Author Topic: Turbo plenum  (Read 106037 times)

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saltfever

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Re: Turbo plenum
« Reply #135 on: November 04, 2008, 02:06:20 AM »
Is there a problem with going well overkill for the cooler.
For instance, lets say I use one that is rated at 2K HP....my real HP will never be over 650.
Because the intercooler is being fed from a water tank with ice is there any issues with running a cooler this much bigger (meaning the ice tank wont over cool the intake charge, even at 100% efficiency it wont cool more than the water in the tank).  just wondering if I should target a cooler in the 1000 HP range or is it ok to run one bigger than needed (looking for the future).
JNuts, don't worry, your intake charge will never be too cold in a turbo motor.  Intercooler efficiency can not ever be that good.  Depending on your boost level, your 200 to 350 degree air temp will never get cold enough to cause intake icing at Bonneville...  :|  You just have to hope you can get it down to 100 degrees by the time it gets to the throttle plates.  Keep it simple, any thermal control will be running wide open anyway.
Stainless I agree with you if the IC is sized reasonably for the engine. However, you missed the point of my replies and Jonny's question that started a page back. He asked about running an IC that is 300% larger than his current engine needs; to save future costs if he goes up in engine size. If an 80% efficient IC is providing 100F deg temps, and it is resized 300% larger, you will definitely drop temps below ambient conditions. He asked "what if" and my reply was only about possible conditions to consider.

Jonny: you don't need to add complexity with a temp-modulator-thingie, as pointed out. You don't have to run ice water. You can start with warmer water. All you need to know is how many BTUs you are creating and for how long. So if you need 300 degree air, cooled to 100 degree, for 200 seconds, only enough water is needed to absorb that amount of BTUs. Knowing the specific heat of water calculate the starting temp, ending temp, and volume of water needed to absorb that amount of BTUs. Leave the line with those parameters (and confidence in your calcs  :wink:) and you will have a good run.

Offline Stainless1

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Re: Turbo plenum
« Reply #136 on: November 04, 2008, 09:49:39 AM »
JNuts, the Plenum you are considering, what is the inlet and outlet size?  Most 2K HP intercoolers have very large intake pipe sizes, whatever you do, don't do a lot of necking up and necking down from your turbo to your plenum. 
Be sure to let us know if you get intake icing problems....  :roll:
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Offline fredvance

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Re: Turbo plenum
« Reply #137 on: November 04, 2008, 10:11:21 AM »
JH you definitely need to look into doing all your tuning thru your ecu. There is all the info and people to get you going on SH.org.
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Offline 1212FBGS

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Re: Turbo plenum
« Reply #138 on: November 04, 2008, 12:55:11 PM »
saltfever, nope i gotta disagree with ya... increasing your intercooler 3x is not gonna lower your charge temp 3x... you will be able to pass 3x more air at reduced drag or pressure drop but the temp will stabilize at the tubes ability to dissipate the heat.... ambient temp doesn't have a really big deal in this equation either (and the crowd goes oooohhhh), look so ya tune the car in the shop at 85f and ya then go to bville and it 105f...20 deg, big deal especially when your new cooler drops the charge temp hundreds of deg.... below ambient? hopefully! below freezing? probably not! the only problem i see with a huge cooler is plenum volume. But hey were not drag racing here so a softer spool up is good just as long as is will come up to desired pressure... so heres how i size em up, take a Stanley 25' tape measure (the one with the chrome plastic case) and measure the size in the engine compartment.... then with the same Stanley tape, measure the size of your boost tubes, the next part is very time consuming...log on to ebay!.... i bought 2ea $1600 spear-co coolers from a Chinese import company for $250 each the sizing is what i needed but i had to cut the tanks off and re-weld 'em cuz i wanter my inlet on the front and the outlet on the back...no big deal cuz i saved $2500....good luck and stop overthinking things out....keep it simple...
Kent

Offline Sumner

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Re: Turbo plenum
« Reply #139 on: November 04, 2008, 01:20:39 PM »
........ I am going to have an additional box (megasqurit) to control the secondary injectors.................

If I understand dieselgeek you could control all the injectors and the ignition with the megasquirt.  Hopefully he will comment.  I hope to use that approach.

c ya,

Sum

Offline dieselgeek

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Re: Turbo plenum
« Reply #140 on: November 04, 2008, 03:47:06 PM »
you can definitely have megasquirt control the "whole thing" - it's come a long ways in the past couple years.

I'm still a fan of MS1 running the "Extra" code, which is loaded down with a ton of useful options.


The RPM limitations of the old megasquirt aren't really an issue, the version 3.0 (and later) circuit boards all have provisions for high resolution trigger wheels.  The limitations for RPM aren't actually "RPM" but, how fast the hardware can "count" the pulses from whatever kind of input trigger that is used.  The lowest resolution triggers, which are typically "one pulse per firing event" (distributor pickups, for example, or MSD crank triggers with 4 teeth) are the lowest speed, thus capable of incredibly high RPM...   whereas higher count trigger wheels, like a 36-tooth "Ford EDIS" trigger wheel, will record 9 pulses for every firing event. 


