intercooler piping size

[4g63mightymax]

Ok, hypothetically speaking..........If the outlet on a turbo is 1.5 inches big and the throttle plate is 1.5 inches big, would there actually be any benefit if you made the pipes from the turbo-intercooler and the intercooler-throttle body bigger than 1.5 inches? What about if you removed the intercooler from the equation and it was a straight pipe from the turbo to the throttle body. Would there be any benefit to having big intercooler pipes? Any thoughts or opinions?
Jeremy

 

[gixrman]

Originally posted by 4g63mightymax
Ok, hypothetically speaking..........If the outlet on a turbo is 1.5 inches big and the throttle plate is 1.5 inches big, would there actually be any benefit if you made the pipes from the turbo-intercooler and the intercooler-throttle body bigger than 1.5 inches?
What about if you removed the intercooler from the equation and it was a straight pipe from the turbo to the throttle body. Would there be any benefit to having big intercooler pipes? Any thoughts or opinions?
Jeremy

Were are you getting 1.5" from? stock piping is 2 1/4".

There is no benifit from removing the intercooler for a dialy driver, you are actually going in reverse as far as performance that is. The whole point of the intercooler is to cool down the incoming air to lessen detonation. Maybe if you packed the intake with dry ice every couple of miles.

 

[Drifte]

i think he ment removing the intercooler from the equation, as a point to the length of the charge piping to be run and ect. But i think larger piping would benifit if you look at it as you would the guage of electrical wire to the lenght w/ amps. The longer the wire the larger the guage. Of course with electricity if you start of with 12guage, going bigger doesn't help. but i would go with bigger piping.
-peace

 

[focusedrage]

i belive that the thing is smaller piping will cause better trottle response, bigger will cause better topend power and this is why...

when the throttle is open the turbo will spool and must pressurise the whole system from the turbo to the intake manifold befor max boost is atained.

the bigger the pipe the larger the total volum of this space is, that longer it takes for the total pressure to rise.

small pipe mean less volume to pressureise faster boost, but cant flow as much in the high rpms, i figure that the best betis to go the same size as your throttle body which will ultimatly limet the flow, there is no sense goign from turbo to large, back to small inlet on ic, bact to large, back to small inlet on tb

 

[kpt4321]

The 1g throttle body is 60 mm, which is 2.36 inches.

The increased volume from a bigger intercooler and bigger IC piping will not effect lag. At 3000 rpm, the turbo must fill the 2 liter motor 1500 times per minute. That's about 50 liters per second of airflow. Toss another little bit of volume in there, and it's not going to make much of a difference.

...Kyle T.
93 TSi AWD "TURBO4"

 

[focusedrage]

im gonna use the following rebuttle...

still

 

[Defiant]

Interesting thoughts, Jeremy. I've wondered the same thing, what's going on in these intakes that go to an FMIC, and have three or four liters of volume between the compressor and the valves? What's the one about pressure in a chamber being equal in all directions, is it Boyle's or Dalton....? So as soon as the intake's pressurized, it's the same pressure at the backside of the intake valves as it is at the compressor output, in theory.... but what of the piping drag between the blower and the valves? How much does it penalize when under non-boost conditions?
My '84 200SX Turbo runs a T-25, straight up from the blower, across the valve cover to the plenum. No intercooler, no BOV, and very little boost (I never had a gauge on it). And nothing like a DSM- after I test-drove a GSX, I thought the Datsun had been tied to a tree for the drive home. But its 1.8 gave 30 miles to the gallon, too....

