Intake Manifold Design

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NyCowboy87

New member
Im getting ready to build a set of individual runner intakes for my p pumped 7.3, jsut curious to what others ideas were on design, runner length, and plenum size.
 
All that depends on what RPM you want it to work best at. Runners have a very narrow effective RPM range and the intercooler pipes are plenty for plenum space.
 
In my limited experience with different intake manifolds, the one thing that stands out is that with forced induction the intake manifold size and design seems to be a lot less critical then with forced induction.

I have seen on the dyno an intake manifold make a 25hp difference n/a, and the same manifold only be worth 5 hp once breathed on.
 
Tormentor said:
All that depends on what RPM you want it to work best at. Runners have a very narrow effective RPM range and the intercooler pipes are plenty for plenum space.
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Is this based on your vast tractor engine experience, or with <2L toy engines?

Can you post up any real info, or is this all opinion?
 
dvst8r said:
In my limited experience with different intake manifolds, the one thing that stands out is that with forced induction the intake manifold size and design seems to be a lot less critical then with naturally aspirated.

I have seen on the dyno an intake manifold make a 25hp difference n/a, and the same manifold only be worth 5 hp once breathed on.
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Fixed.
 
NyCowboy87 said:
Probably be runing around 4700-5k.
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1-1.5x displacement is something that's been stuck in my head for FI plenum. Larger typically means longer spool times.

dvst8r- were those gains on a head with reasonable port sizes or was it one of these choked up low-rpm diesel heads?
 
I figured design/size would have less of an impact on a forced induction engine than a n/a. I am kind of thinking about making them like the ones on Chris Watson's ss d-max engine. Ive also seen a set similiar on another p pumped 7.3.
 
joefarmer said:
1-1.5x displacement is something that's been stuck in my head for FI plenum. Larger typically means longer spool times.

dvst8r- were those gains on a head with reasonable port sizes or was it one of these choked up low-rpm diesel heads?
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408 LSx with some afr 230's iirc.
 
What's amazing to me is that some of the pro mod gasser cars must have many multiples of engine displacement when they have the turbos in the nose of the car and then run 3" or bigger pipe all the way back in the cabin to a big A/W IC, then all the way forward again. And some of these guys would be high 20ish psi (or more).

It just seems like a boatload of volume compared to what one would normally run across in a typical truck setup.
 
my guess is that having an intake plentum a certain size bigger than the cubes of your motor would help stay ontop of the charger at the end of a pass bc of the larger volume of compressed air. and it really doesnt take much more time to spool a larger volume intake on a dmax, at least not on the engine dyno.... however it does bark the charger significantly harder at the end of a pass
 
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nwpadmax said:
What's amazing to me is that some of the pro mod gasser cars must have many multiples of engine displacement when they have the turbos in the nose of the car and then run 3" or bigger pipe all the way back in the cabin to a big A/W IC, then all the way forward again. And some of these guys would be high 20ish psi (or more).

It just seems like a boatload of volume compared to what one would normally run across in a typical truck setup.
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Just to really throw a wrench in it, in a promod car it is almost exclusively 4" piping and they run low to mid 50's psi of boost.
 
duramaxsandwich said:
my guess is that having an intake plentum a certain size bigger than the cubes of your motor would help stay ontop of the charger at the end of a pass bc of the larger volume of compressed air. and it really doesnt take much more time to spool a larger volume intake on a dmax, at least not on the engine dyno.... however it does bark the charger significantly harder at the end of a pass
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I don't think it works quite like that - for air tools, yes, but an ICE...
 
What if you could build a manifold for truely individual runners, and machine the head likewise? Like just tie all the runners into the end of the 3" or 3.5" pipe instead of the side of it like a plenum? Wouldn't this promote the quickest spool by decreasing volume to fill?
 
Ghostman said:
What if you could build a manifold for truely individual runners, and machine the head likewise? Like just tie all the runners into the end of the 3" or 3.5" pipe instead of the side of it like a plenum? Wouldn't this promote the quickest spool by decreasing volume to fill?
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I feel that this, done right, would provide a more precise same amount of volume of air and pressure to each cylinder, this is an uneducated assumption though...
 
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