Shroud Confusion Help please!

It's very true that the more you research a topic on here (and, especially on the Samba) the more confused you will assuredly get.  So I'm not going to go into a whole bunch of options, just tell you what I'm running:

I have a 2,110 T-1, with J-pipes (no heat).

I am running a complete OEM shroud from a 1973 Beetle sedan, including the oil cooler tower, air vanes, bellows thermostat and working air vane linkage.  This is NOT the round-top 36hp style, but the flat-topped later Beetle shroud.  It is set up for heat - the horns are there but they've been plugged with metal expansion plugs for a Ford V8 block.  I think they look decent (they're painted black, same as the shroud).

I'm also running all of the other tin from a 1971 Beetle engine; head tins, breast and back plates, L/R sleds and "H" baffles.

In addition, I am running a 16-pass, fan assisted, DeRale oil cooler with the fan thermostat set to start at 180F.  The engine is set up for full-flow oil with a Berg pump, blocked case outlet at the pump and a 125 pound Berg pressure regulating oil pump cover.

I have checked the engine temp with a "Mainely Custom By Design" dip-stick thermometer at various speeds and outside temps.  Up into the 90's F ambient and hammering it hard on a turnpike the oil temp will sit at 200F.  If I pull off to stop for something it will rise to 205F and sit there til I get back underway and then drop back to 200.  I'm more than happy with that - this has been an excellent set-up.

I can't help you with the round-top 36hp shroud - I have zero experience with them.

The "Better than OEM" fan shroud that Jake was talking about is his later version DTM (Down the Middle) shroud.  I don't know if he is still producing them, but I remember that they were relatively expensive.

Gordon

Hello All,

I was recently given a VW doghouse shroud, with heater ports removed and the 'dog house' pieces bumped out / widened to accept a type4 upright cooler. 

The shroud is complete with all the dog house tins necessary for install. I was thinking about selling it, but don't know how much to ask for it. It will need to be cleaned up and resprayed.

If this is something you think you'll need, let me know.

Ted

Also, just found out from vendor that running Scat 36hp need the widen fan?Huh? The stock one currently doesn't cool as well, won't fit?

Yup, forgot about that - I have the wider fan, too.  It's about 3/8"-1/2" wider than the earlier ones and moves 30% more air.  

If you're getting a new, wider fan, then get one that has had the blades welded so they won't fly apart when you rev to 6 Grand.

Scott-

I have to agree with Gordon; the more you read, the more confused you can get! 

 I remember reading about Jakes' fan shroud tests, and while his data concerning adding flaps to the aftermarket round shroud may be correct, I don't remember seeing any numbers, so never found out whether he's talking about a 5 or 75' rise in temps. I'm not disputing his results, I'm just saying that (as far as I know) he's not expanded on that statement.

What I do know- Lots of guys use the aftermarket 36hp doghouse shroud (with or without flaps and thermostat) and their engines run within the proper heat build-up and cooling parameters, the difference doesn't seem to be enough to affect engine life, and the rest of the system can deal with the extra heat and still cool the engine properly. I'm not usually one to depend on anecdotal information (I like to see "data" when people make claims), but these shrouds have been around a long time now and enough people have achieved the desired results (engine longevity and reasonably balanced cooling) that I will use one on mine (should it ever hit the road).

What I think- As long as the shroud has the directional vanes inside to distribute cooling air to both sides somewhat evenly and properly, the engine is installed with all the normal sheetmetal considerations taken care of and there is enough air access into the engine compartment, you'll be alright.

If you want one from all VW parts, check out this- 

http://cal-look.no/lounge/index.php/topic,9621.0.html

And yeah, you need the wider fan. Have it tig welded and balanced.

I had a nice, long narrative tale written, when my computer decided it was time to reboot-- so, you are spared that particular nice, long narrative tale. Here's another.

You're asking for advice, Scott? Good men agree to disagree about all of this, and everybody has an opinion. Here's mine:

All the flap about flaps, etc. really only applies if you plan to drive it in cooler weather, and think you are going to drive the engine 100K mi. You won't and you won't. Here's some tough-love from uncle Stan: a speedster is a fair-weather conveyance for most of us. We'd all like to think we're going to drive 'em 'til the snow flies, but we don't. Top up, they lose 90% of their charm. We also think we're going to be the one guy that can go 100k mi between rebuilds... but none of us (but Jim) will make it-- even if the engine holds together, you'll want to "improve" something before you get there. I drive my car every chance I get. 100k mi is 20 years worth of summer fun, assuming I drive 5000 mi a year (which is a VERY good year).

