m-svt-amg

honestly, it looks to me like 15.5 is generally where people have trouble. The 77 upper and stock lower make 14.4, and maybe a bit less with headers.

I plan on running a 77fsp with mbh headers with a trunk tank and extra heat exchanger, getting the tune dialed in, then calling it done. If my tuner says get injectors i will. I hear the looped fuel rail isnt worth it.

Just enough so my sl55 can keep up with my lightning.

Josh154

About to order that cwa50. Just wanted to clarify its a direct drop in? Anything else I will need to do the swap?

m-svt-amg

You might need to modify the bracket a bit, the new pump is a bit heavier.

Josh154

Sweet just ordered it up. I'm guessing I will need to buy more coolant and somehow bleed the system?

m-svt-amg

I clamped the hoses right before and after the pump so minimal coolant was spilled. Bleeding is always a good idea. You might also considering rewiring the pump to always run when the engine is on at the very least.

Im no sure if i mentioned this, but the sl55 shares ic res with the engine coolant res, which starts off pretty hot. I recommend fabtech split cooling if youre not looking to do a full trunk tank. A member here, latemodel21, like to mention its a good idea to add an ic bleed at the top of the heat exchanger

Josh154

So my dad got the car today. I drove it and did a few launches, very impressive! He wouldn't race it against my truck today but they should be really dam close. I had the esp or whatever off and couldn't really get it to spin. The car has brand new 285/35 michelin pilot super sports on it. We are heading to the track on the 20th to run it.

Intercooler pump should be here Wednesday, i watched a few videos and seems real easy to do. Will the electrical plug from the cwa 50 plug in or will i need to cut and solder?

latemodel21

The CWA50 needs a plug and 3 pins that you can get from BMW for about $10 ...
you will need to add a resistor (1000 ohm will do) to pull up the PWM signal (pin 3) line at the pump.

here is some info on using the pump.

and a picture of some splice on "pigtails" for the CWA-50

and a picture of an adapter harness I made so I did not have to splice

and a few pictures of the mounting bracket I made to install the CWA 50 in my SL55

hope that helps.
Chris

Josh154

Thats helps a lot thanks chris. Do you have a part number for this plug and pins? So basically you just make your own adapter that goes from the cwa into the stock sl55 harness?

Basically i need that bmw harness even if i want to splice into the factory one?

latemodel21

I am not aware of a pig-tail that is ready made (all pics were ones that I have made).

the parts you need are a 1000 ohm resistor (current is trivial, but 1/4watt or larger is physically up to the task).
some wire (awg 22-18 works fine ... I like orange, brown and violet for this harness)

and these parts from BMW

1 x 12527549033 Plastic Socket Housing
3 x 61138366245 Rubber sealing grommets
3 x 12527545858 Individual Socket Pins

In order to make an adapter harness (like I pictured), you need to source the connector off of a bad coolant pump (or off off a Windshield washer pump) as I have found no source for this connector. .... Which is why the splice method is the most practical for most.


Cheers,
Chris

Josh154

so for the splice method i will still need those parts from bmw?

latemodel21

Yes,
the parts list (including resistor, wire and 3 BMW part numbers) is to make the "pig-tail" shown in my first picture above (2 complete pig-tails in that picture). You then either (your choice) splice that "in place of" OR "in parallel with" your factory plug.

"in place of" is the cleaner way ... but "in parallel with" leaves the window open to reuse the stock pump (if you are removing mods and selling car, etc)

Cheers,
Chris

Josh154

Ok i understand now i think. So there is only 3 wires going to the factory pump and that is why i need the 3 pins and pin seals? That connector from bmw will go into the cwa 50 and the pins will go onto the ends of the wires that originally went into the factory pump? Where does this resistor go?

Thanks for the help man i appreciate it.

latemodel21

The resistor goes from pin 4 (+12v) to pin 3 (PWM) of the new connector. An easy way to add the resistor is to have it go from a wire (going to pin 3) to the wire that goes to pin 4. Make this junction at your splice (to the factory harness).

here is a pic of this junction (right before I added the mercedes connector that made it and adapter harness). I also included a couple of pics of re-tasking the WW reservoir connector for the harness.

You may want to look through the PDF I attached earlier for more info.

