FD cool air ducting solutions to SMIC & Intakes?

Aubec · June 16, 2009, 11:10:54 AM

Quote from: Timmy;616495I understand what you\'re saying, but i don\'t think that applies if you\'ve got an aftermarket induction kit as it pulls air from both the ducting and around the engine bay unlike the standard airbox that just pulls in from the air feed.
I know it made next to no difference on my set up which is arc smic and arc airbox, probably because the ducting is no longer the only source of air for induction.

Well at least in theory I would say having the hole open would lower pressure on the cold side of the SMIC as there is an easier route for air to travel into the bay than through the SMIC, so should be reducing flow through.

Only way to be sure is to test it. I\'ll go for a drive with/without it blocked and post back with my intake temps. Think I might buy some magnahelic gauges and measure the relative pressures for myself.

Definitely looking at putting a vent in the front of the bonnet to channel cool air to the intakes, and maybe a duct behind the SMIC to let the hot air out and reduce the overall pressure in the bay.

Nik da Greek · June 16, 2009, 12:10:04 PM

I think that last bit is what you want to concentrate on, a vented bonnet with the vent behind the IC will create a venturi effect through the \'cooler and literally suck air through because it\'s far lower pressure than in the front of the IC, especially with good ducting. The top of the curve on the bonnet is the lowest pressure point from the wind tunnel pics I\'ve seen, which is where good vented bonnets like the MazdaSpeed and Knightsports stylee ones put the vent.

Aubec · June 16, 2009, 12:43:19 PM

Quote from: Nik da Greek;616860I think that last bit is what you want to concentrate on, a vented bonnet with the vent behind the IC will create a venturi effect through the \'cooler and literally suck air through because it\'s far lower pressure than in the front of the IC, especially with good ducting. The top of the curve on the bonnet is the lowest pressure point from the wind tunnel pics I\'ve seen, which is where good vented bonnets like the MazdaSpeed and Knightsports stylee ones put the vent.

Dremel time

Good feedback, thanks mate. I think I need to do that along with a cold air feed towards the intakes though, cos otherwise I\'ll end up with low pressure (good for intercooler) hot air (bad for the intakes) in the bay.

Aubec · June 26, 2009, 10:27:43 AM

Well, my experiment in plastic and silicone has knocked average intake temps down from 55-65 degrees, to 35-45 degrees, with ambient air at 23 degrees or so. Thats conclusive enough for me, its staying blocked!

That\'s with the factory SMIC, HKS intakes and no other changes to the ducting other than blocking that rectangular hole in the cold air feed to the SMIC. Hoping it\'ll be even better when I get an uprated SMIC.

Heatsoak still an issue of course, doesn\'t take long in standing traffic for the temps to creep up into the 60\'s again, but they come right back down when I get moving quickly.

SmbFD3S · July 14, 2009, 07:41:41 PM

This might interest you Aubec??

Decided to try something out and it actually works rather well

Previously i had the standard top air duct (shared with intercooler) mounted to get some fresh air to the Trust Airinx filter i\'ve just put on but this to be honest was a bit crap, didn\'t work very well and also robbed air form the intercooler....

So, thinking about it i got some 2-1/4 inch flexible ali and had a play. Previously also when i had the standard airbox i opened up the side of the radiator as per Rob Robinette site. With this is mind and also slightly based on the Pettit Racing intake i\'ve come up with this:-
Flexible duct squashed to get between body and radiator for airflow to the filter. This at present is cable tied but i do plant to make some more solid duct at a later date but it will do for now to monitor things. Also sprayed it black so it don\'t look too out of place lol....
Comments welcome.

Oh and a while ago i installed a temperature probe (small digital 2.99 thing off ebay) and strapped this near the filters. So we\'ll see what the temperatures do

Before the intake it was a fairly constant 33 degrees unless stuck in traffic or the fans came on in which it obv pushed the temps up but when moving came back down to the 33 ish mark.
So this is what we have:-

Cheers
Scott

Aubec · July 14, 2009, 08:23:15 PM

I was thinking of something similar the other day when I was in halfrauds and saw the flexi hose - couple that with a box round the filters and you could get some reasonable results - let me know how you get on as it is!

