How big is it? | "Big block vs. Smallblock" | Over heat it, over cool it, or keep it just right! | Radial fan kits | Axial fans (911 style) | OVERCOOLING
The Type IV engine will fit in conversion state with our cooling systems into ANY vehicle that previously housed a VW Type I engine. This includes the Beetle, Ghia, Thing and Bus (pre 1968 is a direct bolt up, 68-71 requires some work)
Porsche Speedster and Spyder replica owners as well as early 356/ 912 owners can also convert their cars easily, with our shroud and products, it's a bolt up!
Very, very seldom do we find it necessary to cut the engine bay of the vehicle for the Type IV installation. Almost every engine bay we have needed to trim for install was due to the vehicle being previously damaged from rear end collisions (that was a very early beetle).
The Type IV engine is very similar to the Type I in design. The factory cooling system, (that is not used in an upright conversion), is the single biggest difference in size between the two engines. We can only give generalities of size difference, such as distance between carburetor inlets and etc. when our MassIVe DTM shrouds are utilized.
When converted to upright the Type IV is actually easier to perform tuning and repairs to. Most of this is due to the fact that the Type IV engine equipped with dual carburetors is a whopping 2" more NARROW than a Type I with the same dual carburetors. This allows for easier access to spark plugs, and carburetor adjustments. Our cooling systems make it easy to repair most items in the engine bay, as there is virtually nothing to interfere with the part being removed/replaced. The engine installs the same as any Type I engine. Below is a general difference in physical size between the two engines.
| Dimension | Type 1 | Type 4 |
| Engine width (Carb inlet to carb inlet) | 33-3/4" | 32" |
| Engine length (pressure plate to crank pulley) | 16.5" | 18" (no clearance problems) |
| Engine height | according to cooling system, generally 26-27.5" | no more than 27.5" (no clearance problems) |
| Engine weight | according to state of build, new aluminum cases ARE HEAVIER than a Type IV case! | No more than 30 pounds heavier than a normal Type I engine. Lighter than the new aluminum Type I crankcase! |
The Type IV engine will bolt right up to any 12 VOLT STD VW bell-housing (transaxle) with no adaptor plates needed and without any machining of the transaxle. The bolt pattern of both engines Type I and Type IV are the same..
If you have a vintage Porsche you can also enjoy the transformation of your vehicle into a modern cruiser that is easier to find parts for, and cheaper to maintain. Installing a Type IV engine into an early Porsche is just like doing so with a VW, all the parts needed are available right here! No guesswork involved! If you are looking for a source for a complete engine, visit our sister website www.aircooledtechnology.com. Type IV engines are virtually all we do, and we can incorporate our cooling system into your dream engine.
The Type IV conversion is not for everyone! But for some, it's all we want!
Before reading this please understand that we are not degrading the Type I, as this is a comparison from our standpoint from building both types of engines. We like the Type I, I started working on them at age 8 and will always love them, but we like things different, a new age in "AIRCOOLED TECHNOLOGY" (hence the name) is what our goal is.
From time to time I have phone conversations with customers wanting a 200HP daily driver that will last 100,000 miles and get 35 MPG with no maintenance at all, point blank, that is not going to happen with any modified aircooled engine bought for less than a small fortune.
The Type IV is a great option for enthusiasts that want to drive their car with a lot more power than a stock or slightly modified Type I engine. We have found that Type IV engines from 2.0-2.3 liters is all that are needed for plenty of long living, daily driven power. These engines are built tough and are only slightly modified compared to a Type I engine nearing 2000cc. The amount of modifications needed to be accomplished to a well built 2 liter Type I engine (2007cc) require an over bore of 5 mm, a whopping .200 of increased bore size. The crankcase needs boring and it will also need quite a bit of clearancing internally to allow for the stroke change. The Type I engine will have almost every part of it modified to last a reliable life, when driven and not trailered or garaged. The Type I is an awesome HP engine, and we love them for that reason, plus the fact that they are cheaper to build into "Saturday night specials", however when being built right with a long life desired, it is reality that the Type I cost may reach or surpass the cost of a correctly configured Type IV conversion engine that will have the capability to outlive it, especially when driven hard and abused.
