I love the simplicity, low cost, and minimal pressure drop of the HAI, but have often questioned whether I'd get better performance with one of the commercial CAIs. Just for fun, I decided see if there was a way to devise a HAI heat shield and also bring in cooler air. As most anyone knows, though, the HAI is in a rather cumbersome position to completely shield, and is not too close to any source of cold air, either.


Studying the situation, I felt the hottest part of the engine compartment would be around the exhaust header at the back of the engine. Therefore, even a partial heat shield that blocks air circulation from this area might be helpful. The first pic below shows what I came up with. A piece of sheet metal with one 90 deg bend covers the open bottom of the stock airbox,and another piece is screwed onto this one to extend downwards and closer to the engine. Rubber sheets are glued onto the edges of the metal pieces to form a flexible barrier between the bonnet and engine areas. The second pic shows a side view - a reasonably good seal.

I then realized the shield could direct cooler air from the cowl area, if this were opened up. In fact, the lower portion of the stock airbox, now that it is covered over, also helps bring in cold air from the cowl. Note that the place where the stock snorkel would attach feed right into the HAI.


OK, now to test things out. As shown in the 3rd pic, I sacrificed a K&N filter by drilling a hole in the top for a thermocouple, which dangled an inch or so off the top of the TB. I felt this would best represent air temp entering the TB. I made four runs today, which consisted of a ~6 min drive, a bit on residential streets (30 mph), and short section at 55 mph, and most in the 35-45 mph range with stop signs and lights. At limit for 3 pictures, so I'm continuing this in another post ...

 

Inlet air temps were logged at various points along the course, mostly at stop signs, but in one case after ~1 mile at 55 mph. Between each run, the engine was idled for 5 min, to allow a good heat soak, then allowed to cool down a bit so each run started at more or less the same temp. The data from idling are presented later. The first attached chart shows the data taken while driving the course four times, in the order A thru D. On a cold engine with no extended stops (run A), the HAI takes in air only a few degrees above ambient. The situation is quite different, though after the heat soak. In this case, the inlet air temp at start is 95-100F, or ~25 F over ambient. With the heat shield, these air temps drop to about 10 F above ambient after a couple minutes of driving. Without the heat shield, the temps do not drop so much and are generally around 20 F over ambient. So, the heat shield does appear to help

The second attachment shows the temp rise upon idling after runs C and D, and then turning the engine off. After 5 min, the heat shield has kept the inlet air about 10 F cooler than without, and after 4 min idling + 4 min with the engine off, the heat shield results are about 15 F cooler. Still, the HAI is breathing in some pretty hot air here, 110 F to 125 F, depending on whether the heat shield is in place.

Insulating the heat shield would probably help some, but I’m thinking that the proximity to the IC outlet is the downfall of the HAI. This IC outlet gets hot when no air is flowing thru the IC. There may be a way to insulate this outlet, perhaps this is the next step!

 

 

Don't insulate the IC horn itself. Insulate your shield.

Just a thought here. Reverse the normal CAI thinking and run 3" tubing from the cowl to a smaller insulated box around the HAI.
The major advantage to this, although it would be small, is that the insulated area will be a smaller volume and will evacuate heat faster once in motion. It'll also be easier and cheaper to insulate.

 

wow.... I am so glad people are willing to do this stuff for them selves.... it's great!

 

most commercial offerings can be improved somewhat, so if you want the best, you'll be tinkering no matter what you buy!

And this is the best way to really find out what works!

Matt

 

Very interesting exercise! Although the ambient temperatures were higher than my location lately (it seems from reading your report that they were around 70F?) the best you get is about +10F above ambient at the air filter. I don't think I've ever recorded more than +3F at the airbox with my setup yet with ambient temps between 40F and 65F so far. Of course, summer may tell a different story. My airbox is insulated, too.

Good experiment, and data. Thanks!

 

The inlet air to the HAI remains within a few degrees of ambient if you start the car (cold engine) and drive without stopping. Not a particularly common situation! As expected, the HAI is very sensitive to heat soak, and with any amount of stop-and-go driving the HAI (w/o heat shield) is running 10-25 F over ambient. With the heat shield, more like 5-15 over. Ambient in these runs was around 74 F.

