Project MMPG ~Slow build thread

[erice1984]

Ive read alot of opinions on making more flow through your radiator, personally i think you will lose fuel economy if you try and make the engine run cooler. Cooler intake air will increase flow because of a denser charge thus increasing power. But cooling the engine water temperature will probably provide a more incomplete burn. From my understanding these engines are built to run at 195. And to try and run it cooler than that would be counter productive.

I agree to an extent.

If you increase airflow only through the radiator; you still have a thermostat that begins to open at or around (very close to) 195, you won't lose much economy because the engine will stay at optimal temperature.

If you increase airflow throughout the ENTIRE engine bay.  Thus increasing the airflow in direct contact with the engine then you are cooling it more than what it should need.

With that bit of information and the articles Bugsy provided are a good start to figuring out increased fuel economy.

To add a bit more, if you can redirect airflow that usually strikes the front cross section of the car you can really reduce the amount of drag.  Imagine if you can create an air 'bubble,' a pressurized area someplace around the car to create a more aerodynamic shape, this would increase fuel economy.  Pickup trucks actually get better mileage with the tailgate up than down.  This is because a pressurized air zone is created and allows air to flow down to the back of the truck with less resistance.  I believe Mythbusters did an episode on it.  Also why would engineers that get paid a lot of money otherlook something so simple?

[nathan_b]

Heat is energy, if you have a radiator throwing away a bunch of heat, you are throwing away a bunch of energy.

[erice1984]

Heat is energy, if you have a radiator throwing away a bunch of heat, you are throwing away a bunch of energy.

Welcome to the inefficiencies of internal combustion engines...

The most efficient engines are diesels.  At about 30% efficient.

The radiator should not be "throwing away" heat unnecessarily.  This unnecessary waste would only happen if the thermostat is not working properly.

[erice1984]

I was thinking on one thing.  If you switched from an old brass/copper radiator to the newer aluminum ones you can decrease the amount of air that needs to flow through the same size radiator.

Aluminum is a better thermal conductor than brass/copper.

With that the same cooling capacity from a smaller aluminum radiator or same size radiator with reduced airflow.

[Bugsy_malone 666]

i think what i was getting at with the radiator thing was not about making the engine run cooler, as you want it runnign at around 90c for its optimum temp. What I was trying to get at is that really what you have at the front of the older golfs is the equivilant to a bit open mouth creating massive drag!

So what you do is look at the fact with I know at least on the mk3 golf you have an area below the centre of bumper and the grill itself, if you were to seal the radiator grill with a flat slab that effectively increased aerodynamics as the air that would now flow round the car rather than create a sort of drag by going through the engine bay, the engine would probably run a bit hot with just under bumper cooling area. however if you were to make engine bay ventilation more efficient by venting hot air via something like a naca duct into the airstream in an area of low pressure on the bonnet, would make the radiator work how it should do again, but the principle being drag reduction.

what I was thinking is with the mk1/2 golfs most of under the bumper seems to slope under the car, so if you were to make sure all holes below mid bumper were sealed, then seal the underside of the engine bay using one of the guards off a mk3 golf for instance you would then need to ensure the engine bay was getting enough flow through using just the main grill which cant be made massively more efficient I dont think, my maybe utilising vents in lower pressure zones.

in theory the research into aerodynamics, you kinda need to look at aircraft as obviously they have to be as slippery as possible with minimum drag, then have a look at modern 'eco' cars like the prius, polo/golf bluemotion and compare them to the same version that arent eco models to see where the changes have been made and then see if you can work out how to apply to what your running.

There are also positive/negative effects you have to look at too. For example I already mentioned about the cooling/front area of the car, but theres more! if you were to run Moondiscs and steel wheels you would minimise disturbance of air from wheel rotation, at the cost of brake cooling, leading to brake overheat. however there is the element of compromise, if you look for some eco vehicle hubcaps and see what they run, try and acquire some yourself. say like a seat ibiza tdi ecomotive (do you get those in the us/canada?) it has hubcap/steels with 175/65 R14 (i think) and the hubcaps actually reduce drag but arent smooth, however the vw polo bluemotion has alloys and does about 1mpg less or something.

so there is a fair amount of things to look at/pinch ideas from things that are already running rather than reinventing the wheel

[nathan_b]

Time for some 80's Moon disk hubcaps 

[erice1984]

Yeah, they are sweet 

[maxfax]

Time for some 80's Moon disk hubcaps 

A buddy of mine had an old 60's Econoline (Rape Me) van with those...  I loved popping them off and  putting stones in them when he wasn't looking.. 

AS far as aerodynamics, I wonder if there would be something out there that you could modify the nose from to smooth things up, kinda like the ole Super Birds.. They pulled all the air for cooling from underneath that thing..  The third Gen F-cars (Camaro/Firebird) did about the same thing..   Might look a bit odd on a Golf, but would help accomplish your goal..

[erice1984]

clipper kit def helps aerodynamics

[maxfax]

Indeed..  It's just that big gaping mouth of a grill that's a killer...

[spdrace11]

Ill be watching im in the same boat.

[erice1984]

Yeah, I was making a trip to Canada in my MK1 recently, and I would check oil level/add oil every time I stopped.  I noticed the salt buildup on the entire front of the engine..  The ENGINE.  I thought how the hell is it getting that much airflow and the contributors of this thread helped me realize that it is coming from underneath the car.  I also concluded that this may be causing the engine to take a long time to heat up in the winter...  So, I will definitely be adding some aero kit to the list of to-do's.   Most likely the clipper kit (cabby body kit)

[spdrace11]

Yeah, I was making a trip to Canada in my MK1 recently, and I would check oil level/add oil every time I stopped.  I noticed the salt buildup on the entire front of the engine..  The ENGINE.  I thought how the hell is it getting that much airflow and the contributors of this thread helped me realize that it is coming from underneath the car.  I also concluded that this may be causing the engine to take a long time to heat up in the winter...  So, I will definitely be adding some aero kit to the list of to-do's.   Most likely the clipper kit (cabby body kit)

Wouldnt it be coming through the radiator? 

[erice1984]

Yeah, I was making a trip to Canada in my MK1 recently, and I would check oil level/add oil every time I stopped.  I noticed the salt buildup on the entire front of the engine..  The ENGINE.  I thought how the hell is it getting that much airflow and the contributors of this thread helped me realize that it is coming from underneath the car.  I also concluded that this may be causing the engine to take a long time to heat up in the winter...  So, I will definitely be adding some aero kit to the list of to-do's.   Most likely the clipper kit (cabby body kit)

Wouldnt it be coming through the radiator? 

Either way it comes in, the entire front of my engine is covered in salt spray.  This would lead me to believe the majority is coming up from the bottom rather than through the radiator.

Water flows damn near the same as how air flows around stuff.

This picture may clear up where the radiator is located in relation to the lip on the bottom of the car.

[R.O.R-2.0]

Yeah, I was making a trip to Canada in my MK1 recently, and I would check oil level/add oil every time I stopped.  I noticed the salt buildup on the entire front of the engine..  The ENGINE.  I thought how the hell is it getting that much airflow and the contributors of this thread helped me realize that it is coming from underneath the car.  I also concluded that this may be causing the engine to take a long time to heat up in the winter...  So, I will definitely be adding some aero kit to the list of to-do's.   Most likely the clipper kit (cabby body kit)

Wouldnt it be coming through the radiator? 

wow.. a self adjusting clutch cable on a mk1..

thats almost as bad as using ford parts on a chevy..