10:30 I think what you are seeing in your slam air experiment is the slammed air is making an inertial wall and splitting the chamber into two separate circulation chambers. You have a conservation of mass/energy equilibrium here: (11.6 + 7.5)/2=9.55 I’m just guessing off the cuff here, but I suspect if you were to vary the rpm of the intake air (shop vac) from 0 -> 100 % you would see the ratio of the speed of the air from the left and center ports go from favoring the center port at low rpm to favoring the left port at higher flow rates. Just a guess tho.
I’ve wondered about that, if it would be better or worse with more or less air. I may need to play with that. On my other video I used a leaf blower because of blowing through the entire manifold and it seemed to be consistent with these results. Thanks!
Now that it's winter and cold, I will have some time for flow testing 😅 It would be awesome to have access to a dyno to test several different designs / ideas!
@@modeverything1 no rush! But I am very curious how it compares to others. Maybe someday we’ll have the means to do more back to back dyno testing of these types of things.
Couple of comments: The DeLorean V6 is a 90 degree odd-fire design. And tuned runner lengths work for naturally aspirated engines to boost torque where the resonance reflection arrives back at the intake valve just as it opens thus giving the charge a little help getting going. Boosted engine don't care so much about intake design because of Pascal's Principle which states that all surfaces within the manifold will be at equal pressure....so each cylinder will get the same amount of air unless something obstructs the flow such as you did by blowing air right across the tube which creates a siphoning effect due to the Venturi principal. Inject the incoming air as far away from the inlet openings and the rest of the design doesn't matter very much when under boost. Same goes for exhaust manifolds where NA the tube length matters if you're trying to maximize a certain RPM range, but with turbo's a simple log works pretty much as well because it's pressurized and again Pascal comes into play. People make beautiful 'nest-O-snake' manifolds for turbo cars that look great but really offer little advantage to a simple log as long as that log is of sufficient volume to not impede flow. The big takeaway is that flow happens because you have a pressure differential. Cylinders filling lowers the pressure within the manifold and atmospheric air rushes in to equalize the pressure so best attempts should be made to give all inlets equal access to the incoming air within an adequate volume plenum. Torque can be gained by proper length inlet tracts and more important for Helmholtz resonance is the VOLUME of the plenum. The runners can be tailored to boost a certain RPM while the box volume to resonate at another RPM. This is done on many motorcycle engines where the stacks are tuned for high RPM filling and the box resonance for cruise conditions. It depends on how wide of a RPM range the engine must operate within whether you can use this effectively or not. My SVT Focus engine has a 'Dual-Stage' intake where long tubes for good torque get rotated and pulled out of the short stacks that flow better for high RPM power. Long tubes are great for torque but get restrictive at high RPM. For runners to work well they need to be small enough to create velocity which is what fills the cylinders past BDC...but too small will be restrictive and too big won't generate enough velocity to help. Of course that's NA only and under boost...pretty much only the boost matters making the manifold much less important. Were I you...I'd try making the runners short enough to feed the motor at high RPM and tailor the plenum volume to resonate where you plan to cruise...best of both worlds. Good on you for experimenting and trying to learn!!
There is a "common" acceptance that boost also lengthens runner length. For example another atmosphere of boost doubles the effective runner length. I am intrigued about this slam air theory. I am planning a new intake manifold for my car and a slam air style would be easier to build instead of a lysholm plenum type.
Have you seen/ tested the 3500 upper intake on the equinox. The throttle body is on the passenger side on the intake. I always thought would be great for a turbo. Opposite side of all the heat
Yes, I’ve seen the one you mean. And I’ve seen it used on a boosted engine as well. I’d like to do a comparison of that vs the standard 3400 and 3500 plenum. Thanks!
I’ve considered a “reverse header” style runners from a throttle body to the two plenums, running the feed pipes between the plenum runners. Maybe for a future project. Thanks!
I'm getting into the weeds a little bit trying to improve the intake for my turbo 3800. currently using the f-body intake which I highly suspect is leaning out the back cylinders under high flow conditions as you described. no easy options to fix that but since you're fabbing intakes, have you looked into doing like a lehmann setup? I was thinking it could be done in a simple way if you make a typical mailbox plenum and just have the throttle body go at the end like normal but have it feed an inside tube that runs all the way to the other end and has a slot opening pointing up away from the runners. There's some math to getting the slot dimensioned right but it seems pretty doable.
