I don't know what injectors are you guys using on your engines but I only use these. Bosch EV1 with 4 hole. The spray pattern is not a "pencil" like the regular Fiero injectors everyone uses. These newer injectors spray like a "fan". With that said, The injector's height is strategically mounted to spray right around the intake valve, not on the stem or the intake walls but exactly in the perimeter of the intake valve.
This is actually why I raised the concern, the wider pattern seems like it will put more fuel on the walls of the plenum - specifically on the long wall closest to an injector nozzle.
How much runner length did you end up with? My guess is 3" or less.
This is actually why I raised the concern, the wider pattern seems like it will put more fuel on the walls of the plenum - specifically on the long wall closest to an injector nozzle.
How much runner length did you end up with? My guess is 3" or less.
I placed the injectors high enough to umbrella the diameter of the intake valve. The reminder fuel if any, will puddle on top of the valve to make up for the laggy throtle response. I can model this on the MegaSquirt but I can do it much easier and faster mechanically.
I didn't just came up with this intake. I've been working on this for this for 2 years.
This is how the Supernatural concept was born. Here I found some old videos with the old 2.8L ! I forgot about these!! But anyways, you can even hear the sound in engine frequencies diferenciate from stock. That's when I trusted my gut to stay with the iron heads.
Originally posted by Will: I note that he didn't show the runner entries inside the plenum... for this to work, those have to be carefully radiused and sculpted. They'll also be quite short, but probably not unreasonably short.
You know that stock injector bong tha takes 1/4 of the intake's entry diagonal? Well, in this manifold it is gone.
I didn't think you'd built that box and put it on top of a stock lower....
I know, I just don't have the luxury (money) to do otherwise! I have to spend every penny wisely. This is one man operation relying on side jobs to make my toy make some po'er!. If I had the means of Fishsticks, one blows up and order another one type deal; would be a different story!
[This message has been edited by La fiera (edited 06-09-2021).]
I know, I just don't have the luxury (money) to do otherwise! I have to spend every penny wisely. This is one man operation relying on side jobs to make my toy make some po'er!. If I had the means of Fishsticks, one blows up and order another one type deal; would be a different story!
Don't let my amibitions fool you. I ain't rich, just motivated. It's been a fire sale here at my place as I sell/trade stuff I don't need. Sold the Vortec heads and all the extra stuff off the new longblock I got. Even sold the cracked 327 block to a guy who wants the rotating assembly.
I still think you're gonna have fuel beading issues on those smooth plenum walls.
[This message has been edited by fishsticks (edited 06-10-2021).]
You know that stock injector bong tha takes 1/4 of the intake's entry diagonal? Well, in this manifold it is gone.
That's what I like about the Falconer lower intake... no injector bungs. Also, there's no cold-start or idle air passages. So the intake ports can be bigger.
It also has a big port on the end, for crankcase vacuum. That's what the blue fitting is for.
I agree you're fine in the runner and with injector positioning. I'm worried air rushing into the plenum is going to (partially) disrupt the spray pattern from the injectors since they're so high up and put fuel on the plenum walls.
I have made the world's worst diagram illustrating what I suspect will happen. I apologize in advance for it.
Basically, incoming air is going to ignore the radiused part of the plenum below the TB and head straight for the back wall. You see a similar effect in cylinder head ports, which is why a lot of shaping is done to the ceiling, and sometimes the floor is raised.
I think that airflow is going to push fuel to that back wall, and possibly the other walls of the plenum.
Do I think your design is somehow critically flawed and doomed to failure? Not at all. In fact, I could be flat out wrong. If it were my intake, I'd stick the nozzle of a sand blaster inside there and give the plenum walls a little texture just in case. That's all I'm saying.
Your first manifold appears to have the injectors in the runners still, so I don't see this issue coming up.
Over all, I think you may run into a scenario where the front cylinders run rich and the rear cylinders run lean, and you may have to play with injector timing to compensate. You've given up the individual cylinder tuning of port injection in exchange for charge cooling like a carb or TBI would have.
[This message has been edited by fishsticks (edited 06-11-2021).]
I'm worried air rushing into the plenum is going to (partially) disrupt the spray pattern from the injectors since they're so high up and put fuel on the plenum walls. You see a similar effect in cylinder head ports, which is why a lot of shaping is done to the ceiling, and sometimes the floor is raised.
I think that airflow is going to push fuel to that back wall, and possibly the other walls of the plenum.
That will not happen, this intake is designed to "STALL" incoming airflow speed to maximise pressure and eliminate turbulance inside the plenun so the fuel goes were it is design to go. It is plain physics. I've been modeling this approach for a couple or years now. Same story with the intake I use now, I started that back in 2014.
