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Would there be a major dis-advantage to fabbing a duct for a non-stock SMIC out of sheet aluminum instead of fiberglass? Heat soak, etc, any other factors? I have zero experience with FG other than knowing it itches like a ****.
I am in possession of a regular-sized PFS SMIC. My preference is to maintain the stock battery location and air pump for emissions. I am running stock twins, engine has been rebuilt, stock ports. HP goal is 300'ish??? Whatever can be conservatively achieved with a PFC, DP, HF cat, catback, Efini Y-pipe and larger than stock SMIC. So basic bolt-ons and then a tune at somewhere around 12psi (12-10-12). Am I way off here?
I'd rather not drop another $600-1000 on another used SMIC that has a duct, but I have not completely ruled that out. I am unaware of any other ducts that are known to be compatible with the PFS at this point. None to roll the dice on only to find out that they won't work or fit as intended.
You could always wrap the bottom and sides with heat reflective tape. It would also be hard to imagine the duct heat soaking the air once the car is in motion. It would not transfer much heat based on the flat surface area and velocity of air going through the duct.
Just make sure it's sealed very well as air always takes the path of least resistance.
I don't see any problem with aluminum duct material either. Too bad you didn't get the PFS duct with your IC though...it's one of the better SMIC ducts out there IMO.
Sort of. I watch whatever the reading is that the PFC shows. Have not logged it. I don't even drive the car hard now and my boost is dialed back in the base tune IRP loaded until I go for the tune.
Originally Posted by jibe
You want something Like that?
Yeah. I'm thinking that's kind of what it will end up looking like. Thanks for the pics.
It may not be the prettiest thing but it will work. Ducting is important for everything from heat exchangers to brakes. You should see a significant drop in intake temps with a proper duct on a stock mount IC.
The PFS IC should be good for 12-13 psi. Probably more with AI. But with stock twins 12-13 psi is all I would run just for the health of the turbos.
Good to know. I just wanted to make sure I wasn't missing something, some unwritten rule of FDs.
I ran an entire season of track weekends using the cardboard mock-up of the I/C duct before I finished the aluminum version so... :P One event it was raining and the duct disintegrated so I made another from a pizza box in the paddock. Good times.
So I have finally made some progress on this duct. I was able to buy about 8sqft of .040 alum at a local place for $10.
No bashing but constructive criticism is welcome.
While it is not the most aesthetically looking duct, I think it will do the job. I will prob throw a layer of thermo wrap over it to make it look a little nicer. Pics of of it screwed together right now. Will pop rivet it once all fitment is done and I seal the seams.
I used the front half of the factory duct that goes into the bumper, and grafted on the rest that is fitted to the PFS.
Question/opinion #1: Should I eliminate the provision for porting air to the AC drier? I am leaning towards doing this.
Question/opinion #2: Should I fab up the cold air connection to the PFS airbox? I have an alum elbow that should work to make this connection into the side of the duct (3rd pic). Prob another hour or so of fabbing.
This is sort of a toss up. What is a more efficient use of cool air, sending it into the intake, or through the IC?
Appreciate the skills doing something like this. I can't fab a ham sandwich. But wondering...now that you have it put together, how much would it cost to take it to someone with a TIG welder and finished?
Appreciate the skills doing something like this. I can't fab a ham sandwich. But wondering...now that you have it put together, how much would it cost to take it to someone with a TIG welder and finished?
Thanks. Well what I was thinking was bringing it to where I got the material and seeing if they TIG and how much it would cost. Now that it is almost complete and I not that happy with my "flange" that I made to bolt to the IC. The piece I used was all Home Depot had when I started. So I am going to try and make it thinner and cleaner on the same visit to the sheet metal place.
Nice work Rob! We don't know what we're capable of until we try
As I recall the PFS intake duct grabs air from underneath correct?
If that's the case, I'd lean towards keeping the IC duct just for the IC. Keeping it sealed will def increase the efficiency of the duct for the IC core.
I also agree that the porting of air the A/C drier is better done in other ways.
Adding water injection will only aid in charge cooling so keep that in mind
Nice work Rob! We don't know what we're capable of until we try
As I recall the PFS intake duct grabs air from underneath correct?
If that's the case, I'd lean towards keeping the IC duct just for the IC. Keeping it sealed will def increase the efficiency of the duct for the IC core.
I also agree that the porting of air the A/C drier is better done in other ways.
Adding water injection will only aid in charge cooling so keep that in mind
From what I have seen all the PFS Airbox are fed from the duct. At least all the pics I have seen on this forum. Now the box I have is used and someone "cheap bastarded" it, two big holes on the bottom. I was thinking of trying to feed the box up past the rad, M2 style, or whatever that other Airbox is.
I may try and fab this "even cheaper bastard" duct and adapt it to the PFS airbox.
I'll give you my research notes since I'm doing work on the SMIC intercooler ducting right now too.
Observation #1:
The SMIC ducting works really well while the car is in forward motion. BUT while its stopped (traffic, waiting in the pits/paddock) it works badly as an "inter-heater".
Inter-heater mode:
The car is stopped, so no airflow through the front of the duct.
If the engine intake is tapped into the intercooler duct, things start to become ugly. The engine intake can start to reverse-suck hot engine bay air through the intercooler core, into the duct, heating both the SMIC core and the intake charge. This is bad. Very bad.
Mazda engineers revised the 1997+ cars to NOT tap the engine intake into the intercooler duct for the woeful reason above. The engine airbox intake just sucks a separate source of cold air all the time, and all was fixed. No more reverse flow interheater.
