The ECM was only designed to respond to a single IAC. If you parallel the IAC's then you throw the impedance that the ECM sees at the input and the air reuirements at each cylinbder bank may be also be different.If you parallel the IAC's, I'm not sure that the ECM input buffers can take this new impedance loading. While I really appreciate your work and I don't mean to discourage you; I believe that a single larger throttle body for better breathing might be the easier solution.
If you read his website, you will see how the IAC handles airflow when the iac is open, in order to get more air to *all* cylinders. The balance tube will take care of any irregular flow between the two throttle bodies, as well as the IAC and MAP functions. He could run his EGR to the balance tube, and then he'll be good to go.
You shoot things down so fast it's almost scary Dennis...take a look on the bright side, check out his website, give the man a little credit. A single large throttle body won't do anything for the 3.4, as the intake size will still restrict flow after installing a big throttle body.
Martin, have you put any thought into the EGR yet? I'm also working on an intake similar to Greg's (cooter's), but I'm not as far as you. I'm using a different throttle control setup, but will be using a balance tube and similar IAC tube setup. My engine's torn apart right now so I can't mock it up yet...kind of worried about distributor clearance right now. I think I may reposition the ignition coil to unclutter things, probably over the section of fuel rail that is bare (out of the way of the regulator, in case I want to fiddle with it later). I also have a 3.4 and am sick of the poor intake setup. I have a dynotuner, so things should be a little easier for me as far as post-install driveability is concerned.
Thanks for the updates, they're always appreciated!
Bryce 88 GT
quote
Originally posted by Dennis LaGrua:
Your dual throttle body looks like great fab work but I believe that you must give thought to the engine management and sensor inputs. Since both throttle bodies open together equally; the ECM would be happy with a single TPS signal from one of them. However, the problem as I see it is with the IAC. Both banks of cylinders will need to draw air from each throttle body to idle properly. How do you intend to control the idle? The ECM was only designed to respond to a single IAC. If you parallel the IAC's then you throw the impedance that the ECM sees at the input and the air reuirements at each cylinbder bank may be also be different.If you parallel the IAC's, I'm not sure that the ECM input buffers can take this new impedance loading. While I really appreciate your work and I don't mean to discourage you; I believe that a single larger throttle body for better breathing might be the easier solution.
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10:34 AM
Pyrthian Member
Posts: 29569 From: Detroit, MI Registered: Jul 2002
I dont think Dennis was shooting it down, he was just mentioning some small potential problems. Yeah, he shoulda looked at the site, and he would have seen that it was under control. He has good ideas, and what he mentioned is something that is easy to overlook when in the construction stage of such a cool project.
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10:50 AM
utahfiero Member
Posts: 244 From: Kingsport, TN Registered: Jan 2002
I agree that a bigger single TB would be a solution. My first plan was to do something like WCF larger TB and also trim out some of the intake runners in the stock upper plenum. But alas I don't have the tools to weld aluminum, an I don't have a spare larger TB. I do have the tools to weld metal and I had all these spare parts lying around, so I thought I would give it a try.
As others pointed out I will only be using one AIC since the upper intakes are connected with a cross over tube.
Nascho,
I have thought about the EGR hookup. I will hook it up but I am not sure where. I would like to attach it to the balance tube, but I don't think the EGR tube it long enough to reach. Just means I might have to weld some more. I love to weld.
Martin D. White
------------------ Martin D. White 86.5 GT 3.4 pushrod (dual TB intake in the works) on 88 cradle (2.5" coilovers), gt-40 style hood vent, recessed lights, GA brakes on held drop spindles. 2610 lbs and on diet...
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11:38 AM
Xander Worrell Junior Member
Posts: 1 From: Purmerend, the Netherlands Registered: Nov 2002
The IAC ports the air to the lower manifold via a metal/rubber tube. You could just use one IAC and hook it up like original. So you dont have a problem with one bank not getting air.
xander
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01:05 PM
Nov 15th, 2002
Dutch-Fiero Member
Posts: 15 From: The Netherlands Registered: Nov 2002
Martin, my respect for the idea. I like your experiments (and your website; it's a good source of information).
I'm having little concerns about the square-tube between the two upper intakes. The higher revs may no problem but when the engine is at idle the airflow is very slow. I think the square-tube is to small to compensate the difference in under-pressure just because the restriction of the tube causing an unequal flow of air into the cylinders especially when "falling back" to idle from higher revs.
I'm very hopefull your setup will work but when you're eventually getting problems with a 'smooth' idle that's the first thing to look at (putting one or more bigger square-tubes into it; oh, you like welding anyway )
I wonder what it gives when you put two T3's on it..
------------------ '87GT 3.4V6 5-speed
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08:58 PM
fierosound Member
Posts: 15141 From: Calgary, Canada Registered: Nov 1999
Has anyone actually flow tested the Fiero intakes to see where the bottleneck is, or is everbody just assuming it's the TB? Just wondering whether the throttle body is the bottle-neck, or is it the small ports/runners in the middle intake that are a problem as well. Anyone?
------------------------------- THIS is the intake setup I'd like to know more about. It's in a Fiero, and the car was at a Fiero show. Someone must know the car's owner, who makes this intake and where to get it! From the looks of it, it should solve intake "flow" problems!
As for the crossover tube, it is small, but the vacum lines that run all the vacum assesories are smaller tubes and they work fine so I think that it will be OK. The cross over tube is also bigger than the line going to the brake booster.
