Location of cold air feed?
Discussion
OK I have done a search and come up with nothing, but if I have missed a lengthy discussion please point me in the right direction.
I am about to remove the airbox from my VW Golf Mk2 1.8l 8v and fit a less restrictive and simpler system. I would like to increase power a little but mainly to increase responsiveness ahead of a planned engine refresh / swap. The idea is to create a box out of fibreglass and mount a cone filter inside it, this will dampen some of the increased noise and also isolate the air inside form the hot engine bay. The box will be fed from the outside of the car but there are two possible locations. I could run a duct from the front grill, possibly removing the offside inner spotlight, or I could fit a NACA duct into the front of the bonnet to feed directly into the box. The duct would be slightly easier, as it would not require any cutting, but there would still be a duct running through the engine bay and thus the possibility of heating the inlet. The NACA duct would require more work but would provide air directly into the inlet.
Is there a significant difference in the pressures I would see between the front grill and close to the leading edge of the bonnet? Would these differences be noticeable in the real world and is it worth going on way or the other for these reasons, or am I better sticking with the simplest solution?
Many thanks for any assistance,
Jon
I am about to remove the airbox from my VW Golf Mk2 1.8l 8v and fit a less restrictive and simpler system. I would like to increase power a little but mainly to increase responsiveness ahead of a planned engine refresh / swap. The idea is to create a box out of fibreglass and mount a cone filter inside it, this will dampen some of the increased noise and also isolate the air inside form the hot engine bay. The box will be fed from the outside of the car but there are two possible locations. I could run a duct from the front grill, possibly removing the offside inner spotlight, or I could fit a NACA duct into the front of the bonnet to feed directly into the box. The duct would be slightly easier, as it would not require any cutting, but there would still be a duct running through the engine bay and thus the possibility of heating the inlet. The NACA duct would require more work but would provide air directly into the inlet.
Is there a significant difference in the pressures I would see between the front grill and close to the leading edge of the bonnet? Would these differences be noticeable in the real world and is it worth going on way or the other for these reasons, or am I better sticking with the simplest solution?
Many thanks for any assistance,
Jon
there will indeed be a pressure difference. The front grille will see positive pressure, whilst the leading edge of the bonnet will see a lower pressure. A little heath robinson, but the methodology is good.
There's a useful article here:
http://www.autospeed.com.au/cms/A_1023/article.htm...
and a few more on airflow around the front of a car, pressures and bonnet vents:
http://www.autospeed.com.au/cms/A_2159/article.htm...
http://www.autospeed.com.au/cms/A_2160/article.htm...
http://www.autospeed.com.au/cms/A_2162/article.htm...
There's a useful article here:
http://www.autospeed.com.au/cms/A_1023/article.htm...
and a few more on airflow around the front of a car, pressures and bonnet vents:
http://www.autospeed.com.au/cms/A_2159/article.htm...
http://www.autospeed.com.au/cms/A_2160/article.htm...
http://www.autospeed.com.au/cms/A_2162/article.htm...
Autospeed articles are good.
My question is, I don't want an analog gauge, and I don't want a digital manometer for £100.
Does anyone know of any differential pressure sensors that can be had that just output a signal I can record via a multimeter/pc and tabulate later?
Was thinking a cars boost sensor but not sure how it'd handle vacuum or 0 absolute pressure (0 - 30psi absolute or 0-15psi relative)?!
Also, I guess these sensors don't know the current atmos pressure, so measure pure absolute signals... hmmmm...
Cold air feeds on most modern cars seem to be alongside the front radiator, where the pressure is highest for generating the best flow through the radiator core.
Dave
My question is, I don't want an analog gauge, and I don't want a digital manometer for £100.
Does anyone know of any differential pressure sensors that can be had that just output a signal I can record via a multimeter/pc and tabulate later?
Was thinking a cars boost sensor but not sure how it'd handle vacuum or 0 absolute pressure (0 - 30psi absolute or 0-15psi relative)?!
Also, I guess these sensors don't know the current atmos pressure, so measure pure absolute signals... hmmmm...
Cold air feeds on most modern cars seem to be alongside the front radiator, where the pressure is highest for generating the best flow through the radiator core.
Dave
Read this before you do anything - http://www.clubgti.co.uk/forum/showthread.php?t=19...
Just remember that many cold air feeds are put in a place where the amount of water they will get into the airbox when running at power on a very wet day is still very low.
You need to think that if water can get in you need to get it out.
Damaging the engine for a few ft-lbs of torque is not really worth it in my opinion.
You need to think that if water can get in you need to get it out.
Damaging the engine for a few ft-lbs of torque is not really worth it in my opinion.
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