FM stage 2 fan shroud
 

I just installed a Rotrex on my track car and my water temps went from my old regular 190* on my gauge to about 210* post Rotrex install. I did 3 half hour sessions and it never went higher or lower. I have an FM Crossflow and an oil cooler and as much ducting as possible. I still have A/C and would like to keep it. Anyone add the FM fan shroud and see an actual temperature reduction? Oil temps stay around 245*

No. Fan shrouds are exclusively for street cars with A/C, despite the insistence of certain people. F/I track cars with A/C need vented hoods and extremely good ducting. The fans cannot draw enough air through the radiator to cool the car without additional pressure assistance from both the front and back of the heat exchanger stack, and blocking all the other airflow routes with a shroud is not going to improve your situation.

I also suspect that a larger radiator may be in your future. FM's crossflow is great when you have lots of airflow. If you don't have the airflow, you need multiple cores to make the most of what little airflow you do have, and that's where our dual-row unit becomes superior.

Would something like this actually make a measurable difference?

Flyin' Miata : Engine/Drivetrain : Cooling : Flyin` Miata aluminum louver panel

I just installed the FM hood vents on my LS3 Miata and I didn't notice any change in temps at the track.
In 3rd gear I'm getting excessive heat so I usually just leave it in 4th for most of the course. Having 400rwtq helps in that situation at least.
I have a TSE rad coming and hope it will help as I need to drive in 3rd gear more :D
Andrew I currently have the FM shroud and Stage 2high flow fans. Would you recommend leaving the shroud off?
Thanks.

I had an LS3 C6. Are you monitoring your oil temps? That was an even bigger issue for me.

Yes I'm running an oil temp gauge and it's climbing rapidly while in 3rd gear as well.
The car's equipped with a decent sized oil cooler but I may have to go bigger.

Andrew,

I wish I had got your radiator, but since I didn't, I wonder if a wider tube and fin intercooler would help pass more air to the other heat exchangers. I noticed the Kraftwerks IC is short and the end tank blocks flow.

If someone want to buy a 2 month old FM Crossflow I'd try yours!

Airflow is the important thing. You can have a massive rad, but unless you're actually giving the heat somewhere to go, a bigger rad is simply a larger heat sink to delay overheating. Once you've got the airflow, you need an efficient rad.

Road Cone, I've tested our V8 rad (crossflow dual pass)and an oil cooler with a 466 rwhp LS3 and our airflow kit. 90+F ambient, thin and dry 5000' air, 30 minute sessions. No temp problems.

So, what are you saying Keith? Will the FM Stage 2 fan setup reduce my temps?

210* may not even be an issue, but it could go higher in hotter weather. The 210* is being measured at the hose entering the radiator. Same as pre Rotrex that measured 190*

Fans are literally doing nothing on the track. If your car is overheating on track, forget about fans entirely. They are only for cooling in stop-and-go traffic. Most of the track guys only run 1 fan. Is your radiator fully ducted to your bumper mouth?

Fans are not just for stop and go traffic unless you've got fully managed airflow on both sides of the radiator.

Tomiboy, the airflow kit will help your overheating problems on the street. It may or may not help on the track.

OP has me confused. OP, do you have stock fans on the FM radiator? Or do you have aftermarket fans on the FM radiator with no shroud?

I don't know that just adding the shroud itself will do a whole lot, but if you're going from stock stuff on a big thick radiator to the FM stage 2 kit with the obscene SPAL fans, then yes, it will help.

I have an FM Crossflow with stock fans/shroud. Sorry for the confusion!

I can't imagine the stock fans being matched super well with the now bigger/thicker radiator.

Stock fans are more powerful than most aftermarket fans. AND their ducting is just right compared to most aftermarket fans that have the blades too close to the radiator core.

When we're talking about stock fans vs. the fans specifically being referenced in this thread, no.

How about undertray and ducting? Whenever someone has problems overheating on the track, I've never heard anyone recommend bigger fans or a better shroud. It's always "do you have the undertray?" and "is your rad ducted to the front of the bumper mouth?"

Undertray is in place. Top and bottom is well ducted. Sides could use some improvement. I'll be tackling that this weekend.

Thanks for the advice guys.
I'll try enclosing the sides of the rad ducting a little better.

Any large ducts for the hood recommended?

It took 20 posts for the words "coolant reroute" to show up?