Knapper411

iTrader: (2)

I'm having issues with my 300zx Lq4 with a front mount turbo setup. The engine bay is very cramped and I did what I could to cool the car. In the front I have a front mount intercooler and directly behind it is a 3 inch thick radiator about 16X22, behind the radiator is the intake of the turbo on one side and an 500 CFM derale fan on the other. I also ran a 10X14 1.5 inch radiator at an angle above the crossmember at the bottom of the car with a 2200 cfm pusher fan on top pushing air towards the ground.

The car heats up to about 200 and sits there for around the first 10 minutes of driving and while we were tuning, it slowly creeps up and doesn't cool down even when cruising. It eventually gets to about 225 and I park it back at the shop, it doesn't go much higher but it doesn't cool off either.

My first thought is to run a 160 thermostat, and change the pusher fan on the lower radiator to a 2200 puller fan because I think it's pulling hot air off of the exhaust from the turbo and blowing it through the radiator, hopefully the puller fan will pull cool air from under the car and through the radiator.

The only other thing I could do without huge modifications would be to tilt the intercooler forward a bit and run 2 derale 500 cfm pusher fans infront of the forward radiator.

Any opinions and help would be greatly appreciated I'de like to solve this issue asap.



This is the turbo set up, the radiator is right infront of that turbo as you will see in the other pics.





The waterpump feeds the large radiator in the front on the top passenger side, and on bottom driver side it connects to the smaller radiator then goes to the thermostat.



If I tilt the intercooler forward I have very little room for a big fan, I could squeeze in a couple of 8" pusher fans though.

mangler

The 160 thermostat isn't going to do anything for you if it cant keep it at 200. Does the car stay cool at highway speed or even 50ish mph? You should get more airflow there than the fans can provide so that should tell you if your fans have inadequate flow. If the car can't maintain thermostat temp at highway speeds you have a plumbing/ radiator/ water pump issue.

DW SD

I agree - 160 won't help if you aren't staying cool @ 200. You aren't getting enough airflow and heat transfer.

how can you get more airflow through the front facing radiator? Can you remove the bumper and see what happens?

On the lower radiator, I wonder if you should be using a puller to pull air up from the bottom vs. blowing hot air from inside the engine bay. Still, it seems you don't want the fans working against each other.

See if you can get it to stay at the thermostat opening temp by misting water from a hose. If so, then you know the thermostat / plumbing / pump etc is working properly.

Use an IR temp gun to check temps inlet and outlet of the radiators, too. You should see which is doing what and how much cooling.

Could you move to three radiators where one each is in the front wheel wells? And maybe eliminate the lower radiator?

Pop N Wood

iTrader: (1)

Some good recommendations above.

Double and triple check you got all the air out of the cooling system. Jack up the front of the car and pull one of the steam vent cap to make sure all the air is out of the top of the motor. You can try a can of water wetter also. I've seen guys swear by that stuff.

But my guess is airflow issues.

As an experiment see if you can put that little tiny radiator in front of that massive intercooler. Ducting would be a huge help also. You want the air coming in the front of the car to go through the radiator and not around it. The fan on the back of the main radiator is most likely just circulating it's own air in that little cavity and not pushing it through. That secondary radiator might actually be making things worse since it is blocking airflow out the bottom of the engine bay.

Anyway you can move the intercooler farther out and get more room between the turbo and radiator?

Also try running with the hood unlatched. Might help move some air out of the back of the engine bay.

I've seen guys put heater cores in the fenderwells and hook up fans blowing out of the engine bay and into the wheel wells.

Good luck. You stuffed a lot of stuff into that engine bay.

Knapper411

iTrader: (2)

Driving the car so far I haven't gotten it on the highway, and it's been with no bumper to start with. I can't move the intercooler any further forward at the bottom because I wont be able to fit the bumper on, that's why I showed it just tilted forward that is all I can spare. I will try a few different things this week to see if I can get it to stay cool.

Would a scooped hood help any with getting hot air out from the engine bay?

mangler

A scooped hood may help. Fan shrouds will help. bumper might help because its designed to direct airflow to the factory radiator position. Noticed that little fan with no shroud. Definitely not helping. That's why I suggested getting it up to cruising speed. Then you would know if the radiators have the heat dissipation capacity.

DW SD

Can you direct the radiator flow up and out the hood like a 911 GT3?
Also, I'm pretty sure the GT3 has radiators in the wheel wells and one in the center.
Maybe you can get some 911 / boxster / Cayman radiators?

Doug

JetMech442

iTrader: (1)

I think the issue is the radiator tilted on the cross member. Under hood temps generally reach 220+F , especially boosted applications. You say it is fine until about ten minutes into driving...until under hood temps get hot. You then have a two thousand cfm fan transferring 220F air INTO that radiator, and only a five hundred cfm fan trying to reject heat.

I would first try unplugging the 2000 cfm fan and see how you do. The problem may still persist because that radiator will never reject heat as long as you are pushing hot air through it.

If this were my system,I would size the fan to control engine temps and only use the main radiator.

