can u use pvc piping to successfully make a custom cold air intake, i really want to increase my horepower cheaply and if this works im willing to do it, does it work tho

 

It should work fine, as long as it doesn't have to carry any significant weight or is in a bind. Don't use it as a structural part, it is kinda brittle.

Troy
So Cal

 

what do u mean dont use it as a structural part? what should i use instead?

 

structural meaning like a roll bar or cage. it will work maybe even better than metal as it doesnt conduct heat. look down to homemade ram air.

 

As far as "structural part", I mean do not use it to hold up any weight. it will need to be supported. If it gets a lot of vibration and is carrying any weight (a long tube with a filter on the end) it can crack. Just say no to crack!! ''
\

Just support it is all I'm saying really. Sunlight really attacks the stuff, but that shouldn't be a problem under the hood.

Troy
So Cal

 

Are you sure it can take the heat?

 

Cool idea! My only thought, at least for me, is that once in a blue moon my engine temp bounces up to around the 245-250 range....say for example, the time I had a cheap serpentine belt on and it snapped on the drive home from work and I had to pull over on the side of the high way...so lets say something minor happens like that ok, now whose to say that such a high temp wouldnt cause the PVC to melt and cause a minor problem(minor b/c I ALWAYS carry 1 to 1 1/2 bottles of coolant in my back seat)?!?

My only thoughts on preventing the PVC from melting at high temps would be to paint the inside and out with some VHT Paint....then again, i think you need to bake whatever you use VHT on....guess that wont work...
..hmm....how about just wrapping the outside of the PVC pipe with some high temp foil or whatever that nomex-like stuff that comes in rolls is?!?!?
-G

 

You might want to check out the Technical Articles on this board. There is an article about making a dual snork cai, without using pvc.

 

lets say it does melt. its only gonna cost u 30.00 to make a new 1

 

And that's no problem as long as it doesn't catch on fire, or create a mess that is a problem to clean up.

 

I made a PVC piece to replace the airbox/silencer on my 99 firebird. One day I decided to check on it and noticed that it warmed up and warped. So it went from a circular piece to an oval that didn't seal. A friend of mine used some PVC on his caviler and didn't have a problem. So, if you use it just watch it to be ok.

 

i have a homemade pvc cai. Its been on there since...hmm...July I think, and I havent had a single problem with it...except its ugly, and it needs painted or something. Cant beat it for the 15$ in parts for it. Not including filter of course.

 

Melt?
I missed something here. Exactly how hot do we expect a COLD air intake to get? If it gets hot enough to distort, you have routed it next to something so hot, it is no longer a cold air intake (weather it is steel or PVC), It is now a hot air intake. Since steel is a thermal conductor, a steel intake will actually be much worse in this regard.

Here are the ASTM properties of PVC and the better CPVC:

PVC I (schedule 40) Self extinguishing by law
Operating temp to 140F
Melt temp 300F
Ignition temp 850F

CPVC (PVC II) Self extinguishing by law
Operating temp 200F
Melt 428F
Ignition temp 925F

Operating temp means that it can pass that temprature of water continuously without a decrease in it's pressure burst strength. Air does not conduct heat nearly as readily as water, so ambient air temp before burst or distortion would be greater. If I remember right, PVC is stamped with blue lettering, and CPVC is red, but maybe its the other way around. I would look for the CPVC, it's a few dollars more, and glues and cuts the same way as schedule 40.

The 250 Degrees water temp is a different issue, and unless your PVC pipe is touching the radiator (not smart!!) you should be concerned with a lot more serious damage that warping your PVC cold air intake.

You can always use a PVC connector or elbow to mount the Air filter to, they are MUCH thicker than the lengths of pipe, and will probably require three times the temp to distort.

Obviously, if the PVC melts or burns, your engine compartment air would have to be well over 300 degrees to melt, or about 900F to catch fire. If this was the case, your Cold Air pipe will be the least of your problems, because your car is on fire!

Troy
So Cal

 

thats wat im saying

 

PVC doesn't belong on a car, imo. Why not pop the extra few bucks ang buy steel tubing for big truck exhaust?

 

Uh, you don't want PVC on your car, but you give no reason other that "it doesn't belong". If we followed that kind of logic, we would all still have wooden wheels and drive Conestoga wagons.