I've mentioned the reverse flow issues with tapping the engine intake off the SMIC duct before, and how Mazda solved it, but people ignored me in the past and I felt like I was talking to a wall.
Observation #2:
I've already got my airbox feeding from its own dedicated cold air intake scoop.
My SMIC has its own dedicated duct so there are no reverse flow crossover hot air issues from one system feeding from the other as I mentioned above.
I still see increased intercooler core temps while sitting in traffic. I've sat a digital thermocouple probe on the SMIC core and inside the SMIC duct and tried to work out why the inside of the SMIC duct is getting as hot as the engine bay while sitting still.
My finding is that when the engine bay gets hot enough and the radiator fans come on, they are pushing hot air backwards through the intercooler core , into the duct and heating the intercooler core and the duct in the process.
My fix for this (which I'm doing right now) is to build a mini shroud on the back of the SMIC core and mount a 120mm fan which runs at 1500rpm and moves 97CFM of air.
This fan runs constantly and ensures that even when the car is sitting still in traffic, there is 97CFM of cold air being pulled constantly through the SMIC duct and through the SMIC core, keeping the SMIC cold, and ensuring NO reverse flow of hot engine bay air can go backwards through the SMIC core and heat it up. It has a nice secondary benefit of force feeding 97CFM of cold outside air into the hot engine bay, pointing directly at the water pump area. Its a win-win-win setup and can be fabbed and built for under $100.
I am interested in how quickly the heat drops in the SMIC when driving at speed and fresh air is being forced through the duct and through the intercooler. I would imagine the heat drops very quickly and therefore the fact that the intercooler heats up in traffic or in the pit isn't that much of a concern unless perhaps you are exclusively drag racing.
I always take a slow warm up lap on track before really going for it and I would imagine by then the intercooler temps are more than fine. Actually, I would guess once you are above 30 mph or so the air temp in the intercooler has probably already normalised.
The car is stopped, so no airflow through the front of the duct.
If the engine intake is tapped into the intercooler duct, things start to become ugly. The engine intake can start to reverse-suck hot engine bay air through the intercooler core, into the duct, heating both the SMIC core and the intake charge. This is bad. Very bad.
Mazda engineers revised the 1997+ cars to NOT tap the engine intake into the intercooler duct for the woeful reason above. The engine airbox intake just sucks a separate source of cold air all the time, and all was fixed. No more reverse flow interheater.
My fix for this (which I'm doing right now) is to build a mini shroud on the back of the SMIC core and mount a 120mm fan which runs at 1500rpm and moves 97CFM of air.
I remember reading of the reverse-flow phenomenon but seems like that was with the stock IC/duct and only at WOT conditions.
I think it's just as likely that MAZDA discontinued having the intake scavenge air from the IC duct to simply increase pressure on the front of the intercooler...increasing the ducts efficiency. Seems like adding a fan and shroud at the back side of that IC will only be of some benefit while the car is standing still, but counter-productive while it's in motion since it will tend to add high pressure/interfere with air flow out the back side. Effectively reducing the duct's efficiency.
Originally Posted by NJ-JDM
From what I have seen all the PFS Airbox are fed from the duct...Pic of the way I got the PFS box (one at the bottom of the pic), with big holes to make it lighter.
You're right, in original form they all source air from the duct. I also modified mine ala cheap-bastard, but unlike the PO of your box, limited drilling holes to the surfaces that are actually exposed to ambient air.
My unscientific observations from the other week. It hit 80F in NJ. I took the car out at lunch. From dead cold to operating temp is just about when I hit the highway. I drove for about 13-15 mins at 70-80mph, AIT on the PFC read 40-42C. I was pretty much cruising, not that much boost overall.
The car sat at the Mazda dealer for about 15 mins, full heat soak, hood closed. When I left the AIT was reading 58C. I drove about 3 miles at 20-40mph to get back to the HW, temp really didn't drop that much, maybe a couple of degrees. Once I was back on the HW, I took it easy, but it still took at least 7-10 mins at 75-80mph to get the AIT back down to 42-44C. Stock IC, stock duct with airbox hole taped off.
I was surprised at how long it took to get the temp back down. Would that mean a larger IC would take just as long to cool off, or longer? I really want to add WI but I am hesitant to add another system and additional complexity to the car.
My unscientific observations from the other week. It hit 80F in NJ. I took the car out at lunch. From dead cold to operating temp is just about when I hit the highway. I drove for about 13-15 mins at 70-80mph, AIT on the PFC read 40-42C. I was pretty much cruising, not that much boost overall.
The car sat at the Mazda dealer for about 15 mins, full heat soak, hood closed. When I left the AIT was reading 58C. I drove about 3 miles at 20-40mph to get back to the HW, temp really didn't drop that much, maybe a couple of degrees. Once I was back on the HW, I took it easy, but it still took at least 7-10 mins at 75-80mph to get the AIT back down to 42-44C. Stock IC, stock duct with airbox hole taped off.
I was surprised at how long it took to get the temp back down. Would that mean a larger IC would take just as long to cool off, or longer? I really want to add WI but I am hesitant to add another system and additional complexity to the car.
Extend the lower lip of your stock duct with fiberglass or carbon fiber sheeting. You can capture much more airflow.
There are pictures on here somewhere of this sneaky mod. I think I recall Theorie did it, and some others.
I got some cf sheets here to make a new lid for my M2 intake box: https://www.rockwestcomposites.com
02-05-16, 04:13 PM
Fabbing a SMIC duct
