On a "Production" carbureted engine the more over 200 degrees that you the more prone to detonation you are. New engines with EFI use the fuel to cool the engine and have control over timing and the amount of advance to prevent detonation. They also run higher pressures in the cooling systems to keep the water from boiling from any hot spots that might occur. If you are running a carb with a 13-17 psi cooling system you want to keep the cylinder head temp as close to 200 as you can. Diesels NEED that heat to get the engines to fit right and to ignite the fuel mix. Some air cooled engines run temps of 280 - 300 at the cylinder head but you don't want to do that with a water cooled engine and a carburetor. You want to adjust cylinder head temp to fit the engine system you are using.
I normally don't argue with you because i realize that you are ole school and cant or wont accept the technology of today. But if you single me out as you did i will call you on your beliefs. I personally have a 351 that i intentionally run at 210 degrees, Because at 210 degrees i can get about 2 mpg increase. And this has been Thur extensive research. And yes it is carburetored with a stock duraspark ignition system (nothing fancy done to either) And as far as fuelie motors using the fuel to cool, This is not true. Because if you used enough fuel to cool the motor you would be wasting fuel,( i have saw this done in Blown applications) And we all know fulie motors get good mileage. You are correct in using the timing control to prevent detention, And i did mention that some motors will run hotter than others before detonation will occur. And by the way all nascar motors are carbed and run upward of 220 degrees. The hotter you can run a engine without detonation the more efficent it will be. And if he is running a t-stat of 195 and has no issues why would he need to change? And there is no way that you can say every PRODUCTION carbed engine cant run a head temp over 200 degrees, This is just not true.As i stated earlier this is just my opinion from experience and others will vary.
Well my opinion varies...You can't compare a NASCAR engine to a street engine...they don't buy there gas at the corner gas station. Higher octane keeps detonation at bay. Also their engine spent a little more time in the machine shop and engine stand than a regular production engines. To me, it ain't worth saving a penny or two to get better mileage. Gas is still cheaper than a motor. You can still have detonation and not hear it. I can tell the engine tempature by the way my car runs. Between 180-193 degrees it has more seat of the pants power than it does at 205 degrees. On another note...water temp and head temp are two different numbers. Water (coolent) is moving and gets to be cooled off in the radiator whereas the metal has to sit there and depends on heat soaking it tempature to the water jacket.
For what it is worth, without getting into any other people's arguments, POWER is better on a cooler engine. I picked up 5 hp on the dyno after letting it cool back down to 170 after 4 pulls at 180. May not have been better fuel consumption, which is what the original question was.
Once again you guys crack me up. Your talking fuel mileage on a 30 plus year old hunk of iron. These cars are so far out of the modern age that shoots for emissions and mileage it seems crazy to discuss mileage. So many guys go and install different cams and add ons then try and figure out where the MPG went. Like I tell the majority of my customers MPG is 90 percent driving habits. You install a 4 barrel you drive it harder cause you like the power. For example my 02 300 Special gets 25 MPG average when my wife drives. When I drive it gets 21 MPG average. I enjoy the way it drives so I drive it a bit harder to take advantage of it. To question a t-stat difference with a carb to account for 12 or so lost MPG isnt the way to go. The mileage must have gone elsewhere. Upgrades for power etc. I notice Paul mentioned tire pressure. It plays a big part in MPG and I try to stress it to my customers. 5 psi can make a big difference.
Huh... i had the 180 in and got crappy power, threw that 190 in and did burnouts (yes i have finally acomplished this)
Dont get to confused. It really depends on the car and set up. My car runs noticeably better around 195-200 than at 180. Too many variables to compare car to car. Its what ever works best for your car.
I like mine to stay between 190-210. It runs the best and gets the best gas mileage there. I have to partially cover my radiator with cardboard this time of year to get it up to those temps, otherwise it has a hard time getting over 160. My car gets the best highway mileage at 70-75 mph, low-mid 20's for gas mileage this time of year, a little better in the summer. I've got a 200 with MSD ignition, Taurus fan, header, and Rochester BC carb. C4/2.79 gear. Driving style has a whole lot to do with fuel economy as well.
I have a 302 Maverick, all stock and get 21 mpg...... I can spin the tires at will through second gear....... I run a 180F thermostat, 35 psi in tires, Idle as low as it will and burn 87 octane gas. I have seen many volumes of research on IC engines - all from pre-smog engines through the mid seventy's. All of them recommend 200F cylinder head temperature for best performance. With add-on parts, aluminum cylinder heads, coated pistons, polished chambers, long overlap cams, richer power mixtures or alcohol based fuels you need to make changes to get the best operating engines.
