Ok so intakes are made with metal, plastic, carbon fiber... Could I make one with fiber Glass? What I really want to do is just completely glass over the stock fiero intake to make a mold, and then make a carbon fiber identical copy of the fiero upper manifolds or even just the top one if I can hog out the middle intake enough. So what I would do is glass over the fiero intake manifold, cut the glassed mold in half to get it off, then use it to make a replica with carbon fiber or fiberglass if it is suitable for this application. Since the material would be so much thinner than the metal it would flow much better than stock as it would be way more open. I guess it would be made in two halves and then glassed together. It could turn out looking really nice and I think it is a good idea for anyone who wants a new intake manifold and doesn't want to spend a ton of money and likes the stock look. And it is just a thought to make it look like the fiero manifold, any type of manifold could be made using a cardboard mold and fiberglass or carbonfiber. I think I am going to try it this summer. It would be lighter than stock too.

No offense, but have you actually worked with anything like this before? Copying the stock Fiero V6 intake plenum isn't going to help, even made out of lighter material. The issue is the design of the intake plenum itself. It is relatively flat in design, with many compromises taken in it's design to ensure it fits within the confines of the Fiero engine compartment. All you're going to accomplish making it out of a lighter material is making it lighter, and honestly I would be incredibly worried of the inside sucking fibers into the intake (you would have to gel both the outside and inside - not something easy to accomplish).

If you're wanting to make an improvement over the stock intake for very little coin, cut the bottom of the primary intake neck out and make it rounder. This has been proven, here on the forum, to be one of most hindering parts of the stock plenum, since it gets as small as 42mm at points. Rounding the bottom of the neck increases it back near the same size as the throttle body opening (50-ish mm). Then when you have the new material welded in clean it up and do whatever with it.

I mean the inside of the intake would not be anywhere close to the same size as the inside of the stock intake... it would be way bigger which would increase flow. Why would I make the fiberglass as thick as the casting is? If the exterior dimension of the intake is identicle to stock but the interior dimensions are way bigger, then the amount of air that the intake can flow will increase... the same way porting the intake would increase flow.

And aesthetically, really only the top of the intake (the side you see) would be what I would make identicle to the stock intake. The chamber that goes to the runners could be made bigger, and the angles of the runners off the chamber could be made less steep as well or even totally different. All I am saying for keeping it stockish looking is making the visible part of the top manifold identicle by using the intake as a mold. You could mold the runners and the bottom of the chamber around anything else you want. You could even take like a ribbed tubing and bend it into the shape you want, cover it in duct tape to make it smooth and then glass around that to make your runners.

Also I did state that the mold would be in two parts, and to make sure the inside of the intake is gelled and smooth, the intake would be made in two halves allowing full access to the inside. Then the two halves would be glassed together. It could also be made out of carbon fiber. It really is not that expensive. People make inakes out of carbon fiber all the time. I was just wondering mainly if fiber glass could hold up to the heat and vibration in the engine bay. If it cant I will use carbon fiber. I was just sharing some ideas for possible ways I will make my intake. Maybe I will even make an intake similar to the truello intake with fiberglass but have almost a beauty cover on top that looks like the top of the fiero intake and it is glassed to the intake. It would end up looking almost like the fiero intake but with round runners. My only concern was if the fiberglass could take the heat and the vibrations, not if I would be able to do any of this.

[This message has been edited by zkhennings (edited 04-09-2012).]

Heat is probably of no serious concern. Parts are made all the time out of fiberglass for items such as duct work and the like. A person more knowledgeable on the melting point of molded fiberglass could probably chime in more into potential heat concerns.

My point in reading what you are talking about doing is it's not going to be a cheap thing to accomplish - not by any means. And what I'm trying to look at is your actual cost of product in relation to any potential gains. I'm simply trying to state that there is probably much more cheaper and easier to perform modifications that remotely attempting to build something from scratch.

