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Engine Specific Info and Questions => IDI Engine => Topic started by: subsonic on June 16, 2007, 10:00:22 pm
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Like the title says. I guess if is listed, from the most to the least.
Silicon, aluminum, copper, pvc...?
As a add on, what about the ID size of the pipe? Is bigger better?
So do you want a material that will radiate / give off heat going towards the IC, and a insulated pipe coming back to the intake? Or should it all be the same?
Has anyone ever tried to mount a IC under a hood scoop? Not sure how you would continue the air flow out of the engine compartment. Just thought it would reduce the overall length of the pipe runs. Just a thought.
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Aluminum.
Also, you want the insulation to be the other way. Insulate going to the intercooler and none going to the engine.
The hotter the air going to the IC, the more efficient it will be at removing the heat.
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There is no situation where hotter air entering the intercooler will create colder air out of it.
Andrew
Yep.
Aluminum pipes are best as Al transfers heat very effectively for additional cooling.
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So why don't people also put finned heatsinks on their tubing? Might not even need the IC that way. :lol:
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So why don't people also put finned heatsinks on their tubing? Might not even need the IC that way. :lol:
heatsinks are quite expensive. plus if you put a heatsink inside the engine compartment you will most likely get heatsoak. (except maybe at highway speeds where fresh air is constantly flowing in)
imo insulating the IC pipes would give some gains with aluminum, especially on hot days.
the same concept is used on refrigerant systems. just look under the hood. does the high/hot side have any insulation on it??? nope, because chances are the temps there are greater than the temps under the hood. (if not, you might want to get that fixed :lol: ) after the high pressured (high pressure creates heat) is flowed through the condensor to cool it, it then flows insulated to the evaporator, where the expansion valve controls the flow of liquified refrigerant to be sprayed in. the liquified refrigerant then evaporates, taking with it a great amount of heat, and is then flowed back into the compressor to complete the cycle.
that should make sense to everyone. the only difference between refrigerant system and your intercooler, is the matter being compressed, and the pressures at which they are being compressed. (air vs hydrocarbon refrigerant & 10-20 psi vs 300 or so psi)
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My opinion: the entire purpose of an IC is to cool down the air between the turbo and the intake... anything you can do to lose heat along the way is a good thing.
So, I can't personally see any reason to insulate any part of the tubing... the more heat you lose along the way the better. And I'd paint it flat black to radiate as much heat as possible.... an old VW bug trick that can actually make a real difference. Shiny/chrome is terrible at losing heat... as Beetle owners with fancy chromed rocker covers soon discovered.
If you had to route the tubing over a hot part of the engine you might want some kind of a heat shield.
Finally, ideally I'd put the IC anywhere but in front or behind the rad... you're removing heat from one part of the engine and transferring it to another part of the engine. Obviously the physical realities of each situation sometimes dictate otherwise, but if you can avoid it doesn't make much sense to me to go to a lot of plumbing trouble if you're just moving heat around !!
Just my CDN $0.02 worth...
Vince
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So aluminum gets a few votes. Whats with all the big silicon tubes you see on IC setups? Is that just for the flash of purple neon or dayglow green?
As far as painting the pipes, I live in New England. There are still lots of old homes that have the big cast iron steam radiators. People are always painting them to try and get them to blend in with the room. I hear from all kinds of HVAC guys that this screws up the heat transfer. They should not be painted. Does the same apply here?
What about size -ID-. Is bigger better? Should it be max dia. of the intake-outlet opening of the turbo / IC / intake, or should it neck down to meet them to speed up air flow?
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i know aluminium is very good.
but do anyone have any idea "how much better" it is than metal?
i'm making a intercooler also, i can make the metal pipes myself, or i can give my €$€$€ to someone who can work with a TIG and let him make the alu's.
is it realy worth it to have those aluminiums????
Greetz, Benjamin
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IMHO thick enamel house paint is probably more of an insulator than anything... coating something you want to radiate heat with an insulating layer is probably not the best, but of course there are home-decorating considerations to make !
Air-cooled guys learned that a light coat of flat black (Tremclad is good since you don't need the thickness of an additional primer coat) seem to give optimal heat transfer with a minimum of insulation effect.
Someone once pointed out to me: good frying pans are usually flat black, partly to transfer heat efficiently to your bacon. Kettles are chrome partly to keep heat in and boil water quickly.
