anyone thought about boring out the IAC/cold start injector "tunnel" in the lower intake manifold and burning a new chip to activate the IAC to open at WOT. it would be similar to the import cars that have 2 runners for each cylinder, the shorter ones have a butterfly thats rpm activated, i know on my old prelude u could feel/hear it open up around 3500rpms (it was an 88, so don't say it was vtec or i'll have to smack u!). it wouldn't add like 100hp but would be worth something maybe 5-10 hp extra...

i'm personally installing a 2.8/3.1 camaro upper plenum on my car as we speak, i just need to get some radiator hose and cut up my extra thermostat housing and it'll bolt right on with the TB facing the passenger side of the car, and since my battery is upfront i'm using the stock camaro air hose with a K&N cone filter on the end. i think i'll get a few ponies out of it as long as i can get the TB cable to hook up correctly, there isn't really room to make a bracket for the cable since it has to share its space with the fuel rail and fuel lines. other than the TB cable the only other "challenge" was to reroute all the vacuum lines, IAC tube and PCV lines. i'm hoping to have it done this afternoon, there were some other minor issues but i'll cover them when i post the pics of the manifold when its installed.

Here's an intake setup that's worth a look. It's on a turbo 3.4 in a cavalier. http://www.turboz24.com/

quote Originally posted by SpeedDemon: Here's an intake setup that's worth a look. It's on a turbo 3.4 in a cavalier. http://www.turboz24.com/

Looks a lot like the Camaro intake. But once again like was previously stated, when you turbo/super the motor, the intake design isn't *as* important.

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--Jess--
AIM/YIM: asyferme

If you expect the unexpected, was it really even UNexpected in the first place?

'85 SE, 2.5, 5spd (350 standing by waiting for ole duke to puke)
'86 SE, 2.8, auto (pushrod 3.4 swap on hold)

'02 Yamaha R6, blue/white, 3600 miles, LIGHT case of roadrash, for sale. Will accept Fiero(s) and/or parts as PARTIAL trade.

quote Originally posted by FieroGT87: If you want something "simple" here you go, but it's not cheap. This S/C uses the lower iron head plenum on the 2.8-3.4 engines. It can be set up to use carb or TB. I'll find the link and post it later. Earl R. [This message has been edited by FieroGT87 (edited 01-25-2003).]

ok.. where do you buy it from?

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--Adam--
1987 Blue GT 5-speed
IM AOL: FieroGT5speed
16 years old and already selling my stuff to pay for repairs to my Fiero...which i sold my stuff to buy in the first place

heres the plenum/TB that i'm using:

enjoy!!

bump

quote Originally posted by red85gt: Check out what I built to solve the bottle neck at wot

I had a thought something along these lines - but I was going to use something along the lines of a micro switch which at WOT would click a solenoid, yanking open a second throttle body via a second throttle cable. Maybe one of the power door openers (the ones used on shaved doors, not a PDL motor).

Do you have a hole cut in your hood? Looks like a flange or something at the mouth of the second TB.

That is a aftermath pic of testing. The paper you see around the 2 TB was a airfilter I had rigged up. Well the 2 TB worked so well it ripped a hole in the filter aka papertowel lol. So I removed the filter to prevent it being sucked into the motor. I will have to cut a hole in the trunklid because it is to high. I plan on runnung a cold air intake tube to the roof of the car OR mustang scoup.

it seems when that 2nd throttle body is opened up, it becomes the main air feed to the plenum, so yeah, it'll suck a paper towel down quick!

A friend of mine did something similar to this but for a 3.4 DOHC (which I now own).
http://fiero.cc/fiero-tdc/members/mws/intake/index.html

Does anyone have a pic of the intake manifold base without the middle or upper sections bolted to it? Just curious.

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http://groups.msn.com/joeelutz/

Here ya go:

JazzMan

anything new?

as soon as i get started on my new motor i'm going to attempt making an independent throttle body intake

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86-2m6

Very interesting thread, very intersting indeed. Since I will be designing and building my own intake for my engine when the time comes, this is of great intrest to me.

