damian

iTrader: (2)

thanks i-c-e :-)

Gorilla RE

iTrader: (1)

my plesure!!

ech

Something to think about when considering a shielded solution versus the fully enclosed option that you would see with the M2 or Stock airboxes.

When I had a modified airbox (both stock and PFS) with the bottom cut out, and a ram air tube from the 2nd oil cooler location - I use some remote thermometers to take tempurature readings at several places in the car. I placed one on the filter, and one outside the modified aribox.

What I found was surprising. There was only a couple of degrees difference in the recorded air tempature. The temp sensors are ditital, and I checked them out - seem fine. I figured that there were two things going on.

1) While driving the pressure under the hood is > atmosphere.
2) While the engine is running the pressure at the filters is < atmpsphere (or at least < pressure under hood).

This means that air will flow from the easiest source to the air intake filters. It would be tempting to think that I was pulling air from the special duct that I made that went town next to the radiator, and I bet some air was. But it became clrear that more air was making it through the various gaps and open paths to my air filters.

So the shileding (plastic, fiberglass, al.) was probably doing a fair job of protecting against radial heat, but the was air flow from the engine bay, and that air was hot enough to make the temp at the filters about equal to the temp in the engine bay.

I now have a completeley sealed box - with just a duct going down next to the radiator, so the ONLY place that air can get in is from the "mouth" at the front of the car. I have not - and probably won't test the temp at the air filters because (a) it is hard now that I have a sealed airbox, and (b) what am I going to do if it isn't any better

All that said, I've seen articles that have measured the temp at the intake manifold with a fast responing thermosensor (unlike stock) and by the time air makes it through the turbos and everything, there isn't much of a difference from a filter attached directly to the turbo, and a fully sealed airbox.

I'm not trying to discourage anyone from doing anything. Just want to share the information that I have found - that makes it clear that the only thing that is certain is that the thermodynamic models affecting air intake temps are beyond my grasp.

My guess is that if you had as much time in the world to spend on shielding anything, it would be to cut down on the radial engergy cast off by the Trubos, manifold, and downpipe.

---

And of course, improving the appearance of the engine bay never hurts.

ech

Oh, and when I say only a couple of degrees different between the engine bay, and the air filter - that is max. Most of the time they were the same.

pshaw118

ech: You are the man. I've been wondering about engine temp air getting into my m2 box, and with the difference in air pressure, I can see it happening. So maybe it would be better with just a heat shield or with no shield at all? Or maybe I should seal up my m2 box with silicone gel? What do you guys think?

damian

iTrader: (2)

good post ech, .. i just want to remind u guys about another thread that went on about closed boxes vs open filters

the just of the thread pointed out that the performance gain from trying to keep 'only' cold air to the filters, aka a enclosed box using only the space next to the radiator, was restrictive to the point that it overcame the benefits of blocking out the engine bay air, in other words, think about this a second ....the restriction..causes the trubos to work harder to get the same amount of boost...thus heating the turbos further, thus heating the air even more before it enters the intercooler.... so in the end you end up with hotter air by restricting the air intake to only be able to take 'cold' air!!!!

keep in mind the real important air temp is NOT the temp going into the filters (although colder is better)...its the temp coming out of the turbos to the intercooler...who cares if a intake system makes your filter intake temp lower when your turbo outlet temp end up being higher than before!!! (not relative to each other, but relative to a different setup)

that is why I stayed away from a totaly enclosed box, my main goal was keep the radiator heat away as well as provide a functional flow of nose air to the filters

but I am no thermodynamics or air flow expert either...

damian

iTrader: (2)

here was the thread I was referring to:
https://www.rx7club.com/forum/showth...hreadid=157806

damian

iTrader: (2)

here is a great quote from mmaragos that is in the thread i mention above:

"BUT...It is more important to reduce the intake restriction to a minimum, then concern yourself with intake temps. Do your best to minimize intake temps, just not at the cost of intake restriction. Use the intercooler to lower temps."

NoFriends26

This looks awesome, Thanks for the blueprints damian. I think im am going to start mine later today, but I was jsut wondering if those K&N filters will work witht he stock intake pipes, or do you need the metal ones? Anyways, you are my new favorite member.

JhnRx7

iTrader: (12)

i made the heat shield and i am now waiting for my filters to arrive. i am putting them on the stock pipes...this should help

http://www.rx7turboturbo.com/robrobi...kn_filters.htm

damian

iTrader: (2)

the filters will work with stock tubes, BUT..you need a metal coupler between them, I went to checker auto and in the exhaust tube area thay have perfect size couplers in the there somewhere, they are like 3" long and 2.5" diameter

...i dont need them now because I use metal piping so the filter can go right on the metal pipe

I'll give my metal couplers to you if you want to pay shipping..

NoFriends26

cool, I pmed you.

Kento

Sorry, but gotta add my $0.02 worth to this thread, as there needs to be some clarification.

