I've been thinking about trying to fabricate something similar... Given the time constraints I have at the moment I would love to buy an off the shelf one. So if someone manages to find a distributor or something similar, Let me know too!
The bootlid open at the bottom keeps the motor cooler, is more "police/ RTA" friendly, means you dont have to remove it when it rains, and stops crap (leaves, water, rubbish etc) from dropping in your engine bay and causing problems.
And the standoffs I sell are a lot cheaper.......$45.
Sorry to be a stick in the mud, but this lower lid stand off idea is only going to make your air cooled motor get dusty and run hotter, you cant cool a hot engine with HOT air!! want proof? how many of you vw owners who at one time or another have had a leaking rear main oil seal and noticed fine oil spots on the back of ya dubs? and I mean, even as high as your rear screen? the air that runs under your cars doesnt just keep going out the back and away, NO, it gets heated from going past the bottom of a hot engine & tranny and exhaust system, it gets heated from the hot air expelled from your cooling system and then it goes vertical and straight back into this standoff set up. Close ya bloody engine lids and keep your engine compartments AIRTIGHT , as Volkswagen designed them.
VolksVair wrote:Sorry to be a stick in the mud, but this lower lid stand off idea is only going to make your air cooled motor get dusty and run hotter, you cant cool a hot engine with HOT air!! want proof? how many of you vw owners who at one time or another have had a leaking rear main oil seal and noticed fine oil spots on the back of ya dubs? and I mean, even as high as your rear screen? the air that runs under your cars doesnt just keep going out the back and away, NO, it gets heated from going past the bottom of a hot engine & tranny and exhaust system, it gets heated from the hot air expelled from your cooling system and then it goes vertical and straight back into this standoff set up. Close ya bloody engine lids and keep your engine compartments AIRTIGHT , as Volkswagen designed them.
Sorry, but what you are saying is not exactly the case.
I have tested various engine lids, with various opening options on the race track, freeway, and city driving and you would be surprised at the temp drops that can be achieved.
The engine open at the bottom will decrease engine oil temps by around 10-15%, and engine bay temps are also dramatically decreased.......FACT !
You only need to look at the evolution of the standard vw engine lid to realise that even VW knew they had a potential cooling problem.
1200cc had a fully sealed enginelid.....ok for 36-40hp
1500cc started to gain air vents, with 2 sections on the engine lid........slight increase in HP
1600cc increased the number of air vents to 4 sections.....another increase in HP
And then the final evolution was the 75/76 bootlid which had all 4 sections and an additional thermostatically controlled opening behind the number place......WHY? beacuse VW was trying to 'chase' extra cooling as they increased the motor's capacity and HP
So what happens when you increase the HP to say 70, 80 or 100+.....well you need to also evolve what you do with the venting.
Think of the principal of the cowling on a radial aircraft motor, the high speed air moving past draws out the hot air, which in turns pulls more cooler air into the engine bay............having the lid open at the bottom does the same.
VolksVair wrote:Sorry to be a stick in the mud, but this lower lid stand off idea is only going to make your air cooled motor get dusty and run hotter, you cant cool a hot engine with HOT air!! want proof? how many of you vw owners who at one time or another have had a leaking rear main oil seal and noticed fine oil spots on the back of ya dubs? and I mean, even as high as your rear screen? the air that runs under your cars doesnt just keep going out the back and away, NO, it gets heated from going past the bottom of a hot engine & tranny and exhaust system, it gets heated from the hot air expelled from your cooling system and then it goes vertical and straight back into this standoff set up. Close ya bloody engine lids and keep your engine compartments AIRTIGHT , as Volkswagen designed them.
You are 100% correct, VolksVair, including the use of the term 'engine lid' - as opposed to 'boot lid'.
Keep the engine lid tightly sealed, and if needed, draw cool air into the engine compartment from a HIGH-PRESSURE area.
I'd rather wear a Beetle out by racing it than by polishing it!