PVC is easier to fabricate with, a better heat insulator, and with the right kind of primer (for plastics) can be painted whatever color you like. You can bondo it, glue fins to it, machine it, do whatever you want to it. If you don't like it, you can use it for a pattern to make a steel one. You will be limited by the available PVC bends, so it might look clunky, but it will work fine. It's all personal preference.

Troy
So Cal

 

What are you talkin about man? Paint your pipe black, and it looks just like a stock one. PVC and a steel piece will work exactly the same, why not save all that extra cash and put it to something else instead of a custom bent pipe.

 

why would he buy truck exhaust. who said anything about a truck. i get what your saying. but you should write clearer. if i were you i would do it out of ducting like dryer ducting

 

There is always the option of insulation wrap. I'm not 100% sure how thick the stuff is, but I know plumbers use it on pipes, because my father is a plumber. I can ask my father more about it if need be. That would shield the PVC and keep down temps.

 

pvc doesnt melt as easy as you would think and it is pretty strong. I have made a potato cannon out of pvc! yeah i was bored! It uses any flamable liquid sprayed into it and then it lites an explosion with a bbq lighter. all without even getting warm. AND it hadles up to like 280 psi. PLENTY strong for a cai.

 

Put on an open element and be done with it

 

That's exactly what I'd been thinking about. Fabbing it with the PVC, then getting it made from mandrel bent steel, then send it to the chroming or powdercoating shop! I figure that surely fabbing up a trial run with PVC and bondo is gonna show what'll work and ain't gonna cost too much.

I was thinking of using Samco hoses for the CAI, but it would work out at nearly the same cost as a properly built metal one.

 

The parts I'm talking about cost all of $15 for the steel. Just my opinion, but it seems like money well spent. If you want pvc under your hood thats fine with me

 

The problem with the steel is not really the cost of buying the parts, although $15 seems a bit optimistic, but the fact that you will have to buy a lot more than you will use to get the right bends and straights, and the time to fabricate, fit, and weld it.

PVC is a much better thermal insulator, and you can cut and shape it much easier, and just glue it togther, no welding is necessary. Steel, being thinner and bendable can be fit better into odd shaped spaces and will probably look nicer when finished and painted. Each has it's advantages. For appearance, steel will be better. For function, PVC will be better.

Troy
So Cal

 

I'm obviously in a PVC friendly environment here, so I'll keep my arguments to a minimum, but I have some thoughts.

I'm not sure what you guys are building for cai setups, but mine's super simple. I have a 1LE LT1 elbow going from the TB toward the drivers side which outlets to 3.5" straight to a short radius (to clear the radiator) and then to a 90 that goes through a 3.75" hole where the evap canister used to be. There I have a hole cut, and a K/N cone that bolts up underneath. I've had loads of compliments on it, both on this car and on the 94 that I originally did it to. PS that car CONSISTENTLY picked up.411 AFTER the 60' and 3.7mph with no other modifications versus the previous setup which was a K/N panel.

Let's run down my parts list. 1)90* long elbow $15 1)6" piece of 3.5" pipe $0(muffler shop scrap) 1) short radius ??(I already had it laying around from making my catback). Lets say that you aren't at all resourceful and paid $15 for another complete elbow. That's twice what I spent, but hey, some people aren't as crafty as others. So that's $30. How much cheaper is PVC? Well, to be fair you have to add the stick of straight pipe, the bends, the adhesive, etc. My guess is it takes just as much to build the pvc stuff, and mine will never need to be replaced.

You're off base with the argument that the function of PVC is better. The elbows I've seen of PVC were very short radii, which is HORRIBLE for airflow. The steel has about a 14" radius, where PVC has more like half that. We're talking about a significant airflow loss with the pvc. Besides that, there are transitions inside the PVC that cause unnecessary turbulence. All that is probably immaterial for a 200hp 305, but on something like my motor it's plenty significant.

As for the thermal insulation properties of plastic vs steel, I don't have the relevant data on these two materials, do you? Even better, has anybody measured IAT with pvc vs steel? The air in a 3.5" pipe has to move very quickly to feed a 6,700rpm 357cid engine. Even at 5,000 rpm my 357cid engine consumes 29,750ci of air at 1atm every second. Considering the ~30" length of the system, the volume of my cai is replaced 102 times per second at 1atm, again at only 5k rpm. That would mean that each molecule of air spends .009 seconds in the cai. Of course there is a very slight vacuum in that area, and things are far more complicated than what I just made it sound, but you get the general idea. If I'm off by 100% the air dwells .018 seconds. How much do you think it changes in temperature in that time? I'd bet money that it's not even measurable with any equipment that you and I have access to.