We run a 36-tooth wheel on an engine that sees 9000 rpm, that is the same as running a standard distributor on a v8 engine to 81,000 RPM.  The limiting factor is, a combination of the hall sensor's maximum frequency (teeth counted per second) and there is also a limit in the circuit on the megasquirt itself, which I've never actually tested.

ON a high revving motorcycle engine, a good compromise would be an 8-1 or 12-1 trigger wheel on the crankshaft.  YOu'd have no problem tracking RPM to whatever engine speed you need to.

I like high resolution trigger wheels, and running "wasted spark" because it lets you get rid of a distributor, which wastes a lot of energy with it's extra gap (between rotor and spark tower).

I'm always happy to help.  Some "high tech" weenies like to poke fun at Megasquirt and it's DIY roots, but I've tuned it on cars and motorcycles that range from Jon Huber's 4-cylinder, 170 cid Mustang that runs an 8.80 quarter mile at 155mph on small tires, stock suspension - to GH's twin turbo big block chevy that holds the AA-BGALT record.  It's a rock solid system with many people contributing to development and testing - it's got a ton of features and it's a great way to learn how EFI and engine management works.

-scott

saltfever

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Re: Turbo plenum
« Reply #141 on: November 05, 2008, 04:09:09 AM »
saltfever, nope i gotta disagree with ya... increasing your intercooler 3x is not gonna lower your charge temp 3x...
Nah . . . I never said charge temp would be lowered 3x. I said he wanted to increase the IC 3x. In my example the IC was running at 80% I never mentioned outlet temp. What I meant by “ambient” was on a typical Bonneville 100deg day you could get a discharge of less than the 100 deg “if” your IC was big enough. That is a big “if” and I agree with you it would be rare, but it is doable. I didn’t mean ambient was influential on IC performance.

. . . you will be able to pass 3x more air at reduced drag or pressure drop but the temp will stabilize at the tubes ability to dissipate the heat....
You hit on the key to this discussion and that is to increase the size of the IC. Aluminum has a Thermal Conductivity Value (CTV). It is the time it takes for heat to conduct through the material. (silver is best and aluminum is forth). As long as there is a delta t, heat will flow from hot to cold. If the tube is not transferring heat as you indicated, that means (1) there is either no delta T (the water is the same temp as the tube) or (2) the charge air BTUs exceed the CTV equation (see below). We will assume the water will always be colder than charge air, fairly constant ice water, and of sufficient quantity. So the only way to transfer more BTUs into the water (lower the air temp) is to add more area of material. That means if you make it big enough you can lower the air temp to the water temp. I’m not saying you want it that cold or even if you want a huge IC to package; but you can get 350 deg air to 32F if you want to. By going to copper construction, NOS or dry ice, the IC could be quite small. Using LN would be even smaller, but ridiculous.
The equation used to express heat transfer by conduction is known as Fourier's Law and is expressed as:
q = k A dT / s (1)
where
q = heat transferred per unit time (W, Btu/hr)
A = heat transfer area (m2, ft2)
k = thermal conductivity of the material
      (W/m.K or W/m.oC, Btu/(hr oF ft2/ft))
dT = Temperature difference across the material (K or oC, oF)
s = material thickness (m, ft)
 
. . . when your new cooler drops the charge temp hundreds of deg.... below ambient? hopefully! below freezing? probably not!
If using ice water you can’t get below freezing.  :-)


Offline manta22

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Re: Turbo plenum
« Reply #142 on: November 05, 2008, 11:34:28 AM »
"If using ice water you can’t get below freezing."

You can get below 32F by adding salt to the ice. Remember the old ice cream makers? Now where could you find salt....?

Regards, Neil   Tucson, AZ 
Regards, Neil  Tucson, AZ

Offline Rex Schimmer

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Re: Turbo plenum
« Reply #143 on: November 05, 2008, 08:25:19 PM »
As you increase the size of and intercooler you reduce the velocity of the air going thru the intercooler tubes and if the velocity gets to low the flow can change from turbulent to laminar and the efficiency of the intercooler drops big time. The air flow thru the intercooler tubes must be turbulent to be efficient. So bigger, bigger still and really big may not be the best parameter to pick your intercooler size.

