well i work for a place that builds hydraulic filters/housings and they use it to model there housings and i was talking with the engineer one day and he handed it to me. I havent even started playing around with itmuch installed it and opened it to make sure it worked i was told that if i know my way around a cad program i can figure it out. So I came to ask questions about stuff so i would have a baseline to start from.
intake mani fabrication
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MikeBergy
Blah blah blah....
Basically, it's all about the transitions in an intake manifold, as well as the piping size. The transitions are going to allow for the smoothest airflow, and the runner cross-sectional areas are going to allow for a certain air velocity. You basically want to size your runners for your airflow requirement at your top end. This amount may give you some weird peformance at lower engine speeds due to the lower kinetic energy of the flow going into the cylinders on the intake stroke. The momentum of the air actually continues to force air into the cylinder after bdc, and lowering the velocity of the air in the runners will decrease the air's momentum, and less air will be forced into the chamber. This btw is only really applicable to NA applications, as a turbo app would force air into the chamber regardless. You just need to decide where you think your max mass flow is going to occur, probably somewhere in the 7000 rpm area, and size your runners based on a calculated flowrate at that engine speed (you won't get exact, but then again, engine design is a LOT of testing to go with design, where your fluent would come in: in order to model it accurately though, you'd need to model a simple engine design, probably more than you are willing to do - parametrics will own you.).
The larger the plenum, the more even the flow will be likely to be across each runner. You can see this on a lot of custom manifold designs.
Just round the edges of the transitions, and you should be good to go. Do some screen shots of the fluent when you do it btw. I'll hopefully be doing a fluent model of my uav next month. Keeping fingers crossed.
Good Luck on the design, let us know how it turns out.
The larger the plenum, the more even the flow will be likely to be across each runner. You can see this on a lot of custom manifold designs.
Just round the edges of the transitions, and you should be good to go. Do some screen shots of the fluent when you do it btw. I'll hopefully be doing a fluent model of my uav next month. Keeping fingers crossed.
Good Luck on the design, let us know how it turns out.
ok well so far this is what i have made velocity stacks that do from 5"id to 3/4"id in a real smooth radius they are about like 3.870long so you can imagine the smoothness of the radius.i plan on cuting them to down to the correct id latter by just shortening the length. my plas to start with are a 4.5 box with a .125 wall so it will be 4.250 on the inside and it will be 17" long as of right now im going to star playing with runers that are 1.625id and probaly about 3" long because the velocity stack will be so long. that is just a start
mike, not to discount anything you said, but not being applicable to FI, is wrong. fluid flow will still be similar if not identical, and signifigant gains can be had on FI with a properly designed manifold. the air still flows in a fluid like maner, its just under more pressure and hense more dense. the velocities and such will be nearly the same, just different fluid density.
5" velocity stacks? at the opening? thats freaking HUGE. how do you fit the stacks next to each other?
5" velocity stacks? at the opening? thats freaking HUGE. how do you fit the stacks next to each other?
97Hatch - I'm currently mocking up everything to do essentially the same thing that you are. Except that I'm chopping up an existing manifold (PM6 manifold) and turning the main cylinder part of the IM 90 degrees so that the stacks line up.
I have a few questions for either those who are knowledgeable or those who have experience with different manifolds (sorry to thread jack)
Should the stacks be shorter or longer? I look at different models, the Skunk2 is long, where as the Edelbrock has short stacks. So I'm kind of at a loss as to what I should do, short, long, or medium stacks? what have you found, if any 97Hatch?
I'm with you on this one 97Hatch, why bother buying something, when you can try and build it yourself, and maybe, just maybe build something better than most companies can just by pure fluke... Kind of like what my dad does building my shifter kart motors and having his design copied from the factory and the motors come stock with what he's done.
I have a few questions for either those who are knowledgeable or those who have experience with different manifolds (sorry to thread jack)
Should the stacks be shorter or longer? I look at different models, the Skunk2 is long, where as the Edelbrock has short stacks. So I'm kind of at a loss as to what I should do, short, long, or medium stacks? what have you found, if any 97Hatch?
I'm with you on this one 97Hatch, why bother buying something, when you can try and build it yourself, and maybe, just maybe build something better than most companies can just by pure fluke... Kind of like what my dad does building my shifter kart motors and having his design copied from the factory and the motors come stock with what he's done.
MikeBergy
Blah blah blah....
I wasn't saying gains wouldn't be made on a turbo application using a better designed IM, I just was making the point that on turbo apps, momentum of the air flow has much less of an impact on the manifold's ability to stuff air into the chambers as with NA apps. Typically, if you make the runners big enough on a turbo app, the turbo is going to stuff air into the chambers regardless.
Citizen_Insane
Senior Member
short runners will be better for high volume flow at high RPM and longer runners will be better for low end torque. Now, I'm sure both "short" and "long" have acceptable limits that I'm not going to delve into that b/c I don't know what they would be for an engine as large as 1600 CC +. All the manifold design stuff I've learned about is for 600CC motors.
Also realize that side feed isn't the only kind of manifold you could build. If you wanted to get wild, you could build a manifold that had the intake tube comming off the center of the plenum for better distribution of air to the cylinders. As it stand right now the cylinder on the far drivers side (is it 4 or 1?) gets robbed of air b/c there is more space for turbulence to build up between the filter and the runner. Just something to think about.
Also realize that side feed isn't the only kind of manifold you could build. If you wanted to get wild, you could build a manifold that had the intake tube comming off the center of the plenum for better distribution of air to the cylinders. As it stand right now the cylinder on the far drivers side (is it 4 or 1?) gets robbed of air b/c there is more space for turbulence to build up between the filter and the runner. Just something to think about.
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