Author Topic: IDI to DI Power Potential (Read 16368 times)

Öl-Brenner · « **Reply #15 on:** January 15, 2008, 02:32:56 pm »

I dug up the following info regarding the 1.2 and 1.4 TDI from the A2. There are both 1.2L and 1.4L 3 cylinder diesel that were used in the A2. The 1.2L Engine code "ANY" uses 76.5mm pistons with 24mm wristpin and is direct injection with 61 HP, Engine code "AMF,BHC,ATL" are 1.4L Direct injected with 79.5 mm pistons with 26mm wristpin. AMF & BHC=75 HP, ATL= 90 HP. There are different part numbers for the connecting rods between 1.2 and 1.4 versions. Also all versions are PD injection with Turbocharging and intercooling.

Helliouse · « **Reply #16 on:** January 15, 2008, 03:03:07 pm »

Well well i have found the complete piston stats for the 1.2l TDI
Now does any one have the stats for the 1.6l?
Might be in the shop manual...will check that when i get home.

Piston:
Piston Out Dia. Φ 76.465
Measured: Φ 76.463

Overall Length 63.05
Measured: 63.07

Compression Height 41.865
Measured: 41.866

Ring Groove Width Top 1.841
Measured: 1.842
2nd 2.048
Measured: 2.047
3rd 3.029
Measured: 3.032

Pin Hole Dia. 24.012
Measured: 24.011
Offset 0.48
Measured: 0.47

Land Thickness Top 8.95
Measured: 8.94
2nd 5.0
Measured: 5.0
3rd 2.79
Measured: 2.79

Crown Thickness 8.55
Measured: 8.63
Boss Distance
Weight (g) 469.8 g
Measured: 470.4 g
Found here is a PDF

rallydiesel · « **Reply #17 on:** January 15, 2008, 03:22:20 pm »

The wheels are turning. :twisted:

haybayian · « **Reply #18 on:** January 15, 2008, 03:53:40 pm »

Quote from: "MJF"

Quote from: "haybayian"

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)

I think you are missing my point. A shorter stroke always yields higher rpm in any IC engine, in most cases producing higher HP at the cost of low end torque. It all depends what you want to achieve . My argument is that a VW 1.9 L TD diesel could produce more than 100 hp/litre if it was given an opportunity to rev higher.

MJF · « **Reply #19 on:** January 15, 2008, 06:07:31 pm »

Quote from: "haybayian"

Quote from: "MJF"
Quote from: "haybayian"

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)

I think you are missing my point. A shorter stroke always yields higher rpm in any IC engine, in most cases producing higher HP at the cost of low end torque. It all depends what you want to achieve . My argument is that a VW 1.9 L TD diesel could produce more than 100 hp/litre if it was given an opportunity to rev higher.

So you want shorter stroke? Or rods? Two different things. 128hp/litre at the moment from destroked 1,9 bottom...

haybayian · « **Reply #20 on:** January 15, 2008, 09:01:05 pm »

[Quote
So you want shorter stroke? Or rods? Two different things. 128hp/litre at the moment from destroked 1,9 bottom...[/quote]

I want shorter stroke and I believe that shorter rods is simpler and less expensive than a re-engineered crankshaft (am I wrong?)

It would be useful if you could elaborate on the 128 hp/litre engine you are refering to. What was done to it, actually?

jtanguay · « **Reply #21 on:** January 15, 2008, 10:22:47 pm »

Quote from: "haybayian"

[Quote
So you want shorter stroke? Or rods? Two different things. 128hp/litre at the moment from destroked 1,9 bottom...

I want shorter stroke and I believe that shorter rods is simpler and less expensive than a re-engineered crankshaft (am I wrong?)

It would be useful if you could elaborate on the 128 hp/litre engine you are refering to. What was done to it, actually?[/quote]

that is his 1.7L monster... he somehow finnished the motor and extracted 200+hp!!! :lol:

jimfoo · « **Reply #22 on:** January 16, 2008, 12:49:34 am »

Quote from: "haybayian"

[Quote
So you want shorter stroke? Or rods? Two different things. 128hp/litre at the moment from destroked 1,9 bottom...

Quote

I want shorter stroke and I believe that shorter rods is simpler and less expensive than a re-engineered crankshaft (am I wrong?)

It would be useful if you could elaborate on the 128 hp/litre engine you are refering to. What was done to it, actually?

Shorter rods will only get you lower compression. You HAVE to mess with the crank to get a shorter stroke, then you have to get rods or a piston/rod combo that matches the changed stroke.

moTthediesel · « **Reply #23 on:** January 16, 2008, 08:05:55 am »

Stroke is a function of the crank throw eccentric (the distance from main bearing axis to rod bearing axis X 2). Changing the rod length will affect compression ratio and valve interference, but will not alter the stroke.

In other words, rod length controls where in the cylinder the piston goes up and down, but only the crank controls how far up and down the piston goes.

moT

haybayian · « **Reply #24 on:** January 16, 2008, 09:00:07 am »

Quote from: "moTthediesel"

Stroke is a function of the crank throw eccentric (the distance from main bearing axis to rod bearing axis X 2). Changing the rod length will affect compression ratio and valve interference, but will not alter the stroke.

In other words, rod length controls where in the cylinder the piston goes up and down, but only the crank controls how far up and down the piston goes.

moT

Thanks you guys, indeed stroke is a function of crank rotation.
I stand corrected.
My question remains: what is the best way to increase maximum rpm?

jimfoo · « **Reply #25 on:** January 16, 2008, 09:55:53 am »

Buy a gas engine. Diesels have more forces and pressures. The components are heavier. You aren't going to get the same rpm's out of a Diesel. Lower compression some, increase boost, increase torque. That's what it's all about, the wide range of pulling power so that you don't have to stay in some narrow high rpm powerband.

MJF · « **Reply #26 on:** January 16, 2008, 10:36:29 am »

I don´t understand why you all want to lower your compression. I have 24+CR and works fine with 35psi boost. It also revs very happily to 5800rpm, more higher next summer...

914turboford · « **Reply #27 on:** January 16, 2008, 11:48:58 am »

I'm sorry for the dumb question but why can't you run 1.6 IDI turbo pistons with a DI head? If there is something about the crown shape that is undesirable can you machine them?

haybayian · « **Reply #28 on:** January 16, 2008, 11:49:27 am »

Quote from: "MJF"

I don´t understand why you all want to lower your compression. I have 24+CR and works fine with 35psi boost. It also revs very happily to 5800rpm, more higher next summer...

It looks that I have yet to learn quite a bit about performance in diesels. I would like to know what you have done to your engine for it to rev happily to 5800 rpm. My stock AAZ is rated 75 hp @ 4500 rpm. I had my VE IP rebuilt with performance mods by a guy called Giles in Toronto. I have a Garrett T3, rebuilt too. I will run 25-30 psi of boost. My intercooler is from a TDI. I have made a 3" exhaust system. If you have time please tell me what I should do to get this engine to crank out 200 bhp.

Thanks.

Haybayian

burn_your_money · « **Reply #29 on:** January 16, 2008, 12:11:23 pm »

Quote from: "914turboford"

I'm sorry for the dumb question but why can't you run 1.6 IDI turbo pistons with a DI head? If there is something about the crown shape that is undesirable can you machine them?

IDI pistons

DI pistons

Your CR would be through the roof and there would be poor air turbulence