The small gap between the body and radiator may be restrictive in a theoretical sense, but as long as the airbox openings themselves are large enough, there are plenty of areas behind the opening (near the rear of the airbox assembly) that the airbox can draw air from. That area beneath the airbox is far from being sealed airtight-- it's basically open space towards the DP. So I think overworking the turbo's intake efficiency (thus heating the intake charge as you say) would be more related to the airbox openings being too small, rather than an enclosed airbox's fault for just trying to breathe through the radiator gap.

Again, you're talking about turbo efficiency here, and with the stock turbos with stock boost levels, as long as the airbox openings are larger than the stock pinhole and your air filter(s) isn't clogged, you won't overwork the turbos enough to heat the intake charge excessively breathing through an airbox. Even modded engines can function with airboxes as long as the intake openings can flow enough air.

I'm not knocking your heat shield. But I think you're looking a bit too far into the turbo efficiency problem with regards to relegating pre-turbo intake temps below post-turbo intake temps in this instance.

ech's post brings up an important point that I think many FD owners overlook. If you look closely inside the main intake area in the car's nose (where the radiator, A/C condensor, etc. reside), you'll see a ton of small gaps and cracks where air will basically escape into, basically bypassing the radiator and into the engine bay. This could explain the similarity in temps between the intake and outside airbox surface that ech saw; there's so much air bypassing the radiator and IC that there's not much difference between ambient and underhood at speed. Sealing off as many of those gaps as possible (using pliable closed-cell foam in my case) not only dropped my coolant temps considerably, but it also made my IC more efficient, as there's plenty of airgaps up by the IC intake duct as well. If you don't seal up those airgaps, there's no guarantee that you're going to get any decent airflow into the radiator gap.

Thus endeth my rant for today.

damian

iTrader: (2)

>>If you don't seal up those airgaps, there's no guarantee that you're going to get any decent airflow into the radiator gap.


good point and good info!!

NoFriends26

alright guys, ive got a stupid question...

there are 5 small pipies, about 1" diameter, that attach to the airbox. I know that 1 is airpump, 1 is crv, 1 is bov, one goes to nothing off the side, but what is the one thats long and ends somewhere behind the intake manifold and goes past the y pipe and airpump?

I dont see it in your pics so im not sure what to do about it. I know you should vent the bov and crv, and the airpump one has its own filter, but what does this one do.

Im working on the intake right now, and it will be done when i figure out what do do with this tube, so fast response appreciated, thanks.

damian

iTrader: (2)

here is the scoop, there is really only 4 lines to the stock airfilter box, crv,bov, airpump in, ACV out

HOWEVER, the airbox makes it look like 5 because there are 5 holes, one for bov, one for crv, one for airpump in ...AND 2 for ACV out!!! one in and one out...why you say?

that is because the inlet on the airbox for the ACV output (on the left side of the airbox) is not connected to the rest of the intake air chamber, it has a seperate chamber to baffle the ACV release noise...you can see what i mean by opening the box and looking at the inside top of the box.

clear as mud?

racerfoo

so you can pull off the long tube next to the intake pipes?

NoFriends26

yeah, thanks, everythign is done, it it looks great.

Just one problem. There is a wierd vibration that happens somwhere between 2 and 4k RPMS. I tried to look and see what it could be, but didnt have much time. You have any ideas? If not, Ill jus try to figure it out tomorrow.

Thanks for your help.

damian

iTrader: (2)

did you put the rubber door guard stuff around the edges?

NoFriends26

yeah, but i only bought enough for the top portion on accident. It looks good right now because its only where you can see it, but i guess Ill go buy more to stop vibration.I dont know how long its going to stay on there though because witht the engine heat, the glue in it gets soft and the edging can move. Anyways, how tight of a fit is your shield between the back and the front? Mine is really tight anmd presses hard against the front box on the upper half, and the bar in the back ont he lower half. I think i mgiht need to trim it down because it might be causing the noise.

damian

iTrader: (2)

mine is very tight...i basically had to 'press' it in between the front nose frame and back frame bar, and i get no noise...
however i think that the noise might come from the lower part that sits down against the radiator, it might be 'flapping' around a bit makin the noise...try some rubber stiping here and see if it fixes it...

if not let me know and ill investigate it soe more on my setup...

and pics would be cool too

damian

iTrader: (2)

by the way, forgot to ask if the vibration noise was being mistaken for the airpump reliefe noise?

is is a low rumble rattel, or a high ping rattle?

NoFriends26

At first i though it was the radiator flap too, but after messing around with it for a while, i realized I was mistaking it for the ACV releasing the air and acting like a horn. Do you know how to quiet this down? You dont even seem to have ACV line at all.

Also, I still need to cover my intercooler hole, any tips for doing this?

NoFriends26

nevermind about the intercooler hole. I jsut used an extra piece of metal like you did, but used screws instead of rivets.

damian

iTrader: (2)

>>Do you know how to quiet this down?

i plan on using some baffles, and then routing the exit tube down low

>>You dont even seem to have ACV line at all.

I do, but its just venting out, making the moo noise for now

>>Also, I still need to cover my intercooler hole, any tips for doing this?

this is what i did