Swiss Cheese Engine Bay

I drilled three holes on the wheel well and mounted my oil cooler/fan assembly behind this area. When the fan comes on the heat is driven out into the wheel well.

 

I'm working on making intake cowls near the rear shocks to direct more air as well.

 

 

The first photo shows the holes and the second you can see them in the upper corner of the photo.

 

 

Mitch-

 

I did almost exactly what you are talking about this spring with the firewall fans, but I put two 7" fans in, rather than 1. I was looking around for some pictures in my files, but I don't have them. They blow directly on the air-cleaners.

 

I'm not sure how effective they are, but we are just now getting our first hot weather of the season. "Hot" here is 95* and humid-- we sometimes see temps over 100*, but they are spells that only come every few years. 100* is pretty hot to be in the car for any length of time, anyhow. I am hoping the fans will help in the kind of stop-n-go traffic we almost never get, but which people in cities see every single day.

 

I've got an AL cased engine in the car this summer, rather than the mag-cased engine I normally use. The AL cases run hotter (why, nobody knows), and my oil temps have stayed under 210 so far. As you know, the sweet-spot is 180- 230 or so.

 

One thing I can see that needs done on my set-up is to route the discharge air from the primary oil cooler (on the engine) further away form the intake of the fan on the driver's side. I was going to address this, but just ran out of time. It will get done next winter.

 

I've got a 96 plate EMPI oil cooler and fan in the driver's-side rear wheel well. IMHO, I'm not sure why anybody would use the 72 plate cooler, unless they are running a sub-2L engine. I'm friends with several guys from the central valley who combat the kind of heat you face. Joel Schlotz in Chico uses a Setrab cooler, which is the ultimate solution.

 

Good luck.

You will find out that that little electric fan will do nothing but impede flow. The engine fan pulls so hard it will not need any additional assist. As for vent holes if you search the site you will see most people are trying to seal the engine compartment so the only air comes from the vent in the decklid and the firewall hole. The reason for this is to stop header heat from heating the carb air. When they ran my engine on the dyno the engine fan pulled the dyno room door shut so don't worry about the electric fan

At idle, in stop and go traffic? I beg to differ. It isn't going to change the world, but it isn't going to hurt anything either. 

 

FWIW, hot air rises. The surround tin is very important in keeping exhaust heat separate from cooling air and intake air-- but unless you've got a wrap-around exhaust, there's no exhaust heat ahead of the firewall. Once the car is moving, there isn't any there at, no matter what.

 Guys in the high perf bug world cut holes in the sides of the engine compartment for that reason, and Gene Berg mentioned the benefits in his book of technical articles 35 or so years ago. K&N makes some flat panel filters (I've got some part #'s written down; I'll look them up later if you're interested) in the 4x5 and 5x6" range and only 3/4" thick that would work well for this. If space is tight in your engine compartment they could be taken out to make it easier to pull spark plugs and would help provide more air intake for dual carburetors. Do you have a hole in the firewall in front of the fan as well?

 

Edit- Just read there is a 6" hole in the firewall; a fan may help when sitting in stop and go traffic, but I don't know about putting over the fan access hole. I think that at cruising rev's it would impede airflow- the fan by itself will move 1000-1500 cfm. at 3,000-4,000rpm and no electric fan that fits and only runs on 12 volts will move that much air. A smaller hole on each side of the firewall (in front of the carbs) with fans may be a better way. I just read this in a post from Stan.

 

How far along in the build are you? Have you (or your engine builder) heard of the Hoover mods? Something to consider, since we run these things harder and higher than the engineers at Wolfsburg ever intended or envisioned-

http://bobhooversblog.blogspot...007/05/hvx-mods.html

These modifications will reduce or eliminate lifter bore wear and send oil up to the heads full time to reduce rocker shaft and bushing wear, reduce valve spring fatigue and remove more heat from the heads. Any VW beetle engine built for more power and rpm's should have these modifications done for more longevity and reliability. And if you really want to go to town on updating your engine, Porsche piston squirters installed in the engine case will reduce piston crown heat as well. Al 

Stan, how can the firewall fans help cooling at idle and stop & go traffic?

Are you thinking that even with the hood vents and holes in the firewall the engine fan and carbs won't be able to draw enough air?

I can (maybe) see this happening at highway speeds, but not at idle or around town speeds.

Then-again, as you mentioned, it can't hurt anything either.

