reducing air intake temps

Any form of normally aspirated power mods.
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reducing air intake temps

Post by 350matt » Thu Jul 19, 2018 9:51 pm

Gents

I realise the stock Rx8 inlet system is pretty good but having noted the IAT is pretty toasty in this heat I was wondering if it was worth drilling some holes in the plastic blanking grill behind the number plate to try and get some colder air into the nose. the air intake path does look a bit torturous having to wind its way in past oil coolers and headlights etc
or is there another air path that I don't know about?

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Re: reducing air intake temps

Post by warpc0il » Thu Jul 19, 2018 11:56 pm

Get yourself a Racing Beat Revi Ram Duct
https://www.mazdarotaryparts.com/Racing ... m-Air-Duct
to get a much fresh air into the intake as possible.

Note however, that in the weather we've been having lately, the air temperature 1ft above the tarmac can be reaching 40C anyway.
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Re: reducing air intake temps

Post by PeteH » Fri Jul 20, 2018 12:56 am

I'd think the slight reduction in inlet air temp would be outweighed by the slight increase in drag coefficient.

But who knows. Marginal gains.....

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Re: reducing air intake temps

Post by SeriousSam » Fri Jul 20, 2018 8:28 am

I think there's a reason for that panel behind the grille, something to do with forcing air through the radiator or keeping it away from the engine to control temperature difference across the block, something like that. If you drive a 231, you've already got a cold air intake in the form of the VFAD in the nose, not sure what the 192 has though since I've never seen one.

You could go with the Racing Beat duct like Dave suggests, or the AEM intake sits in the same position. The VFAD draws air from the same inherent location as those two anyway - there's a gap in that plastic panel, right below your number plate. That's where the intake draws air from, just not quite so directly.
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Re: reducing air intake temps

Post by Phil Bate » Fri Jul 20, 2018 9:06 am

I think the elevated intake temperatures are not for want of a more direct path for the intake air, but rather heat soak in the air cleaner assembly and pipework itself. The filter box and MAF sensor tube can get quite toasty, and at idle/cruising RPMs the air is passing through slowly enough to become heated on it's way into the engine. You will see the IAT drop once you are moving quickly and at WOT.


I suspect this does make the car feel a bit sluggish at low RPM on really hot days. I have seen people insulate the intake with foil wrap/insulation and can't see why it might not help - however you then need to consider the effort/benefit equation.
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Re: reducing air intake temps

Post by PeteH » Fri Jul 20, 2018 9:33 am

I agree with you Phil.

I'm not so convinced about foil wrapped intakes though. Foil only protects from radiated energy, not convected energy. (Foil wrapped turkeys still cook :) )The problem with radiated energy is that it's a "fourth law" process. In other words, you need a massive temperature difference in order for the foil to make a measurable difference. This is why foil is very effective when placed on the components around an F1 exhaust, where the exhaust might be 1000degC hotter than the surrounding components, but in the general environment of a warm engine bay I just can't see it making any difference. There is even the possibility that the metalised foil could actually increase the heat convected and conducted into the intake.

I think what you would need is a foam wrapped intake. You need to insulate the intake, and persuade it to stay at the temperature of the air flowing through it, rather than the surroundings, and that means lagging your intake.

But I agree that at any sensible driving speed the air flow is so fast and large that there is negligible chance for the intake air to get heated. So is it really important to be able to use 5% less throttle when pottering around town?

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Re: reducing air intake temps

Post by boosted » Fri Jul 20, 2018 9:55 am

The throttle body has coolant routed through it too for warm up etc and with coolant at 100degC its not gonna take long for whole mass including the plastic to heat soak...
I was think about installing a valve to shut the coolant flow off once car is warmed up...or do away completely on the Westory as it does not get used for winter runs...
Im assuming the coolant route on throttle body is to prevent icing up ...but does not need to be 100deg C coolant...but thats all that is available i suppose.

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Re: reducing air intake temps

Post by untakenname » Fri Jul 20, 2018 10:14 am

When mine went in for a rebuild they did away with the throttle body heating, haven't noticed any ill effects though iirc you can get throttle icing even if the ambient airtemp is in the twenties.

I've also fitted cold air ducting to my stock airbox and at WOT recorded 12 g/sec more aiflow than with the oem routing.
Last edited by untakenname on Fri Jul 20, 2018 12:12 pm, edited 1 time in total.