So, since you're not going to drive the car from November 1- May 1, what you REALLY want is something that cools well when it's 100 deg outside, and you aren't really all that concerned about how it does when it's in the teens. Unless you have access to a pile of really inexpensive OE VW tin, you're really only left with a few options.

A Raby DTM is $500 for a chunk of fiberglass-- but I've got one on the big engine, and it really does work well, even with no "must haves" underneath (no sleds, enclosing tins, thermostat, flaps, etc.). It seems pricey until you start trying to find a Thing shroud, etc.-- which is rare like shards of the true cross. Even if all you want is a modified Scat 36 hp shroud and all the attendant goodies, it's gonna' cost $1k. I went this route with the 2110, because I kept telling myself I was going to drive the bus in the winter. We'll see.

With the DTM-- my head temps all run within 15 deg of each other, all are low, and the oil temps stay under control. It over-cools in cold weather, but I can live with it. Some guys can't get past how it looks, but I'm not trying to fool anybody into thinking it's an original 356 engine, so I don't care about that at all.

You need a Type 4 oil cooler for this option, and a late fan-- but you want those no matter what. You'll be able to run whatever header you want.

I agree with Al about the 36 hp doghouse tin. Everybody slams it, but there are a LOT of guys running it, and it doesn't seem to be all that bad. Could you do better? Absolutely-- but at what price? A Scat shroud it about $100. That's pretty cheap.

Do what you like-- everybody's got a tree they want to pee a circle around on this topic, and a lot of what is said over on the Samba is a bunch of "folklore and common knowledge". Sorting through it has cost me thousands of dollars.

I was thinking along the same lines, Stan, about the flaps/thermostat. I decided not to get into that argument (didn't want to be accused of "heresy"), but yeah, for a lot of people, whether or not their cars have those pieces installed is a bit of a moot point. I will say that they do serve a rather important function (enabling faster warm-ups, which translates into less cylinder, ring, guide and bearing wear) and Gene Berg called them directional devices- when the thermostat open the flaps up they direct the bulk of the air onto the heads, as the cylinders don't require nearly the airflow they get with them removed (the cylinders, especially the bulk of it below the combustion chamber, don't get that hot). I've posted this before, but Gene also claimed 12% faster engine wear in the southern California climate without them. And oh, can I relate to your first paragraph!

And for those of you that drive your car as far into the fall (and as early in the spring) as possible: if the engine doesn't seem to want to get up to operating temperature (you may even be having the occasional problem with carburetor icing) even after sutained driving, pull off the breasplate that sits over the exhaust. Keep it in the car with the screws and a screwdriver so it can be thrown back on when needed. The one guy up here I know that still drives his bug year-round runs like this for about 4 months of the year and says it works like a charm! VW's solution for cars in arctic conditions that never reached operating temps was chromed valve covers (proof, I think, that their heat radiation abilities were measured and part of the cooling system), but I think Bruce's idea is better.

Scott- Are you going to be plumbing a cooler/fan in the return line after the filter? Don't forget a thermostat for the oil line before the filter (faster warm-ups and when a little cooler the engine may never get warm without it). A thermostat for the fan switch so the fan is only running when it's needed is also a good idea. 

That's all I can think of for now; Yoda out.

Oh! Stan- Is the DTM still made in the type 1 configuration? I thought he'd forsaken this platform completely...

Al, yes. I have an external cooler with a fan and inline thermo with the full flow filter. Thank you for the suggestion of where the thermo goes—a question I did have now answered.

Stan, thanks for putting things into practical terms. I'm learning a lot here and want to do things right the first time.

