Airflow April 23, 2020 10:09AM
How bad does it hurt airflow to have 3 90 degree turns from turbo to intake

Re: Airflow April 24, 2020 06:36AM
in home heat ducts have 15 % loss for every 90, not sure on forced fed,dyno guys? Air is hard to "PUSH" !

Re: Airflow April 26, 2020 03:55PM
The wider the radius of the 90 bends has a lot to do with how much the pipe flows. Just be aware that friction increases as you bend the airflow because airspeed increases on the outside of a elbow.

Edited 1 time(s). Last edit at 04/27/2020 05:02AM by gonzo 1066.

Re: Airflow April 27, 2020 12:53PM
We lost 9 HP running (2) 4" 90 dgr bends along with an air filter feeding into a 3" turbo. These are true Dyno numbers on a Cummins pulling motor. So I would say you wont lose much as long as the piping is larger than the turbo inlet. We also have a 180 and a 90 dgr bend from the turbo thru the intercooler to the intake with very good results.

Edited 1 time(s). Last edit at 04/27/2020 12:57PM by prostockpuller.

Re: Airflow April 27, 2020 03:23PM
As important (if not more) is the surface smoothness of the ID especially at any welds/connections. Any kind of disruption with will pay havoc with airflow.

Re: Airflow April 27, 2020 06:31PM
The difference in volume between a turbulent airflow and laminar flow is very significant. Think of the inside of your charge air pipe as you would an airplane wing. Smooth is better.

Re: Airflow April 28, 2020 08:23AM
You will never get laminar air flow in an engine intake ducting.

Re: Airflow April 28, 2020 05:36PM
You will never get laminar air flow in an engine intake ducting.
Exactly, BUT less turbulence is better. This is why extrude hone has been done on many engines. This is why the new plastic intake manifolds are gaining popularity.

Re: Airflow April 29, 2020 02:03AM
Carbon fiber is a good option for DIY. You just make a mold and layer the DF around it. 3D printing is also an option as long as you have a printer with a big enough envelope.


Re: Airflow April 29, 2020 08:36AM
Carbon fiber.. That would be cool for a crossover.

Re: Airflow April 29, 2020 10:27AM

Someone will figure it out. Maybe the Germans already have.

Re: Airflow April 30, 2020 05:15AM
What about pipe diameter I have to make some pretty tight 90 degree turns would I be better off with 3 or 4 inch pipe?

Re: Airflow April 30, 2020 05:40AM
I used 2.5" seems to work fine. You can get fittings at local auto parts.

Re: Airflow April 30, 2020 05:48AM
like was said before, the length of the radius is very important, smaller is faster,

Re: Airflow April 30, 2020 08:42AM
Yes, smaller pipe has higher velocity for sure!

Re: Airflow April 30, 2020 11:45AM
How big is your guys valves only so much can go through the smallest point which will be the valve

Re: Airflow April 30, 2020 12:16PM
Yeah, I guess your right Lewis. I never thought about that!

Re: Airflow April 30, 2020 12:36PM
I have 1.90" Intake and 1.74" exhaust. Planning to use three 90 degree bends (likely short radius) in my pipe. 2.500" diameter.

Does that fit you criteria Lewis?

Re: Airflow April 30, 2020 01:37PM
Has it ever occurred to anyone to research and learn some of this stuff? What are you going to feed with the 2.5” pipe? A Honda? Does velocity create heat? Does heat generation or friction loss affect air density?

Re: Airflow April 30, 2020 02:11PM
what engine and what turbo are you going to run and is it open rpms

Re: Airflow April 30, 2020 11:49PM
You need to do some real research, In reality I was giving you the best advice you can get. I’m sorry you didn’t understand that. Try reading my post again a few times and instead of asking on pulloff research the topic of airflow itself.

Re: Airflow May 01, 2020 04:35AM
410 diesel 2.5/2.6 turbo. Open rpm

Re: Airflow April 30, 2020 02:21PM
Just curious, no it does not feed a honda! I have never seen a honda engine in a pulling tractor. Maybe that's what you are trying to run? If you think that is what someone is trying to run in a pulling tractor, then you obviously don't know much about tractor pulling! The 2.5 inch pipe on my setup feeds a 466 cubic inch engine pulling road gear at over 10000 lbs. Yes I'm sure some of the things you stated, MIGHT be true. However we use this thing called water injection to help remedy those things. Not all setups are the same! What one or many, things that works for my setup maybe won't work with another? I just know that my setup has a 2.5 pipe and it works great. Good enough to get my share of wins! If you think you got something better, then have at it. At least I shared what I had and didn't criticize others and not contribute a real, actual setup for the original post at the top! By the way, I've done research and experiments in the pulling business for years! And oh yes I've learned plenty! One of the biggest things I've learned, Is to not worry about what everyone else is doing and focus on what I'm doing. I dont care if someone has a 6 inch crossover or a 1.75 inch pipe. I'm only sharing what works for me to someone else who was asking for help! Just curious, its people like you who hurt the growth of our sport by criticizing them who thirst for knowledge to contribute to our sport instead of trying to encourage and help a fellow out! Best of luck to all the people trying to learn and get better! I'm out!