Again, just my theoretical perspective as an ex-aircooled guy... I don't actually have an IC on my beast at the moment. When I do it will be mounted away from the rad and plumbed with the biggest diameter flat black tubing (aluminum, thin steel, I doubt it matters as long as it can carry the pressure) I can fit under the hood.
Vince
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I think silicon is popular just because it is easy to work with. Aluminum tubes need to be specific to the car and welding and fabricating the bends is not something the home "tuner" is capable of.
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i don't think it was mentioned the obvious, that aluminum is a lot lighter than steel, which is another clear benefit if this material.
When I do it will be mounted away from the rad and plumbed with the biggest diameter flat black tubing (aluminum, thin steel, I doubt it matters as long as it can carry the pressure) I can fit under the hood.
will there not be a larger pressure drop by using such large diameter tubing?
where else under the hood can you get good airflow with minimal heatsoak than in front of the rad?
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Location is definitely a challenge.
The GTDs have a small IC mounted on the driver's side with a hood scoop.... the other location I like is long and thin under the rad in the front big bumper (mine's a A2)
Have to do some research about tubing but my guess is that the limiting factor is size that actually fits under the hood. I think flow is a consideration as well as pressure... and they are generally inversely proportional to each other as tubing diameters change.
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One reason people use silicone is that it handles heat very well. If you were running a lot of boost, the air might get too hot for rubber tube or connectors.
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So, if we increase or decrease the size(dia.) of the IC pipes this must have an effect on performance would'nt it?
If a turbo is pushing 20psi, the actual pressure must be relevant to the size of the area holding it right? I am thinking of an example of my bike tires. My road bike tires I pump up to about 120psi. My mountain bike tires roll at about 40psi. Both tubes are different diameters. The same volume of air and needed pressure to hit 120psi in the road tire would probably only give me 20psi if I transfered it to the mountain bike tire. I would also not have to work so hard to fill the bigger tire to this level. I am guessing that the air volume would slow down though as well in the bigger diameter.
Kind of an odd analogy, but I 've been up for 30 hours so I am kind of punchy.
Does the same sort of volume(cfm) v.s pressure(psi) thing relate to the turbo and IC tubes? If a turbo is putting out 20psi into a system with a diameter of say 1", is it really the same 20psi if the diameter is now 2" or is more air being moved? Could the same amount of air being moved with the 1" now be achieved with the 2" but at say a pressure of 15psi instead of 20psi? The 1" 2" 20psi thing are all just pulled from the air just as examples.
I was wondering with this line of questions if this would mean that the amount of boost someone says they are running is really accurate? 20psi at what volume, or what velocity?
The sleep monster is starting to win the fight and kick my ass, I'm off to bed..............zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
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Small pipes will restrict volume, with the end result being less air at the intake, or the turbo having to work harder to get that same amount there at the same pressure. If small pipes were good, you wouldn't see 3" and larger pipes for sale.
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Yeah, I don't think pressure is the issue here. If you have a pump that makes 10 psi it will make 10 psi into a pop can or a 55 gallon drum... just a matter of time.
In my mind it's more about flow and resistance.... anything you can do to keep resistance down and flow up is good... bigger tubes, smoother corners.
When I worked for a pipeline company I was amazed to see them replacing *some* of a 36" line with 42"... I asked the engineer what was going on... isn't it like a chain (or a wire) where the weakest link sets the pace ?
Not so, says the engineer, it's all about flow, and any time you can increase diameter you will increase flow... even temporarily helps evidently ! That's why a bigger downpipe is still worthwhile after a restrictive manifold.
As I said.. I still have a lot of research to do... !!!
Vince
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I was wondering with this line of questions if this would mean that the amount of boost someone says they are running is really accurate? 20psi at what volume, or what velocity?
these are excellent points. a ported 1.6 engine will flow more air than a stock 1.6 for instance... and so the peak psi readings (all else equal) should be higher on the stock engine (although the potentially increased exhaust gas volume on the ported engine may spin the turbo faster, and create more boost). a cam with some overlap can cause some boost to go in one valve and right out the other.
Yeah, I don't think pressure is the issue here. If you have a pump that makes 10 psi it will make 10 psi into a pop can or a 55 gallon drum... just a matter of time.
ie: lag
there is definitely a 'sweet spot' where you want your tubing diameter to be. too small is restrictive as mentioned, too large creates pointless lag.