I do have a type-4 oil cooler along with a external oil cooler/fan/thermo and full flow filter. Your right about the cost of original VW tin. I'm over $700 for just 15 out of 31 tin pieces with a modified doghouse (to fit the type 4 oil). I haven't pulled the trigger yet because I want to get this right the first time, and researching what others have done. I'm going to look at the Raby DTM your using since the doghouse, new fan and modified cylinder tin to fit my engine is actual more expensive then the DTM. And I do like the DTM set-up better (looks better too!). Plus I'm more interested in cooling with most of my driving will be in the spring and summer where it' 90+ with 70-90% humidity in the NVA area. So it might seem I won't need to worry about running flaps, etc. I don't plan on going more then 3,000 a year (could fluctuate) since I have a 2 year old and new one on the way—just not going to have huge amounts of time to myself in the near future. Just need to get this installed soon with the best cooling for my options and situation before my wife changes her mind on all this, or before the baby #2 comes LOL!

Question: What tin do you need to use with the DTM in our cars (minus what you said your not—no sleds, etc)? What fan does it require? Can I use my current alternator and stand with it?

Most important, where can I get a DTM for a type 1?

Call Ted. Buy the modified OEM shroud. Quality parts and good value.

Made a mistake, but it's fixed now. Cooler and thermostat should be in the return line after the filter. If the thermostat is before the filter it will only filter part-time.

PS- In an earlier post I quoted Mr. Berg as saying engine wear was 12% faster in Southern CA without the flaps and thermostat. The correct figure is 15-17%. I can attest to the fact that here, in a much cooler climate the figure is much closer to 40-50% shorter life. For your reading- 

http://www.geneberg.com/article.php?ArticleID=238

Nobody has ever been able to explain to my why real 356 (or 912)engines ever ran as good as they did or as long (normals can usually go 100K)without ever having flaps, thermostats or any other type of directional vains behind the spark plug sheet metal, it's just open in there...

Perhaps the great prophet (Gene Berg) was wrong?

Burn me at the stake.

Maybe I don't understand the question.  If we are comparing VW engines, like most of our replicas use, to 356 & 912 Porsche engines, we're talking apples and oranges.  Gene Berg's mods (engine tins cooling flaps, t-stats, etc.) had to do with VW engine compartments, deck lids, etc. and modified engines that needed more oil, air, etc.  When Porsche engines upped the HP, as in Super 90's, Carreras, etc., the rear deck lid was modified every few years to allow much greater air transfer, both for carbs and cooling.  Porsche designed the complete platform for the HP of those engines, including oil flow, air paths, ducts, and louvers for cooling, etc. The later T6's, especially, had central interior louvers, as well as twin exterior grills on the coupes and twin exterior louvers on the GT's.  

One of Berg's main concerns, aside from quality parts, was how to use and tweak a VW platform, designed for 36-50 HP, with engines producing over twice the HP VW designers anticipated.  The difficulty in directing sufficient air flow into and out of the engine compartment in our replicas is a topic that is widely debated, both on our site and elsewhere. 

Jim,

   So VW did all they did because the engine compartment was to small ? How about just popping open the deck lid like the Cal-Look guys do, then is there enough air ? My 356 A is a single grill and I run a big bore 912 engine. In the dead of summer here 110* is not uncommon , my oil temp never goes over 210*. I have no idea what the cylinder head temp is but after a freeway run I can pop the deck lid and hold my hand on any part of the engine for as long as I want. In the 70's I had a 64 bug that was Porsche powered. It was awful hard to tune the carbs in that tiny engine compartment but it never ran hot.

   Back to my original question. Why do VW's need all of that extra cooling paraphernalia when the 616 series Porsche engine's do not ? Is it the better case or do they have better head cooling characteristics, I don't know, that's why I'm asking.

   Jim Kelly, I hope your not looking at this as a challenge, I'm just looking for the answer. The 616 series Porsche engine's are archaistic with the cooler in the  shroud but yet they seem to cool just fine. This is the same wall I've been up against in all the other forums. I wish I could find a guy with intimate knowledge of both engines.

Curt...  

Hi Curt,

No worries, I don't take it as a challenge.  We're all trying to figure out the answers to the hard questions, eh?  Wish I had the definitive answer, but I'm not smart enough.  The issue of 911 fans on high HP VW's vs. stock doghouse coolers with GOOD engine tins has been debated a LOT on this and other forums, with some very strong opinions on both sides.  Guys who build a/c engines for a living talk stink to each other on a regular basis about coolers, air flow direction, after market shrouds, one side runs too hot, one side too cold, and on and on.

It will take more than talking to one guy who is familiar with both engine types to solve this mystery.  Jake Raby is one of the most talented and enterprising engine builders in the business, and he regularly gets dissed online for his opinions that are backed up by real world engine builds.  Back in the day, Gene Berg had his followers and his detractors as well.

