Im excited

I like where this seems to be going.

Raydar

for what it's worth

a 2" throttle body will support 600 cfm which is about 400hp (keeping the velocity at no more than 450 ft/sec)

a TPI twin 43mm body flows about 800 cfm which will support 525 hp.....

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84 Fiero Turbo Vortec 4300 Phantom GT
L35 block
Syclone Intake and ECM
T04B H3 Turbo
http://www.cardomain.com/id/vortecfiero

"Any significantly advanced technology is indistinguishable from magic"

You know, I've been giving this some thought...

The stock TB is almost right at 2", and with a modified intake tube, greater plenum volume, and shorter runners, I'm VERY curious as to what that would do. If it didn't show any results, and was pulling too much vacuum on the dyno at WOT, I could always cut it back off and remake just the front plate and TB adapter.

John Stricker

quote Originally posted by vortecfiero: for what it's worth a 2" throttle body will support 600 cfm which is about 400hp (keeping the velocity at no more than 450 ft/sec) a TPI twin 43mm body flows about 800 cfm which will support 525 hp.....

quote Originally posted by jstricker: I love turning big pieces of aluminum into little bitty pieces of aluminum.

You're a sick man, John

Any results yet?

Speachless in anticipation.

Was there ever a dyno posted from this? I too believe that that much TB is unneccesary for our usually slightly modified 3.4's but think the amount of runner remaining here would be better for torque.
Am I right, the main goal is to increase flow for a good pull to say 5400rpm perhaps 25 hp gain but without sacrificing any torque. I would like to see the TB end of the plenum remain intact so more folks could do this modification. We ran some #'s and detemined the TB total opening area and the upper plenum bottle neck,(the turn in)to be basically identical. With removal of as much material as possible from the "turn in" would assure no increase in pressure there.

I'm hoping a properly designed/sized Upper plenum "Box" with increased volume/flow reaching/blending down to runners that are about the length of what is showing in this picture to balance the hp/torque along with some chip/fuel managment (if neccesary) is what is needed and would enable more to enjoy this idea. Don't get me wrong the fact that you are putting the time out to finally get some answers we'll all benefit from is greatly appreciated. Giddy with anticipation to know your progress. Thanks man, JD

[This message has been edited by vse1fiero@cox.net (edited 02-15-2003).]

just wondering.. wouldnt a turbo solve this problem? or it will still be limited by the intake?

i mean with a intercooler.. would making the air more dence solve the problem of the limited intake??

just my .02

i feel the same way as you do but i dont have the ability to rework a intake like some of you. just trying to look at another alternative..

sounds like a interesting project though..
lots of luck..

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quote Originally posted by vortecfiero: a 2" throttle body will support 600 cfm which is about 400hp

I thought our 52mm or 2.1" throttle bodies are roughly 345 CFM supporting something closer to 220hp. Am I wrong?

We're slowly gaining on the intake, but until I decide, once and for all, which TB to use, it's going slowly. I'm considering a stock one, but for a 3.4L with a cam, like Amir's, I think that's marginal. I also think the LT1 Body is overkill, and has a few things that are a PITA like the throttle cable hook-ups on the wrong side (but it has other advantages, like using the same IAC as the Fiero). I'm investigating now a stock, Mustang TB that is about 62mm IIRC, but would have to custom make an IAC housing. That wouldn't be that hard, but just another thing.

I'm still hoping to have it on the dyno in a month or so. Amir's going to KC for a show the end of this month, he has school and a job, a work for a living, so we have to work within each other's schedules. Of course, we'll also have to have a new chip burned. Amir's using a Wester's chip now, and he'll be glad to do it, but we'll need to have a couple of dyno pulls and check some readouts on the engine before we can give him an idea of where to go with it.

John Stricker

Hi, not much of a motor head and what your into is over my head, but love the Fiero.
Here is a web site that might help if you dont already know about it. Good Luck!! www.60degreev6.com

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JTFiero lovin every minute of it!

Actually, I think you're pretty close. The numbers I came up with were about 360 cfm and 225hp. I'm not sure where the other poster got 400 cfm, but that is dependent on what pressure you draw through it.