Then the outside... well in my opinion those huge humps in the pvc look like garbage. Combine that with the fact that PVC can (and does apparently) melt... hey, it's your car.

BTW I built this thing in maybe an hour. As long as we're talking about somebody's car other than mine, PVC is 100% ok with me, so don't be offended.

 

I can see this is really going nowhere and we basically agree, with a few exceptions. How will your CAI get to 300 degrees to melt it? I didn't suggest it would work for exhaust plumbing.

If your math is correct, why do people get better ET's when they ice their intake manifolds? Why bother? If your "formula" was correct, it would make no difference, but IT DOES!! Why do several intake manufacturers of steel piping offer thermal blankets for their intake systems?

How restrictive the bends are depends on the diameter of your intake system and how much air needs to flow through it. You would be limited by the available elbows for PVC, but I already stated that. The original thread was in relation to a basically stock 305 car that they guy was interested in trying to improve on the cheap. By your pricing scenario, I can create a CAI for free, because I happen to have everything laying around from replumbing my sewer. Some of us are just "more resourceful" than others.

 

Hey, I'm glad you like your setup! If you have any hard data that shows me to be wrong on my assumptions I'd love to see them. You know I dropped out of engineering school .

My point is that I don't believe that the IAT is changed whatsoever by the material of the cai. If you would like to know for sure, send me your pvc deal and I'll run it down the track in a back-to-back test with mine. I would really do this test in the interest of science, and would post the results, whether I"m right or wrong. My DFI records the IAT, MAP and O2 correction, so it would be very easy to do the test. You pay for shipping one way and I'll pay the other?

We all hope that things don't get toasty enough to burn the cai, but it does get hot in there. In fact, in this very thread people have shared experiences with PVC setups melting. I haven't seen anybody in this thread who had a steel one melt .

FYI a bend's radius has a very important affect on it's ability to flow air. Arguing against that would be an incorrect position. It's a well-established fact, and not really an area open to opinions.

And please, don't act like I didn't list a realistic cost for what I made. Any person in any city can get out the yellow pages, open to heavy trucks, and buy the parts I used for $30, plus filter. One trip to a muffler shop and a trip through their garbage would get it done for $15, but some people don't like garbage . How much does a pvc setup cost? You have primer, glue, a stick of straight, a couple elbows, some primer and paint... I'll bet the price of the two are very similar, and I'll also bet that the time involved is very similar.

I guess at the end of the day the question is "would you rather have PVC that could very well fail, or steel that makes more HP and cannot fail" Some people choose plastic. Makes no difference to me

 

The only problem with using PVC as the template is that the radius of pvc bends are way off from most steel bends (the ones you want) and wouldn't really make an accurate model. Why not just make the dang thing out of steel to start with? It's pretty simple to make! Seriously, my roommate did a projec that's similar. No disrespect, he's a cool fellow, but he ain't the sharpest at fabricatin'! He got it done, and so could any of you guys posting here. If you can run that keyboard you can build my deal

Trying to bring a little fun in the debate:lala:

 

Matt:
Since you seem mature and intelligent enough to disagree without becoming an idiot like some people on this board, we can continue a dialog and perhaps both learn something. I changed majors, so I didn't finish engineering school either, so we are in the same boat there.

I think where we disagree is primarily on fabrication of the steel parts. How are you putting them together? If you are welding, you cannot reasonably assume that a "newbie" trying to be cheap will have a welder. If he does not, you have not included welding costs in your price estimate. This is the primary reason I would recommend PVC.

You also assumed that I have a PVC intake. I do not. The person who started the thread was more concered with cost and ease of fabrication than anything else. And tight radii become a restriction as flow increases, sure. The question would remain, would it be better than what he has stock? That depends on what he makes. If he makes a reasonably straight shot, our just uses 45 degree elbows instead of 90s it will be OK. For someone not skilled at fabrication, tight radii and slip fit connectors that he can test fit make fabrication much easier.