Some generalities seem to apply: I'm not convinced the Type 1 VW engine compartment was too small for the engine it contained.  Of course, when you increase HP by 100% over the design parameters, you now need to dissipate twice as much engine waste heat, since waste heat is a direct function of HP.  I have read data that states 1/3 of HP goes to make power, 1/3 goes out the exhaust, and 1/3 goes to cooling. Bigger, more efficient, welded fans, larger oil coolers, DTM shrouds, etc. are all attempts at lowering operating temps on Type 1 engines.  Type 4 engines seem to cool more efficiently.  For one reason, they have about 25% more cooling fins on the case than a Type 1, with a better designed and larger oil cooler as well. 

Yep, lots of SoCal VeeDubbers found that propping open the deck lid really did help with cooling.  It became so popular that it became a design "look" to emulate.  I think the Type 1 platform has been taken as far as it can go, and, in some cases, farther than it should have gone, so that reliability became questionable, even if guys were willing to put up with very short rebuild times.  You're obviously doing lots of things right if your oil temps stay manageable, but I would feel more comfortable if I knew the head temp as well.

It's not fair to say that VW engineers didn't care about performance, and Porsche engineers did.  VW did progress from Type 1 through Type 4.  However, the reality is that VW was an inexpensive, entry level car where mileage and reliability were big selling points, whereas Porsche's design and sales pitch were geared more for performance.  That, in itself, dictates design parameters, parts costs and quality, etc.  It was not unheard of in the '50's for a guy to buy a 356 and take it right to a track to compete against other makes in his class. There are lots of folks on here that are more knowledgeable than I am about the history, design, and progress of the a/c phenomena. I'm sure they'll chime in.   

I'm not going to pretend to be that guy, Jim, but I do think my off-hand, somewhat cynical and cryptic post deserves as much expansion as I can give it.

I thought dsrtfox's question was excellent. Guys with OG 356 and 912 engines don't seem to obsess about flaps, or firewall holes, or any of this other stuff. Those engines run cool, make decent (if not spectacular) power, and have shrouds no more exotic that the Scat/EMPI 36 hp dog-house tin everybody dismisses as totally inadequate.

I think the answer is in the heads. The same heads that make 200 hp on pump gas possible in a 2332 Type 1, also complicate things from a cooling standpoint. Oil gets hot in an engine because other stuff is even hotter, and the oil becomes an internal cooling medium. Air is the primary cooling medium, but oil is a secondary medium. Oil does a better job of pulling out heat "right now"-- but when oil picks up heat, it has to reject is somewhere, because the oil is recirculated. There's a LOT more air available than oil, and the air is a "total loss" medium-- the engine is not recirculating the air with the heat in it (hopefully).

The furnace in an engine is the combustion chamber. Head configuration and combustion chamber design is going to play a large part in how well the engine sheds heat-- heat that goes out the exhaust doesn't need to be picked up by the oil and air that these engines use as a cooling medium.

This is the idea behind thermal coatings. If we can coat the combustion surfaces with a thermal barrier, in theory it should keep the combustion chamber and exhaust port from absorbing heat-- it'll just go out the exhaust and into the big 'ol world, where we'll not have to deal with it. I have no idea if coatings work, but in a higher compression engine, I think it's worth the $400 or so they cost. I did it, but I really, really want to run higher compression.

911s and Type 4s dump their exhaust out the bottom of the cylinder, creating a cross-flow situation for the gasses in the combustion chamber, and naturally providing a lot of cooling air pouring right over the hottest part of the engine. In a Type 1, the exhaust is kind've over in the corner with not so much cooling air running over it. The head gets (and stays) hotter without some extra tricks being played. The oil in the rocker-box acts as a cooling medium because the air can't do such a fantastic job, and thus the need for bigger/more oil coolers. The oil doesn't make very much contact with the exhaust port, either. It's a problem, which is why really nervous guys monitor head temperature as well as oil.

The exhaust ports on a 356/912 engine are laid out much like a Type 1, but they're shaped really, really oddly-- almost rectangular, rather than circular. This cannot be for flow purposes, as there is a lot of surface area to impede flow. So why make it funky shaped?

