blwn rtr 89'

iTrader: (5)

Im currently at the point where im setting up the fuel cell install (15 gal ATL) and out board pump and cage install (upon receiving of welder), and i am still debateing fmic v/s vmic setups. as i have some extra time on my hands, i had an idea to reduce the heat soak problem with most fmic setups in DD,

well its just a thought so let me know what you guys think (though i will attempt this anyways to test if it really works or not)

i want to fab an aluminum casing, around a koyo rad, use 1 large e fan, duct in to the sun roof, exti out of the rear hatch or a cut out space near the mounting position of the fuel cell, to form a air flow path, and have the case enclosed. i only have 1 seat as of now, and the rear hatch has no window and is being finished off when i get more money. run coolant hoses through cabin, and possibly come up with an idea for a electric water pump not based of rpm's to maintain a consistent flow.

once done i would have the complete front to box vent and mount an fmic more towards the CG of the car, as well as prevent heat soak in summer traffic. and to improve cooling.

yay or nay.

i think it would be cool enough to try and test

thoughts?

Hypertek

iTrader: (3)

Id stick with a fmic setup with vented hood, Just make some really good ducting, have a duel electric fan setup with custom shrouding. If you do rear mount setup, possibly **** poor air flow, and your going ot change the aerodynamics of the car trying to cool that thing *potentially create drag or lift at the rear end= no bueno*

blwn rtr 89'

iTrader: (5)

flow over the car is something im real worried about a roof vent where the sun roof shouldent interfere with much or cut a duct in the rear quarter panel on both sides, or even duct from underneath. it will exit from about a 1.5ft by 7 inch vent thats intergrated where the rear window currently is, i need to find the most concentrated flow line and duct it directly the case, as well as some auto cut off switch for the e fan if the flowing air exceeds the movement of the fan through the case.

the CG wont be to off if the rad is mounted horizontal, and the weight distb. more centered due to the added weight of the fmic positioned more towards the center of the car.

no one on speculation?

Aaron Cake

iTrader: (1)

OK....

Why? FMICs don't have big a heat soak problem like the TMIC. Sounds like this setup would take up the entire hatch area...

ericgrau

iTrader: (1)

I don't think you could get enough flow through the sun roof. I'd think it would be easier to increase the flow to the front. Basically cooling is proportional to temperature difference. So, for example, if you want to cool a 180 degree radiator with 120 degree air (180-120 = 60), you need twice as much flow as you would with 60 degree air (180 - 60 = 120).

blwn rtr 89'

iTrader: (5)

your going to tell me that FMIC's do not have a heat soak problem......

sure its manageable, but i dont need to tell you how hot the air is by the time it passes through the rad, let alone sucked through the filter and back through the same system. the fender wall is no where near big enough to get any thing but ambient air its just 1 hot box.

VMIC will continually heat up if the car is not moving fast enough or in a stop and go situation.

the setup im proposing is not very discrete, it will take up most of the hatch area, but will free up so much more, true cold air intake, FMIC with shorter pieing for better response , mounted inward enough to be ducted with the stock clutch fan, enough space to run straight panels right to the ic(ducting), more protected should you go off roding at the auto-x, and most importantly a radiator completely cut off from all possible heat loads from other components with consistent non-RPM bias flow. all im hung up on is the most efficient way to duct the air box that would be in the rear hatch effectively enough.

does this not sound like a concept worth recording results, or am i just wasting my time?

Aaron Cake

iTrader: (1)

ANY intercooler can have a heat soak problem, but in this case it is NOT caused by the fact that the rad is behind the intercooler.

The intercooler sits in front of the rad, and thus air passes through it first.

Maybe I'm confused, but we were not talking about "V" mount intercoolers.

And then some...

Keep in mind that you need some rather serious ducting to bring enough air through the rad. Look at the size of the stock bumper opening for an idea. You'll also have to enclose the whole thing in a bulkhead to prevent any issues should a cooling pipe/hose rupture or the rad fail. This will effectively turn your rear end into a major blind spot. And you will need to cut a huge hole behind the rad to let the air back out.

