Thread: Big Block...safe running temperature?

Tweet

I'm running a 496 Gen VI block, 13.5 :1, Dart Pro 1 335 cnc'd heads, pretty radical for the street. I drove it around a couple days ago, and watched the temp climb to near 200. Is that reasonable? If not, how can I bring it down? I have a be cool alum radiator, w/ fan, electric water pump, 180 thermostat. Thanks for any input.

Here's an article that several of us old-timers have contributed to. Read through it and you may find something you missed. In the end though, I would expect a 13.50:1 motor to make additional heat over a run-of-the-mill SCR.
http://www.crankshaftcoalition.com/w...cooling_system

200 is not bad . you may want to play with water speed . i had a to 548 14.8 on the street my 572 and now 632 the boys at BECOOL still do not know how i do it with a stock 66 gto rad a many smaller hi cr engines that ran around that temp. i built/machined alot of bbc for others 200 in it self is not to bad as long as it stay there .you want as much timming as you can get off ilde this can help it run cooler BUT under a load you need to pull some timming out . i have played with bbc for 30 years now some bigger engines and more cr engine s are going to run warmer.

As Pat said.....200 is not hot for that HP.
Using an electric water pump does have its drawbacks. Understand that an electric pump flows X number of gallons per minute(GPM) whether you are going 100 or sitting at idle, it flows the same. If the car is at idle or just in a cruisng situation 25-35 mph , you are not using much HP so you are not making too much heat so the pump can keep up with the cooling.
But once you get out on the highway and start doing 55-65 mph, you are using more HP and making more heat, but the pump is still flowing the same GPM as you are at idle. Upside is the airflow is better at speed so it can help out alot.
A belt driven pump can be overdriven by using a smaller pulley on the pump and larger on the crank which will push more coolant at low RPM and even more at higher RPM. You are limited with an electric pump.
But again...........200 is not that hot for that HP.

Thanks a lot for the input. A few friends that run their big blocks on the street, felt that it was too hot, thinking that the alum. heads were at risk. I questioned that logic, since I previously had a couple of built c5 Corvettes that always ran at 210 - 220. Yes, they were LS small blocks, but they also had alum. heads. Thanks, again.

Originally Posted by lodilobo

Thanks a lot for the input. A few friends that run their big blocks on the street, felt that it was too hot, thinking that the alum. heads were at risk. I questioned that logic, since I previously had a couple of built c5 Corvettes that always ran at 210 - 220. Yes, they were LS small blocks, but they also had alum. heads. Thanks, again.

well i had a 548 that ran at 220 all the time. it ran the best warm past 160 .i was going to rering/rebearing it as we beat the hell out of that engine was thinking it would be toast inside it was like the day i put it together so that change my way of thinking about water temp 15 years ago. were the sender is comes in to play as well you may not be as hot as you think ??

I used to run the 160 thermistat in my BB Dodge's it always ran about 180.
The other thing I used to do when I had thin cylinder walls and it ran a little hot
was to run water flow restrictors, Summit, Mr.Gasget, Moroso all make them.
You get about 3 in a package which are differant sizes for differant temps.
They usally cost about 8 bucks for a pack with a gasget.
Kurt

Originally Posted by vara4

I used to run the 160 thermistat in my BB Dodge's it always ran about 180.
The other thing I used to do when I had thin cylinder walls and it ran a little hot
was to run water flow restrictors, Summit, Mr.Gasget, Moroso all make them.
You get about 3 in a package which are differant sizes for differant temps.
They usally cost about 8 bucks for a pack with a gasget.
Kurt

yep and if your cheap like me you just cut the center out of a old stat and then i used diferent size OD valve spring shims and tack welded it to the old stats bodys to see were the best size hole was . but for 8 bucks may be less for some if you do not have a VSI spring shim cabinet

Something also to remember.................the sending unit for most gauges is located at the front of the manifold, right near the the top radiator hose outlet . So as the coolant passes the sending unit, it is picking up the coolant at its hottest point. But it is coolant that is leaving the motor, not whats in the motor.
If the pump, rad, and fan are all doing there job, the coolant temps coming back into the block at the bottom hose should be 15-20 deg cooler.