Quite frankly to make a 2000 cc or larger Type I engine reliable it requires a lot of modifications to equal the power that could be achieved with a very mildly built, pure aluminum crankcased Type IV engine. The Type IV engine has a broad, power filled torque curve that is capable of being driven on long road trips to car shows and events without needing a trailer to get there, and without hauling an entire craftsman tool box in the trunk to repair small problems on the way.
The Type I engine is becoming plagued with aftermarket companies that are slowly killing its longevity, the days of quality German parts are almost gone. More and more the words "Made in Taiwan" are appearing on parts that in the past have said the names of an OEM supplier. The Type IV engine is a performance engine and has been used by the 914 racing crowd for years and never do I see the words "Made in Taiwan" stated on our performance parts or any Type IV specific part for that matter! Most of the Type IV parts are made in Germany or in other countries known for their quality raw materials and products. A good example of this is the new Type I Aluminum crankcase, its truly aftermarket and lacks MANY of the featres that VW incorporated into the Type IV engine. This crankcase weighs 12 pounds MORE than a Type IV crankcase.
A lot of the Type IV engine parts we use and sale are made in the USA. Presently some new companies are working to make the Type IV world even more advanced, with parts unparalleled in quality. One of these companies is LN Engineering. They are hardcore VW enthusiasts that are true engineers and have designed their products to last. Visit them on the web at http://www.lnengineering.com/.
In short the parts for a Type IV engine may cost a little more but rest assured that they are the best quality available. Names like JE pistons are what we deal with on a daily basis.
The Type IV engine benefits from updates made to it by the VW engineers, a whopping 30 years after the development of the Type I engine. These changes were directed to solve engineering problems with the Type I engine, and provide a longer lasting engine to push the heavier vehicles that new safety laws were making a reality in the US market. Please see our other pages directed toward the Type IV engine for direct information concerning the conversion.
Over heat it, over cool it, or keep it just right!
The cooling system of the stock Type IV engine will only fit into Type II (1972-79 busses), or Type III vehicles; all other applications will require an upright conversion shroud. These can be grouped in two designs, radial fan and axial fan. The radial fan systems use Type I cooling components, and the axial fan shrouds use the Porsche 911 fan that can deceive the normal enthusiast with its unbelieveable physical appearance. Do not be fooled, these articles are here to help you understand which one you need, and why.
The single biggest challenge concerning the Type IV conversion is the selection of a cooling system! The cooling system is something that can effectively cool, effectively OVER COOL or completely overheat and destroy the conversion engine. Enthusiasts that make their selection only upon physical appearance may well be letting that decision decide the fate of their engine! A cooling system is designed to cool, not be a showpiece, just as an engine is designed to be driven, not polished. You will see in the pages to follow that it is possible to have an outstanding, unique engine and do it all practically. The Type IV engine is a piece of art in itself, as a general rule we feel that "looks kill"
We do more Type IV upright conversions than any shop in North America, we have used most all shroud systems and many of them more than once, and some more than 50 times. The main thing when looking for a shroud is cost, practicality and effectiveness. The cost of the cooling system is the single biggest investment that the enthusiast will face when doing the Type IV conversion, this is also the single most important factor for longevity, effectiveness, and practicality.
A good shroud must be easy to fit. We have used some shrouds that require fabrication and tons of machine work, and some that would not even bolt on as advertised, or as intended. Some took more than 15 hours of milling machine time to MAKE fit. The cooling system can be simple, or complicated, there are "do it yourself" options available. Joe Cali of Next Generation has a great book that goes into detail on the entire conversion and is an excellent piece of reference material for anyone contemplating a Type IV conversion project.
The Type IV engine has 23% more cooling fin surface area to dissipate heat than a Type I engine does, and because of this, the same amount of cooling air can be routed over the cylinders and effectively cool the engine, even better than stock. The "radial fan" kits (such as our MassIVe DTM) that route air over the cylinders the same way as the stock Type I are more cost effective and simpler than the Porsche style "axial kits" and can cool properly configured performance engines to over 2600cc. I have done this on my personal car on more than one occasion. With a Type IV, just because you have added performance, it does not mean that you must add extra cooling. This is due in part to the added surface area for heat dissipation, and the engines ability to shed its heat easier and faster than a Type I.