While I think the stock one would probably work for our purposes, I'm really not comfortable running it quite that close to the ragged edge and that's why I'm looking into the mustang TB. FWIW, Amir already has a bored TB on his car, so we'd be using a 54mm which would help a little.

I'll decide the next couple of days or so which way I want to go. If I find a really cheap stock Mustang TB, I'll probably by it just to see what the swap would entail.

John Stricker

quote Originally posted by vse1fiero@cox.net: I thought our 52mm or 2.1" throttle bodies are roughly 345 CFM supporting something closer to 220hp. Am I wrong?

quote Originally posted by jstricker: Actually, I think you're pretty close. The numbers I came up with were about 360 cfm and 225hp. While I think the stock one would probably work for our purposes, I'm really not comfortable running it quite that close to the ragged edge and that's why I'm looking into the mustang TB. FWIW, Amir already has a bored TB on his car, so we'd be using a 54mm which would help a little. John Stricker

John, Since the TB limit is roughly 225hp and its unlikely your going to get near that, (BTW the guys at IRM tell me they build up 3.4 fieros getting well over 200hp with the 52mm), opening up the turn-in on the plenum then creating a new larger cavity for it would allow us to see just how restrictive that sucker (plenum) is, no pun intended, on its own.
With the right design and mangment 15-20+hp?.
But whatever you do I'll be paying close attention. Great work so far! JD

[This message has been edited by vse1fiero@cox.net (edited 02-15-2003).]

John,
Have you considered the Quad4 HO TB? I am not 100%, but I think they are around 56mm, and I think they bolt right in place of the stocker. I am not sure about linkage arrangements. This would allow more flow over stock, but eliminate all of you issues with IAC and TPS you might have with the Mustang TB. Another option might be the '96-up 3.4 DOHC...they are pretty big as well.

Marty

quote Originally posted by RacerX11: John, Have you considered the Quad4 HO TB? I am not 100%, but I think they are around 56mm, and I think they bolt right in place of the stocker. I am not sure about linkage arrangements. This would allow more flow over stock, but eliminate all of you issues with IAC and TPS you might have with the Mustang TB. Another option might be the '96-up 3.4 DOHC...they are pretty big as well. Marty

The 3.4TDC TB and stuff is hard to find and expensive if I remember right. I think its going to be interesting to see what we can pull on the dyno. Most people dont really think its worth the trouble cause the 3.4L has no potential, but me and John both have the 3.4, I am happy with it, and Im not totally interested in running extreme times and breaking things every week. If we can pick up roughly 30hp we could be seeing 3.4s all day long in the 14's which is very respectable as I remember NOS3800's 3800n/a motor went 14.86@92mph and that car has 205hp and 225ft/lbs of torque. Its definitely something in the right direction, I can always add Nitrous if I want later on just to hit some 13's. We will keep you posted.

Amir

Hi Marty,

Of course, availability and expense come into play. The Quad 4 and 3.4 DOHC bodies aren't nearly as common as the Mustangs, as those guys tend to like to swap theirs out for BBK's or other aftermarket.

I hadn't really thought about the Quad 4, but maybe I need to take a look at it. Simpler is better. :-)

We do have all the aluminum cut and fit, ready to weld, which I hope to do next week. The only reason it isn't done yet is that I want to bore my inlet hole in the front part of it before it's welded in on the mill, much easier to handle that way, and I need to decide which TB in order to size the inlet pipe.

If I knew for sure what would work, I could find one on car-parts.com fairly easily, I found 2 late model Northstar bodies there, one for $25 bare and one for $50 with sensors. But I need to be certain of what will work. Maybe some of the guys with 3.4 DOHC's will post a picture of their TB's and give them a quick measure.

Although I agree that the stock TB, especially Amir's bored one, is probably sufficient, I think it could be barely sufficient and I'd like to have a little extra to play with.

