Why not insulate the engine instead? Coatings, wraps, shielding, reflective surfaces, blankets, etc... Many products for heat retention.

This will in turn reduce engine bay temperatures and improve engine economy. It will help smooth the engine idle as well and make use of more exhaust gas energy.
Make sure to run the engine at least minimum 190*F ideally.


Heat extraction is like opening the lid on a grill- you have to turn up the gas to maintain the cooking temperature. Good for when you need to throw away the heat to make high power with cheap fuels (Intercoolers, water injection, aim to trash energy to preserve the engine) but we are talking 800+rwhp from a 5 to 6L using 93 octane V8 before that starts being a thing.

 

Help me understand this? You are talking about retaining heat we are trying to get rid of it

 

heat is energy. Look under the hood of modern vehicles. They are heavily insulated with plastic insulating materials and thick shields where needed. They run high coolant temps 220*F~ and more. Exhaust tubes are thick to retain energy. It is economical.

If you retain the heat inside the engine then the heat won't be inside the engine bay. The difference in temperature between two objects is the rate of heating. If you for example insulate exhaust with exhaust wrap and ceramic coatings the surface of the exhaust will transfer less heat to the air and the inside of the exhaust will become higher temperature which will increase exhaust gas velocity which improves cylinder scavenging when the exhaust is designed properly (almost all OEM use this technique to reduce energy wasting on the intake stroke and it is why people report losing torque when they chop off the exhaust system - no more free energy from exhaust to pull in fresh air and the intake cam event is not intended to utilize the piston for it's suction on the intake stroke fully)

That heat is money from gasoline. You don't want to throw it away! The radiator is doing plenty of that already. Keep the rest. Insulate. Profit.

 

Here is a philosophy of mechanical engineering perspective

The engine as a machine desires fully warmed oil and coolant. The shape of its parts demands the correct oil and coolant temps for ideal longevity and reliability.
We monitor the oil and coolant temps and bring them into correct ranges. For modern vehicles its a bit warmer than old 80's and 90's stuff sure but in general for performance apps whether 2L 3L 6L Engines the target starting point for oil is around 205*F to 212*F , and for coolant always about 5 to 10*F lower than the oil. 198*Fcoolant and 210*F oil is ideal example.
These starting points give the necessary warmth to engine parts for smooth operation and oil character for protection. They are also low enough to give headroom for temp rise during performance outbursts. And high enough to supplement the vaporization of fuel and smooth engine operation and so forth.

Beyond the temp of those coolants (oil is a primary coolant), we have a lot of room to play with for other parts. For example plastic intakes run around 112*F on an LS application whereas metal intakes on carb apps for sbc run higher perhaps 140*F or more because the metal is absorbing heat from the head which runs near the temp of oil and coolant. The heating of metal intakes also tends to heat the incoming air so people historically use low thermostat coolant temps for reduced air intake heating, however slight. This will go away from the philosophy of mechanical power plant requirements because engine cylinder wall diameter influenced by coolant temperature creates potentially excess wear and tear for engines intended to run with warmer coolant. For example boat applications using cold lake water must be machined for tighter piston-wall because oil will be hot 200*F but coolant cold 140*F or whatever to keep the manifold cold and air cold and cylinder tight. It is better to find your power in other places which will not influence engine reliability.

What do. The intake manifold and fuel reservoir needs to stay cool in all applications if possible. Electronics such as coils and fuel injectors also would prefer to be operating temp and not higher. There are different methods for different applications but I will give a general overview for all carb/efi. We consider each vehicle in turn and apply custom patching where needed. For example in a vehicle with 1200rwhp and 3 fuel pumps we just run 1 single pump on a PWM to keep fuel temps low for normal operation. PWM is a great way to reduce fuel heating with a single pump. Alternatively if in a carb application a recirculating (return line) could keep fuel refreshed at the carb by cycling back to the fuel tank exactly like an EFI car. Insulating materials between carb and manifold additionally with some reflective surfaces helps keep the carb temp down. Mainly, making sure the fuel isn't being heated by some ridiculous reason, like a fuel line near exhaust and lack of a return system, you can easily modernize the carb and EFI to maintain low fuel temps. The reason we like low fuel temps is because everything in the fuel system tends to last longer when A. pressure is kept low as possible and B. temperature is kept low (both, reasonably low). It is more for the reliability and consistency of our parts we do this, not performance boosting. Again like with temperature of coolants we accept the range and work around it, don't try to fool it with gimmicks that provide nickles and pennies of power at the cost of reliability.

Insulating the exhaust keeps alot of the heat out of the engine bay. use thick tubes and ceramic coatings. And shields. And Blankets. Exhaust wrap works good but it really really ******* sucks to work with. Excuse my language but I want to drive home the point about the wrap being a devils deal, absolute control but at what cost.

