Mazdabation

iTrader: (9)

If your worried about the temp of air just do what I did, have the UIM ceramic coated. Not only does it help in keeping hot air in (exhaust) it also helps in dissipation of hot air around.

After a good run for a few hours open the hood and lean your hand on the UIM, is it not hot?
The UIM does heat soak from the high under hood temps. Ceramic caoting the UIM does help in lowering the temp of what the UIM takes in.

Herblenny

iTrader: (13)

I agree, but I don't think thats the case with the UIM. I believe its better to have UIM extruded but its costly and also for money, could get other mods... especially when most of us aren't ever going to be that level. Thats pretty bottom of my list, as I learn more about these cars..

the_glass_man

iTrader: (2)

I've had this discussion several times with a couple different people and as others have already said the difference if any would be negligible. There's a lot of other things to worry about. Though it would be nice to have a carbon fiber UIM.

edv

When you live in Canada, this subject never comes up.
As a consequence, I've painted my UIM black, as well as all other air pipes. I'm not too worried that I've reduced the thermal dissipation capacity of the system. In fact, we all have block heaters.

FDjunkie

Another aspect no one has mentioned is that painting or powder coating the UIM will act as a thermal insulator, possibly creating more heat retention than the ever so slight loss of radiating area lost to polishing.

jimlab

Ramy, just drop it.

Paint it, powder coat it, ceramic coat it, polish it, or take a big **** on it, because IT DOESN'T MATTER. The air charge doesn't spend enough time in the intake to pick up a significant amount of heat on its way through. Period. End of discussion.

Herblenny

iTrader: (13)

Jim, I think you quoted someone else... thats not Ramy..

Either case, I agree with Jim.. I was going to go on and on about this thread, but I'm done..

scotty305

iTrader: (2)

The question is, do you really want to eliminate heat from the intake manifolds? What if they've been designed to dissipate heat from the engine? Aluminum will dissipate heat more quickly than cast iron, so think of your aluminum manifold as a heat sink as well as an air intake. I'd rather have a 150* (degree) F UIM than a 500*F rotor housing. If you look at the big picture, the temperature of the UIM is really not that big of a deal.


[note, I pulled those temperature numbers out of thin air. I don't know the max. safe temperature of the rotor housings, but I think it's very possible that the intake manifolds might be removing enough heat to help maintain that margin of safety.]

-s-

jimlab

FDNewbie, FDjunkie, same thing.

I'm just so used to Ramy beating subjects to death that I stopped reading at FD...

FDNewbie

iTrader: (10)

Gotcha. The turbo manifold is what's cast iron, right?

Figures.

That's what most ppl have said. The reason I was asking (and what Jimlab has yet to figure out...even w/ his ever so expanding knowledge base) is that I often ask questions to understand the concepts behind it all, not simply because I wanna know if I should do this or that to my car. That's retarded. I'm trying to learn more about a field that's foreign to me, not just mod my car.

For example, in medicine, it's very well known that your intestines have villi and microvilli which serve to increase the surface area by how much? SIX HUNDRED FOLD. So loss of villi in any considerable amount (or removing any considerable portion of the intestines) will have a marked impact on your ability to absorb nutrients in your intestines. That's what was going through my mind, because that's my speciality - medicine.

I'm not a car guy, in fact before buying my FD, the extend of my automotive knowledge was minimal at best. I knew how to change your oil, and that turbos made your car fast. That's pretty much it. But over the past two and a half years, I've gained sooo much knowledge and hands-on experience from this forum and from fellow RX7 owners, mostly by reading and asking. And since I realize physics and mechanics aren't my strong points, I asked this question to see just how considerable or negligible the polishing of the UIM would be - and if in fact it was left bare like that specifically for increased surface area to dissipate heat. Because again, this isn't my field or speciality, so I couldn't tell just how vital those bumps were, or even what the goal was - dissipating or insulating. And apparently I wasn't the only one who had this question, as ptrhahn and others have posted.