I'd be willing to lay down a lot of money that says you can't tell the difference between 3.5 feet of intercooler piping and 4 feet. There is nothing preventing you from sending your intercooler pipes right through the rad supports which significantly shortens the run compared to going behind the headlights.

A FMIC is already "ducted with the stock fan".

You can do that anyway on any front mount...

Just don't mount the intercooler at the lip of your front bumper. Move it in a little and there's no issue. Why people stick their FMICs right on the plastic of the bumper lip is beyond me....

What does this mean?

Do you mean that the heated air from the FMIC and oil cooler no longer pass through the rad? Not really a big deal...

The stock clutch fan or an aftermarket e-fan already provides a "constant non-RPM biased flow".

I'm hung up on why you want want to make such a radical modification for no benefit.

That would be "Option B for $1000, Alex".

texFCturboII

iTrader: (17)

Interesting concept, but I really don't see any benefit. I'm with Cake, there would be WAY too much work involved for WAY too little payback. Just get a nice Aluminum radiator and call it a day.

NoDOHC

These Ideas are awesome and should be recorded for use on a rear-engine car such as a Porche or Fiero or Volkswagen Beetle (the older ones) but a front-engine car already has a nearby source of cold air and very convenient OEM cowling to use it.

The RPM dependant fan is a GOOD thing, do you think that the intercooler needs the same airflow to cool the intake charge at 7000 RPM as it does at 1000 RPM?

As Aaron said, you need to reseach front mount intercoolers for the RX7 for practicality. If you have lots of money/time and want to do this for fun, go for it.

blwn rtr 89'

iTrader: (5)

im aware VMIC is not the topic, this is a relative alternative to both ( benefits of both drawbacks of none)

ive looked further into my concept and ducting from directly under the car would flow more than enough air into the enclosed bulkhead to be more effective than the front air duct, as well as serve as a diffuser when ducted out my rear hatch.

i am not concerned about blind spots, my rear hatch (currently being molded) is more or less a flat CF panal contoured to the curvature of the stock window, so there is no window hence already a blind spot.

a duct along that, near the bottom of the hatch will create a suction pulling air from underneath, through bulkhead, out hatch.

so basically a big diffuser with a rad in the middle.

with the UIM and turbo header i have in mind its more like likely ill end up needing 2.5 feet of pipeing or less (depending on how i mount end tanks)

that is true, however the consistent non-RPM bias flow i am speaking of has to do with completely disabling all load from the engine, a electronically motorized water circulation pump ( alt. will need to be changed for a unit with more charging capacity)


my whole goal, is a more responsive turbo set up, more efficient cooling abilities, improved platform for torque, equal weight distribution as to compensate for every thing taken out, eliminate the need for a extra ugly expensive diffuser, 1 bad *** endure-o car (im still reading up on SCCA class rules to see if this is legal in what classes)

rx-711

iTrader: (2)

there was a rwd impreza for drifting with this

blwn rtr 89'

iTrader: (5)

if you run a 130mph pass with peak RPM of lets say 8000k, slow to about 45mph, accel to 60mph, your cooling system will not be as cold as if your coolant flowed (as well as your fans) at 8000k level constant (assuming thermostat is fully open)

alexdimen

iTrader: (13)

Why are you asking? You've obvioisly got your mind set on it.

Black91n/a

I think it's a totally rediculous project. Sure it might be made to work, but it won't be worth the effort or the compromises.

NoDOHC

If you can find an electric fan that flow as much as the stock RX7 fan at 7000 RPM (if it stays clutched in) Buy two, I want the other one.

My only point there is that you need more cooling for higher engine speeds.

Either way, the airflow due to vehicle speed will make up the difference on a FMIC, because the FMIC has low pressure air under the vehicle on one side and high pressure air (at the front of the vehicle) on the other end. Where you will get very little help from vehicle speed, as you will have to pump low pressure air from under the car into low pressure air behind the car.

