I have ordered the parts for my intake and didn't want the polished finished showing so I was thinking of adding the black fiberglass header wrap around it. Whilst in my daydreaming state I also thought it would be slightly beneficial to wrap the upper plenum also to keep heat soak out and the charge air cool.
My thoughts are to wrap the plenum in some kind of light batting, cover it with a wrap of plastic or duct tape and then cover the outside in fiberglass wrap with a layer of resin on it. The plastic or duct tape would keep the resin from impregnating the inner layer and keep a layer of air between the fiberglass and plenum. This would keep the intake cooler than just wrapping the plenum in glass because resined fiberglass does transmit heat pretty good.
Any thoughts on this? Any info on how much effienency would be gained? Also, what about insulating the fuel lines and lower runners...
Insulating the intake...
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Q45tech
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Re: Insulating the intake... (T45)
Important to study the air speed flowing thru plenum and runners to arrive at the heating time of air in contact with the metal walls.*6.33 cubic feet per second is the plenum inlet flow.
As to runners 34 cubic inches of air moves down 16" of runner in 12 milliseconds.
Thermodynamics tells you that even with a 100F hotter plenum or runners the time is so short that the air temp increase will be less than 10F at WOT or less than 1% density decrease.
Don't confuse idle with WOT where are moves up to 50 times faster!
* Only the molecules in direct contact with the walls get heated by friction, conduction since the other air [air from wall to center ] is a great insulator.
Drill and install a fast acting thermistor into plenum air stream to measure average temperature. It's a good education tool - especially if supercharging.
When you make a homemade plenum and runners how do you equalize the actual air flow to each port? Just making the runners perfectly equal won't do it....................the taper and shape of plenum must be modelled as the distance from the inlet is different for each runner.
As to runners 34 cubic inches of air moves down 16" of runner in 12 milliseconds.
Thermodynamics tells you that even with a 100F hotter plenum or runners the time is so short that the air temp increase will be less than 10F at WOT or less than 1% density decrease.
Don't confuse idle with WOT where are moves up to 50 times faster!
* Only the molecules in direct contact with the walls get heated by friction, conduction since the other air [air from wall to center ] is a great insulator.
Drill and install a fast acting thermistor into plenum air stream to measure average temperature. It's a good education tool - especially if supercharging.
When you make a homemade plenum and runners how do you equalize the actual air flow to each port? Just making the runners perfectly equal won't do it....................the taper and shape of plenum must be modelled as the distance from the inlet is different for each runner.
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ScottJackson
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But tech, you forgot to mention boundary layers! This is the very thin amount of air that moves slowly along a surface while the main air charge is going substantially faster through the tube. With that in mind, there's even less heat transfer than tech mentioned. Yes, drag racers will put a bag of ice on the intake between runs to get every last bit of a percent of power, but that's about all you get. Personally, I don't think it's worth it except for maybe those drag racing situations where you have nothing better to do with your time but watch a bag of ice on an intake between rounds.
Lol, thanks for the replies. Lots learned in a short time.
I knew about that stagnant layer of air against surfaces, particularly smooth surfaces. I am all about efficiency so if wrapping my intake will equate to a cooler charge at idle through WOT then I may just wrap it in the fiberglass wrap without the resin. At least I know that heat in my intake ISN'T contributing to my engine's performance or lack thereof.
I always wondered why engine modelers don't make the interior of air passages in engines like a golf ball with the dimples. A golf ball flies much shorter distances without the dimples so wouldn't a dimpled surface equate to higher velocity airspeeds in an intake and heads?
I knew about that stagnant layer of air against surfaces, particularly smooth surfaces. I am all about efficiency so if wrapping my intake will equate to a cooler charge at idle through WOT then I may just wrap it in the fiberglass wrap without the resin. At least I know that heat in my intake ISN'T contributing to my engine's performance or lack thereof.
I always wondered why engine modelers don't make the interior of air passages in engines like a golf ball with the dimples. A golf ball flies much shorter distances without the dimples so wouldn't a dimpled surface equate to higher velocity airspeeds in an intake and heads?
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SaintlyCharBoy
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Re: (T45)
In a way, they do - you know how everyone always tells you to leave the intake a bit "roughed up" while your exhaust is polished, it's to maintain that boundary layer on the walls of your intake.
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ScottJackson
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Yep, and the reason to polish the exhaust side is to prevent carbon build-up. It's been proposed that cars have a dimpled surface (much like the golf ball) for less wind resistance. I can't remember the exact explanation, but unless you're dealing with something that's mostly round, the dimples wouldn't help much on a car body.
Another question about the intake I'm fabbing up...
When placing the MAF in the intake system, where is the optimum placement? At the airbox just after the filter, in the middle of the piping or close to the TB? I am running about 24" or so of intake tubing so placing the maf halfway through wouldn't be a problem. I figure it should see nice smooth airflow so close to either the filter or TB wouldn't prove as smooth but that's just a guess. Anybody with input is welcomed!!!
When placing the MAF in the intake system, where is the optimum placement? At the airbox just after the filter, in the middle of the piping or close to the TB? I am running about 24" or so of intake tubing so placing the maf halfway through wouldn't be a problem. I figure it should see nice smooth airflow so close to either the filter or TB wouldn't prove as smooth but that's just a guess. Anybody with input is welcomed!!!
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SuperHatch
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Re: (T45)
Your guess is spot on. You don't want to be too close to the throttle body or air filter to avoid turbulant flow. You also don't want to be too close to and sharp bends or transitions in the intake piping as well, because that can alter MAF readings. A general rule of thumb is 10" of straight piping before and after the MAF, however we all know that's almost impossible, so do the best you can.T45 wrote:Another question about the intake I'm fabbing up...
When placing the MAF in the intake system, where is the optimum placement? At the airbox just after the filter, in the middle of the piping or close to the TB? I am running about 24" or so of intake tubing so placing the maf halfway through wouldn't be a problem. I figure it should see nice smooth airflow so close to either the filter or TB wouldn't prove as smooth but that's just a guess. Anybody with input is welcomed!!!
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SuperHatch
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Re: (T45)
T45 wrote:Yeah I can't get 10" no matter how hard I try, but my old lady is happy with what little bit I do have...
Uh, nevermind. I can probably get about 7-8" or so of straight pipe before and after. I'll see what happens. Thanks for the input!
Like I said, it's a goal, not a hard requirement. Plenty of people run their air filters clamped directly onto the MAF. They can get away with this because of the radiused inlet on the MAF adaptor....
Re: (SuperHatch)
Pshhht, TRY TELLING HER THAT!!!SuperHatch wrote:
Like I said, it's a goal, not a hard requirement.
Quote »They can get away with this because of the radiused inlet on the MAF adaptor....[/quote]Uh, what radiused inlet? You mean the one I threw away?