I need to re-do these tests now that the weather is colder and the IC exit horn is insulated. +3 F for the HAI is probably a pipe dream, though, under typical road conditions.

 

inimini, this is good stuff! I'm excited to try something like this myself now...

Again, the ingenuity these days on NAM is so refreshing to see; and the willingness and ability to share in nice detail as well!

Of course the whole point of all of this is not just to have cooler air at the TB, but ulitmately in the combustion chamber, or IAT. This will help with that for sure. What I've always pondered though is how much.

To expound... Without this mod (normal HAI), let's say the pre SC or TB temps run 20F over ambient, on average. With this heat shileding, let's call it 10F over. Can we expect this same delta (10F) to also reveal itself post SC or pre IC core, and post IC core, or which is essentially IAT?

If a more effective IC system drops temps 10F, we can pretty accurately know how this impacts IAT as there is virtually nothing else of note afterwards to influence that state; so IAT will have been lowered by about 10F...

It would be really neat to see how this 10F delta holds-up after the SC beating and IC revival. Heck, maybe it's even more than 10 degrees of impact for IATs. At least I envison a scenario where this might be true...

inimini, if you can log IATs in conjunction with your previous numbers, that would be very interesting to see. Either way, lowering initial temps are a plus, so kudos to you!

 

but I'd have to think at it's time to watch football! But if you really want to answer these questions well, Corky Bell has a bunch of approximate eqations that will let you know what the change in combustion chamber temps end up to be! And you can figure out the what the differences are along the path as well....

The actual answers to your questions are left as an excursize for the student!

Matt

 

Long night driving through the mountains, getting lost, encountering snow and ice... but well worth it to borrow BimCom from you. I gave it a shot moments ago but my battery is so dead (3.87 volts! ), I can't even attempt to do so...

I then come back inside and you tell me to go check-out some book!

All the more reason to get it though...

 

Thanks, Tony. You have a good idea there, the only trouble would be uninsulating the IC exit horn to do the tests, which would be a pain.

It seems to me that the IC can transfer more heat as the air entering the IC increases in temp. After all, the delta T between the external - internal of the IC is the driving force for heat flow. So, the final temp improvement in shielding the HAI probably is somewhat less than what is measured right at the TB. On the other hand, P/T is really what we want to maximize, and cooling the inlet air to the SC allows each SC rev to pack in a few more molecules.

 

Hi all, I've had the HAI on my car for a while. I really liked the concept. But then I did the dumb thing of logging data, and I found that it wasn't as good as my butt dyno had indicated (results here.)

But I fell in love with the throttle response, so I just lived with the crappy air temp performance.... Until now.

Figuring it's just too much of a pain to really seal the HAI in a box, I assumed all I really could do was interfere with the paths hot air would take, and aid paths the cold air would take. So I cut open the radiator support and bent a bit of Al sheet. On a side note, I couldn't find annealed Al nearby on short notice, so I just annealed it in my fireplace! I was shocked at the difference it made....

Anyway, here are some photos.... The first one is the baffle...

Nothing special. Just bent Al. I used some Al tape to seal some corners and cover some rough edges. The foam is to make a seal against the throttle body.

Here's the front view....

I used pop-rivits to instal it. If I really like it, I'll switch to nutserts to make it more removable.... I also used Al tape to seal the gap around the edges of the Al sheet.... It covered the pop rivits so I took the photo without it on.

Side view....

Here you can see how it seals. The other piece of sheet metal was a first effort from a scrap I had lying around. IT's gonna go as it doesn't cover enough.... But WTF, it's there and I'm out of other sheet.

That's it for now! I data logged this and found it added 20.13 gazillion HP!


Matt

 

Nice work! I had a 67 Mustang....fastback. It was sweet! Although I think I like my mini better....

what'd you think of your DFIC?

