400 + HP ABY Coupe Project / full engine rebuild

[bartolomeus]

So, here goes my story about my 1993 Audi S2 ABY which I bought in 2008.
Since then I invested so much money and time in it since it was in a poor condition when I bought it. Also I didn't know so much about cars and S2's so I may have spent more than I should have on some parts.

This year I've decided to update the power. Under PRJ advises I got a:

Holset HX35/K26 Turbo
Updated Bosch Injectors
Updated Fuel Pomp
RS2 Replica Exhaust Manifold
Conversion to 3B single mass flywheel + Sachs Racing clutch set

I've installed the components only to find that the car produced only 1.2 BAR boost and then instantly the boost dropped to 0.4-0.5 BAR.
I had the car checked for problems with the help of a mechanic and s2forum topics and found some other problems.
I've solved all the problems and the car had the same low boost problem.
Then I took the car to pasbogdan and he inspected the car. He found some other small problems, fixed them and the car still didn't go as planned.
So he put the old (original) turbo back in and went for a test drive with his ECU from his S4 (PRJ remap as well). The car was doing just fine 1.5 Boost. So everything was in order.
Either the new HOLSET turbo was defective, the ECU, the PRJ software or the engine.
We measured the engine compression and some pistons had a not so good compression rate.
We decided to take the engine a part (the odometer was 220.000 km with service book but who knows) to see the interior.
We have found that things were not quite good at the interior, the valves didn't keep the pressure, the pistons rings were very used, etc

The conclusion was to remake the entire engine. I bought brand new:

FCP pistons (wossner) with 81.5 mm
FCP rods
FCP springs and retainers
ARP MAIN STUDS
ARP HEAD STUDS
OEM EXHAUST VALVES
AFTERMARKET INTAKE VALVES
AFTERMARKET LIFTERS
1.8t coil conversion
14 point 7 - SLC DIY2, Bosch 17014 Lambda Sensor, Manifold Absolute Pressure Sensor
NEW CAM BELT SET
NEW DETONATION SENSORS
Many gaskets and other small things
ETC

At this time the engine is being put back toghether...

[bartolomeus]

And some other pictures.
Any advises are most welcomed.
Forgot to mention the car has a 3" exhaust directly from the turbo and a Magna-Flow final.

[s2_wot]

Great project, do you have some more photos of that Holset beast?

[bartolomeus]

PRJ said it's baby turbo

[Greg_S]

Huge coldside on that turbo. What made you decided to go for the HX35? What type of response are you look for from your rebuilt engine?

[bartolomeus]

PRJ advised me to use this turbo.
I don't know what to answer to your second question please explain better what you mean.

[prj]

Btw bart, I have two turbos from the same batch on other cars and they both easily produce 2 bar boost.
You can always take the turbine and compressor covers off of the turbo and inspect the turbo for damage, but I doubt you will find anything.
The turbo also has warranty, so if you are convinced there is a problem with it, send it back to me, and I will have it looked at.

I have a few ideas that you can try - I suspect some incorrect N75 plumbing (the turbos have different inlets), so probably you have a custom turbo to MAF hose or metal piece made up and maybe that is the problem.

[bartolomeus]

Btw bart, I have two turbos from the same batch on other cars and they both easily produce 2 bar boost.
You can always take the turbine and compressor covers off of the turbo and inspect the turbo for damage, but I doubt you will find anything.
The turbo also has warranty, so if you are convinced there is a problem with it, send it back to me, and I will have it looked at.

I have a few ideas that you can try - I suspect some incorrect N75 plumbing (the turbos have different inlets), so probably you have a custom turbo to MAF hose or metal piece made up and maybe that is the problem.

Hey Dmitri didn't hear from you for a while Wassup?
I am convinced 99.9% that the problem is from the engine.
That's why I've rebuilt it with the help of pasbogdan.
If I wasn't convinced that the engine is to blame I wouldn't have spent so much money on it.

I have a question, pasbogdan is saying that with the new parts I have installed on the engine, it can safely run a 600 hp setup (of course with other turbo). Is that correct?