I wish I could find the thread here on PFF and I tried looking for a bit but came up empty, but around half a decade ago a forum member took a spare plenum and cut the bottom of the neck completely out. They then welded in a half-moon type rounded piece of metal to "open" the neck up. As was shown in the thread, the biggest hinderance in the Fiero plenum is that neck portion immediately after the throttle body. It goes from quite a large opening, to a very narrow path. While the actual runners themselves could be somewhat of a hinderance, they're not as bad as the neck itself, and the member was able to show through their modifications that performing that simple cut-&-removal of material really opened up the intake - more so than probably anything you could create from scratch that mimic'ed the original Fiero plenum design.

I swear if I find that thread I'll bookmark it, since this topic does come up from time to time.

You could perform that modification above, and then simply do something like throw a carbon fiber wrap on the stock intake (I have yet to see ANYONE do that on a Fiero) and have something that not only would perform well for little money, but also look unique. That's what I would do if I were looking to make a custom intake for dirt cheap - modify the stock one, and throw my unique twist on how it looks. You could probably do it for under $100, while seeing a good bit of gain in air coming in.

There's a reason the Truelo works as good as it does - it basically eliminates all of the design problems of the stock plenum. But with that comes a price. That same price would eventually be assertained in anything that you would design. You obviously would likely not get the design right the first time, meaning more work to produce another product, then refining an eventual working product, only to get something you probably could have bought.

However, what ever you decide to do would be interesting to see, and it would be interesting to see if anyone else has ever done anything else similar to this. I have a good handful of stock plenums lying around and may one day tinker with one and see what I can come up with.

So the actual creation of an intake with fiberglass is not a horrible idea? Im going to try this and then I will show you what I mean =) I think that you think I want to make an exact replica of the intake manifold already, but thats not so, I just want to make an exact replica of the top of the upper manifold because the fiero has a unique manifold. Unfortunately it sucks performance wise so I am going for a compromise. And it would be very difficult to do that with metal, But with fiber glass it would be easy.

I think it's possible to create a new plenum from fiberglass, but I wonder whether you will see any performance gains without a very good understanding of the science behind intake design. The current system uses a specific cross-sectional area for the runners to ensure a certain air velocity, and a very specific length for each runner to resonate at 3600 RPM. These characteristics are what optimize the peak torque of the engine. Start changing these values and you'll change the performance characteristics of the engine, not necessarily for the better. If you want additional performance, you need to consider where in the rev band you want those improvements and design an intake manifold (plus an exhaust system, and choose an appropriately matched camshaft, and tweak fuel delivery curves) to reach those goals. Anything less and it's a stab in the dark what your results will be.

On the other hand, if you're looking for a way to change the looks of the engine bay, then there is no easier medium to work with than fiberglass. You'll have to be careful to make it with enough strength to rigidly bolt the throttle body to it, and it may be a challenge to keep all the various vacuum ports that you'll need air tight. Good luck whatever route you choose.

quote Originally posted by zkhennings: So the actual creation of an intake with fiberglass is not a horrible idea?

Most of the intakes on GM's new cars, are molded out of plastic, though I forget which exact type of plastic, right now. They are built to pretty exact measurements though, and hand-moldting something out of fiberglass, while plausible, is probably not the best idea. Ever tried sticking your hand in an intake? Now try sticking your hand in there, with a dremel tool and sanding drum bit, to try and smooth and polish the inside the right amount, so the air flow isn't totally messed up, and you get all the extra fiber and resin cleaned out.

You're better off making a sheet metal intake. But you're probably going to end up with something very close to the Trueleo intake if you really want a "better intake" for the stock Fiero 2.8.

quote Originally posted by dobey: Most of the intakes on GM's new cars, are molded out of plastic, though I forget which exact type of plastic, right now. They are built to pretty exact measurements though, and hand-moldting something out of fiberglass, while plausible, is probably not the best idea. Ever tried sticking your hand in an intake? Now try sticking your hand in there, with a dremel tool and sanding drum bit, to try and smooth and polish the inside the right amount, so the air flow isn't totally messed up, and you get all the extra fiber and resin cleaned out. You're better off making a sheet metal intake. But you're probably going to end up with something very close to the Trueleo intake if you really want a "better intake" for the stock Fiero 2.8.

