Overheating Track Car JZA65

[timottaway]

Hi all,

Just wondering if anyone can help with some an ongoing cooling problem on my track drift car.



a vid from recent QR prac, 3-6 course, 2:12 and 3:25
http://au.youtube.com/watch?v=nbcd4W1OJUY

My car is an RA65 with a 1JZ running stock turbos and boost, runs an Adaptronic ECU(170rwkw) with factory dump to 3" pipe with resonator, 100mm front mount, serck 19 row oil cooler, bosch 040 intank pump(factory tank baffle), runs a davies craig ewp110 water pump, a koyo 3 core copper JZA70 radiator running 1x supercheap 14" inch fan mounted straight onto core, the factory waterpump was cut off and welded shut so the factory flow path was retained and not cause any cavitation, the thermostat was cut out and the ring was left to provide some restiction, the bypass between top waterneck and waterpump housing was blocked off, only these 3 components of the factory cooling system have been deleted/modded. The front of my vehicle has some aluminium sheet ducting to direct air to the 3 different cores.

pic of front ducting to the 3 cores water, oil, air


another pic of front


14" fan straight onto radiator core


a pic of the ewp110


a pic showing engine to radiator clearence...no space for even a factory shroud


engine bay pic


I've been tryin to come up with an explanation as to why my track car gets hot after appox. 3 consecutive laps of any track I have visited regardless of ambient temp. The car will see as much as 105-110 degrees water temp and 125 degrees oil temp according to defi gauges. The water sensor is mounted on water neck near factory sensor and oil temp sensor mounted on sandwich plate after oil cooler. I chalk up the overheating problem could be caused by in no paticular order....

1. Still some Fuel surge because of no surge tank installed. I always run a full tank or close to so i have figured this is MAYBE not the case....
2. Radiator not up to task, double or triple bypass aluminium requred???
3. Air flow not enough, better thermofan needed along with proper shrouding for the fan
-I believe the airflow problem is the most probable cause, with such little space to only fit one 14" fan on such a large surface area with no shrouding.
4. The davies craig electronic pump not up to task?? or possibly the setup of the cooling setup causing cavitation or hot spots, or possibly not enough restriction due to lack of thermostat.

If anyone has some educated opinions could they please voice them..

Regards,

Tim

[hybrid_turbo]

could the rad have a blockage maybe?
just changed mine over for that reason, runs alot cooler now..
although im not running a 1jz lol.. just the 21r

[oldcorollas]

if it was running lean so much that it caused engine to get hit after 3 laps... surely engine would be dead by now?
2. maybe nto radiator, although larger surface area always helps. having more rows will marginally help.
airflow is always a problem, especially if you are not maintaining high speeds (we are talkign relative to engine usage here) or direct airflow (being sideways )

fan will not do much when you are going 60km/hr IF you have clena air getting to front of car. sliding may reduce the effectiveness, but still, surely if you are going mroe than about 60 or 70km/hr continuously, then the fan is not the problem?

the pump..
as discussed in recent thread, some restriction is good, to cause a pslight pressure in the block to help stop hotspots forming.
what pressure can the davies craig pump flow?
how big is your restriction? (i've heard numbers like "6mm hole" being bandied about when thermostats are removed.. but this is with stock water pump

i would suggest that it is combination of factors, the biggest being that the davies craig pump does not have enough oomph (even with a better restriction), and your restriction is not big enough... fine for highway and aroudn town.. but thats not how you are driving

have you looked at the Mezierre (sp?) elec pump for the JZ motors? they seem to be much much more beefy than tthe davies craig.


is water temp sensor (in stock location) on the inlet or outlet of the radiator? can you datalog the temps during the runs, to see if it suddenly goes up, or just slowly climbs?

if the pump is doing the job, then next is airflow... do you have something to stop the air from going over the top of the radiator, between rad support and bonnet?
if you are not going fast all the time, then any easy air loss path will be taken... block it up good and proper.. try usign foam or something to begin with.

to get more serious, and assumign your forwar dspeed is not enough to make rad do job (how fast do you usually go anyhoo? not top speed, but kind of average speed.. got a datalog?.. from front wheels ), then can you move radiator forward and stick two big.. say.. 16" high flowing fans (ie, not just any old shit ones), on the back with shroud? that should at least help the situation, regardless of the pump..

can you measure the water temps in and out of rad and log them to see if rad is working effectively?

[oldcorollas]

http://store.summitracing.com/partde...5&autoview=sku

this one....


edit: can you try making up a front splitter, to try and keep a bit of air out from under the car? real estate signs for a test run? the way the nose is doesn7t seem to make the air want to come out from behind the radiator...

