IDI to DI Power Potential

[Helliouse]

Hello all,
Exciting news in the FAQ post, IDI to DI conversion is an option!
1Z/AHU head, just to keep some of the excitement in check, you will need DI pistons in you IDI, so 1.6ers will have to wait, for a set or look into what it takes to get a pair of 1.9l pistons in (not sure if possible). There is mention of a 1.2l DI(PD) piston that might work.

Now the big question for some of us is what is the Power Potential out of the 1.6l IDI/1.9l head or 1.9l IDI(AAZ) vs. a DI 1Z/AHU engine vs. electronic/EFI DI ALH (I think)

VNT 20, Dave's port work, with Dave's cam. Or and apples to apples compare.

As i am not, and haven't looking in to DI performance in the VW world, i am not sure what they are capable of. I have seen You Tube vids, of TDI at 200hp, also had a VW mech, tell me 200hp what easy to get on a TDI/DI engine.
I also know that in the IDI world 200HP is a hard, very hard, number to reach.

Thanks for your posts ahead of time.

[malone]

By the time VW diesel modding became popular, TDIs were already here for a long time. Getting more power out of a basic TDI was easy by tampering with boost and fuel sensors. An IDI on the other hand needs its fuel injection pump taken apart for crucial performance.

TDIs can handle more power out of the box, which is appealing. TDI owners also had more money, which attracts business/tuners into making power enhancement parts for TDIs. Doing business for VW IDIs exclusively is not very feasible (been there, seen it) so most of the R&D-proven stuff are in TDIs.

There are some non-VW IDIs that make a lot of power.. particularly the inline-5 3.0L MB engines.

According to this paper, IDIs still have potential. fspGTD, who was one of the most knowledgeable members here, experimented using a TDI turbo on his 1.6 IDI with interesting results - see the second post in the above link or search for his threads.

Personally, I'd choose a TDI for 200hp because it's just easier (I'm lazy), and they yield slightly better fuel economy. I had a 1.6L IDI with Dave's work and it made very good power (with 0% smoke) given the stock IDI nozzles, 9mm pump size, and no intercooling. Fuel economy was still good. I believe 200hp is very possible. The only obstacle AFAIK is the headgasket lifting. One solution is o-ringing or fire-ringing to keep the headgasket together, but that means more work.. not appealing to the lazy diesel modders.

The IDI needs high compression to function in daily driving, which may be an issue high performance + PCP. VW TDIs can comfortably start in Canadian winter with 17.5:1 or lower compression. Original ALH TDI headgasket setup + 200whp = no problem. VW IDIs begin with 22 or 23:1 CR and you can't go much lower than that without affecting cold starts signficantly.

I'm still very interested in seeing VW IDI research continue.

A lightweight 1.6 IDI converted to TDI with 1.2 TDI pistons might make a very cool high-MPG machine in light vehicle.. the 1.6 has a pretty short stroke though. More torque at lower RPM may be better for MPG.

Cheers,
Mark

[MJF]

There are some non-VW IDIs that make a lot of power.. particularly the inline-5 3.0L MB engines.
Cheers,
Mark

5-cylinder 3,0 MB could be compared to Vw IDI, not very good. It´s the 6-cylinder 3,0 MBs that rocks

[Vanagoner]

I have heard of a 1.4 DI vw in europe, but not a 1.2.  Anyone know how those pistons compare with the 1.6 bore?

[jimfoo]

I believe the 1.4 had the same bore as the 1.9, and is a 3 cylinder also I believe.

[Vanagoner]

I can see that- a 1.6 4cyl has the same bore as a 1.2 3cyl (assuming the stroke is the same). just never heard of such a thing before.  There are some mystery pistons on thesamba-  if they are out of a 5 cyl they might be close- ?
http://www.thesamba.com/vw/classifieds/detail.php?id=414152
this kind of conversion would take some close checking of design dimensions, but once someone cracks the code...

[jimfoo]

Those have to be gasser pistons as that dish is way to big for a Diesel.
2.2l turbo.

[itzdshtz]

This engine is used in the Audi A2 In Europe, it has the same bore and stroke as the 1.6 TD but uses an all aluminum engine.

It would be interesting to find out if the piston pin diameter is the same and if the connecting rods have the extra weight on the bearing cap that the 1.9 has to offset the extra weight of the piston.

Here are the specs: www.audiworld.com/news/01/A2TDI/chart.htm

          Herman

[jimfoo]

Here is the 1.2 in a bike. Unfortunately no video. 90 hp with chip tuning.

[haybayian]

Thank you Mark for this outstanding contribution.