In stock form the Type IV engine has the cooling fan attached to the crankshaft, via an adaptor hub and is driven at 1:1 crankshaft speed, this means that the air must be forced back, over the cylinders, and diverted to the oil cooler, and cylinders with the aid of the thermostat flap assembly. This method of cooling has proven to be less efficient than upright cooling, and must have all pieces of Type Inware in place and in serviceable condition to avoid overheating. The problem with most stock Type IV cooling systems is that they have fallen prey to non-familiar mechanics and abusive drivers over the years. Most of the engines that we see with failures were stemmed from those that left pieces of tinware off, or just did not care enough to reinstall them. The stock cooling system is one that is not simple to work with. When the engine is converted to upright it becomes much simpler and less particular to changes resulting in heat!
I have grouped the common cooling systems in two different categories for a better explanation concerning them. I will attempt to go over these in depth and answer as many questions as possible, cooling is important!
There are a few Type IV conversion kits on the market that come complete and ready to bolt on to a Type IV long block. Several of these use the same type shroud as the "Cali Conversion" that we covered in the DIY pages of these articles, these work fine for smaller engines, and are practical as they are normally in the neighborhood of $2-400 US dollars, according to how many parts the enthusiast already has (Type I alternator, fan and etc.). These kits still should only be used on very mild engines, as the non offset shroud does start to work on the #3 cylinder after a period of time in larger applications, or where the driver is neglectful to the engines state of tune. To date there are only two kits that incorporate the radial fan, we will address these separately in the following pages.
The main problem with cooling system choices is that way too many enthusiast judge the products appearance only, cooling systems do not have to look good to work well, in fact some of the best looking systems, work the poorest, since their designers are "exterior decorators" please do not be fooled by the appearance of some products solely.
Oregon Performance Products' DTM
The DTM incorporates practicality, simplicity, appeal and function into one term, "extraordinary''!!!
(This was wrote by me in 1999, prior to ever buying the DTM name or molds from Oregon Performance. I bought the molds and decided to make this shroud, because I believed in it! I have not changed my article, but please take note that we now offer the DTM, and not Oregon Performance.)
The best engineered and highest quality shroud kit we have used comes from Joe Locicero of Oregon Performance Products. Joe is a retired 50 year veteran of the VW scene and has been producing his shroud kit for 12 years in it's present state. (See VW Trends Magazine (What's New, Dec.1991 issue)
Joe's shroud is a high quality fiberglass shroud, that is a one piece design and incorporates vanes internally to route air where it needs to be for effective cooling of ALL the cylinders (including #3 and #4) . To date Joe's kit is the highest quality kit that we use, and his personal customer service is unparalleled by any company that we deal with. This kit works, and is rugged, with a unique appeal that is unlike anything else in the VW industry. It looks like a Type I, but with the unique personality of the Type IV. The DTM comes 100% complete and ready to bolt on, in beautifully polished gel-coated fiberglass, painting or finish work is not required.
Joe calls his kit the DTM (Down The Middle) due to the design of the shroud, which conforms to the offset of the cylinders this kit is well suited for nearly every engine from stock to over 2600cc. I have personally had the DTM on my 2613cc engine in the "Blue Bonic Plague" and effectively kept cylinder head temps below the 375° degree range even in the middle of summer, while cruising at 80+MPH for hours. The DTM installs easily with NO MACHINE work required, only a few holes to be drilled, and it will fit into any Type I or Type II that needs upright cooling. The nicest thing about the DTM is that it uses the stock Type I cooling fan arrangement and distributes the air very evenly where it needs to be. It even uses the stock Type IV oil cooler and diverts the needed amount of air to the cooler, even better than stock.