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Re: reducing air intake temps

Post by boosted » Fri Jul 20, 2018 10:26 am

Thats why ive left the coolant on mine as i dont have any rx8 stuff...just 1 air straightner about 8" of straight pipe and a gert big ramair cone poking out the top of my nose cone so it gets plenty of fresh air...and maybe some ram air effect. It may worse than standard lol but no where for it...Image

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Re: reducing air intake temps

Post by Phil Bate » Fri Jul 20, 2018 11:31 am

PeteH wrote:
Fri Jul 20, 2018 9:33 am
Foil only protects from radiated energy, not convected energy
I don't mean a bit of Bacofoil stuck to the intake with PVA :D I was thinking more along the lines of the stuff building control made me fit under the plasterboard of the sloped ceiling upstairs. Some sort of metalised film outer, sandwiching a layer of air trapped in insulation (to ward off conduction/convection, rather than just radiation).
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Re: reducing air intake temps

Post by Phil Bate » Fri Jul 20, 2018 11:33 am

I do prefer boosted's solution of fitting a Westfield ;)
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Re: reducing air intake temps

Post by warpc0il » Fri Jul 20, 2018 11:36 am

That's the "bubblewrap construction" stuff I was referring to in another related thread
https://www.screwfix.com/p/ybs-airtec-r ... -25m/6520p

I did wonder if this might work on the inside surface of the airbox, which would be much more discrete, but I suspect that it would be difficult to prove any benefits.
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Re: reducing air intake temps

Post by Phil Bate » Fri Jul 20, 2018 11:42 am

The stuff I used at the inspector's request had some sort of fibre insulation rather that bubbles, but that could work too.
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Re: reducing air intake temps

Post by boosted » Fri Jul 20, 2018 12:33 pm

Wayne aka MrSpiller has a nice set up...bumper cut cold air feed...should negate any heat soak.

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Re: reducing air intake temps

Post by 350matt » Fri Jul 20, 2018 2:46 pm

untakenname wrote:
Fri Jul 20, 2018 10:14 am
When mine went in for a rebuild they did away with the throttle body heating, haven't noticed any ill effects though iirc you can get throttle icing even if the ambient airtemp is in the twenties.

I've also fitted cold air ducting to my stock airbox and at WOT recorded 12 g/sec more aiflow than with the oem routing.
got any pics?
Also is it worth disabling the VFAD then so it breathes from the short intake all the time? as according to the blurb the long intake is just there to shut it up

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Re: reducing air intake temps

Post by V8 Power » Fri Jul 20, 2018 3:28 pm

My old set up
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Re: reducing air intake temps

Post by zippyonline » Fri Jul 20, 2018 3:45 pm

What about "chimneys" to vent hot air off the exh manifolds and cats up and out the bonnet. If you encase the exhaust line in a heat shield and the top of that shield vented up and out to a suitable bonnet vent...

Al la Aston Martin:

This would remove a lot of the heat in the engine bay. :-k
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Re: reducing air intake temps

Post by warpc0il » Fri Jul 20, 2018 3:56 pm

If it could be done neatly then the challenge would be to position the vent in a low pressure area, at all road speeds.

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Re: reducing air intake temps

Post by mrspiller » Fri Jul 20, 2018 5:35 pm

boosted wrote:Wayne aka MrSpiller has a nice set up...bumper cut cold air feed...should negate any heat soak.

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Re: reducing air intake temps

Post by exiled--viking » Fri Jul 20, 2018 11:23 pm

;)
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Re: reducing air intake temps

Post by 350matt » Sat Jul 21, 2018 10:23 am

I do like that undertray, I've run something similar on other cars and found they can have a very strong effect, I take it you made it yourself?
where did you get the louvre panels from?

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Re: reducing air intake temps

Post by ChrisHolmes » Sat Jul 21, 2018 12:08 pm

Phil Bate wrote:
Fri Jul 20, 2018 11:31 am
PeteH wrote:
Fri Jul 20, 2018 9:33 am
Foil only protects from radiated energy, not convected energy
I don't mean a bit of Bacofoil stuck to the intake with PVA :D I was thinking more along the lines of the stuff building control made me fit under the plasterboard of the sloped ceiling upstairs. Some sort of metalised film outer, sandwiching a layer of air trapped in insulation (to ward off conduction/convection, rather than just radiation).
Multifoil insulation the trade name of that stuff, available in various thicknesses and stops radiant and conducted heat travel but only comes in big rolls.
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Re: reducing air intake temps

Post by Phil Bate » Sat Jul 21, 2018 12:16 pm

That's the stuff. It works very well as the bedroom I fitted it in (mine) is now an oven at night (it stops the heat getting out #-o)
Also, fitted between studwork and the plasterboard it makes using drywall screws a nightmare, as the insulation bunches and wraps around the screw #-o #-o
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Re: reducing air intake temps

Post by exiled--viking » Sun Jul 22, 2018 7:38 pm

350matt wrote:
Sat Jul 21, 2018 10:23 am
I do like that undertray, I've run something similar on other cars and found they can have a very strong effect, I take it you made it yourself?
where did you get the louvre panels from?
yep make most parts my self the louvre panels come from www.carbuildersolutions.com ;)
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Re: reducing air intake temps

Post by Liam22 » Sun Jul 22, 2018 9:34 pm

Phil, do a search for "nimbus heat shield" - formable and very effective. But prices to match...

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