Cheers,
Chris

Josh154

So we went to the track on Friday. Let the car cool down for a good hour and half with hood open before making a pass. My dad was driving the car, esp off no burnout resulted in a 13.5. Second run he jumped and third run was a 13.9. The track was pretty cold like 55 degrees. The car hooked good though with the 285 pilot super sports. 60's need some help Forsure. We left the hood open the whole time in staging and left it shut off.

The cwa 50 was not on the car at this time, to me it sounds like the car was heat soaked as it should be running a good 12.5? Here's a slip, the time is on the left.

m-svt-amg

Turning off the car might be what hurt your temps... the pump doesnt run while the car is off, so you were likely heat soaked right off the line (probably what hurt your 60 ft too)

m-svt-amg

Id recommend getting an obd scan tool and logging temps next time out

Josh154

So leave car on hood open to keep coolant circulating? I have a edge insight cts2 for my truck, it's all ran off obd2. Can I hook that up and view intake temps?

m-svt-amg

Yup. Some people install a switch to enable their IC pump to run when the car is off, or some wire it to run whenever the key is on.

I dont know what an edge insight does... but if it reads obd2 it should

Josh154

Ok sweet. Well the next track day is in a month. I will get that pump put on there and leave car idle in staging. All I need is that resistor

m-svt-amg

That should help you see a big improvement. Also remember, the ic coolant uses the same reservior as the engine coolant, which starts off at almost 200 degrees on a warm engine.

I highly recommend split cooling.

A lot of people like to put in an oversized tank so you can fill it with ice for a track run. Some people put in a tiny bottle and essentially create a closed loop system like a cpu water cooler in a custom computer.

There are positives and negatives to both.

Josh154

Makes sense. So if engine coolant is 200 degrees that means intake temp is going to be the same temp as coolant?

m-svt-amg

If your pump isnt flowing... yes.

When your pump flows, it takes the 200° coolant through the heat exchanger. If your car is in a staging lane, the heat exchanger isnt getting much airflow over it, so the coolent effect is reduced. While driving, it gets lots of air over the core of the exchanger, and cooling is much more effective.

For the closed loop system, you can expect to have hotter starting temps out of the hole, because you werent moving to bring down the core temps which in turn bring down the water temps. But, your water will cool.down immediately when you start moving and you might be a little colder near the top end since the system has very little volume to cool down and the car is getting lots of head wind through the exchanger.

For the big tank system, you can sit in the staging lane circulating water that hasnt been through the hot part of the system for up to a few minutes. This helps keeps temps down while sitting, but they can slowly creep up, meaning you might not see them drop very quickly once you do get air over the exchanger since they have such a large water volume to cool off. The big win is the ability to put ice in the tank and ideally keep a 32° coolant temp for the entirety of the pass.

The main difference is how you want to plumb the HE in line: for closed loop it doesnt really matter because its so short, but youd likely retain the stock flow of HE into IC. For open loop with a tank, youd likely run the tank to the ic then to the HE back to the tank. This means youre sitting with a backup of cool fluid in case you reach a situation where the HE wont be getting air for a bit (traffic or staging lanes)

The best of both worlds might actually a very small tank (maybe a gallon or so) with a big enough opening for ice and a set of fans on the heat exchanger. Ice is for track runs, small capacity prevents heat soak from prolonging power loss, and fans prevent heat soak while not moving.

m-svt-amg

However, its important to remember that real world numbers are different than ideal equations.

Technically, your inlet temps will be:
Starting ambient air temp in front of your intake
+ heat absorbed from the intakes passage through the the engine (the whole reason for a CAI)
+ heat added by the supercharger (more heat at higher rpms, less heat with bypass valve open)
- heat removed by the IC system. Which is mostly based on the difference in temp between the two and the efficiency of the heat exchange in the IC core.

The last item is mostly comprised of starting coolant fluid temp entering the ic, the amount of fluid that passes through the ic per second, and the ability of the ic to absorb the heat from the air into the fluid as it passes through. We only really have control over the first 2, a stronger pump means more volume over time. Good ic system design and control minimizes the temps. Theoretically your flow should be tuned based on the pressure efficiency curve of your pump and you system with the exchange efficiency curves of your intercooler and heat exchanger... however, most data collected by Nicks testing suggest more flow is almost always better.

Josh154

If it was my car I would forsure look into the split cooling. He just wants it reliable and to run the mid 12s they do stock.

m-svt-amg

Fair, and maintenance reliability is always nice.

Personally im more about performance reliability... it hurts having an 11 second car that cant jump around a prius in traffic because your supercharger may or may not engage when you hit the gas...