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According to Corky Bell, Maximum Boost pg 61, 304 MPH or 0.4 mach is the point at which airflow meets increased resistance (drag) and flow losses are experienced.
I found these flow numbers and thought I would pass them on.
0.4 mach = 304 MPH
2" piping
1.57 x 2 = 3.14 sq in
300 cfm = 156 mph = 0.20 mach
400 cfm = 208 mph = 0.27 mach
500 cfm = 261 mph = 0.34 mach
585 cfm max = 304 mph = 0.40 mach
2.25" piping
3.9740625 sq in = 1.98703125 x 2
300 cfm = 123 mph = 0.16 mach
400 cfm = 164 mph = 0.21 mach
500 cfm = 205 mph = 0.26 mach
600 cfm = 247 mph = 0.32 mach
700 cfm = 288 mph = 0.37 mach
740 cfm max = 304 mph = 0.40 mach
2.5" piping
4.90625 sq in = 2.453125 x 2
300 cfm = 100 mph = 0.13 mach
400 cfm = 133 mph = 0.17 mach
500 cfm = 166 mph = 0.21 mach
600 cfm = 200 mph = 0.26 mach
700 cfm = 233 mph = 0.30 mach
800 cfm = 266 mph = 0.34 mach
900 cfm = 300 mph = 0.39 mach
913 cfm max = 304 mph = 0.40 mach
2.75" piping
5.9365625 sq in = 2.96828125 x 2
300 cfm = 82 mph = 0.10 mach
400 cfm = 110 mph = 0.14 mach
500 cfm = 137 mph = 0.17 mach
600 cfm = 165 mph = 0.21 mach
700 cfm = 192 mph = 0.25 mach
800 cfm = 220 mph = 0.28 mach
900 cfm = 248 mph = 0.32 mach
1000 cfm = 275 mph = 0.36 mach
1100 cfm max = 303 mph = 0.40 mach
3.0" piping
7.065 sq in = 3.5325 x 2
300 cfm = 69 mph = 0.09 mach
400 cfm = 92 mph = 0.12 mach
500 cfm = 115 mph = 0.15 mach
600 cfm = 138 mph = 0.18 mach
700 cfm = 162 mph = 0.21 mach
800 cfm = 185 mph = 0.24 mach
900 cfm = 208 mph = 0.27 mach
1000 cfm = 231 mph = 0.30 mach
1100 cfm = 254 cfm = 0.33 mach
1200 cfm = 277 mph = 0.36 mach
1300 cfm max= 301 mph = 0.39 mach
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Now that's research... thanks for the numbers.
Next question will be... how many CFM does a Garrett T3 pump out at 25 psi on a standard temp and pressure day ??!!
Vince
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Wow, nice bit of info! You should copy that over to the FAQ section for sure.
With those numbers you can see some pretty dramatic velocity drops as the Dia. increases if you keep the same cfm flow rate.
So going to a 3" IC pipe could really increase lag time on the turbo.
When you are doing the math to figure out turbo maps/ surge/ etc.. do people look at the IC loop and factor that in as well? It seams like it could make a big difference.
I am guessing that you will want the flow of air in the turbo-IC-manifold loop to be moving as fast as possible ( up to just under 304mph) to reduce lag. How the hell do you figure out what your cfm requirements will be?
Could you increase velocity right before it enters the manifold by having a slight neck down in the pipe right as it enters the manifold?
Could you figure out a real, corrected boost measurment with this info? Kind of like recalibrating the speedo for larger tires?
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How the hell do you figure out what your cfm requirements will be?
RPM X displacement X PSI?
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Ummmm...I don't know :?
Could you run a turbo into various dia. pipes and into a flow meter to get info as to what the tubo is actually putting out for cfm at various levels of psi input? OR..perhaps we could have one of our physics friendly contributers whip up a formula to help solve this?.
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I never found it of any real benefit to use a larger diameter than what is the inlet of your intercooler and well as the outlet. The largest outlet I have seen is 2.25" off my TC intercooler. I have always used OEM intercoolers of various makes, bu then I am also keen to keep my projects cost down to a reasonable level..
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I think you're pretty close there. From what I see it, and the way I read it in "maximum boost" you can figure out CFM this way:
First, figure out the pressure ratio you are running according to how much boost you are using. For example, say you are running 8 psi:
(14.7+8)/14.7 = PR of 1.544
14.7 being 1 atmosphere, or 1 bar.