 

[4g63mightymax]

The reason this all came about is because I have a 1G engine, stock turbo, and stock intercooler in my mightymax. I bought some 2.5 inch pipe to make some intercooler pipes and then said to myself, "what the heck is bigger pipe going to do for be besides make the air flow much more sloppy. So I wanted to get some opinions on if I should use the 2.5 inch pipe or is it foolish since everything else is smaller? I guess I can understand that a turbo could pressurize a bigger pipe in a matter of seconds, but at what point would it be too big? Would it be a good idea to make a air big chamber for the turbo to pressurize before it goes to the throttle body? How do you figure out what the max volume of air a turbo can pressurize in a given amount of time at a certain rpm (1 second lets say at 3500 rpm?). Idealy I would think that would be the amount of air volume you would want you pipes/intercooler to take up, no more no less for the turbo to be most efficient....hmmmmm........any thoughts?
And yes, I would actually do this If I could figure out the right volume.......I have the time.............
Jeremy

 

[focusedrage]

well, i think that for most purposes this is not a matter that needs to be considered. I plan on using 2.25" tubing for my ic pipes. I think the whole point of the intake manifold is to provide a resivoir of pressurized air that the pistons can draw from.

I know little about the dynamics of intake manifolds, but i do know that the aftermarket ones, have much shorter runners, so esentialy less total volume.

If you have the time, why not try it, find a long strait section of intercooler pipe, and bodge it up so you can easiy swap in a large "tank" section so perhaps ther pipe goes from 2.5" to 6" to 2.5" and see if your tank idea works... report back, i would like to see the results, good luck

 

[MaineDSM]

Originally posted by Drifte
Of course with electricity if you start of with 12guage, going bigger doesn't help. -peace

Actually, electricity works a little differently from a water or air flow.

A tiny, short wire will flow just as well as a large, long wire. The only reason huge 4 gauge wires need to be used in car stereos is because they need to run a long ways from the battery to the amp in back.

A 3 inch section of 16 guage wire spliced into a long length of 4 guage wire will not reduce the voltage noticably.

I know this is a little off-topic, but I just wanted to clear that up.

 

[focusedrage]

voltage yes, current no, resitance of a wire depends on lenth, material, and cross sectional area, i could probly run a billion volts though a 12 gage wire... but any more then meby 70 amps... and the wire would heat up and explode, i have seen it, look around on the internet, people discharge many amps though small wires to whatch the boom, so yeah

"The only reason huge 4 gauge wires need to be used in car stereos is because they need to run a long ways from the battery to the amp in back"

this is because they are running rediculous curent for those amps... 1300 watt stereo??? thats nerly 100 amps of power so they need thick wires, the voltage drop is negligable

 

[4g63mightymax]

Well, now that we have electricity outta the way, lets talk airflow......heheheh, Im just kidding. I am hoping for some more opinions and thoughts on the subject, even if it does include electricity references. Anybody, Anybody..........Bueller?
jeremy

 

[focusedrage]

now that i think about it... and im not exaclty sure, but a large volume intake tract would, in additon to flowing better, i think, might improve spoolup between shifts, because there is still a larger resevoir of air... i dont know thats just kind of mouth pooping... anyway

i think it is just like electricity, pressure and flow corespond with voltage and current... sort of the simple fact is in electics or fluid dynamics, the flow will be limeted by the smallest point.

 

[pneumo]

What if the smallest point isn't flow limited?

The best reason to go with larger diameter pipes is to reduce pressure drop. With small pipes the velocity is very high, and there are friction losses as the air scrubs against the piping walls. Slower moving air has less friction in the pipe. So does short route piping.

Short route piping is also prefered because it helps throttle response, which is the time from when the throttle is opened to when the MAS starts flowing more air. It's not instantaneous, opening the throttle causes a low pressure wave to travel from the throttle back to the MAS. It doesn't take long, but it's the reason the ECU has an "accel enrich" function built into it, sort of like an accelerator pump on a carburetor.
I agree that turbo lag is not significantly affected by large piping.

