Whats an M-Tdi?

[GoLfMan]

i've been reading around on the net about TDi tuning and i've noticed alot of mentions of a M-TDi, what is it?

[gldgti]

ok...

so, your normal run off the mill TDi from the 90's has an ECU which takes airflow data, boost pressure, rpm etc etc etc and throttle position, and controls the injector pump like that.

problem is, all that rubbish takes a lot of wiring to run... and a diesel engine doesnt actually NEED any of that.

you take the same kind of VE injector pump as is used on the earlier diesels, like the AAZ in my car, and the 1.6TD's, and you replace a couple of internal parts of the pump (specifically the high pressure pump cam plate, and plunger) with that of the TDI pump. not you have a mechanically controlled TDi, or an M-TDi!

so, an M-TDi is a "mechanical TDi"

why did VW make TDi's electronic?

its easier from the factory to make tune changes to different models etc, using a software upgrade.

for mr hotrod mk1 builder, its not. infact, all the electronics only get in the way of making BIG POWER. so we get rid of the silly electronics, and replace with a nice little system of springs and levers... ahhhhhhhh

[Preen59]

Woo! lets hear it for parts you can SEE and mechanically adjust!

[GoLfMan]

can you do this kind of thing to your model of TDi? any way of bypassing all the electronic hibbidy gibbidy?

i've heard the 1Z's pistons are only good up to 140hp...

[gldgti]

my car (the mk3) is not TDi - its just plane old turbo diesel goodness. no electronics, no funny business.

its also not direct injection - ala 1Z. the engine in my mk3 is an AAZ - basically the indirect injection version of the 1Z.

indirect injection (old vw diesel) offers high reliability, good high rpm performance, tough as nails, runs on anything technology.

direct injection offers more low end torque, less top end, not quite as versatile for different fuels but slightly more efficient.

i like the old IDI engines personally, since they drive more like a petrol engine and you can rev them out happily. the TDi's arent so happy to do that, and really excel between 1500-3500 rpm

[GoLfMan]

thats awesome!!!

i've heard that the 1Z has its tuning limitations!

[gldgti]

theres nothing inherently limiting about the 1z apart from the very undersquare configuration - nothing that cant be overcome anyway.

my aaz has the same undersquare borexstroke combo - 79.5mm bore and 94.5???mm stroke? i think...anyway its a big difference.

there are lots of TDI engines.... the 1z, ahu, aha, alh.... the differences arent that huge.

[Preen59]

theres nothing inherently limiting about the 1z apart from the very undersquare configuration - nothing that cant be overcome anyway.

my aaz has the same undersquare borexstroke combo - 79.5mm bore and 94.5???mm stroke? i think...anyway its a big difference.

there are lots of TDI engines.... the 1z, ahu, aha, alh.... the differences arent that huge.

Nothing bad about undersquare forced induction engines. There is no need to rev them to improve the efficiency because you can fill the cylinder better with boost. Diesels are good because of their huge torque, and their flame speed is low, so long stroke is a good thing. So you are just improving the qualities that are already good.

[gldgti]

yes, your right..

what i should've said is there's nothing inheretly bad about it apart from undersquare being difficult to rev hard.... haha

never sounds as happy at higher revs as the little 1.5 or 1.6 does

[Preen59]

yes, your right..

what i should've said is there's nothing inheretly bad about it apart from undersquare being difficult to rev hard.... haha

never sounds as happy at higher revs as the little 1.5 or 1.6 does

I agree. I'm very glad we have some seriously switched on diesel tuners like yourself on here. Diesel tuning is very interesting and I like reading up on what you're doing.