Theglassman even mentioned how he'd had this discussion with several others before. So yea, I agree w/ dgeesaman, this IS a good question. In fact, any thread that manages to pull out a response from Crispy is a damn good one in my opinion , So Jim, you just need to look past your biased "hey will this get me more hp" blinders you're judging me w/, as can be seen in this post of yours:

Jim, simply said, I'm not afraid to ashamed to ask 1001 questions, because at the end of the day, the guy w/ 50 posts and the fastest FD but has no clue about how it works is not the guy who I want to be. You shoulda seen me in Calc & Physics class (back in the day)...I musta asked an average of 10 questions a class - and it paid off, cuz I ended up w/ A's (barely lol). That's not to say I need to justify my asking questions, but you obviously don't understand or realize the purpose behind the questions I ask.

I don't think I said in my original post "hey guys should I polish my UIM or not, cuz I'm not sure if it will decrease it's ability to dissipate heat, and I don't wanna lose hp." Rather, I relayed the info I got and left the question open-ended in hopes of maximizing the amount of information I can get in response. If my post count remained at 1, I'd still continue to ask all my questions and still be very adamant about getting answers, cuz I wanna be the guy who understand how it all works together (mostly), even though hey may never be adept enough to do the entire install himself. I'm not there yet, I'm not rolling w/ "the big dawgs," but I'm on the way, and I'll get there eventually - be it w/ 5K or 50K posts. It may take more ?s than others, but that's because the knowledge base I'm starting w/ is very different and the time I have is much less than others. But leave worrying about that up to me, eh?

Thanks...good point. Ok, so I don't need to worry about it. But I'm still interested in the premise itself.

And you just answered the premise here. Speaking of which...

I've read about this before...on that note, then wouldn't this treatment be counterproductive? http://www.rx7trix.com/store/custome...cat=202&page=1 The ceramic coating on the outside is great, because it would be insulating the UIM from the surrounding hot engine bay, but wouldn't the inner teflon coating provide too smooth an airflow, decreasing the mixing of the air? You'd want the inside to be a bit turbulent, right?

maxcooper

Heat flows from hotter to colder. The air flowing through the UIM is cooler than the air that surrounds it. By reducing the heat transfer at its outer surface (polish, coatings), you will be keeping heat out, not keeping it in.

However, it's probably true that effect is minimal, as some have pointed out, since the intake air rushes through the manifold pretty quickly. I decided to give some coatings a try, though, and had a "chrome" ceramic thermal barrier coating applied to the outside of my UIM and LIM.

-Max

FDNewbie

iTrader: (10)

Wow...now practicaly ALL the "big dawgs" put their $0.02 into this one. No Rynberg or Howard Coleman tho? We get them, and we practically got an All-Star thread The only thing missing would be a classic reference from Jim, something along the lines of "do you know how fast the air rushes through the UIM? In my V8, it's ...."

Max, thanks for clearing that up.

maxcooper

I might be wrong -- but that's my best guess.

-Max

FDSkyline

dgeesaman

iTrader: (7)

Yep.

Airflow is a funny thing. Sometimes you want turbulence, sometimes you don't. When applied to heat transfer, it gets even less intuitive since the speed of the flow can for both for and against you. So at full throttle and idle conditions are vastly different, and no surface treatment is optimal for all conditions. Just like aerodynamics, a basic understanding of transient heat transfer and intake flow isn't enough to draw conclusions - you need to either do experimentation or some detailed analysis to really understand what to do. I suspect that's why the folks with an aerodynamics background stay quiet around here. This thread has crossed into several such disciplines at once. Very easy to draw logical questions, very hard to get conclusive answers.

In the case of injected air, even distribution of fuel and air is a challenge and affects things like preignition and detonation. In theory, the turbulent air helps swirl around the atomized fuel spray (atomization not "itemization" ) to get a slightly better mix. So clearly it's important to rotary engines, especially on tuned cars. In practice, good injectors probably help more.

