Differences between TDI and IDI Plungers..

[xud9te]

Hi,

I apologise if this has been asked and answered already!!

What are the differences between TDI and IDI Plungers?  Can you use either in either?  

I was reading another post on the board (écrit en français!) in which there appeared to be a problem relating to an extra hole on the TDI plunger, presumably to do with pre-injection, which decreased performance.

Whats the deal with this?  Will it still work in IDI?  Are all TDI plungers like this?

cheers!!  

[Tintin]

I think that it's me which has write this post, I should edit it, i thought a long time that the plungers stays different,  after of having had several different model IDI and TDI,  I does not see real difference.

They is true that there exists different model plungers,  and what worries me, it's that it have there with 2 delivery port,  I does not understand yet why?

Some other models with an extra hole to lubricate.

[Benjamin]

as far as i know there is no difrence.
i drive a fiat croma tdid (tdi) 11mm plunger in my fiat 1.9td.

there is a difrence in the camplate, the offset, i think this difrence camed in years or something, i dont know.

thats all i know.

Greetz, Benjamin

[xud9te]

It looks like the second hole on the TDI plungers is a smaller outlet which still  lines up with the injector outlet port at a time when compressed fuel is avaliable.  So surely some fuel is injected into a cylinder at that time?  

Is it possible that this hole is to facilitate the pre-injection event that is used to quieten the diesel knock and reduce NOx on DI engines?  

The spacing between the main outlet on the plunger and the smaller one is 140 degrees (or 220) which means that the smaller hole would be delivering fuel to a cylinder 70 degrees (or 110) before (or after) the main sqiurt.  Could it be the pre-injection for the same cylinder, or more than likely for the next cylinder to fire?  (Pre-injection is usually around 25-30 degrees before main injection)

Anyways, on an IDI engine, would this not just serve to waste fuel if the preignition injection is not needed?  I am sure most of this fuel wuld be burned, but it would be better used if it were injected at the right time?

So, would it be worth blocking this hole up?  I dont thing welding would work as it would distort the plunger with heat, but knocking a small dowel into the hole might?  Or would it not be worth the hassle for the gain in fuel economy and power?  Or is there even some random benefit in the idi's?!

cheers

[Tintin]

Is it possible that this hole is to facilitate the pre-injection event that is used to quieten the diesel knock and reduce NOx on DI engines?  

it is what I said too.

When the main hole injects into a cylinder, the small hole is aligned in the following cylinder.

On the other hand, 10mm TDI have only one hole, and the 11mm automatic have two of them ........     ??

12mm iveco plungeur
   

[xud9te]

Hmmmm,  very strange!!  So there are TDi's with only one hole on plunger?  Are they low pressure injectors maybe?  Anything else on the TDi's that distingushes the pumps with one hole?

Funnily, one two-hole plunger that I have is from an older perkins DI engine that uses a mechanical VE pump with quite low pressure injection (in comparison) with the TDi's, but it also has two holes!!

I wonder who could answer the question?  

I am still agreeing with you tin-tin as I am sure it is pilot injection, but this means that the TDi's that have 1-hole plungers must use another method for the pilot squirt.  Maybe using a two stage a spring injector can give the desired effect?

Cheers
Greg