DIY Intake Spinoff Thread for Sheet Metal Design

[6leakertweeker]

OK here's my design. I think i might try to build one of these. Doesn't seem like it would be too hard. Only thing I can't do is cut the flanges but I have a buddy that can. Ill also have to have a flange cut for the intake horn, although brackets, ect ect. I want to make this a stock fitting replacement.

It needs some fine tuning but that's only like 45 mins worth of work.

 

[Pizza pig]

not bad, I would think using a oval tube versus more round would work better

 

[6leakertweeker]

Really? Why is that? That might be tough to find.

 

[Powerstroked162]

OK here's my design. I think i might try to build one of these. Doesn't seem like it would be too hard. Only thing I can't do is cut the flanges but I have a buddy that can. Ill also have to have a flange cut for the intake horn, although brackets, ect ect. I want to make this a stock fitting replacement.

It needs some fine tuning but that's only like 45 mins worth of work.

While I do applaud your efforts, i hope you do realize there is more too it than just cutting and welding some pieces together..... Things that seem logical to you may not flow that way on a bench or attached to the engine. Something to think about before you invest money and time

 

[6leakertweeker]

I understand this. I've done plenty of fabrication in my life but have no experience on a flow bench. Why don't I build this and you put it on your flow bench for me. this my friend is called R&D

 

[6leakertweeker]

If I had some numbers to work with I could things a little bit more accurate. As far as flow goes I almost drew one up where the vertical runners leaned slightly toward the front of the engine to help reduce turbulence in inside the intake. But like you said its going to bring hard to tell until its tested.

 

[Lubbockguy1979]

Logically all we are tring to do is trade a coffee straw (stock intake) for a mcdonalds drink straw (modded/new product) so we can Move more volume.
Past the logic it has to fit and work. It dosent appear to be a large amout of room under a stock trucks hood where the current intake sits.

 

[6leakertweeker]

That's what I'm worried about. Im going to get some more measurements tomorrow but I think this should clear. The fuel bowl is what is going to give me trouble. Also the wiring harness is already pretty tight so I'm not sure if it'll stretch over the top or what.

 

[Pizza pig]

get rid of the fuel bowl oke:

 

[6leakertweeker]

get rid of the fuel bowl oke:

Working on it. : )

 

[wetnsloppy4x]

Please forgive my ignorance. Those drawings were done in Solidworks, correct? Isn't there an application within Solidworks to simulate airflow? Or is that some other add on?

Powerstoked162 has a valid point. Shotgunning a pipe diameter and saying "That should be good." will only get you so far. It's tough to tell where inherent stagnant areas and turbulent areas might turn up. By my relatively untrained eye, you have a big turbulent area in the making at the end of the plenum which could negatively impact flow to the rear cylinders. Simply changing the length of plenum extending past the rear ports would have a big impact on this aspect, be it positive or negative.

There is plenty of head room to work with as far as manifold height goes. Clearance for turbos is the thing to keep in mind here IMO. With some creativity, the height of the intake elbow can be manipulated with a scratch fab deal like shown here.

An aspect I find very interesting about your approach is the ability to tune runner length and plenum volume. It's concievable that different runner lengths and plenum volumes could be made for different set up an hp goals. Lower RPM/power setups would likely benefit from a longer runner where the higher RPM/power setups would be less likely to need a longer runner. You just don't know until you start mapping cfms and airflow paths. With tall enough runners, a guy could simply run the harness under the manifold.

Please don't take my out loud thinking as naysaying. People putting thought and time into these aspects of our motors is very encouraging.

 

[wetnsloppy4x]

get rid of the fuel bowl oke:

Oh, and LOL

 

[Beast6.0]

One thing to consider, when playing with airflow simulation, is the firing order of the engine and how it effects the airflow in the intake. For example, say back by cylinders 6 and 8 (which happen to fire one after the other) when you're at higher rpms. I always figured the firing order was the reason the early intakes had the crossover in the rear, to help feed cylinder 8 equally at higher rpm. ( but that's just a guess on my part, because it made sense to me) Balanced flow, or as close as possible, to each runner is a main goal.

Plenum volume is definitely beneficial to boosted engines. It's like a bigger tank on you're air compressor. I've read this in muliple books by people far more educated on the subject than I am. I have also read that runner length is not as critical on turbo/supercharged engines as it is to n/a engines, due to the fact that our pressure will give us adequate velocity in most cases. I've seen some turbocharged intake designs that had the intake runner itself, start higher inside (right below the centerline of the overall plenum height) instead of off the floor of the plenum to take advantage of this less turbulent, more consistenly dense area as a way to gain equal flow to each runner. Just different things I've come across in intake designs and books about them that might be worth considering.

 

[6leakertweeker]

Please forgive my ignorance. Those drawings were done in Solidworks, correct? Isn't there an application within Solidworks to simulate airflow? Or is that some other add on?

