Was it worth your time to post it's not worth your time? :gay:

I used the Ford Probe IC (bigger then Eclipse) and relocated the in/out tubes myself with propane and alumaloy rods I got at the hardware. I love those rods. It's like soldering aluminum. I run 10-15lbs with it. When I hook the wastegate (9lb spring) to the turbo outlet I read 8psi at the manifold. So at 9psi I only see a 1lb loss thru it. Not to bad for $10 at the junkyard. I'm looking into getting a larger IC now. I plan to relocate the AC accumulator to where the charcoal canister used to be. That give alot more room for centering the IC. Yeh... I kept my AC. :bigtu:

WOOHOO! I'm a veteran pro!
So, despite Jwarriners awesome explanation of IC design theory, we've found through a lot of experience that it really doesn't matter what IC you go with on these cars. Tall/skinny/short/wide/thick/thin/etc... The old Bell IC's were very small, and of the thinner/taller variety. The huge open mouth design of the Miata bumper means that plenty of air will always reach the IC/condensor/radiator. The problem with the Miata design has always been to get more hot air out of the engine bay. Hence the need for a splitter/NACAduct/scoop/dual-fan mod/water wetter/Randall cowl thing/headlight cover gap/and a few others.
Most of the IC's in the power range we're talking about will come in 2.5" inlet/outlets. Conveniently, that's the diameter of the throttle body inlet. You'll just need a englarging/reducing coupler coming off the turbo as I don't think I've ever seen a 2.5" compressor outlet. They're always 2" or 3". Corky did lots of experiments and found that for under about 400whp or so, there was ZERO difference in power delivery or ability between 1.75" and 4" IC piping. The advantage to smaller piping is that it's easier to route. I run 2" piping. Most guys run 2.5", which makes the hot side for the PS/AC guys a little more challenging. Cold-side routing there's plenty of room. Also, if you didn't want to spend the money on enlarging couplers... silicone responds really well to being boiled and "made" to fit over something larger... a little KY works wonders: https://www.miataturbo.net/forums/at...9&d=1161906523

For ease of installation and a proven product, the eBay specials for $100 that Brain and I linked above are hard to beat. You just have to fab a basic mount for it, but there are plenty of attachment points and a small piece of aluminum stock from Home Depot is about $5. You could go with the Starion/Saab/etc. and be totally happy as well. I chose mine because I loved the way if perfectly filled up the mouth of the bumper. It just looks "right" in there.

I'm really not as smart as I make myself out to be...

Most people will tell you to use the largest intercooler you can fit. While you want the largest surface area possible, there are other things to consider when sizing an intercooler:

1. Do not block a lot of airflow to your radiator. (The air passing through the intercooler will be hotter than in front of it)
2. Match the intercooler size to the engine's airflow for the most efficient system.
3. Too big of an intercooler wastes your money...the efficiency increase of utilizing runners longer than 18-20" is minimal at best.
4. Keep pressure drops across the core to a minimum, 1.5 psi at full boost max.
5. Quality can make up for size. A better conducting cooling medium, such as aluminum, will increase the drop in temperature.
6. Mount the intercooler so it can get the most air that passes over the fins.
7. Seal the intercooler and direct the airflow to increase efficiency.
8. 6-7 sq. in. of internal flow per 100BHP

Let me touch on #3 a bit. If your runners are say 40" long, you will recieve little benefit vs. an intercooler with 20" long runners....yes, the intercooler has doubled in length, but the cooling effect is minimal...think diminishing returns....if 20" can cool at an 80% efficency, 40" might be 82%.

and #1, the intercooler heats the airflow to the radiator...if you fill the entire mouth, the radiator will not work as effiecent, so you my have awesome air intake temps, but your water temps & cooling system could be compromised.

try to get as much airflow to both the IC and radiator, so seal the top area by the hood-latch, try a scooper from below and block the sides of the mouth so air is forced to pass through either one.

Size is a little important Sam, take Ben's latest dyno run. He's running a small Saab 900 intercooler; 15 runners 7.5" long x 2.5" wide; 13.85 sq. in of internal flow. He's seeing about a 36° increase in the manifold at 15psi of boost (74° to 110°). What's most likely happening is that the intercooler did not fully cool the charge before it exited out of the I/C. I'd expect to see that thing start to heaksoak (or maybe it was) after a bit of time. If another 5-10" of runner was on the same intercooler, I'd expect he'd have lower intake temps.

So lets take mine now for example, (which is still a bit small), It's bar & plate and 3" core; 16 runners 11" long x 3" wide; 18.18 sq. in. of internal flow. I was only seeing a 14° increase at 12.5psi of boost (82° to 96°). It could be due to a few thing, larger core, larger runners, bar&plate design etc.

Airflow could have played a big role on the dyno as well, as we have just a fan providing airflow....

but let me touch on #8 now:Ben's:
7.5 x .31 x 15 = 34.875 / 2.5 = 13.95 / 6 x 100 = 232.5HP * .83 = 193rwhp

Compared to mine:
11 x .31 x 16 = 54.56 / 3 = 18.18 / 6 * 100 = 303HP * .83 = 251rwhp

Compared to the 18" core:
18 x .31 x 16 = 89.28 / 3 = 29.76 / 6 * 100 = 496HP * .83 = 412rwhp

anyways, with all that said, I'd go for an intercooler that didn't fully block the radiator (or had provisions to scavenge airflow from below directly onto the radiator), had somewhere around a 18" long core, and had enough internal airflow to support a given HP range.

