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914World.com _ 914World Garage _ Variable length intake runners
Posted by: toon1 May 18 2015, 09:51 AM
A new intake plenum and runners have been on the "to do" list for a while now.
While doing some reading the specs. on the Cayman, I noticed "variable length intake system."
Of course this got me thinking....." 914 retrofit!!!!".
Anyone ever tried this?
Posted by: McMark May 18 2015, 11:12 AM
Just the guys who have installed VarioRam 993 engines.
But seriously, I think about this kind of stuff all the time, and most often it falls in the bin titled, "Neat idea, but there are easier ways to make power."
It's not an overly complicated system though, especially if you can scavenge some of the mechanism from a 911 engine...
Posted by: toon1 May 18 2015, 11:36 AM
Just the guys who have installed VarioRam 993 engines.
But seriously, I think about this kind of stuff all the time, and most often it falls in the bin titled, "Neat idea, but there are easier ways to make power."
It's not an overly complicated system though, especially if you can scavenge some of the mechanism from a 911 engine...
What years did the 911's use this system?
Posted by: r_towle May 18 2015, 11:43 AM
why?
Without variable valve timing, does this buy anything?
If so, what does it do for the motor?
rich
Posted by: Mueller May 18 2015, 11:45 AM
Just the guys who have installed VarioRam 993 engines.
But seriously, I think about this kind of stuff all the time, and most often it falls in the bin titled, "Neat idea, but there are easier ways to make power."
It's not an overly complicated system though, especially if you can scavenge some of the mechanism from a 911 engine...
It is my understanding it has nothing to do with making absolute HP.
The variable parts just change when and where the power/torque happens.
Keith,
Look into the Mazda racecars.....
http://en.wikipedia.org/wiki/Mazda_787B
I'd imagine there is more info and pictures on the setup.
Posted by: toon1 May 18 2015, 11:56 AM
why?
Without variable valve timing, does this buy anything?
If so, what does it do for the motor?
rich
Longer runners create more torque on the low end. As the rpm increases, long intakes are not needed, and actually decrease performance.
Short intakes are needed as the air velocity increases.
It's how the intake air resonance works at low and high RPM's
Posted by: screenguy914 May 18 2015, 12:36 PM
I suspect adapting onto a different engine will be a WAG as to whether runner length and ID are optimized for the engine. And if not installing on a 911 engine, what do you do with the extra runners?
And then, the method of controlling the VarioRam hardware.
Posted by: McMark May 18 2015, 12:47 PM
Yep. There will probably be some improvement, but to really optimize the system you need either dyno time and a way to change components around, or FEA of the intake stream at different RPM.
Cut them off and do some creative plastic welding to make it 4cyl.
But by the time you do all that, you could build a bigger motor or just buy something bigger.
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