LS6427

iTrader: (2)

Without the factory shroud, you are doomed. Or fabricate a new shroud that is sealed. Its the only way to get cooling efficiency.

.

JetMech442

iTrader: (1)

I agree with ls6427 the art a shroud is mandatory. but in this case a shroud would only help transfer heat into the small radiator.

have you been able to find out anything since your last post?

Knapper411

iTrader: (2)

I have since tried a different set up, I ran a pusher fan on the front of my main radiator with my intercooler tilted forward. Also a puller fan on the back of the main radiator and I put a shroud on a puller fan on my lower radiator. The issue took longer to happen but isn't solved.

My main question that i have right now is is my problem air flow or do I not have enough cooling.





Also side note, Permacool fans are garbage I don't recommend anyone buy one. CFM ratings are way over what they advertise.

My next experiment is going to be driving the car with the hood off to see if air escaping will help. Also I measured my radiators to see if anyone had an opinion if I had enough radiator.

My main radiator cooling fin area is 17" by 13" the tanks are 2x2.75 and it is a 2 row radiator. The secondary radiator fin area is 13x10

Knapper411

iTrader: (2)

Drove the car again today with no hood but tried several things differently, I filled the line for my steam vent with coolant and ran the car on the lift for 25 min. The car reached 190 n cooled back off to 178 with the fans and I was blown away with excitement. I drove the car to get gas n after awhile the same issue came back, driving home I realized something.. My steam vent is hooked up to the upper part of my coolant reservoir and I've been spending some time reading and it appears that isnt at all what I was suppose to do. I am going to weld in a line on my upper radiator hose (the hot side going into the radiators) and run a heater hose to there to see if this solves any issue.

If anyone thinks my new plan has any faults please let me know your advice.

DW SD

I welded in an AN-6 fitting to a coupler in my upper radiator hose for the steam vent. been working for me.

I wonder if being up on the lift allowed more air flow through the lower radiator, since it wasn't so close to the ground?

Doug

fire67bird

This issue could be timing related. I pulled back on my timing when I first installed my turbo to protect against detonation until I could get it tuned and this caused my engine to overheat. I would add some timing back in if you have removed a bunch and that may get it running cool again. Apparently retarding the timing generates a lot more heat in the engine to the point where the cooling system just can't keep up.

Knapper411

iTrader: (2)

In boost I have the car retarded 16 degrees, 24 degrees while cruising and idling.

autocomman

You cant have a radiator pointing at the ground not shrouded. On the rack there is plenty of room for hot air to blow out and away. When the car is on the ground, you not only have the heat of the road. But air blowing out towards the ground isnt necessarily going to just go out the back, it could be getting back into the way of the front radiator. MORE SO that radiator is keeping air from flowing through and out that engine compartment. I would bet you might see some results by removing it completely so at speed air is coming in and exiting the engine compartment somewhere. Your best bet may be to have a custom radiator made. Also who knows if the waterpump is properly moving the water through the 2 radiators setup like that, it may be cavitating or just not moving it enough. 2 puller fans on the one radiator. If your still having an issue, duct the radiators so air coming in goes out under the car, so it isolates them from the engine compartment better

Your timing I dont think will be an issue here.

DW SD

I've bought several SPAL fans from thefanman.com .. very high quality fans. The last was a 16" 1800 or 2000 CFM puller for about $140, I think. It draws 20 amps when running. With a homebuilt shroud keeps my setup with AC cool by itself. Would that fit next to your intake on the radiator?

Had you considered my ideas of the boxster / 911 radiators in the wheel wells? Suspect they are plentiful. With fans and some open access to the bumpers, it might free up airflow and add to your cooling.

Doug

fire67bird

Your engine is close to stock when not in boost so your timing should be close to stock when not in boost, especially when idling and light cruise. Add timing to your non boost portion and see how it runs before throwing cash at cooling system parts. Your car will also make more power when not in boost with the added timing. The main thing is to smooth it out as it transitions to boost. I'm not at my computer to look at some tunes but 24 degrees seems really low for idle/light cruise.

fire67bird

I posted a tune that has a good looking timing curve for a boosted 6.0.

Also check out:

http://www.automotiveu.com/SolvingOverheating.htm

Knapper411

iTrader: (2)

Tried changing timing, problem persists. My tuner hasn't done many LS motors but is well experienced and we both agree the car just isn't flowing enough air to cool the motor.

I removed the cooling system to try and make a larger radiator fit and change things around. I am figuring on running an air to water intercooler and from what it looks like with the bumper on the biggest radiator I can fit is about 27.5x15.5x2.5 or 3 while using 2 puller fans and a shroud.

I found this radiator that is a 2 pass radiator http://www.summitracing.com/parts/gri-1-58241-x

I think this with 2 derale 2000cfm puller fans would be enough...
Anyone running radiators this size with a turbo car and it works? Or have any other suggestions before I buy this and try it.





The only other option I can think of would be to run this radiator in addition to 1 or 2 smaller radiators in the wheel wells with fans but if that is the case I am going to need a 200amp alternator.