No its not Solid works.

Powerstoked162 has a valid point. Shotgunning a pipe diameter and saying "That should be good." will only get you so far. It's tough to tell where inherent stagnant areas and turbulent areas might turn up. By my relatively untrained eye, you have a big turbulent area in the making at the end of the plenum which could negatively impact flow to the rear cylinders. Simply changing the length of plenum extending past the rear ports would have a big impact on this aspect, be it positive or negative.

I believe youre right in this aspect. Like I said earlier I'm not sure what the engine requires as far as volume and cfm so I just went with what seemed logical at the moment. Also at the rear of the manifold I also agree that areas needs work.

There is plenty of head room to work with as far as manifold height goes. Clearance for turbos is the thing to keep in mind here IMO. With some creativity, the height of the intake elbow can be manipulated with a scratch fab deal like shown here.

An aspect I find very interesting about your approach is the ability to tune runner length and plenum volume. It's concievable that different runner lengths and plenum volumes could be made for different set up an hp goals. Lower RPM/power setups would likely benefit from a longer runner where the higher RPM/power setups would be less likely to need a longer runner. You just don't know until you start mapping cfms and airflow paths. With tall enough runners, a guy could simply run the harness under the manifold.

I was basing my design office that theory exactly. The angles, sizes, length of all the tubes can be changed at any point.

Please don't take my out loud thinking as naysaying. People putting thought and time into these aspects of our motors is very encouraging.

I'm not mad at all. Responses like this is what i was looking for. If we keep brainstorming we should be able to find something that works. Isn't that this whole point of this website?

 

[6leakertweeker]

One thing to consider, when playing with airflow simulation, is the firing order of the engine and how it effects the airflow in the intake. For example, say back by cylinders 6 and 8 (which happen to fire one after the other) when you're at higher rpms. I always figured the firing order was the reason the early intakes had the crossover in the rear, to help feed cylinder 8 equally at higher rpm. ( but that's just a guess on my part, because it made sense to me) Balanced flow, or as close as possible, to each runner is a main goal.

Plenum volume is definitely beneficial to boosted engines. It's like a bigger tank on you're air compressor. I've read this in muliple books by people far more educated on the subject than I am. I have also read that runner length is not as critical on turbo/supercharged engines as it is to n/a engines, due to the fact that our pressure will give us adequate velocity in most cases. I've seen some turbocharged intake designs that had the intake runner itself, start higher inside (right below the centerline of the overall plenum height) instead of off the floor of the plenum to take advantage of this less turbulent, more consistenly dense area as a way to gain equal flow to each runner. Just different things I've come across in intake designs and books about them that might be worth considering.

I've wondered the same thing. Is that rear tube hollow? If it becomes a problem I'm sure we could just tap -15AN or bigger fitting into the rear of the manifold and run a line between them to balance it out.

I've kind of wondered that about the more volume concept. If you look at all of the high HP engines like Schieds is one I can think of, they have huge tubular intakes with small runners similar to my design. So, I think it may be beneficial to remeasure and see how big of tubing I can fit in there.

 

[Hotrodtractor]

You should know exactly what the engine requires for CFM. You know the displacement and your target RPM? You now know the target CFM.

 

[6leakertweeker]

You should know exactly what the engine requires for CFM. You know the displacement and your target RPM? You now know the target CFM.

OK so off the top off my head.

CI. =365
RPM =5000
VE = 85%

5000(365)=1,825,000
1,825,000/3,456=528.07
528.07(.85)=448CFM.

Sound about right?

 

[6leakertweeker]

OK so VE for our engines is actually 1.6. So that would get us to 844 cfm

 

[steedspeed]

OK here's my design. I think i might try to build one of these. Doesn't seem like it would be too hard. Only thing I can't do is cut the flanges but I have a buddy that can. Ill also have to have a flange cut for the intake horn, although brackets, ect ect. I want to make this a stock fitting replacement.

It needs some fine tuning but that's only like 45 mins worth of work.

My first thoughts are that you need bigger plenums. The cylinders at the far end are going to get more air than the first ones in line because the air hits a wall at the end increasing the air pressure there. Can you make a crossover to the other plenum to provide a cushion area? Also, with such a small plenum air velocity is going to be very fast blowing across the first set of inlets. What happens on an airbrush when fast moving air blows across the nozzle that feeds the paint?. What it does is it sucks on the pipe so the flow across the inlets will starve those cylinders by creating a vacuum. I'd say the first cylinders would be ok at lower roms and would start to starve at higher rpms. You would have to build it to find out I guess.

 

[6leakertweeker]

Man that's a really good point. Very logical in my mind. I was just speaking with my uncle on this (an ex engineer for Boeing, NASA, Loockeed Martin, Skunk works, and the Titan V project) and he brought up the issue of air resonance. Resonance could greatly increase or decrease the air velocity inside the intake so that would have to be taken into consideration as well.