 

I wish I had annealed my Al sheet, as it sounds like it's much easier to get complex shapes. It's cold here now, so maybe I can through some sheet on the fire tonight!
And, --of course-- it adds HP. Im just surprised it's so small an increase. A gazillabazillion sounds very possible without the rivets.

Good one, Doc!! I love this kind of engineering. You might consider thermal insulation on the underside to keep the airflow cooler!

cheers,

 

Waiting for new data..... Looks like it'll do good though.

 

Matt, I remember seeing that aluminum tape the last time I saw you... Looking good! Thanks for sharing.

 

TonyB, that was from another hack I was working on... But it planted the seeds for what I just posted. But if you're gonna stay with a HAI, we can get a sheet and bend one up for you to! Just let me know.....

Motor On.... Don't hold your breath. I may get some temp data from this set up, but I've lost the ability to quickly go back to stock.... So no real deltas. But I could see how much above ambient I'm getting.....

DrPhil... The annealing helps a bit, I could bend things with my hand easier. But compound shapes will still need hammers! To anneal, get a flame that's buring rich, and move the Al through the yellow part. Don't get it too hot, as that would be bad. It shouldn't get hot enough to glow, and will get all sooty. Let it cool slowly... Wash in sink with dishes so wife gets pissed. No, don't do that. Don't ask me how I know!
I've got some tricks for insulating the back. But now it's pop rivited. I kind of like it so I may pull it out and insulate the back and pop it back in.... Hmmmm.
I think I got all the power there was to be had. I put the smooth side of the rivits in the airflow!

macnamaraz, thanks! I liked the Bullitt car, but I'm a 64.5-66 guy all the way. What can I say? My hot 4th grade teacher had one, and I've been stuck on them ever since.
As for the DFIC, I like it fine. It's still on the car. But I've tested a lot of ICs and any one doesn't tend to stay on that long.... So who knows.... I'll be playing with a GP IC soon, and I want to test a water to air, but don't have one to play with yet.

Matt

 

I was just curious to see if you had a baseline to see if you were able to get a volume pressure or temperature change in similar conditions (so I guess we'll wait til summer) and see if there is anything significant enough for an approximate gain.

 

Cool mod DR. O

I have always been interested in trying the DIY HAI. It seems in theory it would be very effective and it is cheap.
So for the average consumer like me it is one I could try without giving up too much money.

Dr. O and others out there how do you really feel about the performance of the HAI? How does the power gains compare to say a ALTA or K&N? I have the K&N typhoon right now, which to me pretty much appears to be a HAI anyway. Although possibly not as efficient as the DIY HAI. On mine there is no real sealed box, just a partitioned wall. Basically the HAI is like mine without the long tube... which could make it more efficient?????

Which intake do you think performs better the DIY HAI or the K&N typhoon?

More power through the rev range? Better thottle response?

More Superchargerwhine?

Do Tell?????

TIA Jasun

 

Matt: I wonder why keep the gasket that seals against the bonnet above your new duct? You're using the bonnet as the upper surface of the vent to HAI anyway, so I don't see the gasket having any role to play, other than get in the way of air flowing to the air filter. Again you show us that air *flow* and management is our friend. Excellent.
And thanks for the how-to on annealing--I will try it next project!

 

I cut throuth the top of the radiator support. The seal is the only thing that keeps it one piece.... But something else to think about.

As far as other intakes, the reason I like the K&N is the CARB number! The Al tube gets warm, but it may have a better filter exposure... Who knows? Get a logger and tell us!

Matt

 

Dr O... I would like to see this at AMVIV...I'm all about the cost effective mods. That's why I love the HAI.

 

you can ogle as much as you like.... It looks better in the photos because I'm a hack with sheet metal... But with the air filter, and the Al sheet, I'm out a total of about $45!

Matt

 

This is what I want to do for my CAI!

Rather than diver airt from the IC scoop to the CAI which some are playing with - I believe this is the way to go. increase the opening and inhopefully increase the tubing to the CAI. Even w/ the stock tubing you would be able to pressurize and push more air back to th eCAI.

Nice job.