The stock scoop & IC work reasonably well. Various figures have been reported for thermal efficiency of the stock set-up (i.e., [Tin-Tout]/[Tin-Tamb], so that at 100% efficiency the outlet temp = ambient). These range from 55% to 70%, and mostly sit around the low 60's. My own tests have shown 55% to 68%, which is in line with what others have measured.

To do better than stock, paying $500-$800 for a bigger IC seems to be the rule. I could find a thermal efficiency posted for only one after maket IC, the M7 DFIC, at 71%. You can do better than this, for less than $50 and a bit of time! Follow these steps to get a reliable TE of around 80%:

Insulate the IC
That's right - the IC has many surfaces exposed to hot air from the engine, not exposed to cold flowing air. These include the front and back, and the bottom surfaces of the channels (between the fins, facing the engine). I think many of the after market ICs really suffer from heat absorption, especially those that extend back over the spark plugs. I'll go out on a limb and say that the main benefit of the M7 DFIC is relative immunity from engine heat, due to its horizontal orientation. You can do just as well, though, with some insulation on the stock IC.

Here is a pic of my IC with the ends insulated with silicone foam, and the bottom insulated with self-stick woven glass fiber with reflective aluminum (not great for reducing heat conduction, but good for radiant heat transfer).

https://www.northamericanmotoring.co...=&ppuser=16996

I've also insulated the inlet manifold from the radiator hose and the SC exit horn. These are very hot items, and close to the air inlet manifold. Although the IC outlet air temps are not directly affected by the downstream intake manifold, it just seemed like the right thing to do, and very easy as well.

https://www.northamericanmotoring.co...=&ppuser=16996

Make a better IC diverter
The stock diverter, as many have attested, could use some improvements. It doesn't use the air from the right side of the scoop, it has only one fin to divert the air downwards, it leaves gaps on the left and right sides of the IC, as well as a big gap between it and scoop. You could buy the Alta version, or make you own that is probably better. Here is mine. It has 2 fins, and additional foam to prevent leakage. I've left the stock foam "U" in place. As you can see, my diverter extends much farther forward than than stock piece, so it can meet up with the scoop (more this later).

https://www.northamericanmotoring.co...=&ppuser=16996

To get the diverter to mate up well with the scoop, I found I had to remove the two front IC mounting brackets. These hold the diverter up too high, so if extended it runs into the scoop instead of under it. Here is a pic of the IC on the car. If you look closely at the far left side, you can see a black "undermount" bracket I made, so that the IC is at least held on 3 of the 4 corners:
https://www.northamericanmotoring.co...=&ppuser=16996

Open up the stock "mailbox slot", and eliminate the scoop - diverter gap

The stock scoop has two pieces - the outer painted part, and a black plastic inner piece. The bottom section of the inner piece forms an overly narrow slot, and also interferes with extending the diverter forward to eliminate the gap. Cut the bottom of the inner scoop off, like this:

https://www.northamericanmotoring.co...0&ppuser=16996

This probably gives at least 20% more area for flow. Next, glue some rubber strips on the bottom of the painted outer scoop, so they extend over your diverter. Here are the rubber strips I glued on:

https://www.northamericanmotoring.co...0&ppuser=16996

Since the rubber is black, you can't see them from the outside. The scoop looks totally normal. The idea is to have the scoop and the diverter mate up like this drawing tries to show, so that the engine can move back and forth without opening up a gap:

https://www.northamericanmotoring.co...0&ppuser=16996

If you do all this, what do you get?
Here is some data I logged today, under a variety of conditions. I forgot to mention in the table that ambient temp ranged from 60 to 62 F, so I used 61 F for the calcs. The best TEs are found during acceleration, probably because the thermal mass of the IC helps cool the inlet air during these brief periods. Averaging just the cruising values, though, gives 79.9% TE .

https://www.northamericanmotoring.co...0&ppuser=16996

If you do nothing else, take the first step and insulate the IC. I did the diverter/scoop mod first, but adding the insulation makes a noticeable in the seat-of-the-pants, particularly after idling the engine a while.

Also keep in mind, I have no OCC! So there is still room for some small improvement!

 

Excellent!

Where did you get the silicone foam?

 

This is exciting stuff here!
Now, I'm going to do some experimenting with the M7 DFIC and the Pegasus Racing insulation I just got in a box this week.

Yipee!

Paul

 

And the self-adhesive foil-backed glass fiber?

This is a great solution! (A really great idea - inimmini....) I really like this kind of out-of-the-box thinking....:thumbsu p: (Out of a possible 5 )

Edit: I have no idea what is causing the broken thumbsup. Mods????