Rei has a good point. The air isn't going to fly straight back and bounce off the back wall, like a ping-pong ball. That's not how aerodynamics works. The top part of the plenum will act like a diverging nozzle, and the bottom part will act like a converging nozzle. The middle of the 90-degree bend is where airflow will be the slowest. There might be a dead spot, up in the corner. But I don't think that will push the fuel spray around.
That will not happen, this intake is designed to "STALL" incoming airflow speed to maximise pressure and eliminate turbulance inside the plenun so the fuel goes were it is design to go. It is plain physics. I've been modeling this approach for a couple or years now. Same story with the intake I use now, I started that back in 2014.
We will agree to disagree then. There's little about a box with sharp corners that's going to do much to shape airflow, and your throttle body opening is too large to cause that plenum to be much of an expansion chamber. Where does this massive charge deceleration happen, especially at significant RPM and high air velocity? "Plain physics" says you'll have a low pressure area that air is going to try to fill as quickly as possible, and also that air likes to travel in a straight path.
quote
Originally posted by Blacktree:
Rei has a good point. The air isn't going to fly straight back and bounce off the back wall, like a ping-pong ball. That's not how aerodynamics works. The top part of the plenum will act like a diverging nozzle, and the bottom part will act like a converging nozzle. The middle of the 90-degree bend is where airflow will be the slowest. There might be a dead spot, up in the corner. But I don't think that will push the fuel spray around.
You are taking a diagram which I warned was bad (with exaggerations drawn in) literally.
I'm kinda over this, so let me bring one last point up and I'll be on my way.
OEMs, even in performance motors, have been moving point of fuel entry closer and closer to the combustion chamber for decades, to the point that GDI is commonplace now. There are reasons for that - charge precision and detonation resistance among them. F1 cars are on the wagon, so this isn't entirely a CAFE driven move.
What Rei's done is the opposite of that, and he's going to experience situations that were rendered moot by port injection and GDI. But hey, maybe he's found some secret sauce in "plain physics" that everyone else missed.
I HOPE that I'm wrong and he makes 500whp on this thing, but I suspect I'm not.
Originally posted by fishsticks: Basically, incoming air is going to ignore the radiused part of the plenum below the TB and head straight for the back wall.
So, if that's the case airplanes would not fly! Instead of me drawing what my intake concept is designed to do lets allow a physics simulator to do it. Velocity and pressures are for reference only but regardless of the values the result is the same, velocity goes up and pressure will drop and vice versa. And by varying the shape and volume in the plenum you can achieve either result.
Incoming velocity= 43.1ft/s @ 8.9psi hi velocity and low pressure Plenum velocity= 4.6ft/s @ 18.87psi low velocity and high pressure.
That's a 89% velocity decrease and 100+% pressure increase. If an airplane gets this percentages changes on its wings in mid air it would cause the plane to stall and fall to the ground. That's what this intake is designed to do.
Pay attention how the black dots follow the contour or the radius below the "TB".
So, if that's the case airplanes would not fly! Instead of me drawing what my intake concept is designed to do lets allow a physics simulator to do it. Velocity and pressures are for reference only but regardless of the values the result is the same, velocity goes up and pressure will drop and vice versa. And by varying the shape and volume in the plenum you can achieve either result.
Incoming velocity= 43.1ft/s @ 8.9psi hi velocity and low pressure Plenum velocity= 4.6ft/s @ 18.87psi low velocity and high pressure.
That's a 89% velocity decrease and 100+% pressure increase. If an airplane gets this percentages changes on its wings in mid air it would cause the plane to stall and fall to the ground. That's what this intake is designed to do.
Pay attention how the black dots follow the contour or the radius below the "TB".
I get what you're saying, I don't believe laminar flow over an airfoil (wing) is the best example. All else the same, the same quantity of air would need to flow faster through a smaller throttle body than with a larger throttle body to maintain equilibrium for the same engine output, or to maintain the same flow rate on the backside of a smaller throttle body, the media would have to move at a higher velocity, than with a larger.
Likewise, a larger plenum has more reserve, so the pressure drop as cylinders pull air in from it, will not occur with as much velocity through the throttle body as it would with a smaller plenum, basically, you're less likely to feel one cubic foot of air being sucked out of the back door of a house, while standing in the front door way, than you would while standing in the doorway of a small room as it's being sucked out of a window. So yeah, I can see how inlet air on a plenum that size will not likely affect the fuel injection stream.
