Type 4 DTM FAQ
Frequently asked questions for the DTM Cooling System courtesy of Jake Raby's Aircooled Technology. Source http://aircooledtechnology.com/dtm-faq-page/
How easy does it install?
What color does it come in?
The DTM is provided in a Gelcoat Black fiberglass finish. Shrouds can be prepped and painted by an auto body shop if customization is desired.
Does it have a thermostat?
No it does not incorporate a thermostat. We have found that in the winter months simply swapping to an earlier type of cooling fan (say from a 13-1500cc engine) will provide excellent warm up, even in cold climates. The addition of an oil thermostat is a plus, but is not needed.
What core engine is best?
It doesn’t matter, all Type IV engines are strong, and great for conversion. I personally prefer a 1.8L core engine.
Do I need to cut my car for it to fit?
It is very rare to ever need to cut a vehicle for an install of a DTM. Please see out the following fitting pages that cover most models in detail.
Will the TIV engine fit into my current transaxle?
If you have ANY VW Type I / Type II gearbox or Porsche 901/915 gearbox, we can set you up with a no guesswork interchange. The Type IV slides right in.
What engines/cases will the MassIVe DTM fit?
The DTM will fit any engine with an open breather chimney. This includes any W,CB,CD,EA,EC,ED,GA,GC,GD, and GE cases. Basically any 1700-200CC engine. In other words unless your engine came from any vehicle other than a ’80-’83 Vanagon, our shroud will
easily bolt right on. It will not fit the CV cased Vanagon engines without serious modifications.
What cylinder heads will it work with?
Any Type IV cylinder head, of any year or engine size, from 1.7-2.0 and even the 2.0 Porsche original heads. It will also work with Scat Split Port heads and a few of the aftermarket heads that are on the market with some modification.
Does the engine need any machine work for the shroud to fit?
No, almost all the 911 arrangements require machining of the case, but the DTM does not. The DTM requires that 3 holes be drilled, and then the shroud slides right on and bolts down like a charm!
What if I have a lot of cylinder shim, due to having a stroker Engine?
No worries, the shroud easily accommodates a 0.250″ shim per side of the engine, and can be made to do more. I have used up to a 0.455″ shim on a long rodded 2.8L engine with slight mods to the shroud.
What Carburetors work best?
We have found that Weber IDF and Dellorto DRLA series carbs give the best tuning and bang for the buck. The shroud is easy to use with these and everything clears easily. Some customers have used Kadron carburetors, but we have had poor luck with these on conversion engines.
What Linkage works best?
I prefer hex bar linkage from www.cbperformance.com when working with Webers and Dellortos or Sync Link Throttle Linkage.
What Alternator? Will A Generator fit?
Yes, the shroud will work with either an alternator or generator. The shroud was designed and fitted with an AL-82X alternator, and that’s what we mock them up on with here at the shop, on our test fit engine. The AL-82X is what we recommend, because it is the best available today, and the simplest to wire up. We offer these in our Stage IV and deluxe kits. If you have a generator, you may need a small shim between the alternator stand and the Generator to correct belt geometry.
What cooling parts work with the DTM?
Any 1971+ Bug “doghouse” cooling fan, alternator and backing plate assembly from a VW Type 1 engine. Basically all the parts including the generator pulley and strap.
Is the Alternator hard to change?
ABSOLUTELY NOT! I think this is a very strong benefit of the DTM. Many alternators are hard to change, or take an hour to remove. With the design of the DTM remove 6 bolts and the entire assembly is out in less than 5 minutes in a beetle!
Is the Type IV engine heavier than a TI?
27 pounds is the difference between a DTM converted engine and a stock 1600cc Type I engine. If your Type I engine is built on one of the “NEW” cast aluminum cases, then your engine case is HEAVIER than a Type IV and ½ as strong!
What type of exhaust is best for the conversion?
Currently Ahnendorp BAS has the best system for a conversion engine, IF YOU ARE WORRIED ABOUT COST! If you want the ultimate,
Tangerine Racing's exhaust systems. Exhaust on the Type IV engine is of utmost importance and cannot be overlooked.
Does it work?
When we say “Dyno Proven” We mean it! Our system cooled 75°F degrees BETTER than the best 911 system we tested in a back to back session. To put it simply, the shroud is unparalleled!
Will my engine overheat?
There are a lot of variables with engines and the heat they produce. I can say that I have used DTM shrouds on engines above 2600 ccs
with great results. The design of the engine is very important (that doesn’t
mean just set your CR Low!!) and some engines will overheat in Antarctica, no
matter how they are cooled. Our test engine was a 2270cc, 160BHP engine with a
static Compression ratio of 9.5:1. The engine ran extremely cool and basically could would not attempt to overheat
until we doubled the load and RPM of the tests (that’s in a 160 degree dyno cell). No other system would do this, Not even a 911 system. Basically if your engine is designed correctly, size does not matter, the DTM will cool it. We do discourage the use of cylinders over 96mm unless Nickies are used, simply because they are not needed to make a powerful engine, and they drastically reduce the longevity of the longest living aircooled 4 cylinder engine available.
What if I live in Arizona or Nevada? Will my engine run hot?
Once again, your engine will not run hot unless you have a misconfigured engine. Even though the temps are high in the desert, the humidity is low, dyno results show low humidity and high temps barely affect head temperatures. I have sold engines with DTM shrouds as far away as Singapore, and not even that engine ran hot!