John Stricker

quote Originally posted by RacerX11: John, Have you considered the Quad4 HO TB? I am not 100%, but I think they are around 56mm, and I think they bolt right in place of the stocker. I am not sure about linkage arrangements. This would allow more flow over stock, but eliminate all of you issues with IAC and TPS you might have with the Mustang TB. Another option might be the '96-up 3.4 DOHC...they are pretty big as well. Marty

Guys,

I have a bored out TB, ported heads, ported lower intake manifold, slightly ported intake manifold to match, Darrell bored upper intake.

My used 3.4 made 149.8 hp with a stock diameter exhaust and a hollow cat and blown muffler.

Prior to doing that run, I had bad timing and was only making about 136hp. I popped off the top of the EGR and put a curved 3" pipe to direct the exhaust away from my car and I picked up 10 hp and tq across the board to over 145hp.

I ended up putting the EGR cap back on and finally got the timing straight and that's when I got the 149.8 hp and called it a day.

My point is that I believe I have done enough to my intake to give it sufficient air coming in and now it is time to invest in a slightly bigger collector for the exhaust. 10hp gain with bad timing could mean 15hp with good timing given a proper exhaust system. More air in = more air out. I am exhaust limited right now, not intake limited. I'd love to see 165rwhp from a NA 3.4 with stock compression.

Also, I did a run without the air filter and that resulted in a power shift of 1000 rpm. My peak was at 5500rpm instead of 4500rpm. If I was a marketing major I would advertise a 10-15 hp gain from 4800-5800rpm and ignore the loss below that. Howerever, this does mean that a bigger air filter element and housing could help the "top-end" more without sacrificing much low end. Maybe a valve system could be added somewhere to the stock housing to open at over 4500rpm there by stretching the car's powerband without losing power below 4500.

quote Originally posted by vse1fiero@cox.net:

wouldnt that not clear the distrubter?

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--Adam--
1987 Blue GT 5-speed
IM AOL: GTFiero
Fiero mods almost done...i know that because im running out of possesions to sell for money

quote Originally posted by GTFiero1: wouldnt that not clear the distrubter?

I was using that picture only to illistrate the amount of runner to maintain in order to keep torque up. IMHO JD

If you'll look at the pictures I posted after I milled the top, it's very close to what your picture is. That wasn't quite as short as I'd have liked, but I kept the "floor" of the plenum and I was afraid for it' getting too weak and perhaps cracking while machining. I could possibly have shortened them another 5mm per side, but I doubt that would make much difference.

LouD-

I don't remember what else you had downstream on your exhaust. I'm surely not going to argue that the exhaust can't be better! We're going to concentrate on the intake this time. Amir's car has WCF headers, no cat, and a Borla exhaust. It should be about as good as it can get and still remain similar to stock.

I'm glad you mentioned the intake pipe and filter again though. We'll be sure and pull a run or so with and without the intake tube hooked up, and see what the difference is on that side as well.

John Stricker

quote Originally posted by vse1fiero@cox.net: I was using that picture only to illistrate the amount of runner to maintain in order to keep torque up. IMHO JD

quote Originally posted by lou_dias: Guys, My point is that I believe I have done enough to my intake to give it sufficient air coming in Also, I did a run without the air filter and that resulted in a power shift of 1000 rpm. My peak was at 5500rpm instead of 4500rpm. If I was a marketing major I would advertise a 10-15 hp gain from 4800-5800rpm and ignore the loss below that. 4500.

Huh?
Maybe due to your ported heads you were able to take advantage of some increased flow (good advertisment for porting heads) but a 1k rpm peak hp increase from removing the filter would be impossible for the average 3.4 conversion.
Most of us I believe are using a K&N filter and have removed the water separator/intake muffler box which for me yielded a noticable upper end power gain and upped the roll off point slightly to 4700 or so.
If you have'nt got rid of the in fender flow slower and installed a K&N yet you oughtta.
Sounds like with that extra head flow to capitalize on the increase you'll hit your 160+hp goal.
I do believe increased plenum volume (done right) would be another 10-15hp for you. As the middle and lower plenum is more open to start with the real gain is more u plenum volume. JD

[This message has been edited by vse1fiero@cox.net (edited 02-16-2003).]