Let’s also not forget that it is not pressurized air entering the throttle body but a vacuum formed at the mouth of each runner, that alone will encourage the air to bend around the short radius of the intake. As demand increases at higher rpms there will of course be some momentum that the air will have that will send air at the rear wall of the plenum, but I don’t think it will be drastic due to the large plenum volume relative to the size of the intake ports. There will be some vortices that form at the dead spot in the corner that could disrupt the spray pattern, but with each runner demanding air and fuel it should help guide the injector spray where it is trying to go. At the same time I don’t think the suggestion of texturing the walls is a bad idea as regardless of plenum shape, spraying fuel near shiny surfaces will probably result in some puddling of fuel. I just want to hear this thing on the dyno.
Originally posted by fishsticks: OEMs, even in performance motors, have been moving point of fuel entry closer and closer to the combustion chamber for decades, to the point that GDI is commonplace now. There are reasons for that - charge precision and detonation resistance among them. F1 cars are on the wagon, so this isn't entirely a CAFE driven move.
OEMs, yes. Not so in motorsport. High RPM race engines with a throttle per cylinder have been using shower injectors ABOVE the throttle plates for a long time. This was every F1 engine before the new turbo era. Also race bikes as well. DI works better with forced induction, which is why F1 cars have DI in the new turbo era.
That's what I like about the Falconer lower intake... no injector bungs. Also, there's no cold-start or idle air passages. So the intake ports can be bigger.
It also has a big port on the end, for crankcase vacuum. That's what the blue fitting is for.
I had to go look at my stock lower to see the injector bongs indeed taking up a chunk of vertical space. So in the much different Falconer intake it must have a different Middle and different Upper as well?
It may be worth keeping in mind engines like that don't need to idle well or pass emissions or be terribly reliable or be tractable at low speeds. None of these are obstacles to pursuing your vision, I just think it's important to remember that things that work well on race cars don't always translate to street cars. I've got a friend who's a well-known E30 M3 enthusiast and he'll be happy to tell you why his personal '88 M3 is mostly as it came from the factory and not similar to the DTM cars. 9000rpm is intoxicating but 2000rpm is pretty important for getting to work.
I would probably be looking more towards things like ITRs than AR DTMs.
[This message has been edited by thesameguy (edited 06-24-2021).]
It may be worth keeping in mind engines like that don't need to idle well or pass emissions or be terribly reliable or be tractable at low speeds. None of these are obstacles to pursuing your vision, I just think it's important to remember that things that work well on race cars don't always translate to street cars. I've got a friend who's a well-known E30 M3 enthusiast and he'll be happy to tell you why his personal '88 M3 is mostly as it came from the factory and not similar to the DTM cars. 9000rpm is intoxicating but 2000rpm is pretty important for getting to work.
I would probably be looking more towards things like ITRs than AR DTMs.
Absolutely! That's why my Fiero is a dedicated race car, not a daily driver.
Rotating assembly is finally balanced! Due to the lightweight of the pistons, rings and rods the crankshaft had to be lightened 40g! Next, the heads. The porting part is done, just waiting to finish the fitting of the new valves!
Either this will sound glorious or you'll launch a piston to the moon. Both outcomes should be considered a success.
Thanks Random!! The piston to the moon will be very unlikely, I've been doing the math for over a year before making any parts. As far as the glorious sound, I can't wait to hear it because it's never been done!
Some progress. Got the block and front cover ready for the upcoming mods. I'm deleting the old cooling pipes and replacing all the rubber hoses to -20 AN lightweight hose.
[This message has been edited by La fiera (edited 11-20-2021).]
Some progress. Got the block and front cover ready for the upcoming mods. I'm deleting the old cooling pipes and replacing all the rubber hoses to -20 AN lightweight hose.
Glad you are still working on this project. Are your new pistons standard bore or oversized?
That front cover doesn't look familiar. What engine is it from? I really like the clean look.
It's off the 3400 roller block. Since I don't use the mechanical water pump I wanted to clean the front of the engine and reduce clutter in the engine bay. I may have to put a bleeder on top of it once I modify the intake manifold with a -20AN fitting on the thermostat hole.
[This message has been edited by La fiera (edited 11-23-2021).]
for this to work, those have to be carefully radiused and sculpted. They'll also be quite short, but probably not unreasonably short.
It's been a fire sale here at my place as I sell/trade stuff I don't need. Sold the Vortec heads and all the extra stuff off the new longblock I got. Even sold the cracked 327 block to a guy who wants the rotating assembly. 
So, if that's the case airplanes would not fly!