Even better (but fugly) would be a small bonnet scoop above the filters (I\'ve come to the conclusion that my HKS filters are too far forward to put a NACA duct in to feed them), and a box around them to keep the cold air isolated. If I had a spare bonnet I would try it...

leon · July 15, 2009, 11:08:41 AM

Yep SMBFD3S has the right idea, im going to be doing similar with my single setup, as theres no point sucking in the hot air, from what ive read a lot of it is down to how you duct the air :Thumbs-up Air will take the path of least resistance, so make sure there are no other routes other than where you want it to go.

SmbFD3S · July 15, 2009, 11:19:43 AM

Quote from: leon;626508Yep SMBFD3S has the right idea, im going to be doing similar with my single setup, as theres no point sucking in the hot air, from what ive read a lot of it is down to how you duct the air :Thumbs-up Air will take the path of least resistance, so make sure there are no other routes other than where you want it to go.

Well it Deffo makes and improvement, outside temperature was what 16 degrees last night and i was seeing 18 on the temp probe when moving which is located directly underneath the filter so they are deffo getting some nice colder air than before. Intake temps on the Commander where showing 26 (ARC SMIC) so yeah all good me thinks for a fiver lol....

Will let you know how it fairs in the daytime with ambient temps and keep you posted but it\'s all looking good to be honest.

Leon - yep how you duct it is important and if you want to go to the n\'th degree then you could insulate it aswell... You also have to consider where high and low air pressures are too if the air wont be "forced" as it could have the opposite effect and actually creating a vacuum

leon · July 15, 2009, 11:38:43 AM

True, reading that website opend my eyes a little to how airflow really works, I was thinking of just giving the air the option of going via the intercooler/rad or going up the intake pipe. I was going to relocate the filter to down within the ducted area.

Hi RX7 · July 15, 2009, 05:19:58 PM

I\'m looking into getting some headlight covers with a slit similar to the Attain design (obviously not the same in case of copyright) made they will be for both sides not just the side with the air filters. depending on what they cost me I\'m hoping to have both plain and carbon fibre covers made up. I\'ve been messing around with my leaf blower to try and simulate flow and so far the mock up does allow a flow of air which after alterations to the plastic lips fixed to the bonnet are carried out improves this further.

fil_auto · July 16, 2009, 01:41:51 PM

keep us posted - sounds interesting :chat

Quote from: David Wiltshire;626639I\'m looking into getting some headlight covers with a slit similar to the Attain design (obviously not the same in case of copyright) made they will be for both sides not just the side with the air filters. depending on what they cost me I\'m hoping to have both plain and carbon fibre covers made up. I\'ve been messing around with my leaf blower to try and simulate flow and so far the mock up does allow a flow of air which after alterations to the plastic lips fixed to the bonnet are carried out improves this further.

Spartacus · July 17, 2009, 05:04:51 PM

Quote from: Aubec;616325Yeah, but you still need an air source if you are going to box in the intakes and block the air route from the intercoolers intake duct - which is really what the second part of my question is about. Perhaps a NACA duct or a scoop in the front of the bonnet and a double walled metal airbox around the intakes?

This is something I have been working on a while ago on a spare bonnet to get cold air to my filter on my LS1 V8 conversion. The NACA duct works and fits really well with minimal dremeling required, but I may now look into an over the rad solution as I would prefer to keep the bonnet standard looking.

Hi RX7 · July 18, 2009, 09:32:18 AM

Yes I agree about the bonnet line remaining smooth I\'ve made a point of looking out for every aftermarket bonnet and don\'t like any of them, I\'m sure many of them do allow underbonnet heat to get away quickly but I just don\'t like the look of them. I have seen some subtle intakes around the number plate area which can look good but I\'m still trying the headlamp cover route