Just finished putting the 400 ci Miniram-injected motor in my brother's 87 GTA. Naturally it runs like a scalded cat.

Keeping it cool is worrying me. We drove it 300 miles down from my house (Philly) to his (Norfolk) last weekend in 100* temps. Runs 185-190 on the open road (180 stat in the intake). Sitting still in traffic, however, it's a nail-biter. The fans kick in at 210 (just like TPIS programmed them to) but the temp doesn't fall. Just sits there. In a 110* tunnel near Norfolk it actually crept up to 220-225.

Here's the details: Yes, it's a big motor, but it IS tuned correctly. Timing is per TPIS spec, all the block learns are between 125-135 so the fuel curve is pretty damned close. It has a new stock replacement V8 radiator, a new stock replacement cast iron water pump, fresh 180 stat, and a pair of 12" aftermarket puller-fans to cool the radiator (the stock ones where trashed). Both fans come on together at 210. I have stright water in the rad now and a 16lb rad cap. Voltage is good even at idle (700 RPM) with both fans running.

What's the main "bottleneck" in keeping a big-cube 3rd gen cool? Do I need bigger fans? A bigger radiator? High flow water pump? What's gonna give me the biggest cooling "bang for the buck"?

 

The usual cooling problem with all of these cars is when they are running down the road. The plastic air dam gets worn down and no air makes it to the radiator.
The only way to keep it cool at idle is to have fans that move a lot of air through the radiator. If everything stays cool running down the road then there are only two possible problems at idle.
1. The fans are not pulling enough air. Solution: Get some really big fans that cover as much of the radiator as possible.
2. Your water pump is not spinning fast enough to move the water through the engine and through the radiator. Solution: Smaller pulley on the water pump or a better water pump.
3. You just plain down't have enough radiator. Solution: Buy a bigger one.
Now diagnostic techniques.
The next time the engine gets up that hot turn on the heater to full. I know it will really suck in the car but it should get the temperatures down. If the temps come down then the fans are at fault. If the temps stay up try a good aftermarket high flow aluminum water pump. If that doesn't work put a smaller one on the water pump.

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84 Z28 383
Stripped w/Cage back halved w/ladder bars and coil overs and 9 inch
700R-4 3.73

 

check out www.stewartcomponents.com/chevy.htm

they have different stages of water pump based on the engine and they are pretty reasonable.. i would say get one of there water pumps and get a new air dam and yourll be fine..

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91 camaro RS
- 305 TBI
Mods: Performer TBI intake, 1" TBI spacer, K+N, jet fan switch ,160 thermo,Accel control module, Jet Stage 2 chip, edelbrock TES headers, Compleate 3" Flowmaster exhaust, Edelbrock springs, KYB struts and shocks, 700R4 built by TSI, SLP tq converter, b+m trans cooler, white guage faces, megashifter..
next month: spohn LCA's and panhard rod, BMR relocation brackets, 323 gear, lt1 cam , 350 heads

 

Well, You're running pretty cool down the road! That's a plus!

And you're only running water in the system.
I'd say go the cheap route first.
Go and get some Havoline Antifreeze and a bottle of water wetter. Both will cost you under $15.

Drain the rad and pour in the waterwetter and the antifreeze and then top off with water.
Keep in mind about air pockets when doing this.

Then head out for a ride and see if there is any change.

If not....
My guess the rad is not big enough for the engine. If it's stock, it's more than likely a 1 row rad. Move up to a 3 row rad and you'll have much more cooling power.

They make a 4 row rad, but you'll have to make mounting adjustments and may have some clearance problems.
A 3 row drops righ in and bolts up just fine.




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91 Mystic Teal RS Convertible (1 of 5,000+ made in '91)
Stock 305 TBI, Auto Trans, Stock Rear End

Stereo
Nakamichi CD-35z, Infinity Kappa Series 4x6 & 5 1/4" speakers, Fosgate 12" sub in a custom box, 200watt amp for the sub.

Future Mods & Add Ons

• Infinity Basslink
• Hooker Headers
• 3" Exhaust using Flowmaster 80 series muffler
• MSD Ignition
• K&N Filter
• Some Suspension Improvements

 

It could be something simple...if you have AC, check to see it there is a bunch of junk trapped between the evaporator and the radiator. I had this problem, you will be amazed at the carp stuck in there, I found a smashed coke cup in mine! I have no idea how it got in there!

 

Bigger radiator and/or better fans. What are those fans rated CFM? If it stays cool down the road, I would guess the radiator, pump, and other stuff besides the fans are working good enough. The fans have to compensate for the fact that you aren't moving down the road. My guess is the fans aren't powerful enough to pull the required air.

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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, current red metallic paint. Lots of other stuff...
82camaro

 

All the simple stuff has been done. There is no dirt/leaves on the front of the rad or the A/C condenser.

I figure the rad is big enough becuase it would overheat on the highway if it wasn't (when the engine is throwing a bunch of heat into the system). At idle there is relatively little heat being put into the cooling system.

That sorta leaves us with either not enough air being moved or not enough water.

The fans are typical aftermarket 12"ers mounted side-by side that allegedly move MORE air than the stockers- or so the brochure says. They are getting a full 12V of power through the stock relays even at idle- me made sure of that.

So I'm sorta leaning towards the water pump and/or stat. At idle the water pump turns very slowly (we are using stock pulleys- no underdrive) and the parts-store stat only has about a 1" opening in it, even if it's wide open.

Could it be as simple as a high-flow stat?? Or maybe a (weight-saving) high flow aluminum water pump??

 

I'd say go with the water pump. An aluminum one has less restriction and will flow much better than the factory cast one. Of course they're around $150 for a serpentine setup. But I wouldn't waste your money on a $400+ radiator when the pump may do the trick. A buddy of mine swears by his Edelbrock. He's got a built 355 with the miniram, and originally he had the waterpump and a BeCool radiator. He said when he put the stock radiator back in, the car ran just as cool. He attributes this to the waterpump.

 

Vicious- thanks. I was wondering if anyone had used one of these high flow aluminum pumps with any success.

Fortunately, the 87 GTA has a hybrid serpentive/v-belt system that still uses a normal rotation water pump, so we can get a pump a little cheaper than that. Bonus!