And, IMHO, shorter runners to move the peak torque up in the rpm range which will result in more HP.

I'm with you on the intake. I run a Fiero Store ram tube (fancy name for a piece of pipe) and a KN Cone filter. Amir has a K&N in a stock housing, which was why I thought we might pull the tube off and run and open system for a pull as well.

John Stricker

quote Originally posted by vse1fiero@cox.net: Huh? Maybe due to your ported heads you were able to take advantage of some increased flow (good advertisment for porting heads) but a 1k rpm peak hp increase from removing the filter would be impossible for the average 3.4 conversion. Most of us I believe are using a K&N filter and have removed the water separator/intake muffler box which for me yielded a noticable upper end power gain and upped the roll off point slightly to 4700 or so. If you have'nt got rid of the in fender flow slower and installed a K&N yet you oughtta. Sounds like with that extra head flow to capitalize on the increase you'll hit your 160+hp goal. I do believe increased plenum volume (done right) would be another 10-15hp for you. As the middle and lower plenum is more open to start with the real gain is more u plenum volume. JD [This message has been edited by vse1fiero@cox.net (edited 02-16-2003).]

I was using a K&N but I don't have my water separator punched out.

Keep in mind that an engine is a system and that you will not see your maximun gains without also allowing that extra air that is coming in to leave efficiently.

I have identified my current limiting factor. It is the exhaust.

I'm curious, how much hp do you guys expect to see with stock compression? I think 160+rwhp is about the limit there. The 3.4 DOHC motor made 215hp, what's that at the wheels? Doesn't it have 10:1 compression? I don't want to burst an bubbles here, just trying to be realistic.

NA engines don't run anywhere near 100% efficiency. I think the stock intake can be made to work just fine for the 3.4. Infact I may start to shorten mine like 1fstm6 did. There's your solution for shorter runners. Cheap too.

An area of the Fiero intake that we seem to overlook is the area at the very bottom of the lower intake manifold where it joins to the head ports. Take a look in there and see how much space the injector mounting boss takes up. I did extensive porting in this area and it seems to help.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://turbofiero.fierojoe.com/turbo.htm

quote Originally posted by Dennis LaGrua:Take a look in there and see how much space the injector mounting boss takes up. I did extensive porting in this area and it seems to help.

I can't say 100% for sure, but aren't you supposed to leave the shrouded area of the lower plenum around the injector nozzle to prevent the air flow from disrupting the spray pattern?

Semi-test: Hold out a spray bottle and squeeze. Conical spray pattern. Now do it with a fan blowing across only the top of the pattern. I figure it'll destabalize the mist and recombine the droplets.

I mean... if it actually worked for you - great! I just don't think that much area is killing off the air flow to a single cylinder. I only opened up that area in a minor fashion with mine.

Lou,

As to what I expect, I don't know, but I think my expectations of about 155-160hp at the wheels is realistic. I'm not sure you're off the mark with the your thoughts. The CR of my crate engine is 9:1, I don't know what Amir's is, but I suspect similar to that. Don't forget, we're starting with an engine that had roughly 140hp at the rear wheels so I'm looking for maybe a 15-20 hp improvement. That doesn't sound like a lot, but when we're starting at 140 that's about a 15% improvement for maybe about a $75 investment in parts (hopefully). I'll take that if I can get it. (yes, I know about the labor, but I choose not to count it since I'm not doing this for pay)

Dennis,

I have looked at that bottom intake and I think you're absolutely correct and if this pans out, I think that would be the next place to examine. My thinking is, right or wrong, that until the top is taken care of, there wouldn't be much gain in the lower. I may be all wet with that, but I prefer to work from the top down and see what can happen.

If we don't get rid of the upper restriction first, that will allow the air to get there, the bottom becomes pretty much limited in how much effect it can have.