Now, just to add a few points or discuss farther....

The TB calcs that people have done, does that ccount for the throttle plate and shaft that will add restriction/turbulance?

I think the progressive TB has some merit here, as a small TB opening will keep the air velocity high, but at WOT, you need to flow more air, so I think that will work nice, if someone wants to look into it more, I am thinking of adapting this idea to my engine, have been for a while.

I also have a slightly different though on enlarging the plenum/reducing the runner length...
Would there be enough spac under the stock plenum to add to it there? I'm thinking that there might be some turbulance at the top of the runner trying to feed off a "box" that has the top of the port about mid point up in the plenum.
To take the idea a little farther, look at a genII or genIII upper, you will see the plenum is droped under the intake, and the top of the runners are at the top of the plenum. From what I understand the flow will want to be more on the outside of the raduis than the inside, so that would seem like you would want a nice outside transition from the plenum into the runner.

Thoughts?

------------------
The Raven :Under Construction
"James" 1985 GMC Jimmy, 3.2L turbocharged intercooled hybrid

"Speed Costs, How fast do you want to go?"

I'll add some more thoughts here:

I think that jstriker's measurements pretty conclusively show that the intake restriction is in the neck behind the TB. I haven't seen a stock Fiero intake in a while, so my memory may be slightly off, but it looks like Coinball's Camaro intake is significantly less restrictive in that area than the stock Fiero 2.8 intake. I'd like to see back to back dyno results for these two intakes on a modded 3.4. Dyno results on a stock 2.8 are nice for the average joe, but the greater airflow demand of the 3.4 is going to highlight any change in airflow much more clearly than the 2.8's lesser air demand.

On TB and flow rates in general:
Saying that a TB flows XXX cfm is pointless unless the pressure difference at which it flows that much air is known. If you put 1,000 psi across the stock TB, it'll flow enough air for a top fuel dragster.

Here's the point: Pressure difference is what moves air. From ambient pressure to inside the cylinder during the intake stroke would be about 14.7 psi pressure difference. That's the max amount of pressure difference we can have pushing air into the cylinder. In order to get the max mass of air into the cylinder, as much of that pressure difference as possible needs to show up across the valve opening.
If the pressure difference across the TB is even 1 psi (2" of vacuum), then even if the rest of the intake tract is perfect, you've reduced the pressure difference across the intake valve to 13.7 psi. Consequently, you've reduced the theoretical max amount of air the engine can pull by almost 7%, which is HALF of the percentage gain that jstriker's going for. By pulling even 2" of vacuum ANYWHERE in the intake tract, you're going to reduce the amount of power the engine can make by at least 7%. The more restrictions elsewhere in the intake, the greater the effect of that additional 2" of vacuum.
I think this makes a good case for an oversized TB.

I think an LT1/TPI TB can be quite useable on a 3.4, if the throttle cam is set up correctly. My dad has a TPI on a 400 with ported heads and RV cam. With the TPI throttle cam, it was difficult to get under way from a standing start without a surge, or even chirping the tires. After installing the LT1 throttle cam, which moves the throttle blades much more slowly at small throttle openings, the car was much more driveable from a standing start.

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'87 Fiero GT: Northstar, Getrag, TGP wheels, rear sway bar, rod end links, bushings, etc.

'90 Pontiac 6000 SE AWD: Leaking ABS unit fixed, load levelling rear suspension fixed, still slow

did you ever finish this?

marcus

quote Originally posted by Will: ...I think an LT1/TPI TB can be quite useable on a 3.4, if the throttle cam is set up correctly. My dad has a TPI on a 400 with ported heads and RV cam. With the TPI throttle cam, it was difficult to get under way from a standing start without a surge, or even chirping the tires. After installing the LT1 throttle cam, which moves the throttle blades much more slowly at small throttle openings, the car was much more driveable from a standing start.

This has been in the back of my mind for a while.
I like the idea of a slowly opened dual-port TB, as you mentioned. This, as opposed to one large TB as other folks I have spoken with have suggested. (A 5.0 Mustang TB was one suggestion that I heard.)
On a 3.4, I wouldn't be as worried about a surge as I would be about bogging the engine from the sudden drop in vacuum. (Picture a "too big" mechanical secondary Holley with not enough accelerator pump shot.)

