radiator comparison S54 vs. mishimoto X-line

[peapodf50]

So let me just start by letting everyone know that I am not done with my comparison, this is mainly due to the fact of the weather cooling down now and not being able to duplicate temperatures of the hot summertime. Well, at least until next summer.

Let me give you thespecs of my car so you get an idea of how much heat I was trying to get ridof. I have a 99 M3 with a fully built engine with 8.5:1 compression with a turbocharger pushing about 10psi of boost when I'm on the track. I think I'm around 350-370, almost enough to have the straight line speed of a GT3, just for comparison.
I'll start my story (for a lack of a better word) at Barber Motorsports Park. After I had my engine built and the current turbo kit on it I would be on the track for about 20-25 minutes with temperatures at a comfortable 200-207 for the water. Then the cap would blow off of my expansion tank and I would have to take it to the pits to go and scratch my head. After many months I finally figured out that I had trapped air in the system and it was completely my fault. I was running a S54 Z3M radiator on the car with the stock mechanical fan, no A/C condenser, and completely sealed radiator. The only thing that was in front of the radiator was the 3" wide intercooler and a small oil cooler behind the kidney grills. After I fixed the issues of bleeding, I didn't have an issue. I was running at Barber with the ambient temperature in the mid 70's to about 85 degrees at the peak of the day and water temps would peak at 212 or so.
Next up is Road Atlanta. I was there in March and the temps were in the mid to upper 70's. Beautiful temperatures to be running on the track. The only difference with the cooling system was the mechanical fan decided to break on me. So I ran the rest of that day and the next with no fan on the car. It really was a good test for the car. My high temperature of the day was 212 on the back straight. I was pretty impressed that it held that temperature.
Alright now, this is where that car starts to challenge me on its cooling system. So, I moved to Colorado Springs, CO because of work. So I decided that I needed to get back on the track. So I signed up to go to High Plains Raceway. I went there in the middle of July where temperatures were at 90 for both days. Definitely making the cooling system work. I have the same cooling system with the addition of 2460 puller fan to replace the stock mechanical fan. On this track the cooling system could not keep up with the heat I was producing. I was getting up to 220 within about 3-4 laps of the track and a few times it was getting to 228 with my letting off of the throttle to help try and keep it cool. Plus I didn't know the track very well, so I was not making the engine work like I normally do. I have a feeling that most of this new problem was due to the elevation of about 5000 ft. My understanding is there is about 20% less oxygen at this elevation effectively making the radiator 20% less effective at cooling the engine. Plus being turbo charged, the car really isn't losing a lot of power do to elevation. Just losing power because of 91 vs. 93 fuel and the tune on the car.
So, after that track day I decided to try and fix this problem with the largest radiator that I knew of. The Mishimoto X-line radiator. It is 57mm thick vs the stock S54 of 43mm. and larger capacity. When I put this radiator in I immediately noticed a drop in temperatures at normal city driving. It went from normally running at 179-190 to running at 168-179. By the way, I have a 176 thermostat in the car with a Stewart water pump. So it definitely cooled the car down more with the same ambient temperatures. Needless to say I was very hopeful that the cooling system was up to the task of cooling my car at this elevation with 90+ degree temps. I signed upfor the next track day at Highplains Raceway in the middle of August. Only to find out that it was sold out and I had to work that weekend anyway. So I couldn't do back to back testing to see if this actually helped out my car.
October rolls around,and I finally get to get back on the track. The temps were much cooler. I think the high was about 80 or so for the weekend. The day did start off in the mid 40's vs. 65 in July. The cars temps were better, getting up to about 200-207 with the fan on. I did have one session with the fan not working (switch broke) and the temps got up to 220. I would back off on the main straight a little to help the cooling system out and then return to my normal flogging of the car. I fixed my cooling fan before the next session and it brought the temps back to 200-207 just like in previous sessions. So I believe that the puller fan really does make a difference, at least on my car, I believe that if I had the mechanical fan the car would do better with temperatures, but I don't have it, so I will make the best of it.
So I am looking forward next summer to test out the radiator and see how it does. I wanted to write all of this down before I forgot plus, if anyone has any input to help me out or to give me pointers as to what to try out.
Anyway, So the Mishimoto 57mm has been doing well for me vs. the S54 radiator so far. I have read a lot of radiator reviews, but most of the time they are never the same car with the same driver and they are always different conditions. I will report as to how my car does in the summer when the 90's come back.
If you madeit this far, thank for reading

Michael

[chikinhed]

I have a similar set up but run more boost on the track. I'm using the euro diesel clutch fan. I'd like to use an electric puller but I'm concerned that it would be a step backwards for cooling. At 18 psi boost during a 30 min session I'll see temps at 220°F with about the same oil temps.

I have the X-line z3m rad, euro oil cooler, Stewart WP, euro diesel clutch fan, two 11" Spal fans on the back side of the intercooler and everything is ducted and shrouded.

Here is some info that people often over look. At some point in my cars life the water pump had failed and the impeller had machined a bit of metal out of the front cover. I trouble shot cooling system issues for a few years before I finally discovered this. The clearance between the front cover needs to be small. If the impeller has contacted it and enlarged the bore at all it creates a path that coolant can bypass the pump and you will have a large decrease in flow. When I put the x-line in my car, one side was has hot and the other side was cold but the engine was still to hot. The flow through the rad was not enough to cool the engine with the WP bypassing. It would get hot idling and on the track, cruising was fine.

[NY98M3]

Any update on the testing?

[Cobra1956]

Try better ducting around your radiator. I have s54 e36 with blocked off kidneys and hardly ever see 200. My fan is electric and I never use it. If the car is moving more than 20 mph you should not need a fan at all. Think you might have other issues.