Re: Airflow May 01, 2020 12:33AM
That was a good answer for the guy asking the question by someone who’s been there and done that instead of reading it from a book pressure is pressure

Re: Airflow May 01, 2020 03:02AM
If you want to know how good (or bad) your intake pipe is then measure the pressure drop from inlet to outlet using a couple boost gauges. An optimized system will try to maintain laminar flow throughout the system to reduce losses. The best way to do this is to have a short, smooth, wide pipe with few bends and a high flow filter (or no filter).

Re: Airflow May 01, 2020 02:32AM
Just remember all of that air flying out your exhaust pipe has to come in the turbo.

Re: Airflow May 03, 2020 11:28AM
Just remember that Boost or pressure is nothing but restriction.

Re: Airflow May 03, 2020 02:49PM
Amen on the bost pressure wich means that story book science done nothing

Re: Airflow May 03, 2020 03:10PM
Boost and pressure also.means you have a big enough whistle to get the job done. Lewis knows what I'm talking about. If anyone thinks boost pressure doesn't matter, then why do you need any more than say 1 or 2 pounds of boost max. Any more than that is a waste, according to some because you have a restriction.

Re: Airflow May 03, 2020 11:56PM
Boost is like holding your thumb over the end of a waterhose with the water turned on wide open, move your thumb alil an see how far you can spray, just sayn !!!

Re: Airflow May 04, 2020 12:24AM
Say whatever you want about "restriction".......but take two identical engine setups.....lets say 3" turbo and diesel of course for arguments sake. Engine "A" has no wastegate, develops 90 psi intake boost at peak of run. Engine "B" has the wastegate set to bleed at 30 psi max intake boost. Who will post bigger numbers for hp and torque?

It's a no brainer. By the "boost is just restriction" argument, all Pro Stocks are wasting their time with these 6" turbos..............

Boost pressure may be referred to as a measure of restriction, but that restriction is also what is driving the exhaust side of the turbo.

Re: Airflow May 04, 2020 02:38AM
The "restriction" is NOT what drives the exhaust side of the turbo. Exhaust gas energy(heat and flow) is what drives turbine. You can place a small turbo on an engine and make a bunch of boost, but not make power.

Although, I am not saying boost doesnt equate to horsepower. However, flow must also be there. You can take two engines, one that has a poor air flow and another that is fully optimized for air flow, and make the same power out of each however one will be making it with much more boost than the other.

Re: Airflow May 04, 2020 04:58AM
pure restriction offers little air flow, - hence less hp, remove the restriction with bettet manifilds and then bring restriction(ie, boost) back, then watch the hp go up.

Re: Airflow May 05, 2020 02:14AM
Power is the result of the number of oxygen molecules you can cram into cylinder (fuel is the easy part). Pressure is one factor in determining that. Volume and temperature are the others. In the case of an engine, we are concerned with volumetric flow rate - but for the example, let's just consider one intake stroke - a volume fixed by the displacement of the engine and its volumetric efficiency. Take the ideal gas law : PV = nT. Pressure times volume equals the number of molecules times temperature. Solving for n, the number of moles of oxygen pulled into the cylinder, we get n = PV/T.

Increase pressure while keeping the volume and temperature the same, and you get more oxygen in the cyl. Increase the volume (bore, stroke, better volumetric efficiency with better intake/heads/exhaust/cam, etc) and you get more oxygen molecules in the engine. Decrease the temperature, again keeping the others constant, and again the number of molecules increases. So to summarize:

Pressure: More is better (bigger turbo and/or less losses)
Volume: More is better (increased displacement, improved flow)
Temperature: Less is better (unfortunately, as pressure goes up, so does temperature)

Re: Airflow May 05, 2020 02:28AM
The factor not considered in the explanation above is system back pressure, high system back pressure means there is residual gas (exhaust) trapped in the cylinder that prevents incoming fresh air from getting into the cylinder. I have not tried the math but perhaps delta P for use in the gas law would work?


Re: Airflow May 05, 2020 08:51AM
Whoa, @#$%& mean I have to know math and chemistry and physics and stuff to build a motor to tractor pull? Who woulda thunk it? (Sarcastic tongue in cheek expressed). JW LOL!

Re: Airflow May 07, 2020 03:41PM
Since most turbos work with similar pressures on both sides (5 or 10 psi difference of 70 or more isn’t much) it’s kind of like the engine is waaaay below sea level. Remember how an engines lose power at altitude? Putting a turbo on in some ways is just the opposite. Use that same thinking when considering the overlap period when both valves are open. It still scavenges the same as na, just higher pressures on both sides.

With regards to intake pressure, it depends. If you have 2 engines of the same size, one has a poor head with small valves and the other has big valves and an excellent port job. If you find the turbo and cam that maxes the power potential of the engine with the poor head and then put that same turbo on the engine with the better head, the one with the good head and the right cam for it is likely to make more power at lower boost.

On the other hand, if you took a Pro Stock and replaced the 6” wheel with a 4.1 it would make less boost and less power because you are putting less air into the engine.

As was said above, it’s all about the number of O2 molecules in the cylinder. With a centrifugal blower (turbo or belt driven), higher temperatures come with higher boost, so if you double the boost you don’t necessarily double the O2 molecules.


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