I was just wondering, have any of you had your car overheat while driving a road course? I was down at Maxus driving on Texas World Speedway and my temp gauge was starting to fly up past the middle. Not wanting to pit I turned on my heater to 85 and that got the needle to stay in the middle. My OBD-2 data logger showed temps of 220~225 F that day.

The only mod I have that can cause this is the DEK manifold swap, its esentially a big hunk of plastic over the engine. The '00~'01 DEK heads have extra cooling channels from the factory, so Nissan knew to make it cooler.

This winter im planning on building another motor, most likely a VQ35 hybrid thats built for track racing.

 

Don't think 220deg is high - I get that when street driving. Actually at track speeds you get much more airflow through the radiator than idle at a stop so I wouldn't think it a problem. I've read about some turbo's (not Maxes) on the otherhand, having too large of intercoolers which block the radiator air causing heat issues.

 

Im also losing a bit of oil and there is alot of soot on the muffler. So there is a bit of blow by occuring, on that track day I lost about a quart of oil. Does this happen to you?

I didn't even get a full session completed cause the car felt like crap after about 6 or 7 laps. I may try some better cooling auxuliries but i want to see if they are even needed with these cars.

 

stupid Q, but are your radiator fans working?

At the speeds you were seeing at TWS, they shouldn't be needed, but I'm wondering if they aren't kicking on...

 

Yeah there def working, when I got off the track the fans were blowing heat off of the car. When im moving the fans dont come on, but it seems the engine doesnt have the cooling capacity.

 

strange...
good thing the 3 gen has a honkin HUGE radiator!.. TTZ guys use them as a mod for their cars!

 

Nice, I wonder if it will fit in a 4th gen. If not I can always upgrade to the Griffen radiator that is available to 4th gens.

Or forget all that and just get a real track car...

 

try bleeding the system and adding some water wetter. while you are at it get a new therostat

 

Just changed to Toyota red 70% water and 30 % coolant this winte and threw in a bottle of Redline water wetter as well. Also the thermostat is OEM new and its set to a lower temp (173F as opposed to the stock 183 F) Not to mention I installed a new OEM water pump this winter and cleaned out the coolant system. (EDIT: also put in the toyo red at that time)

Hell even went as far as trying a higher pressure radiator cap (Autozone brand for a 300ZX TT ~ 1.1 bar)

Lets face it, my 4th gen coolant system is not up to task of cooling a DEK manifold swap on track days. This winter im looking to swap in a DEK engine from a '00 Maxima, it has extra cooling provisions in the cylinder head to cool the engine while using the DEK manifold. This should tide me over until I build my VQ35 super motor...

 

Update:

Old radiator is what caused my problems.

http://forums.maxima.org/showthread.php?t=424546

 

How much did that Z32 radiator cap cost you?
How did you re-set the thermostat if it's OEM?

 

the 'yota red crap is what caused the problems.. my VG would drink that sheit like gas... drain and refill with green slime and it was fine after that.

 

I was going to ask if this was the first track day you've had with the manifold and the Toyota Red. If you've run b4 with no issues, I'd flush it all out and go back to whatever you were using...but since you found out the rad was old, maybe get the Griffin anyway and put the regular stuff back in with Water Wetter...Who sells the Griffins? That might be an interesting purchase once I find a new job. I hate layoffs...

 

6 dollars.

Door lock tumblers from a lock smith, search for Jimes posts on this. Was measured to be 173~175 when all said and done.

 

Car didn't over heat with the stock manifold and the toyo red, I reguraly logged temps of 175~185 with the stock manifold in place. Seems to me I had a bad radiator and the DEK manifold pushed it over the edge, cause it went bad with the DEK manifold swap.

Other people on the fluids/lubricants forum spoke highly of the Toyo red so I went with it. The org needs to get it's information in order, everyone says something different.

 

Yeah, but everyone's condition is different, so you do want to be rather, uhhmm, conservative with your decision. If the stuff you used is similar in specs to the regular stuff, I wouldn't think the manifold would have contributed to the rise in temps. I WOULD check the rad and that t'stat mod you did, JUST to make sure it WORKED. Boiling a modded t'stat in a pot to check and sitting in a pipe with coolant under pressure are 2 different things, IMO.

 

That may be true, but I think all the Japanese automaker coolants seem to be alright for our use.

