Can someone explain "tdi-M" to me?

[Topherdiesel]

I was just wondering if someone could briefly explain the idea of a mechanical tdi to me?

Is it a matter of taking a tdi engine and putting an idi pump on it?

I searched around and couldn't find anything, if there is a better thread explaining it, please link me!

[lord_verminaard]

Basically you've got the right idea.  Generally speaking, "M-TDI" is just a way to run a TDI engine without the electronics- so usually that means no VNT turbo and no immobilizer, no ECU, and a different injection pump.  There are ways to mechanically control a VNT turbo though, as some on here have been doing.

There are numerous ways to achieve this, and some have in-fact used an IDI injection pump on an TDI engine.  But as you may know the TDI is direct-injected which requires more fuel injection pressure from the pump to run at maximum efficiency.  Many others build "frankenpumps" from IDI and TDI injection pumps to create essentially a mechanically controlled, IDI pump with TDI pressures.  Others have adapted off-the shelf Direct-Injected pumps that are already mechanically controlled, like the Cummins 4BT for example.  Those in Europe are lucky as they had more 4-cylinder direct-injected diesels that did not have an ECU than us in the western hemisphere.  As more and more people are doing it though, it is getting easier and cheaper to find an "M-TDI" injection pump.  Both well-known pump builders on this list, Giles and TinTin, can build M-TDI pumps for a reasonable cost.  I'm pretty sure Passenger Performance can also build a M-pump.  As this trend is catching on, you will find more and more pumps out there for this purpose.

HTH
Brendan

[Topherdiesel]

So if I have found someone selling a tdi-m with an ALH code engine, this would have been a mechanical tdi from the factory?

[jtanguay]

tdi-m is not from the factory.   there were some early factory mechanical tdi's but they were not called mTDI's or TDI-m's.  in north america there was never a mechanical TDI in a vw.  over in Europe they had some cars with the mechanical direct injection.

[hillfolk'r]

heh,we do know they run good,and still get great mileage
if you get someone to build you a pump,or get the parts for one and have it built,thats the major obstacle in making a TDI-M...
other than the pump,its almost a direct drop in for an idi engine
for example:
i took my 79 rabbit diesel ,built a TDI-M,and used a mk2 5 speed trans
i could have used the mk3 trans ,but that would have required the mk3 trans and all the linkage,etc
and besides the mk3 clutch/flywheel assy weighs a ton,i saved probably 15 or more pounds from the spinning mass(i also dropped the mk3 harmonic balancer for a simple vbelt pulley)
vw's are like legos,you can mix+match all kinds of stuff between the different generations


build one+have(relatively cheap) fun!!!!!

[rallydiesel]

I love that pic!