Ron- a lot of heat is radiated off the engine case and cylinder covers and shroud, so I can see where Stan is going with this. As he said, heat rises (I know you know this) and I can see where helping air move through (and out of) the engine compartment and taking advantage of all those heat radiating surfaces when the car is relatively motionless (in stop and go traffic) would be helpful. Will it make a huge difference? I don't know, but I'm interested in hearing what Stan discovers...

Now I get it-the fans would actually blow the hot air out the engine hood intake vent when the car is sitting at a stoplight.  Interesting.....

 

FWIW - I own a home in Bakersfield, CA. and I am up that way often. (Check out the temps there people). One of my biggest struggles since owning this car has been dealing with heat.

 

I have tried several types of oil cooler and fan combos. If you want serious cooling that works try this... Buy 2 96 plate coolers and two Maradyne 10" 1000 CFM fans. Mount the coolers and fans in parallel behind your firewall. Most important is this - SEAL your engine compartment so the air is drawn from somewhere other than below where your exhaust is!!!

 

I believe our cars create a vacuum on the freeway that pulls air out from the decklid. If you have leaks in your engine compartment the hot exhaust air gets pulled right up into the engine shroud and you start circulating hot air!

 

Kevin Zagar gave me what I think is a great tip. On a Porsche 356 decklid it is open in the area where the latch is located allowing a natural flow to occur at freeway speed. Kevin has drilled that area out and it does not seem to weaken the area enough to be problematic. This is something that is on my todo list.

 

Its not the best picture but look at the opening on this 356 decklid - ours are closed off in this area and can be drilled out:

 

 

Yes Bakersfield is an oven.  What about rain with that opened up lid? I'm sure my CMC could handle material removal, every wheres I've looked the glass is thick.

As far as oil coolers go I would say that a dual setrab oil cooler ( http://vwparts.aircooled.net/S...oler-p/fp920m22i.htm would keep things cool.  I drove my vw superheb from baton rouge LA to Orlando, FL during the summer with 90+ temps outside ran great and the oil temps/ head temps stayed cool even at high speed I could do close to 70mph in 3rd gear and I used 5th gear quite a bit .  I had a Raby Built 2563 Type 4 with the ver 2 of the DTM that had no internal oil cooler and only the dual setrab external oil cooler.

Series / Parallel? You know what I mean...

 

 

 

Mine ran in series because the frame that they came mounted on basically made the two one big cooler with dual fans as well

 

 

Figuring out airflow through the engine compartment while the car's moving and the engine's running is not a trivial problem, even for a good engineer with better tools and smarts than I have.

 

My car came from VS with the usual hole in the firewall. But there's also a sizable gap between the bottom of the firewall and the tins (the tins are sealed pretty well at the sides and rear of the engine bay). This gap opens into the space between the firewall and the rear of the passenger compartment - over the tranny and well in front of the heads and headers. I think it was left open deliberately and that that's where most cooling air is coming into the engine compartment.

 

I also base this funny notion on the fact that dirt - small pebbles and leaves - collect around the bottom of the engine compartment - stuff that probably didn't come in through the grill in the deck lid. I think the grill is maybe a place for air to exit, not enter.

 

Further testing at the Sacramento Aerodynamics Research Institute (okay, my garage) has shown that with the car at rest and engine idling, a newspaper sheet laid across the grill isn't sucked down against the grill. So, in those conditions at least, air is getting to the fan and carbs from the openings through and under the firewall, not through the deck lid.

 

I'm hoping that a fan in front of the hole in the firewall won't restrict airflow much when the fan is stopped, as it doesn't fit close enough to plug the hole. When running, it should increase air pressure in front of the engine's fan intake allowing the engine fan to draw more air. In any case, it would be easy enough to remove the electric fan if it causes problems.

 

My real question is whether drilling holes in the sides of the engine bay will do any harm to airflow through the compartment. It may not help much, but I can't see how it would hurt. It will be a lot easier to drill those holes before the new engine goes in.

 

And no, I don't drive the Speedy when it's 100 degrees out, or even 90. Forget the engine - I'm the one who overheats. But I mentioned this to remind folks that it's hot here a lot of the time.

 

 

 

Mitch - I did an experiment where I used aluminum tape strips which is very paper thin aluminum, I had several places where I secured the tape down and left the rest free. After some miles of driving I noticed the tape in those places were standing straight up indicating a strong pull towards the deck lid. They were not pointing in the direction of the shroud fan.