The fact is that we have found the DTM to cool almost any size of engine, especially our 2270 better than anything else available ( this includes the 911 kit, and we'll go into more detail about that later) Another great aspect of the DTM is the fact that it has the capability of being outfitted with Joe's optional "High volume fan" This fan is a design of Joe's that is a combination of a highly modified Type I fan and highly modified Type IV fan that are assembled with several methods of machine processes and then balanced. This fan really increases the airflow of the system, and can surpass the 911 system due to the better design of the shroud. The DTM with the high volume fan is not normally needed for engines smaller than 2500cc, unless high compression ratios or extreme climates come into play.
A cooling system has to be simple!! If the system is not simple, the engine will be a bear to install, and tune, and even accomplish normal maintenance procedures on. The DTM is the easiest shroud on the market to install and everything is in the kit. Should the alternator or cooling fan need to be replaced, the job can be done in 20 minutes, as it is very easy to access, and remove. The carburetors are easy to access, and everything is simply designed.
A cooling system has to be simple!! If the system is not simple, the engine will be a bear to install, and tune, and even accomplish normal maintenance procedures on. The DTM is the easiest shroud on the market to install and everything is in the kit. Should the alternator or cooling fan need to be replaced, the job can be done in 20 minutes, as it is very easy to access, and remove. The carburetors are easy to access, and everything is simply designed. The DTM is economically priced for it's effectiveness. The cost of the shroud is nothing compared to the risks that are taken with inadequate systems, or homebuilt versions that may appear to be adequate. In short I can say that this system is our favorite for conversions. Joe is refreshing to do business with and has the knowledge that make his product exactly what it is, the best!
If you buy the DTM, you will not be disappointed.
Disclaimer: My company, Aircooled Technology is in no way affiliated with Joe Locicero, or Oregon Performance. We know how important it is to effectively cool an engine, and how important it is for us to be able to bolt on a cooling system to our engines that we can trust.
( once again This was wrote by me in 1999, prior to ever buying the DTM name or molds from Oregon Performance. I bought the molds and decided to make this shroud, because I believed in it! I have not changed my article, but please take note that we now offer the DTM, and not Oregon Performance.)
Perhaps the hallmark of the Type IV engine is a "monsterous" beast equipped with the intimidating look of the Porsche fan sitting on top, wrapped with a neatly paint detailed or glass fiber shroud.
In this portion of of my site I hope to be able to shed some light on the reasons why most engines do not need this, and why some that have it may suffer from it instead of benefiting from it's installation. Most of the time this fan assembly is utilized for "the LOOK". I hope I can clearly illustrate that this look also has to have the ability to generate the heat to need the cooling air that is developed from the shroud/fan assembly. I also hope to share that my newest testing has shown that the Type I and Type IV engine simply is NOT PHYSICALLY LARGE ENOUGH to use all the air that the 911 fan makes!!
Please note that as of the revision of this article, that I have added my own line up of 911 shrouds. In actuality I'm talking about one of my own products!!!! How many people will do that? This is the facts! some people like it, some people dislike it, but it's the facts and I have proven it!
The 911 Porsche 11 blade fan can successfully cool a 3.6+ liter TURBOCHARGED ENGINE (400+HP) successfully, it makes near 3,000 CFM of airflow, this is CAN BE too much for mild Type IV engines in most cases. This includes 5, 11, and 12 blade fan assemblies, and even underdriven arrangements. The statements below are aimed toward the general conversion engine of 2.3 liters or less, larger engines utilize the system much more efficiently, here are our views. The appeal of the shroud does so much to the enthusiast's heart rate that in most cases they don't think about what it takes to do the conversion, or the amount of money that is included. I have learned that very few engines with less than 2.3 liters of displacement actually can use all the cooling air, and get to operating temperature. Most of the engines we outfit with the 911 systems are designed and tuned to make the heat necessary to use the air, even our 2270 "D" and "E" version engines are specifically set up for the system. When tuning a smaller engine for use with a 911 style shroud do not be afraid to run added compression ratio, you may need the heat to ever get to operating temperature.