I briefly here covered the exhaust, intake, fuel, pumping, various temps, for these old cars I do not consider power a priority or concern whatsoever. If you want power you will do an LS turbo swap it is simple as that. The LS turbo provides you with a $almost free engine and over 600rwhp on gasoline with 200,000 miles of reliability, it cannot be beat in performance:budget ratio by anything. What I am saying is, treat your engine (probably a sbc or bbc in this section I guess) like a longevity and reliability app, not a performance app. Do the things necessary to make it run good and reliable , avoid all the performance gimmicks. I can name a bunch here for you to aware of in this philosophy...
1. Use quality OEM-paper or similar air filtering. Off-road filters are good. Avoid oil soak filters if you are not going to oil them and clean them properly.
2. Use the OEM PCV system and improve upon it. Increase PCV intake suction flow to improve oil quality. Measure the crankcase pressure and modify the PCV system to maintain a negative pressure at all times. Ask for help if you need help with this it is very important. Suction at wide open throttle will prevent oil leaks, it pulls oil back into the engine, prevents the smoking behavior. PCV like this also keeps water out of the oil, prevents milkshake in sbc land.
3. Cruise and idle with lean air fuel ratios, 15.2:1 to 15.8:1 is practically ideal for a cruise. You will need a wideband. Lean air fuel ratio improves economy and helps reduce carbon deposits, plugs stay cleaner and the cylinder has less hard carbon over time.
4. Synthetic oil only, change those seals
5. Pressure testing. Pressure test the crankcase (1psi max) and intake system (15+psi acceptably) for leaking. Never allow leaking air because it will carry debris, nevermind the other problems.

The ideology is that we care about the machine functioning as reliable daily transportation more than we care about its performance aspects. If we wanted performance we would use the LS turbo, far more cost effective.

 

However all heat energy isn't necessarily beneficial.

 

A member who went by the name "Bee Jay" did this years ago.

https://www.corvetteforum.com/forums...post1602174249

No pop rivets either

 

I solved this issue by cutting a hole in my hood and to stop it from looking awkward I filled it with a tunnel ram.

 

I think I just might try this smaller one. It looks like the 10.6 by 15.5. Same width but not as long. I already ordered it from Summit, it was the last one they had. It might just be fate. LOL. I also don't want to rivet this louver on, I want to be able to unscrew it if necessary.


To be continued:

I will keep you posted.

 

Unwanted heat goes to the radiator - way away from the engine bay if possible.
The quantity of unwanted heat is a fraction of fuel being supplied, we call it 'brake specific fuel consumption' and measure directly, quantitatively, and can be used to collect data in triplicates to perform statistical analysis p < .05. In the tuning of the engine is a major potential source of extra unwanted heating however let us assume tuning is perfect. Next we consider the thermostat. If the engine water temperature is high enough to open the thermostat it means there is some unwanted heat that needs to go to the radiator. The same applies to oil cooling which should have thermostat as well.

If along the way to the radiator that heat can escape, lets say from the head and intake manifolds acting like heat sinks, spreading heat into the engine bay, then the engine bay becomes the radiator absorbing unwanted heat and this helps close the thermostat almost as if the heat went to the radiator anyways. In fact you may be familiar with engines that are entirely air cooled. Similarly the oil cools the engine parts and removes heat and an oil cooler can take load off the radiator and help by carrying the unwanted heat away quickly somewhere away from the engine. Both oil and water cooling of the engine are used to control the unwanted heating to some precise range of temperatures. If a powerful performance vehicle has issues with temperature usually the best response is an oil cooler and aux oil cooling fan systems which are far more effective at removing heat from the engine and taking it away from the engine bay.

When unwanted heat escapes the cooling systems, for example into the engine bay, it can interact with engine parts. For example hot engine bay air will interact with the intake system and external plumbing. It will contribute to accessory heating, air and fuel, all kinds of things. Sure you can vent it but now you've got an energy leak with no control point- the 'point' of using a thermostat and radiator system for coolants is that you control the heat, sending it off as needed and keeping it away from your engine bay and the parts inside.

 

Im sure if your"Theories" were accurate and feasible then they would be used in racing in all its forms..which they clearly are not.....heat is not beneficial to a combustion engine. moving air efficiently is. If you heat up the air inside the engine, the efficiency goes down because you cant stuff more air in without a forced air induction power adder like a blower or turbos. Then the heat in the cylinder continues to climb and then detonation increases. As for your modern engine high heat theory its backwards as well. The insulation is there to keep the heat away from everything they are trying to keep cool.
Google F1 engine heat and longevity. They run extremely hot and are junk fairly quickly....

 

Are you sure you're right? The guys at the drag strip cool down their turbos with ice , intercoolers and water coolers etc....them stoooooopid blower guys will even pack bags/blocks of ice on their blowers.....hmmmm I'm going to run my big block at 220 from now on and reep all the lost ponies! I'm joking, really.

Ultimately heat kills horsepower and longevity, it's called heat soak. Roughly every 10 degrees F makes about a 1-1.3% horsepower loss. After all what's an engine but a big air pump.

 

LOL. everybody uses turbo blankets, exhaust wrap, ceramic coatings. All OEM use plastic insulation and heavy thick wall tubes. Literally every OEM raised the coolant temperature and increased insulation as time going on. All power plants in the world use the highest possible temperature feasibly.