Now, you can figure out CFM with this:
(cidxrpmx0.5xVE)/1728
Which: cid= cubic inches of displacement, rpm= maximum rpm, 0.5 is the 4-stroke engine cycle only firing once per 2 revolutions, and VE is volumetric efficiency of an engine in percentage. The 1728 converts cubic inches to cubic feet.
So, (using my Jeep's 4.0 since I just did this on paper the other day for fun) we have:
(244x5000x0.5x0.8)/1728 = 282.4 CFM.
So, say I wanted to turbo my jeep's I-6 with 8 psi, I simply multiply 282.4 CFM by the PR that I figured earlier:
282.4x1.544 = 436.03 total CFM. You can divide this by 14.47 to convert to lbs/min which is what a lot of companies use on their compressor maps.
Hope this helps!
Brendan
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I think you're pretty close there. From what I see it, and the way I read it in "maximum boost" you can figure out CFM this way:
First, figure out the pressure ratio you are running according to how much boost you are using. For example, say you are running 8 psi:
(14.7+8)/14.7 = PR of 1.544
14.7 being 1 atmosphere, or 1 bar.
Now, you can figure out CFM with this:
(cidxrpmx0.5xVE)/1728
Which: cid= cubic inches of displacement, rpm= maximum rpm, 0.5 is the 4-stroke engine cycle only firing once per 2 revolutions, and VE is volumetric efficiency of an engine in percentage. The 1728 converts cubic inches to cubic feet.
So, (using my Jeep's 4.0 since I just did this on paper the other day for fun) we have:
(244x5000x0.5x0.8)/1728 = 282.4 CFM.
So, say I wanted to turbo my jeep's I-6 with 8 psi, I simply multiply 282.4 CFM by the PR that I figured earlier:
282.4x1.544 = 436.03 total CFM. You can divide this by 14.47 to convert to lbs/min which is what a lot of companies use on their compressor maps.
Hope this helps!
Brendan
Yep, that is correct. And if you do the numbers for a 1.6 L (98 cu. in. diesel) at 4,500 rpm, Flow rate = 115 CFM. Say you run 15 psi boost. Then, PR = 2.0. Total CFM = 230.
I ran 2 in. piping to my GTD intercooler, which is the factory size. The intake inlet necks down to 1.5 in. so I used a transition adapter. I have no noticable lag.
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One reason people use silicone is that it handles heat very well. If you were running a lot of boost, the air might get too hot for rubber tube or connectors.
Don't forget that intercooler piping often needs some degree of flex to allow for movement with the engine to a certain extent.
Lots of people use "hump" hoses to allow the piping to move a bit when the engine is shifting back and forth.
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A summary of the engine revs required to shift 300CFM cubic feet of air (atmospheric equivalent) per minute at the following turbo pressures:
0psi requires 10700rpm
8psi requires 6900rpm
12psi requires 5900rpm
16psi requires 5120rpm
20psi requires 4530rpm[/i]
Worked example for 0; & 8psi
2" pipe cross sectional area is 3.14" sq this is 156mph
300cfm
300 x12^3 =518400" [ cubic inches !]/min
518400 x 2.54^3 =8,495,054cc/min
8495054/(1588/2) =10,700rpm [4 stroke, STP]
@8psi... (14.7 +8.)/14.7 = 1.54 compression ratio
10700/1.54 = 6929rpm
So 2" pipe 156mph flow STP [300cfm STP] is 6929rpm engine
E&oE :wink:
Does this seem about right-ISH Someone thumb through this stuff :shock:
Seems most of the flow rates are unattainable.
Don't understand why drag only increases at the highest speeds...Surely Reynolds #'s come in to play way before these speeds and create turbulence. Intercoolers require turbulence to work efficiently though.
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There exist a cool link to calculate +- the correct engine flow at different RPM and psi:
http://cybrina.mine.nu:8080/WebModule2/compcalc?size=1.6&ve=85&boost=25&maxrpm=5000&Submit=Submit
Enter the engine specification and desired boost:
http://www.lovehorsepower.com/CFM1.htm
And how to put the result on compressor map:
http://www.lovehorsepower.com/MR2_Docs/compressor_flow_maps.htm