Corky Bell's new book is coming out in Aug and he redid his entire intercooling section, so I'm curious to see what his take on it is now, however, lately, he's been stressing the maximum 18-20" core size on people.

My thinking on the airflow to the radiator is simple. It's better to have warmer air than to block the core. Think of it this way, what does air temperature mean when passing through a core that has <140 degree air to a core that has >200 degree water? I hate bringing this up because you guys are gonna crucify me eventually, but on DSMs we found that a larger core that put the end tanks outside the width of the radiator was better than ones with endtanks that blocked the radiator, especially that passenger side that most of the water flows through.

Also, when you're drag racing, which has been my prior interest, your IC acts more as a heatsink than a heat exchanger. People would even cover them up (for aerodynamics) and just throw a bag of ice on them between runs, people like John Shepherd ran 8s with an air/air IC that was covered. There is an argument for a larger IC in this application.

I want to add a disclaimer. Is this right? Who knows. This is what the DSM guys generally accept as true. Did anyone ever do back to back comparissons mearuring water temp? I highly doubt it. In fact I can only think of one guy who went from an IC that had end tanks blocking the radiator and then went to one that didn't and this resolved some overheating issues. Did the IC solve it or was it merely coincidence? Nobody is going to know but when people do x and y happens they usually thank/blame x. I don't want to fight with anyone about this, it's so trivial it's not worth it. As Sam said, it doesn't seem to matter what IC people run, really.

define better.

Less overheating. I never had a problem with overheating on my Talon. It'd peg a certain temp and never go above or below but some people were plagued by it. When the first mass produced FMIC kits came out the most common one had end tanks that blocked the radiator. Almost immediately FMICs 'caused overheating'. Later a revision to that common kit came out that put the end tanks outside the width of the radiator, overheating was much less of an issue and people came to a conclusion and it became gospel. It's the same in every car community man, don't blame me for believing something that was drummed into me for eight years.

I like my little intercooler; it leaves half of the radiator exposed to air.

I look at the things that other people do and it amazes me.
Water cooled turbo = more heat in the cooling system
colder plugs = more heat in the cooling system
blocking the radiator = more heat in the cooling system
Then they complain about their overheating issues.

My solution is totally opposite, and I don't have engine temp problems. Will my IC heatsoak? Yes--but it depends on how the car is driven. I don't race my car, so it's not an issue. If I did, I'd turn down boost some. Plus my MS has IAT/CLT related advance. When/If we get closed loop boost control sorted, it also has IAT related boost control.

jwarriner has a valid point IMO. Get the endtanks (the part that can't allow air through) outside of the radiator, and even though the FMIC has more volume, it blocks less of the radiator's source of airflow.

BTW, Since last thurday I've been thinking about implementing some sort of an intercooler sprayer. I'm thinking just a mister with its nozzle in the mouth firing towards the ic. A small amount of water will dissipate a large amount of heat.

I'm doing a 30x12 intercooler install this week. It's a 24x12x3 core. I thought when others said 24x12 they meant the core, not the total size. Oh well. I have it now, might as well try it.

I was trying to figure if you meant better intercooling or radiator performance.

I have absouletly no cooling problems at the moment. The only thing I've done is simply, block the flow around the radiator, 1" aluminum radiator, $10 scooper to scavenge air below the intercooler into the radiator.

you do make a point, and that's why it's all a compromise and there really isn't "the answer"

Thank you once again to all that have responded and the compromise is understood between engine temps and IC temps based on size, placement and air flow.....

For intercooling I'd tend to err on the side of "too big", but I think the core these guys run, the 12x11 one is more than adequate for 300+hp, which is far above the average so it's great from the standpoint of intercooling. Personally, I, like Sam, like a core that fills the entire opening and I personally believe that it is better for the radiator as well but I have no actual data to back that up.

Mind you fuckface is up around my altitude, and he will have more problems up at 5800 than you will with overheating at lower elevation.

I am fuckface now? :cool:

It doesn't matter, you won't be around long anyway.

Give me another chance. I'll be good. I'd PM you but I realize you don't give a shit, which I understand. Not asking for any favors but I'll straighten up if you don't ban me. I think if you got to know me you'd see I fit in nicely here: I have thick skin, hate retards and children and am only partially an asshole.

I'm not even the one chompin' at the bit for a change :rofl:

If anyone has a problem with me they should publicly berate me, I'll get the point and I won't cry about it and ask for my posts to be deleted.

I don't follow the "err on bigger" whatsoever.

after thinking about it I really dont buy the endtanks block the radiator more. if you look at your drawing you leave exposed radiator surface for direct amibent airflow. Block the entire front opening, and not only have you heated the air, but the airflow is signifigantly lessened. The only non-heated air will be the little air that travels over the IC.

and if you have some endtanks in the way...well, the airflow should technically just go around it, as so:

https://www.miataturbo.net/braineack...er/airflow.jpg


however, the air exting the intercooler is heated, slowed & turbulent:

https://www.miataturbo.net/braineack...r/airflow1.jpg

so you block the whole mouth, the radiator's effeiciency will be diminised. Not to mention to get the endtanks out of the mouth requires about a 25-27" core, which is a baout 31-33" end-to-end, which doesn't leave you with much room as far as piping is concerned.

Sam, I -=>REALLY<=- hope that's not indicative of how y'all spend your free time on-base. :gay: