TheSamba.com :: View topic - Adding modern scoop for split bus engine bay cooling / pres.

Fri Mar 29, 2013 8:19 am

We're getting into the fuzzy area here of "feel", "think", and "marginal". I FEEL the air vents flow plently not mention the various air leaks around the motor.

I'm not saying your system won't cool or even cool better...what I AM saying is it won't help you. I have demonstrated its not the air flow that can play the biggest factor in your engine temperature, but things like tuning, compression, and fan speed are. I can run my big motor pretty much as hard as I want and I only ever get up to 350 CHT max on a serious climb.

Fri Mar 29, 2013 9:28 am

Sorry..."feel" and "I think" are part of ownership of a statement. This is used so not to confuse people with it being stated as a fact, but merely what I think or feel.

I am not dismissing the success of your engine, or the stats that you have provided based on your observations. Your input as a counterpoint has been valued.
You have stated that there is no problem with air flow, that there is enough for you engine to perform and cool it. Yet your engine is running too cold and you are trying to sort that issue out.
I then would suggest that your engine may not be the best subject for this discussion as you have proven that diminished airflow did not solve your too cold issue.
That is a very unique problem with your engine and not the norm, obviously.

I simply, out of interest, would like to know what pressure the engine bay exists in, is there in fact a pressure drop do to the extra air usage of aftermarket performance goodies.

I don't place engineers on a pedestal, if I did who would design it to hold their weight? I simply don't think that the designers had a 225% margin in the design of air flow to the engine bay of early buses.

The design of the front scoop and a 3" pipe run to the engine bay, that I have proposed, flows enough air to nearly meet the requirements of a stock engine and will exchange the air in the engine bay 43 times/min. .

Gordo.

Fri Mar 29, 2013 10:10 am

Sniperx wrote: Still thinking you're going up the wrong tree....

I'm running 14.3 AF ratio, 6.4x15 tires (30 inch diameter), 3.88rp, 82 4th gear, and am hitting 250 CHT on the freeway. I am also running a Porsche pulley. My oil temp at the sump (pre-coolers I believe) is 170. My motor does not run leaner on the highway due to fan speed and engine volume. My brother, an engineer, described it as this...when your available volume is so large in comparison to the draw or the flow the amount calculated is negligible. Basically consider a dam. It has a HUGE lake on the other side. The amount of pressure lost at the turbine due to the small leaks and cracks is so small its not taken into consideration. When you take the amount of air available to your motor in consideration vs the amount being used....its negligible.

My problem NOW...running too cold. I'm topping at 200 CHT on the road. I guess I could go leaner or raise the CR and get my temps back up.

On top of it all.....I'm getting over 30mpg now on a 2110 stroker.

Yes, running a porsche (smaller than stock) pulley is a bad idea unless it is over 100F outside.
Swap back to a stock pulley and belt until the weather heats up.

Does anyone have any data to say pressure has anything to do with cooling the VW? When I did some tests, I found pressure to be un-important.
Do your own on your running bus, and while it does change some, it is not enough for air density to do more cooling. I found an air flow meter and temp guages to give useful info.

Scoops just blast air through the engine compartment.
My tests showed that w/o external air scoops that the engine compartment temps are 10C higher than outside.
Scoops brought down engine compartment temps to the same as outside.
Scoops also brought head temps down 10C.
Amazing co-incidence that was the same number, huh?

now back to your regular scheduled package of hackage.

Fri Mar 29, 2013 12:00 pm

Short of having a manometer to measure the air pressure, the next best thing is the hose in the bottle with water

If you put your hand over the carb top, the motor will die, but blocking off the vents as an experiment only forces the motor to suck from other places. Gaps, leaks, what not.

I still think a big fan/big carbed motor will run negative air pressure

The Germans def did not plan for us doing what we are doing now, although too bad we cant get some consultation from them

Fri Mar 29, 2013 12:35 pm

My Porsche pulley is a rsult of upping the amperage of my alternator. It needs to run faster to get into the charging window. The added cooling was a "bonus". I'm honestly looking at leaning out more or raising the CR to get the temps back up....those both have wheel turning improvement.

Fri Mar 29, 2013 5:48 pm

sooooo, whats the difference in running no decklid or having one with a dried out or missing seal? a dune buggie does just fine

Fri Mar 29, 2013 6:30 pm

A dune buggy isn't a bug or a bus. Much lighter weight, less heat generated.

The problem with no deck lid is the heat that was just under the engine can curl up in the low pressure area behind the car and take a second trip through the engine. It's really hard to cool an engine with hot air. It's like breathing under the blankets. You can do it for a bit, but eventually that recycled air gets so hot you can't stand it anymore.

Fri Mar 29, 2013 7:32 pm

Derek Cobb wrote: A dune buggy isn't a bug or a bus. Much lighter weight, less heat generated.

The problem with no deck lid is the heat that was just under the engine can curl up in the low pressure area behind the car and take a second trip through the engine. It's really hard to cool an engine with hot air. It's like breathing under the blankets. You can do it for a bit, but eventually that recycled air gets so hot you can't stand it anymore.

