N54 water to air intercooler street build

Nov 20, 2017
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#1
Hi all, I have been wanting to do a water to air street build for a while, I realize that this is not the best way to spend my money to make the most power per $. I am a mechanical engineer, and for whatever reason, this project interests me the most. I like the idea of having the output paths similar for both turbos and the other *potential* benefits that this system could provide. This is going to be a slow project, as my day job and marital obligations wind up leaving me with little free time. If you are a person or a vendor who wants to replicate the project, I may be able to provide some guidance, I have no intent to commercialize the design. If you do commercialize it and make a better design, all that I ask is that you give me a discount on the final product!

Potential benefits:
1)The reduced charge pipe volume will slightly improve throttle response
2)The reduced travel distance, number of bends, and length of travel through the A2A intercooler may provide some marginal high rpm performance gain for stock turbos due to the reduction in pumping losses.
3) Possible sub-ambient cooling at some point in the design

Potential drawbacks:
1) Weight
2) System Complexity
3) Cost

My first selection was the intercooler itself. I searched far and wide for Water to Air intercoolers, and I was never really satisfied with my options. Out of sheer frustration, I decided to try the most obvious choice (OEM M3). I liked that it had dual inlets with internal turning vanes to guide the airflow, had demonstrated good performance, and was made to work on a car that had a similar engine layout.

To my surprise, it was not a close fit, it was an exact fit! It neatly mounts directly to to the stock intake manifold with the same rubber shock-absorbing mounts that the airbox uses!

But there is no way that the hood will close with that thing in there right?

Wrong! Hood closes fine and with room to spare. Attached are some photos that I have taken showing the clearance remaining after shutting the hood. (this is for a LCI e90)

As you can see, the OEM expansion tank will also not require any modifications.
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Jan 24, 2018
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#2
Interesting. Do you have any more pictures of how that thing sits in there?
 
Jun 4, 2017
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#4
In for more pics! Best of luck man!
 
Jan 28, 2018
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#5
Last edited by a moderator:
Jul 27, 2017
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#7
Everyone wants an N54 you can pour ice into before a big pull :D:D:D
 
Oct 28, 2017
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#7
Do you know what total cost would be I would do this just to look sick lmao
 
Jul 27, 2017
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#8
I like your thinking OP, doing it for fun and not worrying about costs too much.

I found that on the rare occasional warm English day when I got to a drag strip that the IATs just rocketed from sitting in a queue to race. No airflow over the intercooler and heat soak under the hood often meant being most of the way down the track before the FMIC could do it's job. I considered a water system. I wanted to just spray icy water over the outside of the FMIC to keep things simple. I already use methanol injection for chemical IAT cooling under throttle. Which works great tbh. Spraying water on the outside of a FMIC seems to work quite well but it's obviously a big no no on a drag strip. The drops will pool on the rubber track and you'll be kicked off. It's fine spraying water during road use and you don't have the need to recool heated water. The cost being to replace the water or ice after each tank. With a pump system of course that then means monitoring the tank level and not letting the pump run when dry, burning itself out.

So like you I went for a DIY project without worrying about actual expense. Just for fun more than anything. I got a CO2 tank, Nitrous solenoid, nitrous lines, switch and some wires and hooked it up to spray liquid CO2 on my intercooler.

I haven't yet had the chance to dry it at the drag strip. I do actually need to make a slightly better outlet to hit more of the FMIC and distribute the cooling more effectively. It was fun. Should be potentially quite effective from the massive temp gradients but I doubt it is cost effective. I have the button in the cabin and pressing it simply opens the solenoid, spraying the gas.

Test outside of the car:

multiple nozzles:

Single nozzle:
 
Feb 6, 2018
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#9
I like your thinking OP, doing it for fun and not worrying about costs too much.

I found that on the rare occasional warm English day when I got to a drag strip that the IATs just rocketed from sitting in a queue to race. No airflow over the intercooler and heat soak under the hood often meant being most of the way down the track before the FMIC could do it's job. I considered a water system. I wanted to just spray icy water over the outside of the FMIC to keep things simple. I already use methanol injection for chemical IAT cooling under throttle. Which works great tbh. Spraying water on the outside of a FMIC seems to work quite well but it's obviously a big no no on a drag strip. The drops will pool on the rubber track and you'll be kicked off. It's fine spraying water during road use and you don't have the need to recool heated water. The cost being to replace the water or ice after each tank. With a pump system of course that then means monitoring the tank level and not letting the pump run when dry, burning itself out.

So like you I went for a DIY project without worrying about actual expense. Just for fun more than anything. I got a CO2 tank, Nitrous solenoid, nitrous lines, switch and some wires and hooked it up to spray liquid CO2 on my intercooler.

I haven't yet had the chance to dry it at the drag strip. I do actually need to make a slightly better outlet to hit more of the FMIC and distribute the cooling more effectively. It was fun. Should be potentially quite effective from the massive temp gradients but I doubt it is cost effective. I have the button in the cabin and pressing it simply opens the solenoid, spraying the gas.

Test outside of the car:

multiple nozzles:

Single nozzle:
ob
Nice job! I have been contemplating making a setup similar to yours. It would be great if you could report back and give us some real world data on how much your CO2 setup can drop IAT’s. Did you use meth nozzles or what? Heat soak while sitting at lights and in traffic is very noticeable. I will often see IAT’s as high as 140F while in traffic, I’m sure the strip would be similar or worse!
 
Nov 20, 2017
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#10
Interesting. Do you have any more pictures of how that thing sits in there?
Sure, I can get more photos, what would you like to see?