 

Under these conditions during extended drives my temp would slowly creep up to the 225 range I believe as a result of hot air being sucked up into the engine fan and recirculated over the cylinders, heads, as well as through the internal oil cooler.

 

After sealing off the engine compartment to the best of my ability I noticed an exponential difference in oil temp while driving under the same conditions. I still have much work to do on sealing my engine compartment and I have high expectations once completed.

 

In Summary:

 

I'm so long winded... I found hot exhaust to be the culprit in my overheating issue. Sealing my engine compartment is where I gained the most improvement not the expensive oil cooler setup.

 

For those of you aircooled.net fans I have a Setrab cooler and fan setup that Rowland Rascon made a very nice rear fender well bracket for that is for sale.

 

 

 

 

Rusty, if I'm reading this right, you're saying airflow was OUT of the deck lid grill, not in?

 

Was the engine compartment sealed off at all before you started making changes (around the sides and back)?

 

Did you seal off the front of the engine compartment, too (at the bottom of the firewall)?

 

 

I have dual Setrabs mounted at the front of my IM.  I don't have the car on the road yet, so I can't post any driving temps.  I also have dual fans, but I doubt they will turn on much, if ever.  I consider them added insurance, because you never know.....

Mitch yes - the air was going up and out of the deck lid as a result of gaps in the seal. It was like a vacuum sucking the air up from the bottom. So much force that it stood the foil up straight. Kind of unbelievable huh? After plugging some of the holes I had much better results. I know this has been well documented and nobody is interested but its new to me.

 

Don't know if you know this but IM's don't have the hole cut in the firewall like Vintages do. I'm thinking about cutting one in. Can anyone chime in on that? Obviously there is something very different regarding the cooling properties between these speedsters and standard VWs.

 

I know VW guys that drive in 100+ degree weather with no problems. I want to be able to do the same.

 

Ron O I am very interested to know what you are doing with yours. I have noticed many of your questions regarding this topic.

Great first-hand experience guys! As you've discovered, recirculating spent, hot cooling air that's been further heated by the exhaust back into the fan and carbs is a major cause of overheating.

 

Rusty- So many guys (when building hot VW engines for their bug) ignore making sure all of the engine sheetmetal is installed correctly and then add a cooler, expecting it to cure the engine's woes. Yeah, oil temps are now under control, but the cylinders and heads are happily overheating themselves into oblivion and when they finally call it quits the only things saveable off the longblock are the valve covers and bails, distributor, and maybe the fuel pump and pushrods. You guys have found out why sealing the engine compartment from the exhaust is so important.

 

Mitch- some flat panel filters from K&N-

# 33-2238 - 5.188"x4.438" (23.02 sq.")x.625" thick

# YA-1602-U - 5.438"x4.3.3" (23.45 sq.") x.688" thick

# KA-0009  - 5.75" x5.25" (30.1 sq.") x.688" thick

 

There are others, but these are fairly compact and thin, I would think making them easy to install in the engine compartment sides, a little higher near the air cleaners, so they wouldn't disrupt the rest of the engine compartment airflow.

 

Driving at highway speeds (and higher!) creates  2lbs. or more air pressure underneath the car than over the top (this info from someone knowledgeable I trust on the Samba), and with the profile of our cars somewhat like a wing (relatively flat on the bottom, longer towards the front and dropping off quickly at the back) I'm not surprised that air is coming out of the engine grille and not going in. If all of the air coming into the engine compartment is coming from underneath/in front of the engine, bringing in enough to create slightly positive air pressure in the engine compartment at speed has the benefit of removing heat radiated from the engine itself.

 

Rusty- If you cut a 6" hole in the firewall in front of the fan intake you'll add 28 sq" of air intake. Oval the hole by 2-3" and you'll add 12-18 more sq." Remember, a bug has all that air intake above the engine in the bodywork below the rear window. Because of the shape of our cars, we need to add way more intake to compensate for all the air being pulled out through the grille. The more air there is, the less the fan and carbs have to fight for air at highway speeds.   

Thank you ALB. I had a feeling cutting the hole was the way to go.

 

Hey - you know me I like to goof around. Another way to test that the air IS coming out of the deck lid... with the Fourth of July upon us try putting a couple of smoke bombs in the engine compartment in a pan of some kind, light the fuse then haul ass having someone video from behind.