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Offline 1212FBGS

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Re: Turbo plenum
« Reply #144 on: November 05, 2008, 08:46:45 PM »
yep thats why my tape measure sizing formula works so well...
kent

saltfever

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Re: Turbo plenum
« Reply #145 on: November 05, 2008, 10:23:18 PM »
As you increase the size of and intercooler you reduce the velocity of the air going thru the intercooler tubes and if the velocity gets to low the flow can change from turbulent to laminar and the efficiency of the intercooler drops big time. The air flow thru the intercooler tubes must be turbulent to be efficient. So bigger, bigger still and really big may not be the best parameter to pick your intercooler size. Rex

That is quite interesting, Rex. My understanding of fluid systems is that turbulence decreases efficiency. We see that in port work by increasing the short side radius, NACA duct entrance designs, duct taping of body seams and cracks (where legal), turning vanes in hydraulic systems, all designed to promote laminar flow and decrease turbulence. Maybe your point is that turbulence in the tubes helps to transfer the heat. I don't know enough about the phenomena you describe. Your point is very interesting and I would like to learn a lot more about the approach. I'm not trying to be adversarial here but am really interested in learning more. Can you point me to some kind of reference or maybe applications where you got that information. If it is a thermodynamics 101 treatise, I'll take a pass. But if it is spelled out in "racer tech talk" I would enjoy reading it.  PM if you want to go off-list.  Many thanx. :-)
« Last Edit: November 06, 2008, 04:04:07 AM by saltfever »

saltfever

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Re: Turbo plenum
« Reply #146 on: November 06, 2008, 04:11:42 AM »
"If using ice water you can’t get below freezing."
You can get below 32F by adding salt to the ice. Remember the old ice cream makers? Now where could you find salt....?
Regards, Neil   Tucson, AZ 

LOL!  Good one, Neil  :-D

Offline Jonny Hotnuts

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Re: Turbo plenum
« Reply #147 on: November 06, 2008, 11:58:28 AM »
Quote
Posts: 69


 

   Re: Turbo plenum
« Reply #145 on: November 05, 2008, 09:23:18 PM » Quote 

--------------------------------------------------------------------------------
Quote from: Rex Schimmer on November 05, 2008, 07:25:19 PM
As you increase the size of and intercooler you reduce the velocity of the air going thru the intercooler tubes and if the velocity gets to low the flow can change from turbulent to laminar and the efficiency of the intercooler drops big time. The air flow thru the intercooler tubes must be turbulent to be efficient. So bigger, bigger still and really big may not be the best parameter to pick your intercooler size. Rex
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That is quite interesting, Rex. My understanding of fluid systems is that turbulence decreases efficiency. We see that in port work by increasing the short side radius, NACA duct entrance designs, duct taping of body seams and cracks (where legal), turning vanes in hydraulic systems, all designed to promote laminar flow and decrease turbulence. Maybe your point is that turbulence in the tubes helps to transfer the heat. I don't know enough about the phenomena you describe. Your point is very interesting and I would like to learn a lot more about the approach. I'm not trying to be adversarial here but am really interested in learning more. Can you point me to some kind of reference or maybe applications where you got that information. If it is a thermodynamics 101 treatise, I'll take a pass. But if it is spelled out in "racer tech talk" I would enjoy reading it.  PM if you want to go off-list.  Many thanx.   



I have given this some thought and Rex could be correct.
In my thinking laminar flow boundary layer and its lack of contact with the sides of the exchanger could in fact lower the efficiency of the cooler vs. turbulent. I am not certain if this is the backbone of Rexs statement but only that there is the possibility (at least in my head!) that this is plausible.

I would have doubted this due to the effects of a drastic temperature drop from one end of the core to the other causing the air to contract and resulting in any disruption of laminar flow but this is just a speculation and honestly Rex may in fact be correct.

------------------------------------------------------------------------------------------------
I now have a BOV, and powder coated it to match the valve cover.

Is there a better location to put the BOV?

Should the BOV be before the intercooler and as close to the compressor as possible?

I have seen many installs where it is on the plenum itself.
Just wondering if there is a better place to mount it.




« Last Edit: November 06, 2008, 12:01:08 PM by Jonny Hotnuts »
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Offline SPARKY

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Re: Turbo plenum
« Reply #148 on: November 06, 2008, 01:14:47 PM »
I would think you would want the BOV as close the the plenum as possible. If the piping has a curve I would put it on the outside of the bend---due to possible wave hormonics.
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saltfever

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Re: Turbo plenum
« Reply #149 on: November 06, 2008, 03:58:19 PM »
Regarding Rex's posting 143 above.
Jonny, It could be that I am musunderstanding Rex's posting. It is fundamental physics (Bernoulli) that as pressure decreases velocity increases up until the point of turbulence. At that point there is no further increase in velocity and the system becomes inefficient. According to Bernoulli turbulence prevents flow. However, we are discussing heat transfer or a thermodynamic system. As you suggest Rex's point could be that turbulence promotes heat transfer. I don't know. I would imagine that laminar flow provides the greatest contact with the tube wall and aids heat transfer even though there is a stagnet layer attached to the wall on any laminar flow system. I suspect it assists in heat transfer. But as I said, I'm not clear on Rex's intent and would like to know more. Rex's postings are high quality and value and I suspect I am missing out on good information.