At least that's my thinking, we'll find out if I'm all wet or not. Of course the other method is to do what you did, engineer a turbo and pound that air through there. (And not a bad solution, I might add )

John Stricker

Next

[This message has been edited by vse1fiero@cox.net (edited 02-16-2003).]

quote Originally posted by watts: I can't say 100% for sure, but aren't you supposed to leave the shrouded area of the lower plenum around the injector nozzle to prevent the air flow from disrupting the spray pattern? Semi-test: Hold out a spray bottle and squeeze. Conical spray pattern. Now do it with a fan blowing across only the top of the pattern. I figure it'll destabalize the mist and recombine the droplets. I mean... if it actually worked for you - great! I just don't think that much area is killing off the air flow to a single cylinder. I only opened up that area in a minor fashion with mine.

I cleaned up the area around the injector mounting boss as much as I could using the theory that it provided more room to allow for air flow and a wider V spray pattern of injector flow.
As for your theory on disrupting the flow pattern by grinding the lower manifold port to the head intake port size; I really can't say whether this is valid or not on my engine. With my turbo blowing 9 psi boost pressure the whole intake system is pressurized from the turbo all the way to the valve. Under normally aspirated conditions, I believe that we would need to put everything on a flow bench to study the effect.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://turbofiero.fierojoe.com/turbo.htm

What happened to the dual aluminum canisters with dual throttle bodies that were welded directly to the middle plenum? That looked like an interesting idea and would make shortening the runners easier. Just curious mostly.

Phil

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87 FIERO GT 2.8 5spd
0-60 in 6.8 seconds!

quote Originally posted by Dennis LaGrua: An area of the Fiero intake that we seem to overlook is the area at the very bottom of the lower intake manifold where it joins to the head ports. Take a look in there and see how much space the injector mounting boss takes up. I did extensive porting in this area and it seems to help.

I bought a ported lower intake manifold from Joe Wynmann 5 years ago. He feels/felt this is the biggest restriction.

quote Originally posted by watts: That's the Fageol blower. Supposed to work great on an S-10 or F-body, but we don't have the room for the belts - you'd also have to completely rework the cooling hoses (not impossible) to work around the snout.

The belts will fit. You can use the 2" belt drive kit. The 3" would fit but it might rub the frame rail during cornering. As for the cooling lines, All you need to do is cut and re-weld the thermostat housing to clear the snout. It needs to angle the other way. (or use an older thermostat housing and add a bleeder port for air.) The only other thing you would need to do is notch the decklid brace to allow clearence for the snout.

WHY DIDN'T I SEE THIS THREAD BEFORE?!

This is my kinda discussion. To weigh-in on the logic it should be pointed-out that the Fiero is actually a step up in performance over the other 2.8 engines of the day. This is due to the increased length of the INTERMEDIATE Intake manifold.

Any mods to the upper intake need to take into consideration the flow characteristics of the Intermediate and lower intakes. It's a system afterall. Reducing the length of the upper runners will provide a reservior of air in the upper intake but the overll effect will be to reduce the length of the entire runner (if you include the intermediate manifold).

What is the optimum trade-off, is the question.

Bump to the top here...

This was starting to get good! What happened to everyone?

If getting more air into the engine is the question, what would happen if you increase the diameter of the runners? Keeps the torque low and allows more hp higher up, if my understanding is correct. My thought is to splice two intakes, increasing the volume of the plenum also, keeping things stock-looking. Throw on a 58mm bore TB...
Just my abstract .02.

Keep up the good work, John!

Right now I feel (like Lou) that my bottleneck is the exhaust. I'm building some true equal length long tube headers and will have them on my car before my next race in June.

Lou and I are working on the exhaust and you're working on the intake so there is finally some real development going into finding the air flow restrictions in this motor. I'm very interested to see everybody's results.

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Doug Chase
'88 Fiero Formula 5-spd (autocrosser)
'88 Fiero GT 5-spd (daily driver)
'85 Fiero GT 5-spd (rally car)
Custom roll cage fabrication available
Custom exhaust fabrication available

jstricker, where are you? My 3.4 and I want to know. Any progress? JD

Check out what I built to solve the bottle neck at wot Works progressivly from 1/2 to full throttle without affecting idle speed and is closed below 1/2 throttle works great on a 3.1.

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Steven's 85 GT 4 speed 2.8