Also, be careful of people telling you that there is no load from an electric fan/water pump. If there is really no load, you have just discoved perpetual motion.

Not only does an electric fan or water pump load the engine (through the alternator) but it stresses an already taxed electrical system. A fan like you seem to want is going to really tax the electrical system, as it will most likely pull 30-50 Amps.

I am not saying that this will not work, I am only arguing that you have better places to spend your time and money. If you really want to do it, go for it. If you do a good job, my hat will be off to you.

blwn rtr 89'

iTrader: (5)

black91n/a if there is some compromises ive over looked please elaborate.

though im set on attempting this, ive posted to get possible ideas for improvement of the concept.

the electrical system (which lacks as is ) is something ive longed to improve for quite some time.

i will most likely make my own cooling fan and electric water pump using a brush less synchronous electric motor that eliminates the need for a commutator, have far greater longevity, torque, and efficiency. way over powering any after market POS e-fan out there. the water pump consisting of an impeller blade and small out board casing.

how to completely mount the bulkhead and selecting a core, and UIM designs are up to debate, this is what i need help on.

blwn rtr 89'

iTrader: (5)

im one step away from just tube framing the ******* thing, but then it would not be street able at all. so i really dont have anywhere else to spend some cash. time yes, but i work on cars most of the time this is way more fun than replacing some asian dude lifters in his accord.

NoDOHC

I am all about projects, I like them and have a few myself. I think they are educationally, psychlogically and physically benefitial. This one will be challenging and could be quite fun. In the end, you will have a one of, a truely unique setup.

I can certainly understand your take on this subject and it is refreshing to hear someone with ideas other than performance.

If you get a brushless DC motor fan setup, I would seriously like to find out how much it costs, because I have a friend who needs a bigger cooling fan, his car overheats at autoXs.

A Ford taurus fan is the best OEM one, or so I have heard. I don't know what your air flow will be, but if you can figure that out, the rest is easy math.

blwn rtr 89'

iTrader: (5)

well ive found a motor that effectively spins at 10k under 6 amps of current, 3.5 turn brush less, but ill have to do heat tests and the fan blades must be made of something extremely lightweight or use something larger than a 540 class electric motor. and ive gotta get rid of the middle man to cut cost.

NoDOHC

You will need more than that.

6 A X 14 V = 84W = 0.1 Hp (that is assuming 100% efficiency.)

You will get almost no air movement.

A Taurus fan moves 3500 cfm (I think) and pulls about 60A. This is about 50% efficient so you will have about 50%X14X60=280W = 0.6 Hp this is only through a radiator, not an intercooler.

In your location you will need much more than that.

I have a friend who can't keep his car cool with a Taurus fan. He is making about 240 WHp and overheats at autoXs

On the interstate he is ok, because he has the added effect of the moving air, which is about eqivalent to the maximum output of the fan at 45 mph, or about 5500 cfm at 65 mph. When pulling a long grade on the interstate (or accelerating to pass someone) his temperature will increase.

If you are autoXing your car or driving it on the track, you will probably need 6000-8000 cfm of air for a high performance (300whp) setup (remember that you don't get much help from vehicle speed).

Because moving air has power P = Q*dP (where Q is the flowrate and dP is the differential pressure across the radiator), we can do a little math.

Across an intercooler (2" water) and a radiator (3" water) you will require at 100% efficiency 8000cfm*5"water of power. Converting to metric this is 3.8 cubic meters of air per second at 1.3 kPa = 5000 W This means that you will need 350A from your battery/alternator to turn this awesome electric fan.

If the cars aerodyamics give lower pressure at the rear than under the car (which they probably do) you will get some help from that. The aerodynamics diagram does not show the ground effect forces on the bottom of the car to allow me to make this judgement.



You can see that the air pressure in front of the car is much higher positive than the air pressure behind the car is negative.

In the end, maybe you only need a 200A fan to acheive this goal, but I think you understand why this is going to be difficult.