 

Bold added by me.

Not true. I posted numbers using a GRS months ago.
In this thread

I've actually improved efficiency some since then.

Acceleration efficiencies, I have found, are always higher than steady state.
Good numbers though.

I do doubt if the insulation on the IC helps though. Insulation works both ways. It will keep heat out but it will also keep it in.
Like you I tested insulating the actual intake manifold. I found it made no difference in keeping the IC cooler. In either outlet temps or surface temps.

Some nice work though and I'm betting you had fun doing it

 

What craftmans ship Very nicely done...and you must disclose your source for the material now

 

I think the OP was referring to manufacturers posting efficiency ratings . . .

 

Very impressive work, inimmini!!
Thanks for posting.

I am also working on increasing the stock IC efficiency, although in a much different way. I am reconstructing two stock intercoolers to make one that flows ambient similar to the DFIC. The stock IC is actually pretty good, it's downfall is it's location and getting the ambient to flow through it. Since I can't change it's location, I can change the way air flows through it. I can also position it where I want it to take full advantage of the Ram Air Scoop.

 

Nice to see you're all interested in this. The aluminized glass fiber insulation is from Summit racing, part number THE-13575. It is probably the same as the material from Pegasus that others have mentioned. The silicone foam was something I had lying around. I've worked in many areas of thermoset elastomers, and I save things from various tests and trials. I've done crosslinked foams for lots of applications. The foam I used on the diverter was also the same kind of thing - a styrene-ethylene polymer that Sentinel polyolefins made into foam. The nice thing about it is that it molds itself to the underside of the bonnet when it gets hot. I don't know if it is commercially available. Silicone foam is available from McMaster-Carr, but I'm sure it is expensive. I imagine there are lots of insulation options for the front and back of the IC that are less expensive than silicone foam.

Obe: thanks for the ref on your TE tests. I do agree that insulating the lower inlet manifold will not help to lower outlet temps from the IC, but still, it should increase engine power potential to preserve the coolness of the air exiting the IC. I was interested to see that in the "show me your iridiums" thread, the change in spark plug appearance from left to right. I think the A/F ratio changes for each cylinder as the air heats up, traveling (after the IC) from right to left. Respectfully, I disagree that insulating the portions of the IC exposed to engine heat will have no effect on IC performance. Any part of the IC not exposed to cool outside air (i.e., only the top & fins) will just pick up heat from the engine. The back of the IC sees high temps from the exhaust manifold, especially during heat soak conditions.

 

Terrrific post picks up and incorporates many tidbit ideas that have been swirling around. Congrats on the numeric results .

It would be interesting to understand how fast this set-up dumps heat once it has built up heat soak. All the insulation while it may retard heat soak also inversely helps store heat.

My guess is that while you have accomplished some DFIC results at speeds, it can't replicate the DFIC temp drop velocity. May out perform the DFIC in temp increase velocity.

Love pioneer work !

 

Thanks, B!

However, with your post and obe's there seems to be some misunderstanding about how the insulation works. To your point above, the insulation itself stores very little heat, because insulators by their nature have low heat capacities. Insulators simply retard the flow of heat. Now, the portions of the IC that I recommend to insulate in no way retard the flow of heat into the cool air passing thru the IC. The top of the IC and the fins remain just as they were. The insulated IC parts (bottom and sides) are in fact exposed to typical underhood temps that are much hotter than the cool outside air, so in these portions of the stock IC the heat flows opposite of the way we want it - into the IC rather than out of it. There is absolutely no down side to insulating these sections. The net result is that a properly insulated IC is more efficient both at steady state conditions and in transients coming off a heat soak. Clearly, I can't say this set-up is better in transients than the DFIC, but it is definitely better than stock!

 

what about that foam that plumbers use to wrap the A/C pipes with? will that stuff work too?

 

That foam is very flammable, I would not recommend it.

 

so will this add as much power as the DFIC??

 

deleted due to double post

 

Agreed, the plumber's foam is polyethylene, and burns well, so it is not recommended. Two ideas for insulation on the IC ends that should be easy enough to find:
- foil backed glass wool insulation

- the rigid green type of foam used to stick flowers into for flower arrangements. Don't laugh - this is an isocyanurate foam, is very thermally stable, and doesn't burn well. Stick it on with silicone RTV, paint it silver, and it would probably work great!

 

McMaster-Carr (www.mcmaster.com) has adhesive-backed high-temp silicone foam available. Try P/N 8645K54 (1/4"x2"x3') or search for "silicone foam". Not cheap, but good stuff...