 

...Do this on a deserted road of course!

I'd be a little concerned about that material being ingested by the engine, but hell, try it and let me know how it goes!

You can't cut a hole in the firewall on a VW as you'd be cutting a hole into the interior. The speedster (don't know about IM) has a void between the rear seat back and the firewall. Air flows past the edge of the floorpan and curls up into this void above the transmission and is a source of clean fresh air when the car is moving. And if you have the sled tins in place, that'll tend to blow the hot air out the back of the car rather than forward into this area even when the car is stationary.

 

Wheel wells tend to be high pressure areas when moving so you can cut holes there too, but they are also very dirty: water, mud, dust, and rocks are all flying around in there. I'd definitely put filters on the wheel well holes if you want to keep the engine bay cleaner.

 

And as already mentioned, the VW has more decklid vent area it can pull air from than the speedster. VW added more vents in the rear as engine sizes increased.

Justin's dead right about the area up top behind the rear seat panel and the firewall. I can attest that it is a very high pressure area. My heater ( IM Soob liquid cooled engine ) is mounted up in there and even with the heater fan turned off, plenty of hot air comes into the cabin area when at speed.

Justin- My older IM is similar to most people's cars; there's a foot between the firewall and the back wall of the passenger cabin.

My IM has so much crap back there that there is no room for an oil cooler. 

Rusty- If you come up with a better pic I'd love to see it. Al

Still experimenting.

 

The pics got a little out of order after posting, sorry.

Do you have this up and running? If you're confining the fan intake to that opening only I don't think it would be large enough, but I'm a house painter, not an engineer. I would think you'd need an opening close to the same size as the hole in the shroud. Al

 

PS- is the checkerboard on the shroud painted? What size is the engine? How high does/will it rev with power? Heads? cam? carburetors?

Agreed. With your current setup you are better off leaving the rubber piece out. Because it has a smaller inlet diameter, you are restricting the flow to the fan. Would you weld a plate over the fan inlet with a smaller hole in it? Leaving the rubber piece out, the fan will pull air both from the hole in the firewall and from the sides and won't be restricted. If really you want to seal the fan shroud to the firewall, which I don't feel is necessary, keep the seal and firewall hole the same size or bigger than the fan shroud hole.

Here you go Al - Here are three pics from cars ranging from 1956-1963.

 

 

Rusty:

 

Wouldn't these adjusted lids allow water into the compartment?

 

 

Thanks Rusty; I see it now.

 

PS- Since I have your attention, can you (or anyone else) shed some light on this engine lid?

 

 

 

Welllllll... That's an easy one. Two words here... Bilge Pump.

That's interesting Al,

The bumper and bumper indents in the fenders peg it as a B/C,  and the lid 'appears' to have two grills (unless I'm mistaking louvers on either side of a single grill)...but the engine opening 'appears' to be dimensioned (side to side) for an A/early B without the slightly wider flared top lid edge such as a T-6 bodied late B or C.

 

My guess is that the underside is a MangoSmoothy type modifications to divert any water away from carbs and electrical connections.

I like 

That's a Carrera lid, Al. The elongated "wells" line up over the carbs and when the lid is closed they separate the carbs from the engine bay. They get their air from the louvers on either side of the engine grill.

That's why  Carrera lids have those extra louvers...

 

 

Edit* Looks like Terry hit submit quicker than I did...

 

Ted

Hello Justin and ALB, I was experimenting with getting air into the fan from outside and letting the grille area feed the carbs. I removed this after I had cooling problems which were from blow by as my rings never seated (another story). I've since added an external cooler with fan and oil thermostat and she runs cool now after rebuilding with new jugs and rings etc. The rubber boot is off at the moment until I can run time on the setup as is right now.

 

The fan shroud was painted ALB, but when I rebuilt it I changed it back, it was making me dizzy. I'm running a 1915 with dual 40 dells and 041 heads.

 

 

Glad to hear you got it sorted out. Do you have a temp compensated head temp gauge? With the external cooler you may very well have oil temps within reasonable parameters but if the heads are still running hot (and you'll not know it unless you have a head temp gauge) the engine could be headed for trouble down the road.

 

And I can see that shroud "overpowering you" after a while. Call me Al; all my friends do. How do I address you?

 

PS- and thanks for the observations about the engine lid, guys. Al