The distorted mouth on the one post was probably more due to overtightening the hose clamp than heat, but accept that if a straight coupler were used there, it would never be an issue.

If I were going to make one, I would use steel. I have a radial cutoff saw, a few welders, and lot of fabrication experience. But that is not what the guys here were asking...

Troy
So Cal

 

Matt - I don't disagree with you, but as far as your timeframe argument I think its invalid - because that would imply in a forced induction engine, for arguments sakes, lets say a centrifugally supercharged one running high boost consuming gobs of air couldn't make use of an intercooler.

 

Sorry, but I'm not sure what your argument is. If you're trying to say that my contention that a metal cai won't significantly increase iat versus a pvc one, and that therefore I am insinuating that an intercooler doesn't work, you have made an amazing leap of logic.

PS if you observe the csa of an intercooler core for a given inlet/outlet, you will see that the csa of the combined core is greater than the csa of the inlet/outlet. Wouldn't that mean that the air slows down? Seems to me it might be key in an intercoolers effectiveness

 

Ahem! Ladies and gentelmen, I appreciate this opportunity to spiel from my soapbox for the next five minutes

Anybody that would like to put my assumptions to the test, my offer stands. You pay the shipping to me, I'll run it at the track with my data logger running. I'll post all the readings, plus track times. Then I'll pay the shipping back to you. I'm guessing the shipping would be $10 each way, and it would settle the argument.

Hey, I ain't at all offended when somebody disagrees with me. Honestly, I'm only continuing to reply because I enjoy a civil debate once in a while. My mind is made up, and I'll never have any pvc under my hood.

I felt obliged to share my opinion because I don't like to see people buy something, then find out they don't like it. Happened to my roommate with the car I now own. I kept telling him not to buy gimmicky junk like power chips, k/n panels, blingy lines, shorty headers... but he always did the opposite of what I told him, I mean at least a dozen times. Then in the end, he wound up selling those shorties to buy the longtubes I said to get in the first place. He returned the chip to the store, I have the k/n panels in a box somewhere, the once blingy lines now look like garbage, and will soon be replaced with good ole black rubber.

That whole process just makes the hobby less enjoyable because it takes much longer to complete the car, it always takes more money to do it twice, and worst, it takes the fun out of the hobby because you're always working on the car. Speaking of which, my motor was done on a pretty tight budget, when the previous owner had it. Now the bottom end is on borrowed time because he used the stock crank, rods and hyper pistons. If I want to spray it more than 50Hp the bottom end is marginal. So, I've got this car that I have all this money in, and I'm thinking about replacing an engine that has under 50 miles on it. He could have spent another $700 and had eagle stuff with srp pistons, and I'd be able to do what I want (150-200hp). Instead I have to build a completely new engine... See what I'm saying?

I personally think that pvc is a far inferior material for the application, and that it's worth the effort to make one out of steel, regardless if it's a little more effort.

If a guy doesn't know how to weld, he can ask a buddy. Anybody can make the part I described, newbie or not.

Take care guys!

 

Were not talking sfc here were talking a simple tube to bring air into the TB. Some people cant get stuff welded peroid. If someone doesnt like using pvc then dont! Bottom line is the pvc will not melt or crack, it with stands high enough heat and more psi then you will ever need. Also pvc is made in so many bends that im sure someone could make a very unrestricted intake very easy.

You can not compare this dicussion about pvc vs steel intake to a motor rebuild or headders, doing so is just stupid.

 

damn aol sucks, double post

 

Like I said, I don't care what you do to your car. Offered my advice, and if it means nothing to you, then you got what you paid for it.

 

lol, you have a very positive way of thinking. Not many on here do.

 

No the point I was trying to make was related to the heating aspect: in your argument a ways back you were implying the incoming air moves at a speed such that it doesn't have time to heat up, pretty much regardless of the CIA's heat.

So I made a rather huge leap of logic, assumed that in a boost situation the airspeed would be greater, and was attempting to imply that, if the air can be cooled in an intercooler in next to no time, then why wouldn't the same principle apply in heating it in an intake.


to go a bit further off topic though:

... serious qeustion, doesn't the fact you'd be running boost in my hypothetical situation imply a greater air speed - even if its slowed on the intake of an intercooler? Or does the boost just imply a far greater air density, cause my natural assumption here (which might be the root of the bad logic) is that pressurizing an intake would cause an increase in speed.

