fortysixandtwo

Don't confuse a managerial decision for an engineering decision.

One of my past bosses used the saying: Stop polishing the steel ball. This is sort of a good fit here because: 1. We're talking about polishing. 2. You're scrutinizing a feature that doesn't require that level of involvement.

lart951

what are you talking about? the discussion was about deflecting irradiated heat by a mirror finish polishing, the engineers said that the different between a painted aluminum IC pipe and a polished in not significant.

http://mpcindustries.thomasnet.com/i...ing?&forward=1

fortysixandtwo

Two different things.
1. Shuttle being used outside of its design environment
2. Benefits of polishing the charge tubes' surface is not worth the time involved. Time would be better spent working on something of more importance.

See "2" above. And you posted your " where are the engineers????" comment after you already received input.

lart951

did you bother to read the whole thread or are you inebriated?

fortysixandtwo

I reread the thread; still have the same take on it.
For the most part, the engineers in the group are in agreement of how the various components are effected by their environment. Also I think they all agree that whatever performance gains or losses attributed to polishing of these components are negligible.

You get your answer. Then ask if anyone has actually tested any of this and to what extent would changes temperature have on performance.

I don't know, maybe I'm taking crazy pills. I do know its not inebriation, because I don't drink.

lart951

is not only the ic pipes, check this intake manifold, what are they trying to accomplish?

333pg333

^Seran wrapped trying to keep the freshness in?

67King

I quit reading this thread for a while, as it started to feel too much like an argument. At the end of the day, you have competing phenomena going on, and the only way to know which is best is to measure something with some device with a good gauge R&R (and that would preclude using a dyno).

Having said that, I don't know whose car that is, but I'm not suaded in the least by that. Looks like someone read something at some point and decided to try it. It does NOT look well thought out in the very least. It may be incomplete, for all I know.

And even though you may find us (the engineers) with differing hypotheses on which phenomena dominate, I doubt you'll find any of us saying that any kind of real world benefit could be measured with a polished manifold. Shoot, if it were me, I'd coat the inside of it.

pettybird

awesome.

lart951

I was saying it also because I have a customer and fellow 951 freak, who happens to be a chief engineer at Northrop aerospace division (defense satellites) not an engineer at a milk farm in Hennessy, who believes that it was cost and maintenance the reason that automakers consider again polished metals. But the used of polished surfaces is more common in aerospace and aircraft industries. But what does he know anyway?

So what would you consider a SIGNIFICANT difference in the following test

with a mapp torch heat the surface of a black painted ic pipe for 15sec and do the same on a equal pipe but polished.

The Polished pipe heats up very slowly and at the end of the 15sec is almost 100 degrees cooler than the black pipe.

I understand that in reality it proves nothing because in the car is a different environment and process going on. As you said it may need to be test in a dyno.

67King

Luis, I used to do engine development for a living for Ford (automobiles), not Bubba's shade tree wrenching. I'm sorry, but I guarantee you that your friend knows a LOT less about engines than me. And if that picture was his car, then he really knows very little. If anything, you want to wrap the IC to TB pipe, which he left exposed, and it appears to be made of a conductive metal. The goal is to keep the air inside of it cool, and the air on the outside is warmer than the air on teh inside. As was pointed out earlier in the thread, the cylinder head is a source of heat exceeding the ambient air temperature into the intake manifold. The intake needs to do two things - get rid of the heat from the head to the ambient air, but insulate the heat from the ambient air to the inside air.

By wrapping it, there is no way to allow it to move heat from the head to the outside. Now the only place for it to go is to the air charge. As I had stated previously, I don't know what the trade off point is. This may be benficial, it may not be. But I do know this, the best way to manage the heat would be to insulate the IC to TB pipe, and to insulate the air on the inside of the manifold (such as through an internal coating), and to insulate the inake from teh cylinder head (such as througgh a phenolic spacer). When we started switching from aluminum to polymeric intake manifolds, we saw a noticable and measurable increase in performance. We used to make prototype intakes out of billet aluminum shells, which we welded together. That turned out to be pretty unrepresentative, so we changed to rapid prototyping using UV cured epoxy, where we basically "grow" a part out of a pool of epoxy by hitting it with lasers to cure it in certain parts.

The aerospace industry polishes parts for a VERY different reason than you assume. Especially when sending things into space, which is VERY expensive. Polishing is VERY beneficial to fatigue life. You can get around your design parameters a couple of ways. First, you can just make it bigger. That is teh cheaper way of doing it, but it also adds weight. Second, you can polish the surfaces to eliminate the roughness that serves as crack initiation points. That costs a lot of money, but adds no weight. Now when you have to spend a few thousand bucks on every pound to get it into space, what is more critical? Obviously, it is more cost effective to polish it. EVERY decision is driven by finances.

I would call your test invalid. You have zero airflow going on on either side of the pipe. You have only one source of heat. You are trying to put heat IN to a pipe, rather than to extract it OUT of a pipe. Want to run a valid test? Take some air charge data with a polished and a black pipe. But as Chris pointed out way back a long time ago, you really need to treat each pipe differently, as one needs to conduct, the other needs to insulate. I'd actually be pretty curious to know what air charge temps are at the cylinder head with a wrapped versus an unwrapped intake. And actually, I said a dyno is NOT a good test - gauge R&R (repeatability and reproducability) are not sufficient.

Last thing - I'm not "against" you, by any means. The parts look nice. And absent data, there may be merit from a performance perspective. I'm just trying to prevent you from saying you know what the whole cherry pie tastes like because you sampled the flour.

User 41221

I would like to point out that it's all a bit pointless without factoring in the velocity of the air in the intake path. I would expect, from a fluids perspective, the change in Q of the air at any particular velocity vs the delta in temp between different finishes will be negligible. This would be a bit out of my area to comment on without real world data, but 67king might be able to answer what the air velocity is inside the intake. After all, intake air temp is the primary concern, not the temp of the engine surfaces.

lart951

Ford??, honestly that would explain a lot of things, j/k I understand. As long as you weren't in charge of the Taurus engine is okay, lol.

lart951

C. White, told me the other day that for a race car since there is a constant flow of air, the heat inside the engine bay may never affect the ic pipes or intake, like you said probably radiated heat is the issue, but what about a street driven car, who sees less flow of air due to stop lights, gridlock etc, wouldn't those factors aid in heat soaking the entire engine compartment?

User 41221

LA gridlock, perhaps, but once the air starts moving through there again, it would cease to be an issue fairly quickly. Even if the air is moving at 5cfm, the under hood engine temp probably wouldn't pose much of an effect. Keep in mind that for most of us, it's a black art to find the sweet spot between air velocity and static pressure in the manifold, much less adding in the proper amount of internal turbulence (not enough and it won't atomize the air/fuel mix properly, too much and it induces unwanted aero drag).

I know two guys that have specialized in this field of study, one with a pHd, and they continually remind me that I made the right choice going into Telecommunications.