Twin turbos would be way cool. I have dreamed about what that would look like.
This intake might turn out to be a prototype for an intake that replaces the middle intake also. I think I can make a bigger tube middle intake. I am also looking at replacing the lower intake. If I am able replace all three intakes I will also hog out the heads to match the bigger tube intakes. (dreams for sometime next year)
Impressive! Tuning for the intake might take some work. I had mine running with the same chip that was used with a modified 3.4 intake and at full throttle it ran great, but not so good at "just off idle". You might want to look at bin files for other GM engines that use a short runner intake to get an idea for the fuel map. Good luck.
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11:45 PM
Feb 13th, 2003
2fn4wrds Member
Posts: 185 From: Santa Barbara, CA Registered: Sep 2002
That's very cool indeed,you might want to add some weld,radius with a grinder,or somehow make the ends of the runners flare out where they enter the plenums.This will help things out immensely. There's a user group on Yahoo that has made their own ECU,it's called "Megasquirt".I found that '88 Subaru throttle bodies are 40mm and are very compact;six of them would be nice on a motor that size.
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01:49 PM
Raydar Member
Posts: 40686 From: Carrollton GA. Out in the... country. Registered: Oct 1999
------------------------------- THIS is the intake setup I'd like to know more about. It's in a Fiero, and the car was at a Fiero show. Someone must know the car's owner, who makes this intake and where to get it! From the looks of it, it should solve intake "flow" problems!
I know your post was a few months old. If you haven't already found out, this is Kris Munson's car. The picture was taken at the RFTH7 in North Georgia, this past fall. It's a Ryan Falconer intake, and according to Kris, "It was a b!tch to tune."
------------------ Raydar
88 3.4 coupe. In progress.
Out of my mind. Back in 30 minutes.
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02:13 PM
flomofo Member
Posts: 181 From: sacramento ca u.s. Registered: Jan 2003
How about those sheet metal intakes like in NASCAR would that possible with fuel injection? Plastics would be better but thats way expensive for aknuckle dragger project.
Hey guys (and gals) I am new here. I have been lurking for about 6 months now, but figured now I might have some useful input.
I built a very similar intake for the 3.4 MPFI engine in my '84 X-11. I actually cut the middle intake manifold to end up with even shorter runners, and avoid the narrowing of the runners as they start to curve upward.
Here is a pic of the middle section:
I then made a y-pipe that went around the distributor, and held a single 65mm Ford TB. This design could just as easily be used for a dual TB setup. I have since swapped the engine out for a 3400. I will post a complete engine bay pic of the intake installed tomorrow (pics are on computer at work).
Marty
[This message has been edited by RacerX11 (edited 02-13-2003).]
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08:00 PM
G-Nasty Member
Posts: 2099 From: woodlands,TX,USA Registered: Jan 2001
X-11: prepare for take-off... That looks like the tail end of a spaceship. Does the Ford TB hookup easily? Also how did did your citation run w/ this intake setup? OUT>
G-Nasty, The Ford TB fit pretty good, but that is because I fabbed the y-pipe myself. I used a 2-1/2 header-type flange at the other end of the y-pipe (the same flange that is on each of the plenums). I then drilled and tapped the flange from the Ford TB for the 3-bolt pattern. The TB comes stock with a 4-bolt pattern.
The car ran pretty good. I was able to get consistent 0-60 runs right at 6 seconds flat with a G-Tech. I never got a chance to run it at a dragstrip. The TB is a bit on the big side, but I got it for free.
The engine had awesome mid-range power, but it really ran out of breath above 5000 rpm. I am guessing it was putting out ~200HP at the crank. Unortunately, I never got a chance to dyno it. A dyno shop opened a half mile from my house a month after I pulled the engine out. I had hoped for better top-end out of this setup, but I guess the iron heads were a bottlenck. The heads had only minor port work done (gasket match, minor cleanup of bowls and exhaust ports).
Marty
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09:20 PM
jstricker Member
Posts: 12956 From: Russell, KS USA Registered: Apr 2002
I'm curious about your using the Mustang TB. PM me or Email me at jstricke@rwisp.com as I have some questions for you.
John Stricker
quote
Originally posted by RacerX11:
G-Nasty, The Ford TB fit pretty good, but that is because I fabbed the y-pipe myself. I used a 2-1/2 header-type flange at the other end of the y-pipe (the same flange that is on each of the plenums). I then drilled and tapped the flange from the Ford TB for the 3-bolt pattern. The TB comes stock with a 4-bolt pattern.
The car ran pretty good. I was able to get consistent 0-60 runs right at 6 seconds flat with a G-Tech. I never got a chance to run it at a dragstrip. The TB is a bit on the big side, but I got it for free.
The engine had awesome mid-range power, but it really ran out of breath above 5000 rpm. I am guessing it was putting out ~200HP at the crank. Unortunately, I never got a chance to dyno it. A dyno shop opened a half mile from my house a month after I pulled the engine out. I had hoped for better top-end out of this setup, but I guess the iron heads were a bottlenck. The heads had only minor port work done (gasket match, minor cleanup of bowls and exhaust ports).
I come up to Peoria on a reagular basis. Would you mind me dropping by and taking a look at that intake. I have been wanting to do something similar and would like to look into it more.
Jeff, That is not a problem. Drop me an email: mdurbanc@yahoo.com; Actually, this intake is for sale if you are interested. I don't have a need for it anymore, since I am using the TB with the 3400.