Those plastic UIM gaskets on eBay at first sounded like a joke, but thinking more about the heat conducting from the block to the LIM to the UIM, it makes sense. I'm tempted to try using some high temperature insulative fiberglass as a gasket to see if helps keep idle intake temps down. What would make more sense to me is either putting an ice bag on it before a hard run (ala autocrossing style), or adding a fan to force some cooling air around in that part of the engine bay.

Regarding the Teflon treatment: Until you've dealt with icing, carbon buildup that goes beyond cleaning the UIM with carb cleaner when it's off the car, and fuel spray issues, how do you know if it works? Someone would have to try it and see if it works.

I understand Jim's tiredness of the subject. There are a million things in the auto world that logically sound like an improvement, but in practice don't work or don't matter. But all of them can be sold to make money. Unless you have a background in racing where you've actuallly experimented with them, or a background in engineering to help filter the ideas a little, it's got to be blinding. I get quite sick of reading them too, especially since the sales pitches that do quote experimental data are usually manipulated quite cleverly to show off the product.

Dave

jxl914

yeah, according to the logic in my last post, which probably sucks, polishing the intake will be counterpruductive from the standpoint of promoting turbulent flow

Herblenny

iTrader: (13)

HAa?? I don't know about that.. I think we all need to sit back and realize, polishing or not polishing, painting or not painting, or coating or no coating, the exterior of UIM will not contribute enough to really worry about.
Ramy, I know you were comparing with structure of intestine to maybe the exterior functionality of UIM.. But better way to compare will be which INTERCOOLER design will better cool the compressed air. I think people tend to get stuck on one thing and not realizing that there are more important things to worry about.. Also, shortening the length of over all IC piping, pre-cooling of the IC piping, the number of turns, angle of those turns, insulating cooled air after IC, etc etc..

Also, some might haven't thought of this, but the hot coolant flows through the throttle body.. If you still have your coolant line to TB, it will be warm as your coolant.. Serious, Get your UIM polished.. Its mainly for looks.. I did it and did it not because its going to optimize my intake temp, but to look shiny and ricey!! If you want some sort of performance out of your UIM.. get it ported and extruded.. Some say it makes 10+ more HPs... Otherwise, think of other **** that matters more.. I think this would be something that you have exhaust all the other priority mods and now you just absolutely ran out of things you could optimize...

jimlab

Of course I do. It takes you 10 posts to come to the conclusion that someone else might in 1 or 2.

Then you might want to consider that your questions still exhibit a lack of understanding of "things automotive" (and sometimes common sense) that I haven't seen improving significantly as time passes. Sometimes I think you ask questions just to get involved in a thread for something to do, and I don't get the sense that you're really processing the answers.

Fair enough. Just telling you what I see.

The fact that they say the Teflon helps with "fuel itemization" should tell you something. Since they're not smoothing the insides of the runners in the process and since fuel doesn't enter the intake tract until the air is past the upper intake manifold, it's irrelevant anyway. Just another way to separate a fool from more of his money, if you ask me.

jimlab

Don't even get me started on Extrude Hone.

As a way to remove material from areas where a traditional tool can't reach, it's great. But as far as improving flow, keep in mind that enlarging the diameter of the intake runners is going to hurt velocity at low rpm. In other words, it'll cost you low end power and give you a minor gain on the top end, especially with stock twins. If you're a drag racer with a huge single turbo or twins and your intake is literally the bottle neck, then hog it out by all means. But for 99% of the FD owners on this forum, Extrude Hone is a complete waste of money. If someone says it makes 10+ more horsepower, find out where in the rpm range and with what combination.

You'll note that cylinder head porting is still done by CNC machine and by hand, not by Extrude Hone. That's because "increasing the diameter of the firehose" is not always a good thing. My 215cc (intake runner volume) heads were delivered raw and then ported. They actually ended up at about 213cc. You want the highest volume of flow with the smallest possible port to keep velocity high at low rpm for good drivability. That's what makes a good street head. If my heads were for racing only, then I'd be in the 230+ cc range with a cam that would barely idle below 1,500 rpm, and running a steady diet of 116 octane with 14.0:1 compression.