I have recently finished extensive tesType Ing with all these fans and arrangements. If you have quesType Ions about what fan would be best for your applicaType Ion, and you want to run the 911 arrangement, please see the summary at the end of our cooling systems dynamometer tesType Ing results. Those of you who opt for our 911 style shroud will get the added benefit of knowing that we have done the tesType Ing to support our product and know its strengths and weaknesses and pros and cons, better than anyone in the aircooled industry.
Overcooled oil:
The overcooling of an engine poses a problem with the engine oil. Engine oil that never gets to 180 degrees can become filled with contaminants, especially condensation. When engine oil gets upwards of 200 degrees, the engine lubricates better, and all the impurities are burned from it. This is very important for engines that hope to have longevity filled lives. In some applications an "oil themostat" can be used to get the oil temperatures to satisfactory levels, it adds in some cost, as well as extra plumbing and places for oil leaks with the additional bypass circuits that most of them have. An oil thermostat is recommended with 911 style shrouds that are used on smaller engines than 2.3 liters, or in areas with a colder climate. The easiest way to know if your engine suffers from overcooled oil is a milky white residue that forms in the breather hoses, and under the oil cap, this is condensation.
If you have a smaller Type IV engine and think you may have an overcooling problem, try running the 5 blade fan with a 1.16 drive ratio (the larger 3.650 top pulley) Our recent testing has proven that these set up will work well for a smaller displacement engine, but do not work well for a larger engine.
Cooling the heads:
Cylinder heads need to warm up as well, an engine that never fully heats up suffers from lack of expansion, and can prematurely wear, an overcooled engine in some ways is WORSE than an overheated engine, and some people do not understand this. In our experience most engines (Type IV) make their biggest power between 340-385°F. An engine that is held lower than 325°F can not fully expand, can lose power, efficiency, and can prematurely wear.
Overcooled heads can develop cylinder leakage and can also suffer from scored cylinders. All of these are bad things and can be avoided by configuring the engine to make the needed heat to correctly warm up or by choosing the optimum cooling system for the application, and sometimes it is not the 911 system.
The 5 blade 911 fan with the 1.16 drive ratio (large upper pulley is also effective in this situation also as it makes less air volume and spins 800 RPM less than with the higher drive. In our testing these fans were the least effective on a larger engine, so they may actually cool a smaller engine well, and decrease the risk of overcooling..
Climate:
With the 911 system, climate is hardly an issue. It can still overcool for guy in Arizona and Southern California (especially near sea level) just as it definitely can for someone in New York state in the middle of January. With this much cooling air, guys in hotter climates may actually get to operating temperatures with their smaller engines, but this is no real excuse for going to the system, many other systems may cool the engine just as well, and allow for faster warm ups.
Once again, in a cooler climate, slow down the fan drive to 1.16:1 and use a 5 blade fan for the best effectiveness. The radial kits would still be a better choice, but if you want to look, of the 911, try the 5 blade
Update: Since the writing of this article we have been doing a lot of testing. We have simply found that a tremendous amout of the air that the 911 fan makes cannot be blown out of the engine, and simply stagnates in the housing. What this results in is losses of HP at various RPM and engine temperatures that are not even on all 4 cylinders. This is especially true with the high driven 911 set ups, like the 1.3 driven fans.
Underdriving:
This is an option, but does not make very much of a change. The crankshaft pulley on most systems is already smaller than that of a stock 911, under driving farther is possible, but does not make a huge impact on the situaType Ion, as the lower pulley can only be reduced so much before charging becomes an issue. I like 1.3:1(4.250 lower pulley and 3.300 upper pulley) best for the drive raType Io of the 911 fans we use on our engines needing the system. Please do not think that slowing the fan down will solve all the problems of overcooling, it helps but not much.
Power losses: Fans take power to drive.
Some companies claim that up to 17-20 HP can be lost from driving the 911 fan, but we have found that on the Type IV engine, driven at 1.3:1, that this is far from true. The fact is that maybe the sources of these statements do not desire to build an engine that is custom and takes more time, regardless we have found that it is far from true, at least on a Type IV engine. The Type IV engine has a lot more cooling surface that the Type I engine does (23% more surface area). I feel that when a 911 fan is used on a Type I big HP losses could occur as the fan must work HARDER to move the greater volume of air past more restrictive cooling fins, plus there are less of them, the end result is a fan that cannot move more air than it can expel, and therefore it backs up in the shroud/fan and pulls more HP from the engine.