@@codithheretic110 had to google a picture of the RWD 3.8 intake because I’ve never seen one in person. Many FWD 3.8s though. It’s definitely a straight shot from the TB into the plenum which makes it not so great unfortunately. I’ve seen some people on TH-cam building manifolds with a “cone” under the plenum with a slot along the length pushing air up into the plenum. This sounds similar to what you’re describing I think. Not sure, but it seems like it might be a better idea than the stock version. Thanks!
@@JohnBoyBuilds I’ll keep that in mind! I’ve been watching some of the 4200 builds out there. I’ve wondered about that engine years ago because of the inline 6 cylinder characteristics. Thanks!
I've been surprised to see several supercharged applications also using a tunnel ram. Without really getting into the science.The tunnel ram seems unnecessary when you have boost. What's the real answer on this?
Hard to say without testing it vs others on an engine dyno. But if you check out some of Richard Holdener’s dyno videos, his general approach is boost will just increase whatever it’s doing when naturally aspirated. Thanks for watching!
Have you tried a collector style? Like a set of headers would be only on intake. I realize it would be difficult to get under the hood but just curious on how it would flow comparatively.
@@justinjenkins4337 GM actually used that style on some of the Quad 4 engines many years ago. I’ve never tried it but I’ve wondered about using that style to have multiple tubes feeding the “slam air” into a plenum for more evenly distributed air.
ill look into that. Dont rememberif it was mentioned but, what works good in a boostedapplication may not work well in a n/a application. @xlr8ing_zgarage
I really like the video. Appreciate all the work you put into showing this!
Appreciate it! Thanks!!
Nice, lots of interesting stuff here.
10:30 I think what you are seeing in your slam air experiment is the slammed air is making an inertial wall and splitting the chamber into two separate circulation chambers. You have a conservation of mass/energy equilibrium here: (11.6 + 7.5)/2=9.55
I’m just guessing off the cuff here, but I suspect if you were to vary the rpm of the intake air (shop vac) from 0 -> 100 % you would see the ratio of the speed of the air from the left and center ports go from favoring the center port at low rpm to favoring the left port at higher flow rates. Just a guess tho.
I’ve wondered about that, if it would be better or worse with more or less air. I may need to play with that.
On my other video I used a leaf blower because of blowing through the entire manifold and it seemed to be consistent with these results.
Thanks!
Wonder if varying lengths inside of plenum with end mount throttle body could tune them to be same.
Now that it's winter and cold, I will have some time for flow testing 😅
It would be awesome to have access to a dyno to test several different designs / ideas!
@@modeverything1 no rush! But I am very curious how it compares to others.
Maybe someday we’ll have the means to do more back to back dyno testing of these types of things.
Great video. Love the office reference without even having to say it lol. But truly a great visual aid for us simple peasant type folk! Well done sir
@@danscustomprojects4486 thank you for all your help in building these things over the years!!
And FYI there will be more!!
Couple of comments: The DeLorean V6 is a 90 degree odd-fire design. And tuned runner lengths work for naturally aspirated engines to boost torque where the resonance reflection arrives back at the intake valve just as it opens thus giving the charge a little help getting going. Boosted engine don't care so much about intake design because of Pascal's Principle which states that all surfaces within the manifold will be at equal pressure....so each cylinder will get the same amount of air unless something obstructs the flow such as you did by blowing air right across the tube which creates a siphoning effect due to the Venturi principal. Inject the incoming air as far away from the inlet openings and the rest of the design doesn't matter very much when under boost.
Same goes for exhaust manifolds where NA the tube length matters if you're trying to maximize a certain RPM range, but with turbo's a simple log works pretty much as well because it's pressurized and again Pascal comes into play. People make beautiful 'nest-O-snake' manifolds for turbo cars that look great but really offer little advantage to a simple log as long as that log is of sufficient volume to not impede flow.
