Anyone know physics or thermal dynamics?
 

I'm trying to figure out how much heat my exhaust produces. I'm not all that interested in exact temperatures, but more of the workings of it. Basically, will using a larger piping which obviously creates a larger chamber for exhausts, lower the exhaust temperature in general? Does this make sense? Also the larger the exhaust piping the more it flows creating less pressure. So will this also drop temperates? don't ask why i want to know, i just want to know. ;]

I'm not sure how it would work in an open exhaust system, but in a closed system such as a cylinder, increasing volume (such as by moving the piston out) will decrease the gas' temperature.

I would assume that in an open system such as an exhaust system, larger diameter would increase total volume, which in my opinion would only increase the time it takes for the exhaust piping to warm up, but once its fully warmed up, I don't think there will be a significant temperature difference.

Also, gases travel faster at higher temperatures. I don't see why you would want a cooler running exhaust. The advantage to using wider pipes is to fit more exhaust gases in it.

sorry i should have specified, i'm interested in ambient temperatures. i'm trying to figure out if the pipes will give off more or less heat, or the same.

Yes. It will produce less temperatures. Think of it kinda like a radiator. The more surface area there is for wind/air to hit, the cooler the temperatures will be. Also, if you have your exhaust polished, it'll reduce heat as well. Let me know if you have any other questions.

<--- science and physics geek. :D

makes sense, thats what i figured.

what do you think is the best way to reduce ambient temperates for say, radiator hoses? is there something safe the wrap them in or can you replace them with something else?

Header wrap. I actually have some laying around here some where. I have about 25' of it. If I find it, I'll let you know.

what about on hoses? my headers are already jet hot coated which i think is better than header wrap.

I'm not sure if wrapping radiator hoses will help reduce under hood temps if that's what you're getting at. Radiator hoses are just a conduit in a closed loop system. Whatever heat is contained by wrapping the hoses will just flow into the radiator and be dissipated there and flow under hood anyways. Also being rubber, radiator hoses are not conductors of temperature anyways. Running both fans on high speed would probably do more to cool under hood temps I would think.

Increasing air flow under the hood would keep things cooler but too much will cause turbulence and additional air flow resistance for the car if not done properly. (increased drag coefficient.) :2cents:

Also, are you familiar with the theory of Conservation of Energy? This is the basic concept.
http://en.wikipedia.org/wiki/Conservation_of_energy

i have heard of people removing the rear seal above the firewall. this allows air to flow out the rear, but not causing drag because you are only creating an exit point to increase flow. i've heard this reduces underhood temperatures significantly with the only negative consequence that there is a increase in cabin noise. but my exhaust is so loud now, i dont think that matter.

thanks for the info allout. yea, im not big on the physics stuff :\ it's just that when i was working with the radiator, the hoses create a ton of heat, and as you all know they sit directly under the throttle body. granted the heat contained in the hoses would go thru the radiator, at this point that doesnt bother me bc my radiator is a monster. lol. i always thought there was a point to aftermarket radiator hoses such as www.samco.com and other places but maybe none of it is really what i think it is, but merely just creating a durable/strong/long lasting hose.

would wrapping the intake tubing in a reflective heat shielding reduce temperatures inside the intake?

I don't want to sound weird, but before I put on the custom cat back on the exhaust gases were not as hot as they are now. With opening up the exhaust system you're allowing the hot gases so to escape faster. The mid pipe is extremely hot after the engine has been running for a while, and even hotter if I'm keeping the RPMs up for a while; I can smell the steel burning off any dirt that was collected on the pipes.

well what is your system exactly? i think my system is pretty wide open, it may be a bit much open, but i think it does the job for now. i feel like it's flowing a lot, but your post says the mid pipe is getting hotter than stock.

wow... im gonna sit this thread out, too much mumbo jumbo

I was thinking to wrap the hoses with the wrap. But wrapping with reflective wrap would keep the heat from heat-soaking the hoses. I'd also say adding a switch to your fans to keep them running more would help as well.

Megan headers, RT high flow cat, 2.5" to Twister mid muff, 2.25" back, I'm sure it's too wide open because I've hit the gas at WOT and my car would sit until I let off the gas then backfire :rolleyes: Getting those mufflers should help out with having a little more backpressure that's really needed.

Don't you think that having the Mugen mods on his car helps the most? Why need another switch? I understand what you're talking about though, but it doesn't seem necessary.

x2 this is way too stoner for me. I don't think at our level it really makes a difference.

Agreed - Mugen Mods work to keep coolant temps down. Turning the fans on even sooner would work to keep more air flow under the hood to purge heat.

I'm sort of a stoner, but still smart enough to comprehend simple physics.

Then again, science isn't for everybody.

Pulling the gasket at the cowl might work if there's enough of a gap to flow air. Could even give you some more down force at high speed.

wrapping the intake tubing might help a bit. If you're using an icebox, most piping is plastic which is a pretty good insulator compared to a metal CAI tube. There's quite a bit of air flowing through the intake and I'm not sure how much energy can be transferred in the time it passes through the intake. You're sucking in 3.5 liters of air every two rotations of your crank.

For efficiency, a hood scoop would be the most direct CAI punched through the hood. :tomato: It would be butt ugly but...

^^^I wonder if someone will do that? :tomato:

Well.... MntBkr had an Eclipse style bump in his hood, and that looked cool. So who knows :shrug:


(And yes, I know the bump was for his direct port nitrous.)

this is why alot of drifters do the JDM hood pop to the rear of hood, to let some of that rising heat escape through that gap....I did it to my current car. It makes sense to me, hot air rises, without a opening, its trapped and just builds.

as for the direct CAI, how bout a tube that bends down and goes out to the roadlamps/inserts, and take them out and have a horn/ velosity stack there.

i have the icebox which already tubes downward and has a funnel facing the road lamp area. and my front bumper flows nicely. i'm looking into ways of pushing more air to that area without hurting the radiator/condenser.

if you really want the low down i recomend EricL first then scalbert then allmotor...it'll make more sense as you move down the list

Look up in a thermal book

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