 

I thought that the areas that you covered while not directly part of the IC heat exchange process still exchange heat when air touches them and that by covering those sections you denied that transfer - for as little and as poor as it could be. Even though the insulator reduces exposed surface area, like you point out its surface area that is not part of the direct heat exhange process

I got it

 

Sorry I didn't see it until today....

A couple of items...

Will this work better than other aftermarket ICs? Really depends, but the price sure is a lot less! In general, I think the stocker is a good unit, and all the aircooling airflow improvements may finally allow it to perform to its potential. As far as the DFIC, it may well perform better, as the DFIC has a larger pressure drop than the stock IC. If you start getting better thermal efficiencies, then it's a win!

For TEs, they depend on so much stuff that there is no unique number that charachterizes an IC.

Obe: youre comment about better thermal efficiencies under acceleration is interesting. I've really only done work at red-line at WOT, but there it seems that the much higher charge temps and air volumes at WOT would lead to lower thermal efficiencies, not higher. I get the best TEs when I'm running at light loads. Same amount of cooling air, but much less intake air.

And there are lots of TEs out there.... Here are some more, all WOT in 2nd at red-line....
Stock 64.2%
Alta TMIC 61.0%
Alta Flow Through prototype 54.5%

Matt

 

--Good job inimmini! I've been watching the products that have been coming out for improving the IC and airflow in general for the MINI and I've been a little less than underwhelmed. Heat soak seems to be a really big problem when running for long durations throughout the day especially with a top mounted intercooler. That's probably why the first mods that the Subarus WRX and STI kids do is get rid of it and put in a front mount. Too bad for us our bumper space is non-existant without some heavy cutting and body kit mods.

I'm very interested in this as the average temp in Hawaii is about 85 degrees. Needless to say our oomph during acceleration suffers and it shows in the quarter mile times at the what used to be our track.

I am wondering about engine reliability though. Can you think of any adverse affects of insulating the parts you insulated? For example serious hard core racers have been known to tape their exhaust headers in the engine bay with thermal insulation tape and while that produces a cooler engine bay eventually it destroys the header which is all taped up because the heat has no where to go except out to the exhaust.

By the way I've also got to compliment you on your fencing skills here in the forum. Very good sportsmanship! You take criticism and opinions very well and only parry back with science, facts and good logic. Bravo! Keep it up!

 

The posted DFIC data was not done by M7 so what he was referring to was not manufacturers data. It was posted by Dr O.
Therefore my point is still valid.

 

Let me try to explain what I meant more clearly.

When acclerating, let's say from 30-65mph, WOT in 2nd, and you grab a point in time reading(~60ish) you can easily see figures like 175ºF In over 100ºF Out on an 80º day. This'll get you a 79% TE.

Then drop it into 6th and cruise at 65Mph until temps stabilze and you'll see 125ºF over 95ºF which sets you up at 67% TE.

This is based on real temps I've mapped in the past.

Thats why I like the steady state stuff. Easier to duplicate. If I'd cruised at 65mph in 2nd outlet temps would have shot up and efficiency would have taken a tumble. Once the IC core temp stabilzed the decrease in TE would have leveled out.

If the IC is x% efficient at cruise it will obviously perfrom well under acceleration condtions. If it's x+5% at cruise it'll do better.

 

Thanks for the kind words. On the durability question, I can't imagine that insulating the IC would cause any problems. The IC is nowhere near as hot as a header, and in fact the IC insulation keeps the IC cooler, which is just the opposite of the what the header insulation does for the header ..

 

"For example serious hard core racers have been known to tape their exhaust headers in the engine bay with thermal insulation tape and while that produces a cooler engine bay eventually it destroys the header which is all taped up because the heat has no where to go except out to the exhaust."

Is this true?

 

I like what you've done, inimini! Substantial progress can be made incrementally, and your mods suggest some of us have already come a long way. I am about to start a new scoop project, to increase the area of the hole in the scoop, and saw the Palo Uber (?) scoop on another thread--which has a large "gathering" area, but a very small hole through which the air must enter to get to the IC. Which raises the Q: what can we expect from a scoop that *rams* a lot of air into a small opening versus a scoop that just lets a lot of air get to the IC? Of course, I have a DFIC, so I can make the opening considerably larger than with a stock IC and still not worry about the air not getting to the IC. I'm just wondering what the equations say. I guess a larger volume of air traveling slower has about the same thermal transfer capacity as a smaller volume travelling faster...but I'm no physicist.
btw, mistro, those quotes about header wrap refer to mild steel headers rather than SS ones. The mild steel headers tend to rust away--that's what "destroying a header" means.

cheers,