Am I missing anything?

Is there any difference between a 305 and a 350 TPI TB? Seems like the 305 would be plenty large.

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Raydar
88 3.4 coupe.

Coming soon...
88 Formula, presently under the knife.

[This message has been edited by Raydar (edited 11-12-2003).]

quote Originally posted by coinball: anyone thought about boring out the IAC/cold start injector "tunnel" in the lower intake manifold and burning a new chip to activate the IAC to open at WOT.

Why not just plum a valve into the EGR tube and have it open?
The EGR only opens at idle so if its closed then why not use the tube as a secondary at WOT?

quote Originally posted by Jake_Dragon: Why not just plum a valve into the EGR tube and have it open? The EGR only opens at idle so if its closed then why not use the tube as a secondary at WOT?

Other way around. EGR doesn't open at idle.

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'87 Fiero GT: Northstar, Getrag, TGP wheels, rear sway bar, rod end links, bushings, etc.
'90 Pontiac 6000 SE AWD: Leaking ABS unit fixed, load levelling rear suspension fixed, still slow

I am going to try this on my modded 3.4. I wanted it to look stock, but flow more. I also have bored out tb. I will have the car on a dyno once I get it broken in. Maybe it will help, maybe not?

If youre looking to make a dual Tb intake. And you want to have the second Tb open fron part throttle on and closed below that look up my thread and my intake I built. The second TB is not connected to the primary. It is controlled by vacuum. The throttle spring opens the Tb and Vacuum holds it closed. The only thing attached to the second tb from the first is a return cable to close it when you let off the gas. Very simple design and works very well. That was a test intake of my idea. Now that I know it works exactly like i wanted I was going to build a better one to fit under the hood. I havent got around to it yet. BTW the IAC was able to compensate for the leakage of the second TB. Idled at 900 rpm hot. I Dont know if it will work with a auto but I see no real problems. THE 3.1 CAV Tb is very easily modded to make it a second tb. The IAC and everything is mounted on the side so all you have to do is make a alum plate to cover the side and it is sealed shut. There is also a vacuum port on to to plug. I would encourage people to use it. That set up used the fact 3.1 tb to control idle speed and controll the computer. The second one was blocked so the only air that flowed was through the center.

[This message has been edited by red85gt (edited 11-13-2003).]

[This message has been edited by red85gt (edited 11-13-2003).]

Paging JS... Will you pleeeease chime back in and share with us what became of your hacked up plenum...and this project. Happy new year!

JD

quote Originally posted by Will: Here's the point: Pressure difference is what moves air. From ambient pressure to inside the cylinder during the intake stroke would be about 14.7 psi pressure difference. That's the max amount of pressure difference we can have pushing air into the cylinder. In order to get the max mass of air into the cylinder, as much of that pressure difference as possible needs to show up across the valve opening. If the pressure difference across the TB is even 1 psi (2" of vacuum), then even if the rest of the intake tract is perfect, you've reduced the pressure difference across the intake valve to 13.7 psi. Consequently, you've reduced the theoretical max amount of air the engine can pull by almost 7%, which is HALF of the percentage gain that jstriker's going for. By pulling even 2" of vacuum ANYWHERE in the intake tract, you're going to reduce the amount of power the engine can make by at least 7%. The more restrictions elsewhere in the intake, the greater the effect of that additional 2" of vacuum.

I'm kindof confused, and I think something needs to be cleared up. Pressure difference is what drives air, so there has to be a force pulling the air into the engine. That force is the vacuum from the piston dropping, and the restrictions in the intake (and valve) that keep a certain amount of air out of the cylinder, in order to keep that pressure difference.

I agree that as pressure difference drops, so does flow capability. However, it must be stated that while losing flow at low engine speed occurs, you gain flow at high engine speed. This is because all of the effects caused by opening up an intake (pressure drop) is only at a certain flow. As flow is increased, the pressure drop increases with it (theoretically, but I believe that a drop is noticed in flow benching, and this is at engine speeds below the torque peak, since the optimum flow occurs at the peak), until the flow area is so small that while the pressure is high, the flow is low.

