Turbo intake plumbing, series or parallel?? see pic

mike mueller · 05-11-2006, 10:42 PM

stumbled upon an ad for turbos and such on The Samba...interesting intake config.

Does anyone have real world experiance with it? I want to say that the 1st set of cylinders will see more pressure and higher temperature, but I have nothing to back it up, just a hunch.

I like this method instead of the usual "T" which feeds both sides equally and at the same time.

maf 914 · 05:32 AM

I agree that the first pair of cylinders will see more boost that the second pair in series. But, the packaging works.

Is that an intercooler of some sort on the boost tube? Also, that looks like an AC compressor in the corner. Lots of effort in that installation.

When you look at photos of early turbo installations in various racing classes, for example Indy cars, the intake manifolds were typically very simple. The were often tubes fed from the turbo at one end with individual runners in series for the cylinders. Obviously flow and pressure would not be constant across the length of the tube. But turbos initially offered such a performance boost that no one worried about the details. Hell, just crank up the boost! Once everyone had a turbo with similar performance designers started to refine the details and crudely made intake manifolds became beautifully made carefully shaped and sized plenums of aluminum and later carbon fiber that provided uniform conditions to all of the intake runners.

Joe Bob · Joe Bob's Garage

One would think that there MAY be some loss on one side....but I would like to see a manometer plumed in to confirm. I'm not convinced that there is a loss.

As soon as my Turbe Type I is out of the shop and the intercooler is plumbed in....I will be playing with diagnostic equipment to more understand this stuff....like getting rid of the clunky CB Performance EFI and replacing it with the Megasquirt.....

The CB seems to run rich as hellalladatime.....it's not a killer but I'm leaving tons of HP on the table....

Joe Bob · Joe Bob's Garage

BTW...there are two threads on this same subject.....maybe DDDDDD can merge them.

Twystd1 · 05-12-2006, 07:48 AM

The intercooler is a liquid to air cooler.

A great solution for mid or rear engined cars.

Twystd1

sammyg2 · 05-12-2006, 08:05 AM

Calcumalate the frictional loss in the crossover tube at a given volume and you will have your answer.

Joe Bob · Joe Bob's Garage

Calculations and real world use sometimes don't jibe......

Acox914 · 05-12-2006, 08:25 AM

Quote:

Originally posted by Twystd1
The intercooler is a liquid to air cooler.

A great solution for mid or rear engined cars.

Twystd1

i noticed that, but what liquid would they be using on an air cooled motor????????

oil gets pretty hot at 200 ish degrees........

standalone pump and resevoir? (coolant)

maf 914 · 05-12-2006, 08:45 AM

Ditch the heat exchangers for some hi-po headers and use the inetrcooler water for cabin heat!

Mark Henry · 05-12-2006, 08:51 AM

Although I think it's a clean install and I know he did it because a T3 has no room under the hatch, I wouldn't do it that way If I had the room to do a "T" near the center.

RandyLok · 05-12-2006, 08:52 AM

Ok, if you take a 4 foot piece of pipe, put a balloon on each end, hook an air hose to the middle and inflate... which balloon inflates faster? What if you move the air input closer to one end?

If the first side was "using up" energy from the air as it went by, that's one thing. But if positivie air pressure fills the whole thing and two sides are drawing from it, it doesn't matter where they are positioned.

Brian Mifsud · 05-12-2006, 08:59 AM

Mike,

I've done a heck of a lot of air-flow system design, fabricating, and balancing.

There may be NO pressure imbalance. If you add a restrictor to the first throttle-body/carb, you can "tune" it so the pressure it "sees" is the same as the second. This will work over a given Flow Rate range, but not at ALL flow rates. That may be moot as the range you tune it for may well encompass the engines' whole range.

The best setup IS where no flow restrictors are needed of course, (generally a symmetrical arrangement) if you have the space for packaging.

If I designed it, I'd use a "Y" instead of a "T", and keep all transitions smooth to minimize pressure losses. And, while it's not "blingy".. I'd also insulate the tubing after the intercooler since it's probably aluminum and sitting on top of a hot engine.

I like the liquid to air intercooler. The loads on it won't be anywhere as high as cooling a whole engine, so you most likely DON'T have to run it forward/ nor punch holes in any of the bodywork.

John Rogers · 05-12-2006, 09:04 AM

They would be the same. Once the intake is pressurized under boost conditions when the valves open they even out the sides.

Andyrew · Andyrew's Garage

Why go through all those steps?

This would make it "right"

RandyLok · 05-12-2006, 09:47 AM

Ok, let's try a simpler illustration. If you have a pressurized tank and you put two taps on it, will the location of those taps have anything to do with how much air pressure you can get from them? No.

Brian Mifsud · 05-12-2006, 10:14 AM

Randy,

Actually, the location will matter once that tank is emptied out and the air compressor is trying to fill it up again (just like in a turbo-intake-manifold relationship).

The farther the tap is from the source, the lower the pressure will be UNLESS, the rate at which you fill the TANK is far far far higher than the rate at which the air is leaking out.. but this isn't the case in a turbo-intake-manifold relationship unless you have a seriously oversized turbo which would not be a good thing

RandyLok · 10:26 AM

I respectfully disagree.

And as always, I may very well be wrong but I'll keep playing devils advocate because I like how it brings out the discussion and helps me learn...

If we were talking about drains in the bottom of a water pipe, then I agree with your point - it will take the first / easiest exit.

But air doesn't flow around looking for the nearest exit. Air exits a container when there is positive pressure inside the container. Even if that pressure is low or building.

The size of the exits will have an effect on how much velocity comes out, but the location is irrelevant.

Brian Mifsud · 05-12-2006, 10:30 AM

Here, I'll try and state what I mean more clearly.

Take a pipe and cap one end. Drill equal sized holes in equally spaced from the capped end to the open end. Put pressure gauges opposite each hole. Pump air in the open end of the pipe.

You will see lower pressures as you get farther away from the source of the air. This is due to the frictional losses of air traveling FAST over the surfaces inside the pipe.

You can MINIMIZE these pressure differences by doing the following:

1) Make the Pipe really big in diameter compared to the "leaks".... basically this is a "tank". The air will travel more slowly over the surfaces since it has more room to move around.
2) Make the pipe really short, the total distance the high speed air has to travel has minimal surface to contact with.
3) Make the insides of the pipes ultra smooth... may help.

This also holds for water or any other fluid or gas flowing through a pipe at a steady rate.

RandyLok · 05-12-2006, 11:21 AM

Getting back to the configuration at hand, with a pipe that has only two taps... If you put pressure gauges at those taps, and pump air in, how much pressure difference do you think you could measure? I do not believe it would be significant.

Thank you Brian. I appreciate and trust your knowledge. I'll concede now because I'm realizing it would take real-world results to convince me.

John Rogers · 05-12-2006, 11:21 AM

That appears to be in a bus, type 4 maybe so the fire order is 1-4-3-2 so one side gets the air charge then the other side. Or cyl 1 gets some air, then over to 4 and 3 then back to 2 and then 1 again. This would probably negate any distance worries? Additional things to consider, the inside of the pipe is probably oil coated (our 1987 930 is) so frictional losses are minimum from the surfaces and the velocity of the air charge is very low, not enough to worry about the velocity losses. Why is that, figure the cylinder capacity for the 2L engine then figure RPM, say 6000 then what is the turbo output in relation to that and you'll have much more air than you'd need.