Audi 80 Avant

[LeafBox]

Haha

I'll pay you to get them too, right?

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"Handling Fee"

[A80Avant]

Well looking to see what a short block stroker can do on a 3071 gen 2 soon... watch this space!

[mackenzie50]

Here is something my sister made....
https://youtu.be/Lj8dgebqMhQ

Took me awhile to catch up here - wow, beautiful old avant indeed !

[Spyform]

Here is something my sister made....
https://youtu.be/Lj8dgebqMhQ

great camera work done!!! car is awesome))

[A80Avant]

So story goes like this.

I had a spare block that can be machined to 82mm
I had a set of rifle drilled 144mm rods.

All I needed was a set of pistons to make things happen. The rest were easily obtained.

Spec will be somewhat like this:
9:1 compression 95.5 crank short block.
Displacement will be expected to be at 2540cc

Head is a 7a uncracked converted that will have +0.5mm oversize valves inconel all 20 of them, new guides and seats, ADU cams on stock ADU sprocket. We won't be porting, however we will polish the combustion chambers.

Pistons are 4032 alloy which I hope will allow for less oil consumption along with the standard oil ring from JE. Bottom end has been balanced and crank lightened to 21kg. 7a flywheel left alone.

The inlet will be my current one, Wagner, exhaust SQ original and turbo 3071r gen 2 at 0.63ar.

My current setup (stock head ADU, stock pistons, H beam rods ) produces 390-400whp on 3d gear reaching 2.1bar at 3900rpm.

This engine has now done 5000miles (7000km roughly) and works flawlessly has zero oil consumption on Mobil 1 0w40. All going well, this engine will be stored and kept until this stroker project reveals it's teeth

[bazburn]

Swèeet...
What is the aim? Quicker spool and more whp ?

[A80Avant]

Quicker spool for sure.

Physics say that at same boost and timing I should see more whp given that all the rest are the same, however even if it makes the same power, the quicker spool should make it nicer to drive.

Also as I'm not fond if the larger frame turbos, this setup produces maximum power at 6500ish rpm. So given the short block my rpm won't go past 7000rpm

[diesel des]

It will be nice to see how the short block stroker works out. The compression is quite high so with the 0.63 AR turbine knock on pump fuel could be an issue. Can you choose a lower compression ratio, or is that your only option?

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[A80Avant]

I could have gone with 8:1 or 8.5:1. It will now be 9:1 and that given that we want the engine to be agile even off boost.

Although the GTX series seem to be very efficient above 2 bar, I have seen my current setup to use about 13deg of timing @ 2.1bar with a slow rising slope to make the 400whp. Anything above that gives knock.

With the stroker I have been told that timing should not change dramatically if I use the same compression. I haven't had the chance to look at stroker timing maps to check.

I plan to use my trusted headphones before I enable knock control on vems anyway.

What kind of compression and timing do you use dieseldes?

[diesel des]

My 2 strokers have about 8.1 to 8.2:1 compression. Timing numbers are about 15 or 16 degrees up top from memory. After the one in my urq melted down from knock it's being rebuilt with just under 8:1. Pump fuel sucks.

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[diesel des]

Also the gen 2 gtx turbos arnt very efficient, they just have a wide compressor map that has been stretched to give more flow, but less efficiency. Look at the maps for the compressor. Not good efficiency, with maybe 66% at 450 to 500 hp on a stroker.

If you don't have the turbo yet and want to stay Garrett I would look at the new g series 660. It will be 10% more efficient at the same operation point. Look at the map. They use new turbines too which should be faster to respond.

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[A80Avant]

Why do you say that about the GTX series?
I already use the 3071 and I am able to obtain 400whp at 1.9 to 2bar @ 6300 on my current setup. GTX real life experience is what tells me that between 1.5 bar and 2 bar the difference in power is massive. @ 1.5bar I had about 310whp for instance (of course higher timing on 1.5 than 2bar.)

So I have the turbo, I won't be changing turbo again unless it fails. The 660 appears to have a slightly better than the 3071 on flow and efficiency but I am imagining small gains using the 0.70ar in order to match the flow of the 3071 0.63ar turbo.

My assumption on making a bit more power on this engine using same turbo and timing is merely from the fact that the higher displacement will allow for more VE and therefore more horses

[diesel des]

Sorry I thought you where buying a new turbo but I got it wrong. Gtx is good, but efficiency is just average. This is the compromise they made to extend the flow capacity. The compressor on the g series is 79% efficient at peak Vs 72%. That is a big difference on turbine back pressure.

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[A80Avant]

Yes.
Given the numbers I may have with this current setup, if I find anywhere to sell the 3071 for good money I may upgrade. However the 660 needs downpipe and EM modifications as well which increases the cost so it also depends if I can get the 660 cheap too!

[A80Avant]

Recent small upgrade.
I tried the auto vox rear view mirror camera. Seems like a nice addition esp. As my wife drives the car as well. Poor Chinese quality but at least good service. The kit almost immediately died as installed as the soldering points were bad but we cure it and now works properly.