Frequently Asked Questions about DTM Cooling Systems

How easy does it install?

The DTM is the easiest and fastest way to convert your engine in the world! There is no kit that provides the cooling that the DTM does and is as user friendly. I have been using DTMs for years and have become totally infatuated with its ease of installation compared to every other kit on the market

What color does it come in?

Currently only a highly polished Gelcoat Black, that looks awesome and nearly original. We are currently having molds made for a carbon fiber/composite DTM that will look absolutely amazing!

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, VERY rare to ever need to cut a vehicle for an install of a DTM. Please see out fitting pages that cover many, many cars 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. Contact us for more detailed info on your application.

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 bolt right on- Easily. It will no 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 SplitPort heads, and a few of the aftermarket heads that are on the market.

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 suide 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 when working with Webers and Dellortos. We are currently designing our own custom bellcrank linkage to work specifically with a DTM. We will also be carrying the CB linkage kits at a later date.

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?

This is the only battle that we are still fighting, but we have it solved. Currently has the best system for a conversion engine, IF YOU ARE WORRIED ABOUT COST!. If you want the ultimate, see for the ultimate “Superheader”. Exhaust on the Type IV engine is of utmost importance, and cannot be overlooked. We hope to have a system ready for sale by Christmas 2003!

Does it work?

Yes, just see our dyno data on this site. We spent over $500.00 in fuel testing our shroud and over 60,000 gallons of water passed through our dyno. 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 Anarctica, 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 (see our dyno pages for raw data)and basically could would not attempt to over-heat till 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 huge 103+mm cylinders, 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, not unless you have a misconfigured engine. Even though the temps are high in the desert, the humidity is low. Look at our dyno results and you will see that our low humidity and high temps barely affected head temperatures. I have sold engines with DTM shrouds as far away as Singapore, and not even that engine ran hot!