The big takeaway is that flow happens because you have a pressure differential. Cylinders filling lowers the pressure within the manifold and atmospheric air rushes in to equalize the pressure so best attempts should be made to give all inlets equal access to the incoming air within an adequate volume plenum. Torque can be gained by proper length inlet tracts and more important for Helmholtz resonance is the VOLUME of the plenum. The runners can be tailored to boost a certain RPM while the box volume to resonate at another RPM. This is done on many motorcycle engines where the stacks are tuned for high RPM filling and the box resonance for cruise conditions. It depends on how wide of a RPM range the engine must operate within whether you can use this effectively or not. My SVT Focus engine has a 'Dual-Stage' intake where long tubes for good torque get rotated and pulled out of the short stacks that flow better for high RPM power. Long tubes are great for torque but get restrictive at high RPM.
For runners to work well they need to be small enough to create velocity which is what fills the cylinders past BDC...but too small will be restrictive and too big won't generate enough velocity to help. Of course that's NA only and under boost...pretty much only the boost matters making the manifold much less important. Were I you...I'd try making the runners short enough to feed the motor at high RPM and tailor the plenum volume to resonate where you plan to cruise...best of both worlds. Good on you for experimenting and trying to learn!!
Thank you for your insight!
I knew the DeLorean was a 90° odd fire. I just wanted to show it because of the dual plenum.
Thanks!
All engines are boosted. Some just more. Atmospheric pressure is pressure when the cylinder is empty.
There is a "common" acceptance that boost also lengthens runner length. For example another atmosphere of boost doubles the effective runner length. I am intrigued about this slam air theory. I am planning a new intake manifold for my car and a slam air style would be easier to build instead of a lysholm plenum type.
Have you seen/ tested the 3500 upper intake on the equinox. The throttle body is on the passenger side on the intake. I always thought would be great for a turbo. Opposite side of all the heat
Yes, I’ve seen the one you mean. And I’ve seen it used on a boosted engine as well. I’d like to do a comparison of that vs the standard 3400 and 3500 plenum. Thanks!
Good stuff! What about 2 tubes from the central plenum into each outer plenum instead of one big one each?
I’ve considered a “reverse header” style runners from a throttle body to the two plenums, running the feed pipes between the plenum runners. Maybe for a future project. Thanks!
I'm getting into the weeds a little bit trying to improve the intake for my turbo 3800. currently using the f-body intake which I highly suspect is leaning out the back cylinders under high flow conditions as you described. no easy options to fix that but since you're fabbing intakes, have you looked into doing like a lehmann setup? I was thinking it could be done in a simple way if you make a typical mailbox plenum and just have the throttle body go at the end like normal but have it feed an inside tube that runs all the way to the other end and has a slot opening pointing up away from the runners. There's some math to getting the slot dimensioned right but it seems pretty doable.
@@codithheretic110 had to google a picture of the RWD 3.8 intake because I’ve never seen one in person. Many FWD 3.8s though.
It’s definitely a straight shot from the TB into the plenum which makes it not so great unfortunately.
I’ve seen some people on TH-cam building manifolds with a “cone” under the plenum with a slot along the length pushing air up into the plenum. This sounds similar to what you’re describing I think.
Not sure, but it seems like it might be a better idea than the stock version.
Thanks!
Next project please consider trying to do a cheap turbo vortec 4200 catfish camaro
@@JohnBoyBuilds I’ll keep that in mind! I’ve been watching some of the 4200 builds out there. I’ve wondered about that engine years ago because of the inline 6 cylinder characteristics.
Thanks!
I've been surprised to see several supercharged applications also using a tunnel ram. Without really getting into the science.The tunnel ram seems unnecessary when you have boost. What's the real answer on this?
Hard to say without testing it vs others on an engine dyno.
But if you check out some of Richard Holdener’s dyno videos, his general approach is boost will just increase whatever it’s doing when naturally aspirated. Thanks for watching!
Have you tried a collector style? Like a set of headers would be only on intake. I realize it would be difficult to get under the hood but just curious on how it would flow comparatively.
@@justinjenkins4337 GM actually used that style on some of the Quad 4 engines many years ago.
I’ve never tried it but I’ve wondered about using that style to have multiple tubes feeding the “slam air” into a plenum for more evenly distributed air.
ill look into that. Dont rememberif it was mentioned but, what works good in a boostedapplication may not work well in a n/a application. @xlr8ing_zgarage
Ford used that style on many cars in the late 80s , early 90s.
I would go with a duel plenum like a nissan gtr.
Now you tell me.😢 It's it's too late to save me.Just save yourself. Get out while you can. 😊