 

[Defiant]

Originally posted by 4g63mightymax
Well, now that we have electricity outta the way, lets talk airflow......heheheh, Im just kidding. I am hoping for some more opinions and thoughts on the subject

Dang, where's Taboo when we can use him?
Until then, fiddle with this: get one of those nozzle extension tubes off a WD-40 can, and a cocktail straw, and a burger-stand straw, and a McDonald's straw (the one thing the've always done right). Now, blow them. You can usually develop about 3-4psi with your corpus until something painful pops somewhere and reminds you about it for a week. You guys without turbos suck. Er, that is, instead of blowing through the straws, just inhale.
You don't even have to go through all this to get the idea, do you? You can feel it just by reading about it. Now imagine trying it with a piece of 2" tubing. See where this is going? You'll develop full pressure blowing through that little WD-40 tube, but you probably won't be able to blow out a candle unless you're right up against it. You can probably blow hard enough against a cocktail straw that you can develop "full output pressure". But with a soda straw, you'll pass out before you get any backpressure felt, and just that little step up to a McDonald's straw is _easily_ felt on a human scale. And a piece of 2" tube? You may as well not even have it there, it's like nothing.
Now then, pressure drop. Make that WD-40 tube three feet long. You wind up with so much air drag inside the tube that you have no flow out the other end- try to blow out a candle through a garden hose. You see that somewhere along the line, depending on how long the hose is, how strong your lungs are, and how big around the pipe, you have crossovers between being able to blow enough air, being able to blow hard enough, and having enough volume available in your lungs to do anything with the plumbing. The McDonald's vs. normal soda straw clearly and quickly demonstrates just how _much_ such a small difference matters.
Much is made of the "hair dryer" T-25. It's a very modest, not particularly efficient turbo. But in balancing out the whole, Mits got 15 more horsepower out of the 2-liters than the 1G gave. True it dies out before six grand, but how often do you DRIVE at that speed? Driving is pulling out from traffic signals, merging onto freeways, and -for the far greater part of the time- loping along at 4000 rpm with so little throttle that the turbine is just keeping the manifold at atmospheric pressure, no boost at all. When you want to wind the thing up, the T-25 is too small a lung, and the straw is too small. Is it too long as well? And when you're not under boost, look at the length of straw it's having to breathe through.

Just like in Caddyshack, be the ball.

 

[focusedrage]

dude good example

 

[4g63mightymax]

I like that response! Thanks! I agree................
But, now if you take a cocktail straw (throttle body), and duct tape it to the end of a 5 inch pipe (intercooler pipes) with no air leaks in between and blow through the 5 inch pipe, the air pretty much stops in the pipe and your ears pop. Your 5 inch pipe is just overkill for the cocktail straw, and all that mandrel bent 5 inch pipe is wasted because it isnt neccesary. You can only have "so" much air going through the cocktail straw at one time. At what point would the intercooler pipe become too big? How do you find out what size pipe would be the most efficient for a certain application?
Any thoughts, opinions, or straight science on the subject?
Jeremy

 

[focusedrage]

I found some stuff on flow rate with a change in the cross sectional area... that is like when the ic pipe diameter changes. Realize that this is flow rate so it is a powerfull equation, i think that if you know the required cfms of the engine during the peak hp number, then you can calculate the best, most effcient IC pipe diamters....

Variables:

Q = Flow Rate (m3/s) or (2118.879972 ft3/m)
A1 = Cross-sectional Area (m2) or (10.7639104 ft2)
A2 = Cross-sectional Area (m2) or (10.7639104 ft2)
q = Density (kg/m3) or (0.062427 lb/ft3)
p1 = Pressure (Pa) or (0.000145 lb/in2)
p2 = Pressure (Pa) or (0.000145 lb/in2)

Equation:
___________________________
Q =  (2/q) * (p1-p2)/((1/A22)-(1/A12))

Now with out a change in cross-sectional area:

___________________________
Q =  (2/q) * (p/(1/A2))

 

[focusedrage]

oops, that was suposed to be a square root thing, the ?