With the more surface area of the Type IV engine the air is not congested as severely, and is expelled faster, this alone is one reason why the fan does NOT pull as much HP from a Type IV engine as some may have found in testing with Type I engines. As a general figure I have found a 911 fan assembly on a Type IV engine has pulled 8-11 HP from the engine on the dyno in back to back test at the same engine temperatures. The radial fan of the Type I engine normally pulls 9-14 HP from a Type I engine
Basically the larger fan does use more power, but not that much. The condition of the battery and charging system does have impact as well, this is just what I have found in my testing.
Update: During our extensive testing of 7 cooling systems we tested the HP draw of each with each level of drive. What we were able to see was that the higher the fan is driven the more HP it took to drive! It is odd that the arrangements that took the most power to drive, were the most effective> this was especially true with the Porsche 11 blade fan and its best drive of 1.3:1. The 1.3:1 driven 11 blade fan consistently had a power draw of 18HP! While the 1.16 drive drew only 11 HP. The 5 or 11 blade fan did not make that much of a difference, maybe just 1or 2 HP.
Which kits to buy:
The only systems that we use utilize the factory original Porsche fan/ring and alternator. I have tried a lot of the systems that uType Ilize "other" alternators that are cheaper. They all share one BIG problem. This BIG problem is the fact that the alternator lacks the proper thrust bearings to support the thrust of a 9" axial fan, the design of the fan constantly tries to "pull" the fan from the housing. Most of the aftermarket fan assemblies utilize a modified VW watercooled alternator for the conversion. These alternators are designed for the load of a 2" pulley, not a 9" fan. The downward force that is applied by the drive belt adds fuel to the fire, and soon the bearings in the alternator are shot, I have seen this happen in less than 2,500 street driven miles on more than one occasion.
The REAL Porsche fan does not have this problem. This fan has been used for 25+ years in its present state and keeps the 6 cylinder cool and the charging system supplied with 35-90 amps (according to year of fan assembly) of charging power. Porsche knew their stuff when it came to the cooling system, please do not be fooled by the imitaType Ions of the "original" systems. Every 911style system we use is the real thing.
There are several 911 "style" fan conversions on the market, some of them require modificaType Ions to install, and some of them involve as much Type Ime as would be needed to "re-invent the wheel". I have used systems from near every supplier, including those with "European technology". Please keep in mind that all of these kits require some type of case modification. Be sure you have plenty of patience when deciding to go to the 911 style cooling system.
We have made it policy to use the kit from Mike Sharpe, Queensland Australia. I choose not to go into detail with problems we have encountered with the other kits, as I want to be fair, all we do is engines and I have my reasoning for what we choose, and what we use. Mike's kit requires 41mm to be milled off the top of the case (we offer this service) as well as some case welding and other machine work. The kit comes complete with everything needed to fit the shroud to the engine, even the sealing pieces to fit around the engine bay, for a clean and simple install. All that is needed is any 911 fan assembly with alternator and strap to attach to the case. Be prepared for some fitting challenges that are time consuming. Mike's kit is the best we have seen, and it cools the engines that need it superbly while keeping a simple, reliable appeal.
Our 911 cooling system does use the genuine Porsche fan and ring. Our customers who purchase these from us will get our technical assistance in choosing the best fan and drive raType Io for what their engine needs to run at the CORRECT temperature- not too cool and not too hot!
In summary:
If you want the 911 "look" you will also need the budget for it, expect to add $1,500.00 to your budget for a good system, the glassfiber kits are even more. I would also like to reiterate that there is nothing wrong with the 911 system. Configure the engine and cooling system correctly and make the heat to need the cooling, and up the power as well, all in one package. Please just realize that the word "911" means nothing is cheap, just like the "Thunderous Roar" that the engine makes between every gearshift when equipped with this system...
In short: make the power, to make the heat, to make the car fly but be prepared to spend some money, or go to the DTM! These are just my thoughts on the subject