[vcosmin]

You beed some more stuff, but nothing major.

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[vcosmin]

Also you will need to bring dimitri in Romania :thumbup:

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[bartolomeus]

Also you will need to bring dimitri in Romania :thumbup:

Sent from my GT-I9000 using Tapatalk 2

He's most welcomed!

[pasbogdan]

Btw bart, I have two turbos from the same batch on other cars and they both easily produce 2 bar boost.
You can always take the turbine and compressor covers off of the turbo and inspect the turbo for damage, but I doubt you will find anything.
The turbo also has warranty, so if you are convinced there is a problem with it, send it back to me, and I will have it looked at.

I have a few ideas that you can try - I suspect some incorrect N75 plumbing (the turbos have different inlets), so probably you have a custom turbo to MAF hose or metal piece made up and maybe that is the problem.

Compresor-silicon reducer-metal tube-stock hose to maf.This is how the system was and no leak.N75 was routed ok,working mechanicand electric,triple cecked.Bypass valve airtight,routed ok.Wastegate cecked,airtight,stock spring.That had a problem.The banjo on the inlet in lower chamber of wg had a kind of one way valve in it was n75 to wg way I replaced that with aan banjo free flow.With that banjo i imagine car would not made more than spring boost even before turbo replacement and you can figure out why.But that did not solved low boost.Camshafts align ok,camshafts with crank align ok.
Changed maf to one that worked on my car.
Compresion test got something like 12-11-10-9-8 bar,semihot engine.I put a stock k24 on car with your soft/stock injectors and did what it was supposed to do.So dismantled engine.
Found 0.08 mm wear at tdc and 0.8mm ring gap.Not so bad,but not ok for not stock turbo.Found some valves leaking.Found both knock sensors a little cracked.Found some hidralulic tappets gone(maybe noise was taken as a knock? but big turbo did not boost even with wg disconected).Now it is allmost finished.Need to put it in the car,make coil conversion and mount wideband.And see what will do.Log some afr,timing..
Turbine and compressor blades look fine from outside.I did not opened it.Maybe we will have luck.
The car got 1,4 bar max at 4000-4200 rpm and no more to redline.With stock k24 7000 it got 1.5 bar at 2800-3000 and going to 1 bar to redline.So no boost leak,also cecked to 1.5 bar with compressed air.Rs2 style em seems not ok.Collectors are offset in some areas with 4mm.Could that keep big turbo from not spinning?
Can timing(spark)cause so low boost?I did not lok any timing and i feel sorry for that.
Or reducing inlet in compressor to stock dimension for using stock hose to maf can influence so much?

Best regards,

[prj]

N75 was routed ok,working mechanicand electric,triple cecked.

If you still get the problem, then try to put the long end of N75 to atmosphere.

but big turbo did not boost even with wg disconnected).

This worries me though.
Orientation of dump valve maybe something to check, if it is pushing it open...

Rs2 style em seems not ok.Collectors are offset in some areas with 4mm.Could that keep big turbo from not spinning?

Don't think so.

Can timing(spark)cause so low boost?I did not lok any timing and i feel sorry for that.

Nah, it won't...

Or reducing inlet in compressor to stock dimension for using stock hose to maf can influence so much?

Try to put some metal pipe inside the inlet hose to make 100% that it is not collapsing.

[pasbogdan]

Dump valve orientation cecked,also boost leak done with it disconnected from turbo to maf hose to see if it holds.
The hose from turbo to maf worries me.Where it makes the turn to uppwards it is gets a little forced because of the new compressor position.Will add some metal in it or make another system.
Please give me a reference of boost profile with this turbo,maybe a log with iat to be sure we compare something almost identical.
Best regards,

[FCP-ENGINEERING]

Hx35 not big turbo 400hp goal. In 4000rpm you must have full boost. Low boost , will be problem with wastegate vacum conection or boost regulator. I think your turbo now makes pressure about 0.5-0.7bar only right?