How hot is too hot?

[Rubes]

How hot is too hot for an aluminum head motor? The 455 in my GTO runs at 175 to 180 all day long tooling around town, even today when air temps are 98 degrees. Took it out on the highway today and at 55mph (2500rpm) it creeps to 200 or 202. Comes right back down to 180 when I get back on the streets. I'm not overly worried, just wanted to know what the danger zone is for an aluminum head motor. I have a new four row rad, with a custom made shroud and the dual 11" BeCool fans.

Thanx
Rubes

[USAZR1]

If the highest temp you see is 202 degrees,I wouldn't be very concerned at all.

[Steve Chryssos]

Me neither. But you should review your cooling system if you are getting temp creep.
-You may have a seeping gasket (i.e. water pump) that is affecting system pressure.
-Do you have a coolant recovery tank? Cap bypass is plumbed to bottom of recovery tank. Top of tank is vent.
-If you're running an electric fan, is it powerful enough to keep up?
-Is hot engine compartment air getting sucked back into the front of the radiator?

No big deal, but I'm so thrilled to finally have a hot rod with a flawless cooling system that I like to share.
I built a seal panel that runs from the rad support to the front upper valence that helps direct fresh air into the radiator and keeps hot engine compartment air from reaching around.
I run a Vintage Air Monster fan with full shroud that has the big "Mark VIII" motor. That motor is like 3" thick. Those skinny electric fans can't keep up on anything more than a Toyota Tercel.
I run a 2 row/1" tube Fluidyne aluminum radiator.
I wrapped my headers
And I run Red Line Oil Water Wetter.

Output is about 490HP at the flywheel--maybe more. I absolutely HATE babysitting my temp gauge. Now I don't have to. :bananna2:
/Steevo

[Rubes]

-You may have a seeping gasket (i.e. water pump) that is affecting system pressure.
none that I can find...and coolant level stays constant


-Do you have a coolant recovery tank? Cap bypass is plumbed to bottom of recovery tank. Top of tank is vent.
Yep


-If you're running an electric fan, is it powerful enough to keep up?
I thought so.. I got the Be Cool dual 11" puller set (the motors are pretty heffty). I didnt know about the Mark VIII at the time. These are only rated at 2700cfm (but alo rated for up to 700hp). I think I see a MarkVIII in my future. But then again, at highway speed, the fans shouldnt even matter right? I'm thinking that my full coverage shroud is too much of a restriction at those speeds, even though the little "flaps" on the fans should open up to relieve the pressure.


-Is hot engine compartment air getting sucked back into the front of the radiator?
This too is possible, but again I would have thought at highway speed, not applicable. The opened Ram Air scoops (without the supporting underhood hardware) should be helping vent that. I was hoping that the "cooler" air entering there would flow over the headers and out the bottom to lower under hood temps.

Thanx for the input, and although Im not to concerned, I'll be looking into additional tweaks to the system. I too dont want to babysit the temp guage.

Thanx
Rubes

[engine]

Rubes, I get the same thing going on with my '80 camaro. I'm running a 4-row copper/brass rad designed for a 79 'vette, 27.5 x 19 core size. Using an 18" clutch fan and HD thermal clutch, 180" robertshaw thermostat and Edelbrock pump. I have a relatively mild 383 maybe putting out 375-400hp. I'll idle at 180 all day long in sweltering heat, but it'll creep up on the highway. I haven't had it at highway speeds long enough to see how hot it gets because I just never had to go that far. I had it get up to 195 or so. But once I get back on the streets it goes back down to 180 pretty quickly.

I'm guessing that with the motor spinning at 3500 or so, depending on vehicle speed, the amount of heat that is exerted builds up quicker than it can be released through the radiator. As long as it doesn't go above 210 or so, you should be fine. New cars run 210-215 normally.

I've been through my system with a fine toothed comb, and it is performing optimally. Let us know if you find anything.

[Mick_540]

-If you're running an electric fan, is it powerful enough to keep up?
-I built a seal panel that runs from the rad support to the front upper valence that helps direct fresh air into the radiator and keeps hot engine compartment air from reaching around.
I run a Vintage Air Monster fan with full shroud that has the big "Mark VIII" motor.