I am like you, I hope and believe that IDIs have a future and that the advent of DIs, single rail  HDi, etc is not signalling the end of an era for mechanical injection diesels but rather a plateau.

I find your comments (and your source's) concerning the need to redesign prechambers very interesting but as a newbie , a user, (and crude amateur) I can only say: please go for it.

Here are my own thoughts  about TD performance(please don't laugh).

Apart from what you are suggesting regarding fuel atomization  (heat), I would like to suggest that one way to make IDIs more performing would be to  reduce the compression ratio down to 14-1.  The pressure inside the combustion chamber would drop of course to perhaps 160 psi (just a guess). An external compressor (positive displacement) driven by the AAZ crank would provide an additional  175 psi and feed the the cylinders via an air tank.

I would like to rebuild (one day) a AAZ with shorter connecting rods and lighter pistons. This  along with other blueprinting measures would allow this engine to rev higher (maybe 6500 rpm).

Just food for thought. I hope I will not bore anyone.

Haybayian.

[MJF]

1,2TDI has 24mm piston pin. Dunno how long rod it has.

I would like to rebuild (one day) a AAZ with shorter connecting rods and lighter pistons. This  along with other blueprinting measures would allow this engine to rev higher (maybe 6500 rpm).

Why shorter :shock: The longer the better. 1Y already have longer rods (150mm) and lighter pistons  :wink:

[jimfoo]

Thank you Mark for this outstanding contribution.

I am like you, I hope and believe that IDIs have a future and that the advent of DIs, single rail  HDi, etc is not signalling the end of an era for mechanical injection diesels but rather a plateau.

I find your comments (and your source's) concerning the need to redesign prechambers very interesting but as a newbie , a user, (and crude amateur) I can only say: please go for it.

Here are my own thoughts  about TD performance(please don't laugh).

Apart from what you are suggesting regarding fuel atomization  (heat), I would like to suggest that one way to make IDIs more performing would be to  reduce the compression ratio down to 14-1.  The pressure inside the combustion chamber would drop of course to perhaps 160 psi (just a guess). An external compressor (positive displacement) driven by the AAZ crank would provide an additional  175 psi and feed the the cylinders via an air tank.

I would like to rebuild (one day) a AAZ with shorter connecting rods and lighter pistons. This  along with other blueprinting measures would allow this engine to rev higher (maybe 6500 rpm).

Just food for thought. I hope I will not bore anyone.

Haybayian.

An external compressor would be very inefficient. The TDI is a more efficient design. I don't believe IDI's will ever return myself as they will always get worse mileage and have higher emissions.

[Helliouse]

Thanks for all the responses, and the information about pistons.

I guess I should clarify,
A 1.6l tdi revving at 6000rpm, something unheard of for a diesel, is what i am interested in, or 7000rpm.
With out a pre-chamber you gain 20% is fuel mileage, not to mention engine efficiency. Imagine having to cram all that air through that tiny hole your self...then get it out on to the piston.

I like the idi, i love my 1.6l but i my quest for HP, i am not partial to either, i just what a motor that i can drive and kick the pants off of a wrx, celica, or tiberon. WRX might be a little hard :-P, but you get my point.

If running forged pistons in a 1.6l in a DI format would yield the low end torque of a diesel, yet the high-end HP of a revving gasser, you have one hell of an engine, thro a tranny under it that had work that power...look out.

Now i might just be dreaming...usually am, but I imagine this whole idi scene started this way.

I guess this quest lead to finding a good set of pistons that fit, the rest…well that is another story that I am not going to talk about until I have it all ready!
So does any one know where one could get a set of blanks?
Does any one have a 1.6l piston that is ***ed and doesn’t mind cutting into it? How much material is in the piston top?

And does any one have actual number of what the highest factual HP achieve on a m-TDI, TDI and IDI?
I know Andy2 is close to 200, but it is far from a daily driver.

[haybayian]

1,2TDI has 24mm piston pin. Dunno how long rod it has.

I would like to rebuild (one day) a AAZ with shorter connecting rods and lighter pistons. This  along with other blueprinting measures would allow this engine to rev higher (maybe 6500 rpm).

Why shorter :shock: The longer the better. 1Y already have longer rods (150mm) and lighter pistons  :wink:

Shorter connecting rods  and lighter pistons means less moving weight and higher rpm. The cost of course is lower compression (which I addressed in my post).

[MJF]

Shorter connecting rods  and lighter pistons means less moving weight and higher rpm. The cost of course is lower compression (which I addressed in my post).

Shorter rod in not always lighter. I have 20mm longer rods than stock and it´s still lighter than stock. And shorter rod will always be worse than longer (rod/stroke ratio)