Again see my post that I linked. The radiator was the only thing I didn't change and the engine temps were always higher after the DEK swap.

The thermostat works because I can now see the lower temps on my data scan tool, I plotted the temp range over time with various driving conditions. Before the Griffin I never saw the 173~175 F the thermostat was opening at, now it stays around that range when cruising. Stock is 185 BTW. You can argue with me all you want but facts are facts, there was a definate before and after effect with the thermostat change that was done before the DEK swap and now with the Griffin radiator installed. The only thing that raised my engine temps was that DEK swap, nothing else had an effect on the raised temps.

However mine appears to be an isolated case, no one else seems to have raised engine temps from the DEK swap. Judging by the condition of the radiator (181,000 miles original rad.) and how bad its caked with scale leads me to believe it was the culprit and didn't have the extra cooling capacity for the DEK. My conclusion is that a aftermarket OEM copy would of sufficed in this situation but I decided to opt for some bling in the engine bay.

 

Just some general info.
Contrary to popular belief, antifreeze itself does not cool the engine! It makes the water its mixed with work better to cool! ( basicly by raising the boiling point).
Im not familiar with the Toyota red, but if its a antifreeze mix of some sort, then your 70% + 30%= part of your problem.
The best we have found in our race cars is pure water and water wetter.
For a street car you should add antifreeze when the weather gets cold.
Tim

 

Stuff I already knew...

Im running 70% water and 30% coolant as Ive posted above, if i had a race car I would run pure water in there as well but this car sees cooler weather.

 

are u sure of this? because last i checked they had the same part numbers

 

Right, I just checked the numbers and the cylinder heads have same #. It's the engine block that's different. The DEK have a second thermostat which helps keep the cylinder heads at a different temp than the block.

 

haha yeop, i found that out the hard way..

 

Another Update:

Raced the Max again in Texas (90 degrees out) and with the Griffin temps didn't go over 204 F when HAMMERING on this thing.

So fixed one problem and now I got to deal with the brakes and under steer next.

 

Sounds good... I had my Max out on MSR on the 2nd of June. Did great. Had her up to 100+ in the long back straight after the big bend sweeper (which Matt was constantly yelling at me to give it more throttle, lol).

For me, I'd just flushed the system a few weeks prior (I drove to TX from VA for the National Z Convention). I just drained the system, filled with distilled water, warmed it up, drained it again, then filled with a gallon of premixed Nissan Green Antifreeze, and topped off with Distilled Water. Temps needle never moved at the track, and I pretty much had the car at redline as much as possible in 2nd and 3rd the entire time I was on the track! Did great!

As for the understeer... slap a Rear Sway Bar on the car... that will help bring it around. =) I was running Matt's Stage II Tie Bar, H&Rs on AGX shocks, new bushings up front, Front Strut Bar, and the Rear sway bar. Matt commented it feeling like it understeered at first (big surprise) but said from the passenger seat, once I started driving and really pushing it, the car felt prone to oversteer... which it was. There were a couple corners I was not quite full throttle in 3rd and the car was wiggling between plowing and allowing the tail to come around based on how much throttle I was giving it... was a good time. I highly recommend the suspension upgrades I've got!

 

Are there any good reasons not to run with a thermostat on track days?

 

Id say the emissons would be off from the engine running cooler. From what I've read and heard most race cars don't even run a thermostat. One more thing that can break so they opt not to use one.

 

you need to run a thermostat or a restrictor plate in there. the engine and water flow is designed around having to flow through the thermostat, so if you take it out, you run the risk of causing the water not to flow since there's too little restriction. I believe what happens is the pump starts cavitating at high RPM because there's no backpressure on the pump's impeller. speculation there, but nonetheless, you need to run a restrictor plate that mimics the orifice size of the thermostat for your cooling system to run properly.


best advice I have for you is to leave well enough alone. the engine likes to run at a certain temperature, and it uses the thermostat and cooling fans on the radiator to keep it there. between 180 and 205F..

 

Yep, definitely need to run one. Another reason is that with no restriction, it is also possible that the flow is too high, and does not give enough time for the actual heat transfer to occur from the hot spots to the coolant, thus getting no cooling effect.

Had the same thing happen on my A-sedan where I saw oil temps skyrocket, but coolant temps stayed low.