Do you mean phenolic plastic?

quote Originally posted by Fiero84Freak: I wish I could find the thread here on PFF and I tried looking for a bit but came up empty, but around half a decade ago a forum member took a spare plenum and cut the bottom of the neck completely out. They then welded in a half-moon type rounded piece of metal to "open" the neck up. As was shown in the thread, the biggest hinderance in the Fiero plenum is that neck portion immediately after the throttle body. It goes from quite a large opening, to a very narrow path....

You are correct: The factory cast the V6 Fiero's intake manifold with a very crimped neck.

This limitation is illustrated nicely in photos PFF member, triker, once took of a cut-open, Fiero V6 intake manifold (first photo below), overlaid with a gasket for a Fiero V6 throttle body that had been bored out from the stocker's 52mm diameter to 57mm (roughly 20% larger in area):




That second photo in particular is quite an eye-opener, isn't it?

A number of people have made some attempts to address this issue, but I believe PFF member, Dawg, is the only person to have actually commercialized such a modified Fiero intake manifold.

Here are two photos which nicely illustrate how Dawg constructed that commercialized intake manifold:

quote Originally posted by Dawg: I've got some performance intakes for sale. Have a look.

Source: Dawg's 4-23-2010 introductory post in his thread within The Mall section: "Dawg's performance intakes"

Unfortunately, I haven't seen Dawg post anything on this forum for maybe 1-1/2 years now.

quote Originally posted by Fiero84Freak: I have a good handful of stock plenums lying around and may one day tinker with one and see what I can come up with.

What are you waiting for, Fiero84Freak? The pictures I posted above sure look to me like the ones you described earlier on this thread, so go for it!

And zkhennings, while I'd also like to see a working version of the manifold pictured above, but rendered in something other than the stocker's aluminum, I agree with Fiero84Freak's comment:

quote Originally posted by Fiero84Freak: ...what ever you decide to do would be interesting to see....

Go for it, you guys!

THAT'S IT!! Thank you, thank you! You sir get a plus. I knew I wasn't crazy. I remember both those instances where it was first taken apart and then the other member made attempts to sell modified intakes. Dawg's intake is the one I remember.

To the OP, here's the thread;

https://www.fiero.nl/forum/Forum4/HTML/051596.html

Wow. I thought it was a lot longer ago that just two years. Maybe I'm thinking of when this topic was originally brought up...

[This message has been edited by Fiero84Freak (edited 04-10-2012).]

quote Originally posted by Fiero84Freak: Wow. I thought it was a lot longer ago that just two years....

The second pair of photos I posted above were from Dawg, which, as I noted in a footnote accompanying my previous post on the present thread, came from something he posted on 4-23-2010, which in fact was "just two years" ago.

quote Originally posted by Fiero84Freak: ...Maybe I'm thinking of when this topic was originally brought up...

That certainly is possible: In regard to the first pair of photos I posted above, which as I noted in my previous post on the present thread, were from triker --- they were photos I found he had posted on 12-30-2005, more than six years ago --- in a now-archived thread titled, "Improving Stock Intake Plenum" ( https://www.fiero.nl/forum/A...110502-2-069539.html ).

In short, Fiero84Freak, you may indeed be quite crazy ( ), but your memory seems just fine ( ).

If you are going to go through this much work for very little if any gain, would it not make more sense to just put a readily available 3800 or some other motor into the car for far more power and reliability? How do you plan to keep the new intake from expanding/cracking when heated? Air leaks, cracks, etc are quite likely for likely little or no gain...

Looks like you lose EGR also... which means you probably need a reprogrammed PROM to keep the ECM from running on the leaner EGR fuel schedule. Otherwise, the combination of the added intake airflow and the reduced fuel flow could make you run lean, lose power, and run hotter. I'm not saying you haven't, but if you're serious about squeezing a few extra horsepower out by modifying the intake manifold, then you must also consider these things.

When we -trueleo- first decided to build a better intake we looked into making it out of fiberglass.
Whereas we wanted to:
1 - Open up the TB neck
2 - Eliminate the tight runner bends where the upper intake meets the middle section
3 - Incorporate velocity stacks inside the plenum for the runners
4 - Make it lighter than the stock units

With those goals in mind, we simply found it way too complicated to attempt in fiberglass. With metal, we were able to meet our requirements. In addition, it also would have made it much more difficult to do one-off custom intakes such as for those wanting to use larger TBs with say, 4 bolts etc. Not to mention, making versions for the F-body cars.