Really it happens much faster than that....more like farting with your head under the blankets, a "covered wagon".

gordo.

Fri Mar 29, 2013 7:39 pm

flemcadiddlehopper wrote: Derek Cobb wrote: A dune buggy isn't a bug or a bus. Much lighter weight, less heat generated.

The problem with no deck lid is the heat that was just under the engine can curl up in the low pressure area behind the car and take a second trip through the engine. It's really hard to cool an engine with hot air. It's like breathing under the blankets. You can do it for a bit, but eventually that recycled air gets so hot you can't stand it anymore.

Really it happens much faster than that....more like farting with your head under the blankets, a "covered wagon".

gordo.

I thought it was a "dutch oven".

Sat Mar 30, 2013 4:05 am

zombievws wrote: sooooo, whats the difference in running no decklid or having one with a dried out or missing seal? a dune buggie does just fine
This is from the Vanagon punters. The pink swriling bit behind the van is the concern for an aircooled bus. As it will suck this preheated air back.

The reason they stuck the vent up high was so it doesn't suck up all the dirt and road grime not just it looked cool.

Sat Mar 30, 2013 6:58 am

I have two buses, one with a dual carb 1700, one with a dual carb 1600. Both are bone stock re: cams, compression.
I live in So Cal, so freeway travel can sometimes be a "heat em up" problem. I just prop open the decklids for about a 30 degree drop in temperature.
I know, I know.... can't possibly work. Except that it does as evidenced by the Berg Oil Temp sensors that turn off that flickering oil light once the lids are propped.

Sat Mar 30, 2013 7:37 am

I've been on SoCal freeways...they are either one of two things, a super speedway, or a parking lot.

Which does the lid open work on?

Gordo.

Sat Mar 30, 2013 7:40 am

Sambafraser wrote: zombievws wrote: sooooo, whats the difference in running no decklid or having one with a dried out or missing seal? a dune buggie does just fine
This is from the Vanagon punters. The pink swriling bit behind the van is the concern for an aircooled bus. As it will suck this preheated air back.

The reason they stuck the vent up high was so it doesn't suck up all the dirt and road grime not just it looked cool.

Was this an air cooled vanagon? If so was the engine revving at the time of this air pressure video?

Gordo.

Sat Mar 30, 2013 9:20 am

Sambafraser wrote: zombievws wrote: sooooo, whats the difference in running no decklid or having one with a dried out or missing seal? a dune buggie does just fine
This is from the Vanagon punters. The pink swriling bit behind the van is the concern for an aircooled bus. As it will suck this preheated air back.

The reason they stuck the vent up high was so it doesn't suck up all the dirt and road grime not just it looked cool.

And we know that splits and bays have the same swirl to the back of the bus from the oil spots on the back of any leaky bus.

A bug has a different shape, any one have a link to a similar clip for a bug?

What is that hot floating thing at the top behind the vanagon? A UFO following it?
Why is it hot under the front of the vanagon?

Sat Mar 30, 2013 9:36 am

Going to stick my head in here and hope I don't get it kicked. Concerning that air duct to the bilge fan to the rear box: it would flow more air if you had a parallel duct that branched before the fan and in that duct you put a gravity check flap.

Sat Mar 30, 2013 11:07 am

Clara wrote: Sambafraser wrote: zombievws wrote: sooooo, whats the difference in running no decklid or having one with a dried out or missing seal? a dune buggie does just fine
This is from the Vanagon punters. The pink swriling bit behind the van is the concern for an aircooled bus. As it will suck this preheated air back.

The reason they stuck the vent up high was so it doesn't suck up all the dirt and road grime not just it looked cool.

And we know that splits and bays have the same swirl to the back of the bus from the oil spots on the back of any leaky bus.

A bug has a different shape, any one have a link to a similar clip for a bug?

What is that hot floating thing at the top behind the vanagon? A UFO following it?
Why is it hot under the front of the vanagon?

I think the different colors are to show pressure not temperature. Is the pink, therefore, low pressure?

Sat Mar 30, 2013 1:46 pm

Clara wrote:
Why is it hot under the front of the vanagon?

Radiator perhaps? :roll:

Sat Mar 30, 2013 2:02 pm

Derek Cobb wrote: Clara wrote:
Why is it hot under the front of the vanagon?

Radiator perhaps? :roll:

Good Lord!

Any ideas on the small UFO following the Vanagon? Perhaps a drone from the mother ship?

Sat Mar 30, 2013 11:02 pm

The blue is high pressure, pink is low pressure.
Look under your van and it ain't as smooth as your roof.

There is no heat from the radiator, piping, engine, bong or aliens. The block behind the van is a spoiler :lol:

Here are some more wind tunnel test models of the VW Van.

Sun Mar 31, 2013 7:51 am

So, to me, this says that the best place to collect air would be at the front of the vehicle. Taking air from where it is at it's highest pressure and adding it to where it is at it's lowest pressure.

people need to understand that not all design decisions are made by the designers or engineers. The final say comes from the bean counters. Vehicles are designed to just last to the warranties end.

Gordo.