Craig, yes over the years VW did introduce extra intake air vents, but to my understanding, they took advantage from the air that came over the roof and filled the sealed engine compartment with plenty of cold air to be drawn in through the fan, over the cylinders & heads and out via the underside of the VW. I agree with the engine lid stand off at the top as this would act as an air scoop, grabbing cool /fresh air from over the roofline. But to open the bottom is like having an upside down air scoop grabbing hot air & dust. I dont understand how it can improve cooling, maybe I am getting too old, I love all performance modifications, am allways doing shit thats different, your testing seems to prove me wrong and I am allways open to learning something new, but just cant seem to get my head around this, I hope I dont offend you or any one else reading my ramblings, cheers Frank
Adventure Before Dimentia
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
I'm not offended 👍..............funny things happen with air pressure at the back of the vw and this all affects cooling. Put a smouldering oily rag (to create smoke) in the engine bay and go for a drive, you will be surprised where the smoke gets pulled out of :tu......and this changes with speed. Its not always about trying to get more air in.....its also about getting the hot air out.
BizarreModeratorThe artist formerly known as blue74l
I have propped out my number plate and cut out the area below it
I have alos cut out that area where the late 76 flap went - just under the nose / number plate light
I have noticed a decrease in oil temps
I assume a LOT more air is sucked in - I am running dual carbs
Guessing it is similar to propping the bottom
If I am doing a long run in HOT conditions I use the Hoodjax method.
This is great, thanks for all the feedback. It helps people like me to make an informed decision.
My bug is a daily and is mildly tuned; however I'm always looking for ways to help it run cooler especially on hot days.
VolksVair wrote:Craig, yes over the years VW did introduce extra intake air vents, but to my understanding, they took advantage from the air that came over the roof and filled the sealed engine compartment with plenty of cold air to be drawn in through the fan, over the cylinders & heads and out via the underside of the VW. I agree with the engine lid stand off at the top as this would act as an air scoop, grabbing cool /fresh air from over the roofline. But to open the bottom is like having an upside down air scoop grabbing hot air & dust. I dont understand how it can improve cooling, maybe I am getting too old, I love all performance modifications, am allways doing shit thats different, your testing seems to prove me wrong and I am allways open to learning something new, but just cant seem to get my head around this, I hope I dont offend you or any one else reading my ramblings, cheers Frank
Frank, I must admit that at first, I had the same thoughts as you, it would suck heat and dust from underneath.
Basically, it leaves a low pressure area behind the open area - the decklid on the bug, or the venturi on the boat - so as long as the air (on the bug) or the water (in the boat) are replaced from elsewhere, that is where it comes from.
On the bug, the air that is sucked out is replaced by air coming in through the usual engine bay vents. The only way this would not work is if the carbies and the fan sucked out more air than could come in through the usual engine bay vents, but as it appears that propping the bottom of the engine lid works, this is obviously not the case.
I've been running one of these standoffs for about 2 years now, I changed my induction from a stock single carb to a pair of 40mm IDF's and the engine got hotter than it ever has before, (been running it for 12 years), so I looked into it, the increase in air demands on the vents (66 T1) was causing a vacuum in the engine bay. So I got a bottom mount stand off and straight away, 5 minutes between drives from having and not having, the temps dropped a full 20 deg. This was in the middle of summer here in Perth on a 40 deg day. They work, no ifs or buts. The engine does get a little dusty, but not out of control and nothing that a clean can't fix, no water gets in, just more airflow
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
Basically, it leaves a low pressure area behind the open area - the decklid on the bug, or the venturi on the boat - so as long as the air (on the bug) or the water (in the boat) are replaced from elsewhere, that is where it comes from.
On the bug, the air that is sucked out is replaced by air coming in through the usual engine bay vents. The only way this would not work is if the carbies and the fan sucked out more air than could come in through the usual engine bay vents, but as it appears that propping the bottom of the engine lid works, this is obviously not the case.
Well, it makes sense to me. 🙂 [/quote]
This scenario confuses me a wee bit, if the lower standoff principal works in such a way that it sucks out the air & is replaced with fresh air from normal vents, wouldn't it be robbing vital air from getting behind the fan housing? air allways takes the easy way out. if you look side on to a beetle, its body shape resembles the basic shape of an aircraft wing ( rounded top with a flat bottom) the principle of the aircraft wing is that the top rounded side speeds up the air flow causing lower air pressure above the wing which in turn sucks the wing up into the low pressure area. (Which is what keeps the plane in the air) so the area under the wing is also going straight up, the beetle should have the same effect with the air going over & under it, but as the robot in lost in space would say "It does not compute"! cheers Frank