[The Real Roadrunner]

from experience with drift cars i have learned quite a few tricks.

1 the ducting is a good start to fix the airflow problems so that should be sorted.

2 when running a davies graig pump in the lower hose pull the thermostat out and fit a restrictor after the engine (just fit a restrictor of about 22-25mm in your aftermarket sensor adapter) or better yet go back to the factory pump (trust me they are heaps better and the whole 3kws you may use driving it wont affect squat).

3 the more tube length in your radiator the better and also control the water so it uses the entire core (not a prob with thin rads but a huge prob with aftermarket thick cores). you should be able to take your current rad to a radiator shop and get it modified with some brazed in plates to turn it into a triple pass rad, no need to by an alloy one unless yours is getting tired.

4 having all those cores stacked up one infront of the other aint helping your cause much either as the airflow has a hard time getting thru all the cores so i would suggest relocating the oil cooler to the passenger side in front of the wheel

5 if the tune is too safe ie massively retarded timing it to can make an engine run very hot (but this isn't normally the case)

see how you go with those options (alot of work i know but better than a broken motor)

cheers
linden

[oldcorollas]

Linden, does the stock pump have issues with cavitation when held at high rpm? how high is too high?

[The Real Roadrunner]

nope, should be fine within the factory RPM limit or 500rpm over.

and underdrive pulleys for alt,waterpump and PS pump are soooooo cheap from import bitz that id put them on anyway (and they look pimp)

havn't tested the difference between the plastic impeller on the hydro pump and the steel soarer one though.

cheers
linden

[M.J.H]

My first thought on this is the fan is the problem. I remember a post from on here or another forun that basically said the Supercheap fans are crap and are rated at the free speed of the fan not loaded when placed against a core.

The other thing I was wondering was what the hell is that onder the waterpump and along the sides of the motor in the pics above? Have you sealed off the engine bay or something?
If so then the air really has no where to get out so could be a cause of the problem.

[IN 05 NT]

stupid q's...BUT, have you got the fan blowing the right way?

[rob]

also consider the air that needs to escape the engine bay, its pretty crowded having a 1JZ in a RA65 and what air goes in must also be able to get out to let more air in

try shimming the bonnet hinges for a quick fix or getting a rearward facing scoop not too close to the windscreen.

have a look and see if air can easily escape from the bottom of either side of the firewall too

[JustCallMeOrlando]

I always see this, but can anyone actually quantify that raising the bonnet at the back will enable hot air to escape? I can imagine when it's stationary that'd be fine. At speed where the bonnet meets the windscreen is a high pressure area which would achieve the opposite affect.

Why did you butcher the factory cooling system so much? If they're all functioning correctly, and as Linden said provided you're not consistently sitting above the factory revs it shouldn't be a problem.

[Norbie]

Another vote for adequate engine bay ventilation. You've got a lot of hot air getting in but it needs to get out! Some nice big vents in the bonnet just behind the radiator would be the go.

[thechuckster]

given that you've only got the one 14" fan pulling air thru the rad ... perhaps a 16" in-front of the radiator to lift air flow at low speeds thru the core?

btw: does it run better temps if you do laps of QR (e.g. significant speed)? that would certainly point towards engine bay ventilation as well as poor air flow at low-speed thru the core.

[Matt-AE86]

I also have been thinking about the engine bay ventilation and also another one that stands out to me, the intake cooler pipe positioning.

I know that on Coffee's jzz20 his cooler pipe for the intake is inline to the radiator and pretty close to it. His cooler works, but then all the heat soak from the radiator gets into that pipe. Feels pretty hot.

Also try exending your pod filter to the front corner of hte light and getting some ducting to that.

I remember Cruizida had some issues with his uzz10 when his pod filter was really way back in the back of hte engine bay, car started to over heat and he did a quick fix with a vent.

So possibly maybe some bonnet drop venting or vents. also lifting the back of the bonnet abit ?

Im sure you and ant can come up with something substantial.

And then the radiator. Maybe it would be a nice idea for a twin/triple alloy radiator ?

Just my thoughts. Good luck and I love the car

[CrUZida]

Thats a good point Matt.

Tim, what are the intake temps registered on the Adaptronic? (I hope the sensor is in the intake manifold).

My intake temps were up around 70degC, and the car was overheating (only to 99degC).
Got the intake temps down to just over ambient (30degC) and the car cooled down to 95degC and less.