I've got no idea. But I'd bet you a donut that it has something to do with how they cool.

The German engineers were smart guys. They were not, however, the final word on anything. It drives me crazy when the entire hobby acts as if they were the final word on how anything ought to get done. The Type 1 was designed as a 30 hp engine, running on really, really cruddy fuel. Pulling even 100 hp out of the platform means that we are taking the engine places they never intended. As a result, we've got to become out own engineers, trying to overcome some of the issues that are baked into the cake.

Berg preferred to just avoid this particular issue (by running his engines at 8:1 compression). It worked, but not because it was efficient or elegant. Jake Raby proved a few years back that flaps don't help cooling. Berg was interested in using his engines as daily drivers-- running for 100k mi, in all kinds of weather. As a result, he was obsessed with getting the engine up to operating temps as quickly as possible.

For me, that is not the primary obsession for engines that are driven 3000 mi/yr, in cars operated in mostly hot conditions, which have known airflow compromises in the engine compartment.

Exactly, Stan, on the money as usual. I like hi-compression as well!

The thing that always sticks out in my mind is original designed hp versus aftermarket hot-rodding. Yes, the VW was designed as 30 hp. But I like to use the 60 hp DP 1600 and compare it to in the neighborhood of TRIPLE hp output we are running. Almost 180 for me and I know there are a bunch of guys scratching at 200 out of a type 1!

If you look at a 356/912, the last factory output was what, 90 hp? About the same for a type4, I might add. A bored and stroke 356 makes what, 140-150 hp? If a 356 made 180(must be one out there) it would merely be DOUBLE the design hp.

And that right there makes sense to me as a good reason why it is so tough to keep type 1s cool.

Dsrtfx:  Who ever said that "real" 356's didn't have thermostats and air vanes??

They did!  But the thermostat works off of air inlet temp, rather than air outlet (below the cylinder) temp.

In fact, I was just at Meister Restorations in Barnsted, NH, yesterday where they had a newly rebuilt 356 engine sitting there waiting to go into a "C" coupe and it had the thermostat bellows with a shaft leading into the fan shroud.  It is NOT mounted the same was as on a T-1 engine (where it is mounted below the passenger side cylinders) but sits up above the head tins on the back of the engine (fan inlet side).  You can see it in this photo, the gold-colored thingie, just to the left of the fan opening:

The 356 air modulation system may work a bit differently than what we're used to seeing, but the result is the same - restrict cold air to the cylinders when the ambient temp is below about 40F and then lessen the cold air restriction (allow more cold air) as the engine comes up to operating temperatures.  

Some older bugs had a restriction ring at the inlet to the fan to do this (as did some 356's), later ones had the vanes but they all had a way to restrict cold air during warm-up (unless it was removed).

Oh!  almost forgot - Rainer was restoring another 356 coupe there which had a Turbo installed and one of his comments was Yes, it makes a lot of power but it's a bitch to keep it cool with the added hp output from the turbo.  Sound familiar??

Gordon- Aren't there restrictor flap where the cooling air exits at the rear of the lower sled tins (or what passes for lower sled tins in a 356/912)? 

Not sure.  I remember seeing them on earlier bugs, but I thought they were part of the heater system.  They were actuated by the knob on the tunnel, right?

The thermostat on the back of a 356 (and 912) shroud is connected to a rod that runs forward thru the shroud and connects to a lever that operates 2 flappers that sit on top of 2 chimneys that run thru the rear sheet metal apron into the top of the heater boxes. When it's cold out the thermostat opens the flappers and directs warm air to (at) the carburetors, when the engine compartment warms up the thermostat closes the flaps there by keeping all of the warm air in the stale air heater boxes to (sort of) warm the car interior. The thermostat has nothing to do with the cooling air inside the shroud. Most regularly driven 356's here in Arizona have the entire mechanism removed with metal plates bolted over the holes in the rear apron...

Well, if it is used just to provide pre-heat for cold carbs then removing them (it) would make a lot of sense in a warmer climate - or in your case a really hot climate!!

Honestly, I don't have much experience with 356/912/t-4 engines so thank you for clearing that up.  Just goes to show that I still have some research and learning to do on these (just to keep up with the original 356 owners in my local club).  I just remembered seeing a bellows on the fan shroud at the shop and it looked, at first glance, as though it served the same purpose.