Got any photos of your "seal panel". I am thinking of doing same.

[Steve Chryssos]

Sure.
https://static1.pt-content.com/images/noimg.gif

[porschev8]

That engine compartment looks very nice Steve.


-Tim

[inSANe DIEGO]

Rubes

You might try closing off the ram air scoops. The radiator needs a low pressure zone behind it to allow air flow. It may be possible that the scoops are cramming the engine compartment with surplus air, equalizing or even creating a higher pressure zone than in front of the radiator- effectively reducing the airflow compared to what the radiator sees at lower speeds. Ideally, you want ALL air that enters the engine compartment to go through the radiator. This is what the seal panel that Steve made helps do. An extra step I'm thinking of is sealing the radiator to the lower valance panel holes. There is a HUGE gap between the back edge of the panel and the face of the radiator. I'd bet that a lot of air just shoots down underneath the car when it meets the face of the radiator (read restriction in airflow.) I don't know if your GTO has the same situation, but it may. If the "Steve style" seal panel applies to your car I'd definitely do it and I'd try blocking the ram air scoops

My $.02
Good luck

[Rubes]

Thanx John
I've been thinking about the pressure differential issue you mentioned. But I was thinking that at speed, more air was entering the radiator than the fans could pull causing the same stack-up. I'm going to be taking some pressure measurments in the near future to confirm those suspicions, and will do both open and closed ram air scoops.

The GTO's have a factory "Steve style" seal piece available. I'll add that too. As for the large gap betwen the back edge of the valance and the front edge of the rad...yeah I got that too. Those funky little black chin spoilers most cars have are supposed to direct more air up to the radiator. I guess it would depend on the amount of grill oppening if it would be better to close the gap or use some kind of scoop under there.

Thanx for the help guys

Rubes

[EFI69Cam]

Most factory setups turn the electric fans off over 40mph or so. If at all possible, wire a bypass switch between your fan relay and temp switch so you can turn the fans off manually. See if your cruise temps don't go down with that.

I have the same fan setup on a Griffen 1.25" dual row Al rad, in my 69 Camaro, and it keeps a .060" over 454 at 170'. According the the old-timers I've talked too, the old 454s turn into heaters when the overbore exceeds .030". The old cooling system from the 396 would over heat at idle with the 454.

The BeCool fans are Spal which are OEM for many European cars, so I doubt you'd gain by using the Mark VIII fan. Granted, if you did not have a fan, the Mark VIII (or Windstar fans) are smoking deals.

[Rubes]

I almost put a bypass switch in when I was wiring it all in. But I can almost guarantee that I would forget to turn it on someday.

Since the car rarley sees the highway, I'm not bustin' my a$$ to change anything. I'm too focused on my new project right now. But if I can learn something from this to incorporate into that, all the better. Know what I mean??

Thanx for all the input guys
Rubes

[Steve Chryssos]

That engine compartment looks very nice Steve.
-Tim

Thanks Tim.

[TheRoaringEagle]

Mr. Steve, what kind of brackets and pulley system do you use? Why does it have both serpentine and v-belt? And is it custom (expensive)?

[TheRoaringEagle]

Oh and also where'd you get that breather setup??

[Steve Chryssos]

Custom? No. Expensive? Yes. Worthwhile. Yes--especially when you factor in high rpm use. P.S. pump/water pump/damper pulley is serpentine, alternator is gilmer drive. Source is Jones Racing Products.

http://www.jonesracingproducts.com/
Chuck Jones can be somewhat "ornery"--especially when dealing with street car enthusiasts. So know what you want before calling (exact engine/application specs, list of drive components and preferred mounting location) and ask specific questions or Chuck might come thru the phone and bite your ear off. Be sure to specify that you need an alternator for a street car. Better yet, just ask for his son, C.J. when calling. Nothing good is ever easy.

Valve cover/Breather setup comes from Canton Racing Products.
http://www.cantonracingproducts.com/valve_covers/sbc.html
/Steevo