Pretty cool for sure. There's an N55 135i guy that's done this and he seems to like it. Running an EFR7670 with it. I'll be following your build for sure.

Here's the other guys if it helps any. http://www.n54tech.com/forums/showthread.php?t=50300
Thanks for the link, I had no idea, thought I was the first!

I brought up the idea on a previous thread. The question i had was this.
If we replace the existing transmission cooler with an air over cooler(wheel well) style. Does the existing water cooler have the capacity to cool a water/air intercooler?
The existing water cooler is the engine radiator system which targets a temperature of approx 200f. This actually serves the double function of heating the transmission fluid since the engine warms up more quickly than the transmission, and cooling the transmission when the fluid temperature exceeds the radiator temperature.

I am hoping to target ambient +5deg through +15deg or whatever is the lowest feasible target given the system design currently.

In short, no, the radiator will not work to cool the charge air.

These are an interesting option, but I am desperately trying to design this system without compromising my AC system, it's just too hot for me otherwise.

Do you know what total cost would be I would do this just to look sick lmao
Really depends on your level of talent, and how many tools you have. I refuse to weld this project because I know that it will result in excessive build time, scrapped parts, and a crappy finished product.

Budget for:
Inlets~ $350
Outlets~ $150
Used Intercooler ~$350
Custom Heat exchanger ~350-$600
Pump ~$100
Misc hardware/wiring ~$150
Fabricator $$$?? hoping to get out for under $500?
 
Nov 20, 2017
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27
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#11
I like your thinking OP, doing it for fun and not worrying about costs too much.

I found that on the rare occasional warm English day when I got to a drag strip that the IATs just rocketed from sitting in a queue to race. No airflow over the intercooler and heat soak under the hood often meant being most of the way down the track before the FMIC could do it's job. I considered a water system. I wanted to just spray icy water over the outside of the FMIC to keep things simple. I already use methanol injection for chemical IAT cooling under throttle. Which works great tbh. Spraying water on the outside of a FMIC seems to work quite well but it's obviously a big no no on a drag strip. The drops will pool on the rubber track and you'll be kicked off. It's fine spraying water during road use and you don't have the need to recool heated water. The cost being to replace the water or ice after each tank. With a pump system of course that then means monitoring the tank level and not letting the pump run when dry, burning itself out.
I like these projects too, just have to be careful that you are not creating a CO2 cloud that will rob your engine of horsepower. These systems used to be quite popular here among the turbo crowd but seemed to have fallen out of favor in recent years.
 
Jul 27, 2017
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#12
I like these projects too, just have to be careful that you are not creating a CO2 cloud that will rob your engine of horsepower. These systems used to be quite popular here among the turbo crowd but seemed to have fallen out of favor in recent years.
Yes that was my concern as well. So I'd only ever spray it before the run and not during. Luckily co2 is heavier than air and should fall away.
The other option of course is to spray nitrous. There was a guy who posted a video where he has a double walled intercooler and he sprays nitrous around it. Looked good.
 
Jan 24, 2018
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#15
Sure, I can get more photos, what would you like to see?
Particularly interested in how the (is it the exchanger or the IC up top?) sits oriented to the intake manifold. A closer picture from over by the intake mount peg might help. Is that the N54 IM on there or did the S55 one fit? I'd also like to see a photo of how the IC outlet is oriented compared to the throttle body. Is it a straight shot, or offset? Obviously it's not going to be a straight pipe between the two but I'm sure you get my gist.
 
Jan 24, 2018
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#17
Maybe you can look into the specs on the m4 gts cooler
Do you see a difference? I was under the impression the biggest difference in that car was tuning and a "water injection" system.
 

doublespaces

Administrator
Oct 18, 2016
6,551
1,849
AZ
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#19
I like your thinking OP, doing it for fun and not worrying about costs too much.

I found that on the rare occasional warm English day when I got to a drag strip that the IATs just rocketed from sitting in a queue to race. No airflow over the intercooler and heat soak under the hood often meant being most of the way down the track before the FMIC could do it's job. I considered a water system. I wanted to just spray icy water over the outside of the FMIC to keep things simple. I already use methanol injection for chemical IAT cooling under throttle. Which works great tbh. Spraying water on the outside of a FMIC seems to work quite well but it's obviously a big no no on a drag strip. The drops will pool on the rubber track and you'll be kicked off. It's fine spraying water during road use and you don't have the need to recool heated water. The cost being to replace the water or ice after each tank. With a pump system of course that then means monitoring the tank level and not letting the pump run when dry, burning itself out.

So like you I went for a DIY project without worrying about actual expense. Just for fun more than anything. I got a CO2 tank, Nitrous solenoid, nitrous lines, switch and some wires and hooked it up to spray liquid CO2 on my intercooler.

I haven't yet had the chance to dry it at the drag strip. I do actually need to make a slightly better outlet to hit more of the FMIC and distribute the cooling more effectively. It was fun. Should be potentially quite effective from the massive temp gradients but I doubt it is cost effective. I have the button in the cabin and pressing it simply opens the solenoid, spraying the gas.

Test outside of the car:

multiple nozzles:

Single nozzle:
This deservers its own thread, in fact, you should post this here:
https://bmw.spoolstreet.com/threads/c02-n20-fmic-sprayer.1105/

N55 with a Speedtech kit IIRC but he used all OEM parts.

Could you explain how he uses a speedtech single turbo kit with OEM parts? There has to be some custom piping involved?
 

KevinC39

Specialist
Jun 27, 2017
99
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#20

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