Our intakes are designed to peak (ideal pressure to drive air, and enough flow area for the air to get through) at what, 2000 RPM? Similar to a diesel truck. As flow area is increased, and backpressure decreased at a low RPM, they're just fine at a higher RPM, which is the whole point of modifiying a car.

Horsepower is gained by shifting the torque curve of the motor. Improving exhaust and intake flow shifts the torque curve to the right, and thus makes the torque peak at a higher RPM, and since HP is linearly related to torque, the hp peak is higher and at a higher RPM.

I don't think I got anything mixed up, although my head is spinning trying to relate all of this to physics. Let me know if I screwed anything up royally. Thanks.

And somebody make a new casting for an intake already!!

Funny, I was thinking about this the other day after reading www.s10forum.com Pic below. This manifold would be very simple to make. Just use a carb manifold and weld in your injector bungs.

My concern would be tuning. Assume your using all stock sensors and what not. You could use a stock ECM. Where do you get it tuned?
Check out this motor. This is about as simple as it gets.

Note: this is a 90 degree 4.3 v6 NOT a 60 Degree 3.4 V6.

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SSFiero@Aol.com Support Mental Health, or I'll Kill Ya!!
Yellow Formula Signature

• 88 Yellow FORMULA
  
• Black 88 formula
  
• My Shower Cam

quote Originally posted by KissMySSFiero: Check out this motor. This is about as simple as it gets.

I like it!
In that particular pic, it looks like you could take a standard TBI (using an adapter plate), and remove all the fuel metering hardware (injectors, regulator, etc., etc.) and use it with the port injectors. This would produce a setup similar to the 4.9 PFI. Since the two barrel TBI, as used on the 90* Chevy V-6 and small block V-8s, uses the identical IAC that the Fiero 2.8 uses, tuning should be a matter of chip tweaking.
I'm pretty sure there are also aftermarket four barrel throttle bodies that will bolt straight to that manifold, as well. Not sure about the IAC that they use, however.

Of course, the 60* V-6 is a different set of packaging issues, due to the narrow V angle, but it could work.

I like this thread.

quote Originally posted by Raydar: I like it! In that particular pic, it looks like you could take a standard TBI <snip> I like this thread.

I wouldn't consider one of those aftermarket TB's. Those puppies run $647.99 in Summit. There are plenty of factory throttle bodies out there that would work and flow plenty. Making an adapter is fairly simple. All a TB is, is a valve to control air. Heck, the one on my S10 truck with a 4.3 would probably work. I wouldnt go the route of the modified carb intake because I wouldnt want the expense of buying a new intake. And It just doesnt look cool to me.

I have something else in mind. If I decide to try this. But I still have a V8 project to work on. One fiero good, Two fieros bad.

Edelbrock does sell 2 intake manifolds for the 60degree V6. However, both are designed for carb hookup. It wouldn't be too hard to mount a TB to the top of it, but that's one of the problems. The air inlet is smack dab at the top. In most cases this would mean hood clearance issues.

I'm very interested in using one of the edelbrock manifolds, and if the injectors can be welded right into it, it seems much more promising. New intake, TB, port the heads, new rocker arms and valve train parts, camshaft, and exhaust, and the engine might get pretty ballsy.

quote Originally posted by KissMySSFiero: I wouldn't consider one of those aftermarket TB's. Those puppies run $647.99 in Summit.

I just realized that the pic I posted doenst have a TB on it. There were 3 or 4 pics in the thread about that engine. The TB the guy runs is a big 4 barrel(overkill) that you find on aftermarket SBC fuel injection systems. Like the one that chester has on his Dirty Rat.

Anybody have an idea of price to have someone else weld in the stock fuel rail bungs to say, the edelbrock manifold (assuming you already bought it). If it's not too complicated (expensive) I think I'll go out and buy one.

Wonder what metal the intake is made of. The fuel rail bungs would have to be the same, and aluminum means TIG right?