I'm not saying it can't be done, in my opinion it's just not worth the all the work, especially if you can weld.
BTW: if you do give it a try pay close attention to your design for base flange; lots of angles that have to be right. Velocity stacks will add up 15% to runner CFMs so do not overlook using them. Good luck.


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trueleo.com
RSpiderII@aol.com

[This message has been edited by Francis T (edited 04-12-2012).]

Velocity Stacks inside the Plenum? And thanks everyone for all the information. And yea I havent given much thought to runner length. Maybe I will try butchering the stock intake first. I have been thinking of cutting it in half and porting and making it nice and smoth inside and then welding it back up. Maybe I will just make a fiberglass upper upper intake and see how that goes. I have a bunch of fiberglass left over from body work and it is just gathering dust.

If you did not see my post about flow testing the stock intake parts and a modified upper intake and bored TB check out this post:

https://www.fiero.nl/forum/Forum2/HTML/118417.html

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"There is no more formidable adversary than one who perceives he has nothing to lose." - Gen. George S. Patton
http://www.flowbenchtech.com

Cool Thread! Ok well talking about modifying the stock intake... Would it be possible to cut out the whole bottom of the intake and make it somewhat deeper and maybe tubular and have the bottom of the runners cut out too and start out bigger (by being deeper because of the now deeper bottom of the manifold) but taper down to the stock size right before the bend? kinda velocity stacks there. And I'm not talking anything radical too. Or would that simply be too much welding to promise no leaks/ would the inside of the intake be too irregular because of welds to flow smoothly? I don't know if my explanation is really clear...

Here's a really crappy picture I drew in paint... I would have made a 3d model but I am studying for my thermo test!

quote Originally posted by zkhennings: Cool Thread! Ok well talking about modifying the stock intake... Would it be possible to cut out the whole bottom of the intake and make it somewhat deeper and maybe tubular and have the bottom of the runners cut out too and start out bigger (by being deeper because of the now deeper bottom of the manifold) but taper down to the stock size right before the bend? kinda velocity stacks there. And I'm not talking anything radical too. Or would that simply be too much welding to promise no leaks/ would the inside of the intake be too irregular because of welds to flow smoothly? I don't know if my explanation is really clear... Here's a really crappy picture I drew in paint... I would have made a 3d model but I am studying for my thermo test!

When adding to the bottom of like that, you best keep in mind, you're going to need room for the fuel rail/reg and cannot make it impossible to the install either. It took us more than a few prototypes to get it all figured out. Was fun and frustrating at the same time.

I'm not sure if that's the portion where the best gains would be felt, and yes I would be concerned with clearance issues also.

If you were going to make any sort of serious modification to the stock intake, the second best thing to do other than enlarging the neck right after the throttle body would be to somehow make the actual runners where the upper plenum mats to the upper intake more rounded. If you've ever disassembled both, you will see that by design the air flows into a really crisp angle - it's not a really smooth transition at all. It's easy to see with the OEM intake that likely what happens with air coming into this area is it enters the plenum, gets dispersed through the runners, but then when it hits the mating point between the plenum and upper intake it has to take a very harsh turn - it's potentially sharper than ninety degrees of travel. Then top it off that many L44 V6 Fieros likely have worn sandwich gaskets between the plenum and upper intake, and you're getting all sorts of issues with air travel.

Again, this is one of the key points with the Truelo setup is it carries smooth C shaped flowing runners. Then with TLG's dual throttle body setup there is no upper runners at all - the air goes from the throttle bodies directly into the upper intake.

However, this would be one of the more difficult things to even fathom of modifying on the OEM plenum, and at that point you're better off buying aftermarket or going with a different design.

I was reading the results of the flow tests done on the stock and modified intakes and the sharp bend in the runners was not one of the primary causes for poor flow. It makes sense that it would be but hey numbers don't lie so I probably wont worry about it . And yea I figured clearance would be an issue but I was looking at the ppg intake copy where they made the upper intake have no runners and they dropped the floor of the intake to the same height as the bottom of the runners so I figure going that low would be ok. I could also drop it and add spacers which would raise it up and reduce the sharp bend.