Cosworth Plenum FI/NA: Pics Inside!
#441
Why do people hate other shops for no reason??
It's not like MRC doesn't know their stuff.
Some people are so one-sided with things where it just becomes ridiculous.
Most people just can't be open minded I guess...
It's not like MRC doesn't know their stuff.
Some people are so one-sided with things where it just becomes ridiculous.
Most people just can't be open minded I guess...
#442
Originally Posted by in2therain3
Why do people hate other shops for no reason??
It's not like MRC doesn't know their stuff.
Some people are so one-sided with things where it just becomes ridiculous.
Most people just can't be open minded I guess...
It's not like MRC doesn't know their stuff.
Some people are so one-sided with things where it just becomes ridiculous.
Most people just can't be open minded I guess...
Back on topic, Cosworth plenum...Looks very nice, cant wait to se real world testing.
#444
Question about Plenum volume size. The Cosworth looks like it has more volume but how does the increased volume help. I just "heard" that optimally you would want one that is double the size of your motor, so in our case about 7 liters.
#445
Thread Starter
Sponsor
Forged Performance
Forged Performance
iTrader: (92)
Joined: Dec 2003
Posts: 13,733
Likes: 1
From: Marietta, GA
Originally Posted by redline350ZZ
Question about Plenum volume size. The Cosworth looks like it has more volume but how does the increased volume help. I just "heard" that optimally you would want one that is double the size of your motor, so in our case about 7 liters.
#446
Once you get a plenum volume larger than 100% of NA engine displacement the throttle response becomes soft.
As interior space increases (vs. cylinder volume) the buffer or anti-reversion effect increases, but this isn't linear and probably decays to a minimum value with some multiple of cylinder size.
[not sure that matters with drive by wire]
For supercharged make sure the extra air volume is calculated in a desired plenum size. 40% boost = 140% of displacement
Really depends on runner length [torque peak tuning] short runners are more sensitive to plenum volume above [100% of displacement] than longer lower tuned runners...
Unfortunately simple Helmholtz equations get muddy and inaccurate above 5,000 rpm and you need to convert to 1D Wave Equations methods.
http://ceta.mit.edu/pier/pier20/04.980219.Gaffour.pdf
Or jusr cast one in plastic and measure a few volume variations until the point of diminishing returns occurs.
As interior space increases (vs. cylinder volume) the buffer or anti-reversion effect increases, but this isn't linear and probably decays to a minimum value with some multiple of cylinder size.
[not sure that matters with drive by wire]
For supercharged make sure the extra air volume is calculated in a desired plenum size. 40% boost = 140% of displacement
Really depends on runner length [torque peak tuning] short runners are more sensitive to plenum volume above [100% of displacement] than longer lower tuned runners...
Unfortunately simple Helmholtz equations get muddy and inaccurate above 5,000 rpm and you need to convert to 1D Wave Equations methods.
http://ceta.mit.edu/pier/pier20/04.980219.Gaffour.pdf
Or jusr cast one in plastic and measure a few volume variations until the point of diminishing returns occurs.
Last edited by Q45tech; 04-02-2007 at 07:44 PM.
#449
Originally Posted by Q45tech
Unfortunately simple Helmholtz equations get muddy and inaccurate above 5,000 rpm and you need to convert to 1D Wave Equations methods.
http://ceta.mit.edu/pier/pier20/04.980219.Gaffour.pdf
http://ceta.mit.edu/pier/pier20/04.980219.Gaffour.pdf
#450
A few people per year get their Phd from plenum design and spend their entire lives tinkering.
https://dspace.lib.cranfield.ac.uk/b...+revision2.doc
This one is more to the point in latter half:
http://upetd.up.ac.za/thesis/availab...ssertation.pdf
https://dspace.lib.cranfield.ac.uk/b...+revision2.doc
This one is more to the point in latter half:
http://upetd.up.ac.za/thesis/availab...ssertation.pdf
#451
Originally Posted by Q45tech
Once you get a plenum volume larger than 100% of NA engine displacement the throttle response becomes soft.
As interior space increases (vs. cylinder volume) the buffer or anti-reversion effect increases, but this isn't linear and probably decays to a minimum value with some multiple of cylinder size.
[not sure that matters with drive by wire]
For supercharged make sure the extra air volume is calculated in a desired plenum size. 40% boost = 140% of displacement
Really depends on runner length [torque peak tuning] short runners are more sensitive to plenum volume above [100% of displacement] than longer lower tuned runners...
Unfortunately simple Helmholtz equations get muddy and inaccurate above 5,000 rpm and you need to convert to 1D Wave Equations methods.
http://ceta.mit.edu/pier/pier20/04.980219.Gaffour.pdf
Or jusr cast one in plastic and measure a few volume variations until the point of diminishing returns occurs.
As interior space increases (vs. cylinder volume) the buffer or anti-reversion effect increases, but this isn't linear and probably decays to a minimum value with some multiple of cylinder size.
[not sure that matters with drive by wire]
For supercharged make sure the extra air volume is calculated in a desired plenum size. 40% boost = 140% of displacement
Really depends on runner length [torque peak tuning] short runners are more sensitive to plenum volume above [100% of displacement] than longer lower tuned runners...
Unfortunately simple Helmholtz equations get muddy and inaccurate above 5,000 rpm and you need to convert to 1D Wave Equations methods.
http://ceta.mit.edu/pier/pier20/04.980219.Gaffour.pdf
Or jusr cast one in plastic and measure a few volume variations until the point of diminishing returns occurs.
I like how classic DSP things are mentioned as well like doing an FFT with a hanning window, and other classic tools for electrical engineers like Lorentz and Laplace transforms, partial diffy q FTW!
I just had a thought though... how come no one has done any wavelet analysis on something like this, it would be perfect for it.
Last edited by shushikiary; 04-03-2007 at 08:36 AM.
#454
One thing not discussed is the design air temperature is very important especially if supercharging is used as the tuning frequency still varies as the speed of sound varies thru the medium.
50F vs 250F changes tuning by 22% [1107 vs 1306 feet per second]
50F vs 250F changes tuning by 22% [1107 vs 1306 feet per second]
#455
Originally Posted by soccertoad
OK, headers or Cosworth plenum?
Depends on a few things... Do you plan on going Turbo anytime? If you go with the Cosworth, it won't matter either way. If you go with the headers, it's going to cost just as much, if not more in the long run with probably less usable gains.
#459
Thread Starter
Sponsor
Forged Performance
Forged Performance
iTrader: (92)
Joined: Dec 2003
Posts: 13,733
Likes: 1
From: Marietta, GA
Originally Posted by zzerotwosixty
When are you going to get one Sharif?