Okay guys,

I have run several big blocks, all with 180 degreee thermostats. My current 502 will run at 170 forever, even with a 180 degree stat in traffic. Somewhere I read or heard that this is not the best temperature for horsepower, etc. I would like opinions on what temperature big blocks "should" run at for best performance.

Thanks,

Mike

This is something I have been working with all season...I have been running mine at 170-180° down the track only because it gets to 200° on the return road. I have been told that you want hot oil and cool water for best performance, so I just bought a Ron Davis Aluminum Racing radiator to maintain my temperatures a little better and get the thing cooled down faster between rounds. I hope to run mine at 160° this year

Originally posted by chevy_69_chevelle:
hot oil and cool water for best performance, Yup...I stage at the lowest possible water temp I can maintain consistently throughout time trials and eliminations on a given day. It will vary... On hot days it is 160 and cool days 150.

If you stage at different temps your et's will likley not be too consistent as far as competitive bracket racing is concerned.

I hate to break this to you guys..but respectfully so.....cool coolant temperatures (as we measure them) do not necessarily mean more hp? What you want is the most dense charge which means cool induction temperatures per se even tho there can be a relationship to coolant depending on the design of too many things. Coolant temperatures also do not equate to metal temps or peak cylinder pressures either, which we all know are key to hp generation. This cooler approach is a widely held myth to the extent of dropping below the best design temps of 180. I watched Cup engines being dynoed in the shops and their coolant temps are around 205 to 215 for the best power. Most NHRA Pro stock guys are around the same temp by pass time as well. YOu would think that if cool water meant more hp everyone would be clamouring to do it!

I also offer this diatribe with respect to all. First my chart of corroboration borrowed from a site. I love this chart! ;)

http://performanceunlimited.com/illustrations/img212.gif

The graph above illustrates the importance of how critical optimum coolant temperature is to the longevity AND PERFORMANCE of an internal combustion engine. Yes there is somewhat a anomolous relationship to coolant temps and power and yes we already know that warm water minimizes engine cylinder wear,.... but both only to a point.

There is an "optimized" overlap as the chart depicts where both optimum performance as well as minimal wear share similar ranges. That perfect number lies in the 175-180 degree range, which of course requires a 180 degree thermostat. So, don't change that 180....you are doing just fine!

The all too commonly touted and used 160 degree thermostat is way too low to be considered for performance or engine longevity. As the graph again illustrates, engine wear is increased by double at 160 degrees than at 185 degrees. Notice that the in-between "180" appears to satisfy both ends of the spectrum. There is also a correct water temperature required for the cylinders to achieve a minimum specific (or design) temperature in order to allow a fully homogenized mixture to combust efficiently and therefore create the most power as well. That target by design temperature has been 180 degrees forever.

FWIW, I do not recommend 160s for any application and have plenty of dyno proof to corroborate my take here. Running the same engines at 150 to 170 always produce lower readings than 180 to 200 ranges and I would think you would want to address the wear aspect of this issue as well. Especially when you are beating them up so to speak.

Just my two sense :D

Wow, that chart really says alot. Makes me want to get to Discount Auto in the next 15 minutes before they close to change my 160 back to a 180! Too bad the website it's from seems to be a F*rd page! graemlins/sad.gif

---Chris

All that makes theoretical sense, but for the bracket racer, where consistency is the key, 160 is fine if thats what works.

My 30 year old rat runs terribly until those old heads seal good. Around 200 seems to make the most kick. Usually runs the quickest trap speeds right off the highway. Go figure. It'll be off 2 mph when cooler, at least with the few datapoints I have.

But, I didn't believe the guy who ran the old L88 for a bit. Said to use a 195 and keep it hot for best power. I, of course, had to find out for myself and tested 160, 180, 195. Unfortuntely, not scientifically. But it was clear the motor feels quite wicked only when hot.

The good news is, as Steve's chart points out, modern motors oils seem to do their best work when the motor is around 190-200.

And I used to throw 160s in my old motors to "make them last longer" or "run easier". Well, maybe it worked 20-30 years ago.

Hot Rod,

your discussion is certainly valid and I agree with the temp range. The "experts" have always said the BBC makes the most power between 180 and 190.

As most of us in bracket racing only have a coolant temp gauge it must be used to determine a degree (no pun intended) of consistency. It doesn't seem to matter if I stage at 150 or 170, I am still at the same coolant temp at the end of a run 180 to 190....every time except on exceptionally hot days.

Staging at a lower coolant temp WILL make for a quicker ET and 60 ft in mine and most everyone I know with a street/strip car. In fact this is discussed almost every time at the track. This tells me that I am making more Torque with a cooler water temp than I am with a hotter coolant temp. MPH doesn't change.

I cannot offer any opinion on the temp versus wear theory as I do not have any experience or knowledge and have never looked into that aspect of it...something to consider...

It seems cruising on the highway at 160 is wearing out a motor much quicker than if it was at 190.... :(