 

[Defiant]

Originally posted by 4g63mightymax
I like that response! Thanks! I agree................
But, now if you take a cocktail straw (throttle body), and duct tape it to the end of a 5 inch pipe (intercooler pipes) with no air leaks in between and blow through the 5 inch pipe, the air pretty much stops in the pipe and your ears pop. Your 5 inch pipe is just overkill for the cocktail straw, and all that mandrel bent 5 inch pipe is wasted because it isnt neccesary. You can only have "so" much air going through the cocktail straw at one time. At what point would the intercooler pipe become too big? How do you find out what size pipe would be the most efficient for a certain application?
Any thoughts, opinions, or straight science on the subject?
Jeremy

Interesting. Of course, you'd be wasting your lungs (turbo) in filling all that space that can't be used. And so long and it's just compressing into a large volume without outlet, you'd be stressing the blower. I don' t know what the effect would be while running as normally-aspirated (before boost comes on), but I think it'd add quite a lot to lag.

{The "square" in the math equation is what happens when the character set doesn't understand what goes in there. I'm happy when I can get away with using ½, ¼ and °.

 

[kpt4321]

First of all, I do not know why you think that having a big volume to fill will make more power. That's the job of the intake manifold, nothing else.

Second of all, aftermarket intake manifolds do have shorter runners for more power, but they also have larger plenums than stock manifolds.

Sure, if you blow through a 5 inch pipe into a cocktail straw, you will have a restriction. But that's an absured analogy. To retain that same ratio of diameter to diameter with the IC pipe and the TB, the intercooler pipe would be about 100 inches in diameter. Yeah, right. Bad analogy.

Like I ALREADY said, the TB is 2.36 inches (1g) or 2.17 inches (2g) in diameter. If you're using 2.25 inch IC piping, on a 1g, then the piping does NOT reduce in size! Why are you so hung up on this? It INCREASES at the throttle body.

The main purpose of bigger IC pipes to decrease flow speed, and to decrease the turbulence created by the uneven walls of the stock pipes.

Also, somewhere up there, someone mentions the "maximum volume" that a turbo can fill. This is, like, wrong. A turbo can fill any volume to any pressure. However, this is ONLY true if you have no time constraints. With a spinning motor, you have flow in volume units per time unit. Thus, you still do not have a set volume the turbo can fill, without having a time attached to that volume. Also, without pressure, we really can't "calculate" jack.

....Kyle T.

 

[kpt4321]

Originally posted by focusedrage
i think that if you know the required cfms of the engine during the peak hp number, then you can calculate the best, most effcient IC pipe diamters....

The most efficient IC pipe size is infinity. Always. An infinitely large intercooler pipe would require that the air travel at a very slow speed, hance basicially eliminating flow losses.

However, velocity is NOT the only thing to consider here. If you had an infinitely large IC pipe, then the air would be close to stagnant and would pick up heat from the piping, which is heated by the hot engine bay. This would not happen in the piping was a few inches in diameter.

Also, with infinitely huge IC piping, it would take FOREVER for the turbo to fill it all. This, again, is not an issue with IC piping that is a couple inches in diameter.

The fact of the matter is, it's all a big tradeoff. In order to decrease velocity, you take other losses, such as higher heat transfer and slightly more lag. It simply turns out that IC piping 2-3 inches in diameter has the best net result in terms of power.

You cannot simply calculate the size of IC piping that you need. Just use 2.25 or 2.5 inch pipes, or 3 inch if you plan on making 800+ hp.

....Kyle T.

 

[4g63mightymax]

Thanks for the posts, I really do appreciate them........However, it sounds like you are getting angry about the size of intercooler pipes??......Sorry if intercooler pipes make you angry. I am just trying to educate myself..........I wont ask anymore about pipe size and efficiency, I have learned my lesson.
Thanks again everybody for the responses!
Jeremy

 

[Turboniam]

So, why do so many guys running big intercoolers run 2.5" piping??

Is that the best size to go when running a large intercooler like the IRC/Buschar, etc??

 

[focusedrage]

i think this has been discused, you have to compromise between flow and velocity