Herblenny

iTrader: (13)

Jim,

Thats what I've heard also.. Benefit at high RPM.. I was initially going to get one of my UIM and LIM extruded.. but decided not too.. Only reason I considered is because I could get it for free.. but it ended up taking too long and I didn't think it was worth the wait (waited 6months).. Especially within next year to 5 years, I'll have something else in my car.. Hopefully within a year than 5..

FDNewbie

iTrader: (10)

I was showing my thought process. Besides, it's my thread

Gotcha. That makes sense.

Yea I've heard about the ice bag method... As for the plastic Ebay gaskets (http://cgi.ebay.com/ebaymotors/ws/eB...sPageName=WDVW) I see where you're going w/ this, but you know the first thing that came to my mind? Plastic = prob going to melt or get brittle, possibly fracture under the heat and pressure from expansion & contraction of the aluminum manifolds? I'm guessing here...

Dave, I understand your point 100%. I was trying to clarify that this wasn't so much a "should I do this" thread vs. "is this how it works" thread, at least for ME. As was shown, I thought the UIM was dissipating heat, and it turns out it's absorbing it, since the air in it is colder than the surrounding engine bay air.

Phil, I compare w/ what I know

Point well taken. Someone else mentioned how a bigger priority would be to worry about those thin aluminum polished IC pipes. Having said that, would it be smarter to use a thicker material, or possibly even thermowrap them? Or are we again talking about negligible gains/losses?

Yea I removed the coolant line to my TB and the FIC a few months back...didn't like the idea of super hot coolant flowing through the TB. I just know to stay off the throttle until the car's fully warmed up. Not sure how much benefit losing the coolant line was, but it made sense to me...

That's what we all do it for Phil. Just wanted to know if there was something more to it tho.

That may very well be true, but again, keep in mind it's because I'm seeing bits and peices of the puzzle isolated from one another, not the picture as a whole. I really need to get through the "Rotary Engine Illustrated" website and any other good material to walk me through everything (in general) from start to finish to bring it together. Part of the reason why I didn't know whether the UIM was dissipating or absorbing heat was because in all honesty, it wasn't crystal for me how the air was flowing, given all the various pipes and components (intake, IC, radiator, turbos etc)

It's always easier to see if you already understand the equation as a whole, don'tcha think?

Nuff said lol.

Go figure...believe it or not, this was EXACTLY what I was thinking when I read Phil's post. 1) Cross-sectional diameter is inversely proportional to velocity, and 2) You have to have whoever claimed the 10+ more hp qualify the statement (ie under what parameters)

dgeesaman

iTrader: (7)

The good news is that gasket has space to grow, sideways. But, I agree it could cook and then leak.

I guess someone needs to use a temp probe to see how how the LIM really gets. I suspect it's not That Bad, since the mazda gasket is rubber-coated metal, and rubber usually doesn't handle much in the way of temperature.

I was thinking of using G-11, which is an electrical insulator mostly. But it's got good high temp resistance. Unfortunately it could be expensive.

Dave

Herblenny

iTrader: (13)

I just looked at that gasket.. Man.. AWESOME stuff!!! UPTO 5% HP!!! so, if I'm making 300+ I might get 15 horsepower by going with the gasket.. Come on!! What is this "spaceage" material??? Plastic at one point was consider "spaceage material".. And supposed to give "much cooler intake/denser intake charge". It might be cooler, but not sure about "much" cooler.. and also I don't know about noticable HP gain..

FDNewbie

iTrader: (10)

Hit up some of your oldtime NASA boys. I'm sure one of your friends can hook you up w/ some leftover material or something

I think you just answered your own question Phil

Herblenny

iTrader: (13)

Did I??

Ramy, wait, so did you use that TB that Garfinkle polished??
Just wondering.. I thought for some reason, you already had your engine bay all blinged out like mine..