 

Well, we might not agree on everything, but that quote is great. I will definately use it some time.

Next Oprah: PVC Subframe connectors and Roll cages on the cheap! (yes, I'm kidding)

Troy
So Cal

 

With any statement I make about physics I'm speculating, so don't think I'm trying to act like the authority. I'm here to learn what I can and share what I can, so keep that in mind.

Whether or not a forced induction has a faster moving air mass is another thing I just don't know, but the volume of air is much higher, and within the same space, but under greater pressure. Im sure there is a net speed gain.

Intercoolers rely on a large surface area on the outside to do their thing. Obviously the ratio of surface area on an air-air intercooler is much higher than that of a cylinder. I'd also guess that the intercooler slows the air significantly.

Still, I don't think any of this is really relevant in the discussion about the difference in IAT with pvc vs steel. I could well be wrong and would love to have somebody send me a part to tes.

 

Yeah, I saw the stb post and thought I'd drop in and suggest using pvc as a good material. I'm too new here for people to think I was joking so I didn't.

 

look at my setup

 

On my continuing quest to make an ol CAI for my car, I not only opened my own thread but have been reading this one as well.

Based on all I have read, it is surely possible for PVC to at least warp under the heat of a V8. Mind you I have not read anything about this happening to a V6er like myself. Unless I am blind of course

At any rate. For the sake of thinks looking better and lasting longer I have chosen to go with a steel intake if I can find the places to get the parts from.

I appreciate all the information you guys have been providing on this rather sensitive discussion.

I'll post some pics once its all done and let you know how much of a difference it made.

:hail:

 

I wanted a cold air intake that looks good as well as being functional. I stoped at Auto Zone and bought K&N air filter E-1009, Spectre Universal chrome intake tube kit # 8208, and Spectre 3" 90 degree elbow. I then went to Home Depot and bought two 3" rubber with solid metal ring pipe union, and Black Duct tape. The unit went together in about 30 minutes and about $140. I used the duct tape to join the MAS to the universal kit and then removed the rubber from the pipe clamps and clamped around the tape to finish the joining. I also used the stock boot from the plenum, to take up the gap I found a rubber ring in the universal kit.

 

This is going to sound horrible compared to all this fancy stuff...but well...heh...im 16 and im not winning drags like crazy on the strips, so i hope its excusable lol

I took and measured the diameter of my carb, got a peice of stove pipe that fit over it, bent up some brackets and stuck it on there, cut a hole in the hood (stock RS hood) stuck one of those cone-shaped specter filters on it and superglued it so it wouldnt move, then bought a 90* and stuck it on the peice sticking up and pointed it to the front of the car (so the filter was inside the stove pipe itself) and then bought some sheetmetal from the local hardware place and made my own front-facing cowl and riveted it down and bondo'd the cracks and painted it...doesnt look bad, but ive gotta put a damper thing on it so rain doesnt get into the carb

Ended up being like a 3 1/2 inch cowl, doesnt look all that bad in my opinion lol...and it works

 

dont use pvc in your car. just dont, it isnt safe, people here will argue you can paint it and it can look nice and its light and safe. whatever thats bs. pvc is polyvinyl chloride, when melted it releases dioxins, which are fumes that can kill you in mere seconds. even if you think it wont get that hot, even if u think it wont melt, even if u think your paint will cover it, just dont, why not just eliminate the risk? go for steel tubing, most muffler shops will fab you one up for cheap, or instead of pvc, use abs composite(its black, and used for sewage lines)

 

on the tpi intake can you really get much colder air then stock. i mean the air is taken from outside the car and diverted up to the intake. it seems to me that the bigger problem is air flow rate. if you want a better air supply i would try iether diverting more air up or making a less restrictive air intake box.

 

I have seen it done but would not do it to my car personally. Just save up ad get the SLP CAI and bolt it in... it is lke 200 and you don't run the risk of getting any shavings of the plastic into the engne whick would cause some problems...
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I have seen it done but would not do it to my car personally. Just save up ad get the SLP CAI and bolt it in... it is like 200 and you don't run the risk of getting any shavings of the plastic into the engine which would cause some problems...