Please don't take this wrongly, I don't mean to be a naysayer, I am merely saying that the 6A motor WILL NOT turn a fan of any respectable size at 10,000 rpm.

Thanks glhs0867 for the aero flow diagram.

blwn rtr 89'

iTrader: (5)

that was a bad thing to post 6amps will not throw down the power i need

this http://www.motioncontrolgroup.com/pr...-XXXX/overview

should do justice

slo

iTrader: (1)

I found a solution to the FMIC blocking the radiator issue, its called methanol injection. It allows for sub ambient intake temps, in combination with healthy increases in throttle response, excellent decreases in EGT's, decrease of combustion temps and knock. The system I set up controlled by the haltect was cheaper than my ebay setup FMIC that I had before and provides for excellent fail safes incase something goes wrong (easy to do even without a haltech actually.)

Black91n/a

There's always more compromises than you think when doing something like that, and it'll depend on the actual installation, so I can't list all possible ones. Also, thinking you can live with something and actually doing it are two very different things.

classicauto

iTrader: (3)

Post pics of this said CF hatch glass and your FC Lab Rat.

I'll check back to see when this is fully completed and running

1) There's no need to run your cooling system at the requirments for full load, when you're only running at 2% capacity. You'll burn out the EWP faster, thats all. You won't get any "cooler" water, and besides *if* you did - there's this thing called "Operating Temperature" thats actually quite important.

2) Ducting out the bottom of the car? Are you ******* serious?? Please show me where you plan to hack saw a giant vent through the bottom of your car and maintain the structure, the drivetrain, the gas tank.......

3) A CF Rear window? If you're checking into SCCA rules about your drug-fueled radiator setup, why don't you check and see if there's any rules regarding visibility out of your car.

4) This is a streetcar I'm venturing to guess since I see mention of low speed heat soaking problems that you're trying to avoid. So why no rear window?

5) Will this work? Sure, I've done similar mods to off-roaders that have a true concern for damaging rads.

6) Will it be worth the hassle? Considering that you can get better/same results without deleting you rear window, your passenger seat, your sunroof, your ability to NOT have a cabin full of 180 degree coolant hoses, your rear hatch area and part of the car's floor - I'd say a resounding "NO".

7) How does ANYONE drive a rotary powered car with a front mount? Or V mount? or NO intercooler? Pishaw, they must be boiling over every three miles as there's such a problem with these setups that surely the entire car must be built around the funcitonality and seperation of the rad

8) I'm all for new ideas.....but....holy mackrel, this just makes my head hurt. Only thing that could make it hurt more would be pics of this completed - so please feel obliged to take some.

blwn rtr 89'

iTrader: (5)

i will post pics when in complete....

right now the said CF window is just a fresh molded fiber glass set in, the full on CF hatch/window is coming as soon as i prefect my method of molding, its not easy to get all the weaves lined up if you have never messed with CF before. its getting quite cold here so i think ill try resin first than setting it while its cold. unless someone can chime in with a secret.

to make a long story short, i think it would look good good w/o rear window, and they make a thing called a camera that works fine when pointed backwards.

gas tank is going on account of fuel cell, though im still debating what size cell to buy 5 or 15?

i plan on cutting ducts where the rear passengers feet would be, maintaining a 2 seat car, not ducting sunroof anymore.

i have a 12 point cage still not all the way in the car, im sure if i add a bar or 2 the integrity of the car will be maintained properly.

the idea is the impeller pump and cooling fan both work together to maintain a constant operating temp read through a temp sensor, and will respond in steps to keep the car cool (at decided temp) regardless of outside temp. so it will run equal in 5 degree weather and in 90 degree weather.

now if i can effectively complete all of this for under $800 ill be a happy guy (not including rear hatch)

and figure out a way to mount 1 wideband O2 sensor per rotor, and not burn it out in 2 weeks my car would be tuned so easily its disgusting.

you probably can do all this with a window, but i say nay until i find a SCCA rule that says i need one.... you dont need to look at whats behind you anyway.