i dont believe length would matter, as fuel is not compressable, it acts as a "solid", similar to brake fluid. Length doesnt matter, you still get the same volume into your medium at the end of the line
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i dont believe length would matter, as fuel is not compressable, it acts as a "solid", similar to brake fluid. Length doesnt matter, you still get the same volume into your medium at the end of the line
the length of the lines does not matter, but all lines must be the same length.
or it will be hell on your timing.
I still fail to see why the length matters. the line is full of fuel, acting as a solid. if you have a 1 foot pipe or a 6 foot pipe. you push one end in 5", the other end will move out 5" as well, regardless of the total pipe length.
If it was a compressable medium, then yes length would matter.
i might be totally wrong here..
If it was a compressable medium, then yes length would matter.
i might be totally wrong here..
Greg, it has to do with the expansion of the metal when the liquid inside is compressed to 2000 psi. The metal swells out just a little bit. This swelling has to be equal on all the lines or the timing for each cylinder will be off a few degrees.
And, although diesel is not technically compressible, when put under 2000 psi, these actually is a very tiny amount that it compresses. I found a formula online once, but can't seem to find it now.
And, although diesel is not technically compressible, when put under 2000 psi, these actually is a very tiny amount that it compresses. I found a formula online once, but can't seem to find it now.
right, were not in a perfect world here with perfectly rigid materials. With .5 a degree effecting these engines, the metal expansion over X distance would be significant. Ok pay no mind to my earlier post, carry on!
Blind Driver2
Full Access Member
And all diesel fuel has a little air in it.
Problem area here... port velocities will be different from front to back of your "spiders" before connecting up front. Equal length runners (IE, equal flow) are desired...
Plenty of modern cars use a system like you describe (dodge V-10 comes to mind, 92-02) but they use fancy computer modeling to ensure equal flow. Here's a cutaway of a highly engineered manifold for a 4 cyl...
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Does it matter much at full boost? Not likely... but at cruise you'd be very inefficient.
G. Mann
Full Access Member
THere you go.. some of the Bernoulli principle of fluid dynamics in action.. you can bet the boys with the big paychecks and big degrees pencil all of it out before hand..
V-10 gas engine is likely more sensitive than diesel IDI.. however.. every detail overlooked means less available energy to transfer.. Thus my original suggestion that the 30 yr old turbo designs with the "intake snail" and all the other compromises that were made then can be improved on to take more HP and energy out of the same IDI..
I like where you are headed with this line of thinking.. run with it.. please..
V-10 gas engine is likely more sensitive than diesel IDI.. however.. every detail overlooked means less available energy to transfer.. Thus my original suggestion that the 30 yr old turbo designs with the "intake snail" and all the other compromises that were made then can be improved on to take more HP and energy out of the same IDI..
I like where you are headed with this line of thinking.. run with it.. please..
Modeling that stuff is beyond the software I have...
(small) runners, high velocities, and clean flow are needed for bottom end grunt. Someone would have to flow test the factory intake to see how each port flows and go from there
(small) runners, high velocities, and clean flow are needed for bottom end grunt. Someone would have to flow test the factory intake to see how each port flows and go from there
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BD, you mean long runners are needed for low end torque right?
Longer lenght, smaller diameter to keep the velocity up.
Variable volume runners/plenums on cars usually switch to the longer runner intake at low speed conditions
Longer lenght, smaller diameter to keep the velocity up.
Variable volume runners/plenums on cars usually switch to the longer runner intake at low speed conditions
Pretty sure (small) runners for low RPM work... Note the very tall, long runner carb intakes on most drag vehicles. The longer their runners, the higher their optimal RPM band. (not quite right... it's a function of runner length AND volume with harmonics!)
Modern EFI vehicles are hard to directly compare... Some split port, dual butterfly, variable volume etc may use a smaller, longer runner to keep up velocity. Some shut off half the intake stream to drive up velocity for low rpm efficiency... Different ways of achieving the same goals.
Same theory applies with NA gasser exhaust... Short runners keep up desirable back pressure and bottom end grunt, long tubes for high rpm work. (correct for Ford 5.0s)
The modeling pics were just to give a glimpse at the aerodynamic complexity of a good intake. I choose to liken our IDI intakes to carburetor intakes... It's basically the same casting and technology, and lacks the large plenum fed by a throttle body on EFI cars.
Modern EFI vehicles are hard to directly compare... Some split port, dual butterfly, variable volume etc may use a smaller, longer runner to keep up velocity. Some shut off half the intake stream to drive up velocity for low rpm efficiency... Different ways of achieving the same goals.
Same theory applies with NA gasser exhaust... Short runners keep up desirable back pressure and bottom end grunt, long tubes for high rpm work. (correct for Ford 5.0s)
The modeling pics were just to give a glimpse at the aerodynamic complexity of a good intake. I choose to liken our IDI intakes to carburetor intakes... It's basically the same casting and technology, and lacks the large plenum fed by a throttle body on EFI cars.
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long runners are for low rpm power, you are trying to get a tuned resonance inside of them, as well as mainting velocity. Look at an LS engine, notice trucks have very long, wrapped around runner,s while the vettes have short, almsot half the length of the runnerds. Hi rpm power for a trad eoff in low rpm torque. With a short runner you can open it up wider ot get more volume, minimizing flow resistance, at a trade off to slower mass velocity at low engine rpm-resulting in less total air mass flowing into the cylinder head, hence-less torque with short runners at low rpm
i dont like popcorn.
The more I read up on this the more that opinions vary... and some of my stuff IS wrong.
I'll caveat my previous stuff with this: Drag racing, carb'd motors with long, large runners are aimed at a higher RPM band for peak performance.
I'll caveat my previous stuff with this: Drag racing, carb'd motors with long, large runners are aimed at a higher RPM band for peak performance.
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I bet they are using a tuned length to get a secondary or even tertiary sound wave at 8-9k rpm or so.
im going by my internal combustion engineering books on this one, internet is definitely great, but anyone can write something that appears to be legit, but could be totally wrong!
im going by my internal combustion engineering books on this one, internet is definitely great, but anyone can write something that appears to be legit, but could be totally wrong!
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