Its all around you in every engineering facility in every model around the world. "theories" rofl

I am not speaking from theory , I speak from experience and education. I've tuned every kind configuration- water meth alcohol twin sequential roots carb tbi mpfi 2L 3L 4L 5L 6L etc... I have far more experience than majority of humans in this area.

 

If the air temp is 102*F. Oil temp is 208*F. Coolant at 200*F.

Then its perfect. You insulate, no heat in the engine bay, perfect engine, perfect bay, done.

Your 'theories' about somehow melting the engine while the air oil and coolant temps are in check is just hallucination!!!

Would you all like an example of my applied science where i put my money where my mouth is an build a fully insulated gasoline powered vehicle that has reasonable output? Absolutely flawlessly tuned for economy and power and reliability with a factory looking appearance and noise level ah who is doing that these days?

 

Them dual quads are money, ain't factory appearing...but it looks good, it's tuned for horsepower not economy, noise level is almost sexual, it's reliable....whatcha building?

 

Even though I don't like chrome, or stuff poking through the hood, I LOLed at this perfect reply to the other responses on this thread.

 

That said, C7s have hood vents. Some Camaros do, too. So to Ford GT-40s, and lots of other road-race cars. The underhood temps are meaningless, unless you have something under there that actually is heat sensitive (like your ECU), or you defeated the stock CAI that likely came with your car. The hood vent allows more air to flow through the radiator, which increases the cooling capacity of the system, allowing you to dissipate more heat from a bigger engine making more power. As a bonus, it improves airflow and front downforce. In a stock C3, air that doesn't bypass the radiator (bad, add a chin spoiler), will then have to choose between going back under the car (bad), or out the functional side vents. Or through a hood vent. Just don't put it too near the windshield, as that will force air in from the wrong end (that's why there's a seal at the back of the hood, or a sealed airbox in some cars).

If you live on a runway or racetrack, away from speed bumps, and only drive at 150 mph and up, you can get away with a lot less airflow, which gives you even more downforce. To @Kingtal0n's point, you can get more cooling efficiency by increasing the difference between the ambient temp and the coolant temp. NASCAR does this by racing slick cars that look like giant multi-vitamins, with a 30 psi coolant system running at 290 degrees F. Read about it here:
https://jalopnik.com/the-fascinating...hot-1835071544

But most of us drive our cars on the street. So hood vents work, when placed correctly. There's a reason you see them on tracked cars.

 

To mathematically convince yourself that engine bay air should not contain unwanted heat, one may calculate the energy dissipation rate into coolant and compare it with dissipation into the air of engine bay.

One will find that the dissipated energy into the radiator is significantly higher magnitude than that which is dissipated via the air around an engine.
Then, you recognize the heating the air around the engine is nuisance heat, negligible heat.
In other words, heating the air around the types of engine discussed here is not helping the engine cool significantly.
It does not help with the cooling of the modern V8 or old V8 engines. Or even typical 4 and 6 cylinders.

Trapping that heat is likewise negligible, the cooling system and engine don't even 'feel' the difference. It isn't going to overheat any parts, conversely actually it will cool external engine parts and engine bay parts.

 

I am only addressing the heat lost by an engine to its surroundings which did not make it into the cooling system. What you describe is a functional vent capable of removing heat from the radiator for heat which HAS made it into the cooling system- that is like a fan on the radiator. Of course you need a fan and airflow to cool the radiator. A random hood vent will not cool the radiator unless it is well designed. Hood venting is just radiator venting when done to cool the engine properly, like adding a larger radiator fan. If you just cool the air around the engine it will do nothing. Like you said meaningless. I think you are on the same page but alot of these people think the engine bay heat is dangerous and should be ejected or it will overheat the engine parts and cause detonation. Which is absolutely ridiculous and why we are having this discussion. You can insulate the hell out of the engine and place a functional venting and fan system to remove heat from the radiator - fine. But don't put a hole in the hood without considering these details and think you've done anything more than weight removal.

 

Here is thoughtful checklist for your decision making logic:

When you need Insulation
1. My Accessories (ps pump, alt, etc..) are getting too hot!
2. My coils/injectors/wires/sensors are getting too hot!
3. My valve covers/intake system is getting too hot!

When you need better fans/venting for heat exchangers
A. My coolant is overheating!
B. My oil is overheating!


The heat either goes into your precious external parts (insulation) or into the radiator (fans & venting). It is simple logic based on the possibilities due to initial conditions and the way heat transfer works.
The reason this is considered the 'right' way from engineering perspective is because the heat exchangers have thermostats which control the energy from leaking out. For example if we remove the thermostat now the engine can lose too much energy and run too cold. Too cold or too hot, we need the control, we need a thermostat for control. No matter how much you vent and cool the radiator the engine can stay properly warmed this way. I am all for venting heat exchangers as this is a basic requirement. I am against randomly placed energy leaks with no control points that serve no purpose. Well some of them look cool I guess, but I am not into that personally since I was a kid and went through that phase. now my stuff just looks normal.


Is it something good under the hood?

 

You say normal I say boring!