I'm not worried about the hood clearance as much as fabricating the parts. The throttle cable would have to be moved too. Hmmm, maybe one of those "cowl induction" hoods in the back might be in order.

Feed me ideas!

You can mig aluminum, just not with one you get at Home Depot or walmart. YOu could also gas weld it.

quote Originally posted by iluvmacs: Wonder what metal the intake is made of. The fuel rail bungs would have to be the same, and aluminum means TIG right?

Why don't bolt a new manifold directly on the heads without the bottom-intake. Just run some pipes straight up and drill some ports for the fuel-injectors. Wouldn't this work? I think it would have a much better air-flow then the stock manifold.

http://www.turboz24.com/Pics/Current_Engine_22.JPG

Keep on turning those gears in your head!

Philipp

All I can say is that I'm really impressed with this thread. Whew!

The amount of brain cells devoted to this is really amazing.

I guess I'm pretty lazy.

I'm just changing to an Edelbrock Torker II intake and Holley 4160.

Less challenge, but 390 cfm available on demand, (actually flowing a bit higher), more than the stock heads can handle.

I hope you guys get there. My hat is off to your skill and determination.

Arn

Gotta say I have been reading this one since day one and have realy enjoyed the info shared by all, and a big thanks to those who have chimed in to fill in any gaps that were missed by others for the most complete soure of information on these intakes.
For years I have been trying to find a new way to "open" up the stock intake, and have come up with a few solutions myself, but never really liked any to acually apply any of them.
One that I did come up with was to cut apart a stock intake and make molds of them to make a carbon fiber upper intake for my car. The only real obstical I ran into was I had no idea how to work with carbon fiber, I have messed with fiberglass but not enought to go into the realms of carbon. This would allow me to make any changes I see fit that would improve the "flow" of air going to the engine and still retain that stock look. Next I would have to take into consideration of durability from the tremendious amount of heat that these engines create back there, which IMHO is more than there should be for any car, that is why I wanted to go with carbon instead of fiber, carbon holds up better and has a greater heat dissapation compared to fiberglass. All would go well with this idea I feel since they have been useing plastic intakes on a lot of cars these days, but these are made of mostly aluminum (gets rid of heat fast) and thier engine bays, even though cramped, do not get as hot as the engine bay of a Fiero.
I still have not come up with a final solution, but this thread did help with a lot of missing info I did not consider or did not bother to look up that I should have from the start, I look forward to see how this thread develops over time and to see what others have done to push to envelope on this engine.

Just want to keep the thread on top!!! ;-)

Nice info. But what happened to the work jstricker was doing? Was it ever finished?? :?

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Palm Beach Fieros
http://pbfieros.tripod.com

For all intents and purposes, yes, it's done.

Rare87GT was going to dyno it back a while ago. I was in a hurry when I gave it to him and had forgotten to true up the runners where they bolt to the intermediate manifold after all the welding and it had some severe vacuum leaks. (Dumb on my part, that's what happens when you hurry). He brought it back to me but before we could get hooked up to run it, he changed directions and started his 3800SC install. One of these days, I'll get time and a test mule and we'll see what it does, but it's not on the front burner at the moment.

John Stricker

quote Originally posted by Alex4mula: Nice info. But what happened to the work jstricker was doing? Was it ever finished?? :?

You can go here http://www.westcoastfiero.com/intake/intake.html if you are will to pay 700.00 bucks you can get a real nice intake. It says it increases airflow by a whopping 64% The throttle body they use is 2.725 compared to 2.125.

jstricker; I have a 3.4 very similar to Rare87. If you send it here I'll try it and dyno it. I have a Wester chip so I can get it updated for it too. I'm well known so I ain't gonna steal anything. Just to consider

Email me a jstricke@rwisp.com and we'll talk about it.

John Stricker

quote Originally posted by Alex4mula: jstricker; I have a 3.4 very similar to Rare87. If you send it here I'll try it and dyno it. I have a Wester chip so I can get it updated for it too. I'm well known so I ain't gonna steal anything. Just to consider