The Project Pad

So this was posted over on quattroworld. bunch of NOS audi parts. Among those parts I see what they call a 2.0 5 cyl crank and none of the engine codes match what I'm used to.
I've never really seen a 2.0 crank discussed before. I know they existed in the european market, but nobody has discussed whether it would be beneficial in a performance setup. Would this benefit anybody attempting to rev to the moon?
http://shop.autewo.de/Neuteile-AUDI-VW- ... 0498fd9d/q

pilihp2 wrote:So this was posted over on quattroworld. bunch of NOS audi parts. Among those parts I see what they call a 2.0 5 cyl crank and none of the engine codes match what I'm used to.
I've never really seen a 2.0 crank discussed before. I know they existed in the european market, but nobody has discussed whether it would be beneficial in a performance setup. Would this benefit anybody attempting to rev to the moon?
http://shop.autewo.de/Neuteile-AUDI-VW- ... 0498fd9d/q

This crank was found in Italian market only engines. Engine code NM for NA motors.

Chris (loxx)?

Yes, the benefit in a performance application is a shorter stroke, less rod angle, which means less stress on the motor at higher revs. AudiSport used to do this back in the day on their race cars. I can't say if this crank will fit our 5cyl blocks though

could it be a 2.0 diesel crank? wasnt there a 2.0td 5 cylinder audi engine?

Could be interesting in a tall deck block. I'd guess that it fits but could not say for sure.

Or, just build an 07K.

EDIGREG wrote:Yes, the benefit in a performance application is a shorter stroke, less rod angle, which means less stress on the motor at higher revs. AudiSport used to do this back in the day on their race cars. I can't say if this crank will fit our 5cyl blocks though

I think loxx is using this crank. They do fit the 5 cylinder blocks.
The Italian AAN uses this crank IIRC. Italian AAN engines are 2.0.

I thought he was just using the normal crank in a tall block. But I don't know.

Would be too short for tall deck. 86.4 in tall deck will be more than rev-happy. Even 92.8 would rev fine, maybe not 9k+, but healthy 8-8.5k np.

AudiSport used following combos although not sure what block heights they used.

Bore x stroke
79.5 x 85 mm (A1, SportQ, SQ S1, S1 PP, TransAm 200)
79.5 x 86.4 mm (200 q rally)
81 x 85 mm (IMSA 90q)

81 x 86.4 mm (V8 DTM)

85 x 88.1 mm (80 Competition, A4 Supertouring) - these 4 cyl engines had some real trick heads and port work btw to produce 310+chp from 2L motors.

pilihp2 wrote:So this was posted over on quattroworld. bunch of NOS audi parts. Among those parts I see what they call a 2.0 5 cyl crank and none of the engine codes match what I'm used to.
I've never really seen a 2.0 crank discussed before. I know they existed in the european market, but nobody has discussed whether it would be beneficial in a performance setup. Would this benefit anybody attempting to rev to the moon?
http://shop.autewo.de/Neuteile-AUDI-VW- ... 0498fd9d/q

I have quite a few js coded engines. They are 2.0l, kjet 20v, 85kw

EDIGREG wrote:Yes, the benefit in a performance application is a shorter stroke, less rod angle, which means less stress on the motor at higher revs. AudiSport used to do this back in the day on their race cars. I can't say if this crank will fit our 5cyl blocks though

(ed. note: I wanted to reply to this back when it was "fresh" but was having login issues)

Let's chew on a few things. Longer strokes make the cranks weaker because of reduced overlap between the crank and rod journals. The crank becomes less of a solid rod and more of a big bendy stick. This makes the internal harmonics happen at lower frequencies, meaning the critical RPM where crank torsional harmonics want to tear everything apart is lowered.

One way to help combat this is better dampers on the front and nowadays rear of the engine. That's not a cure-all but it is an effective band-aid.

Now, in the Miata world, people have found that if you put a lightweight crank pulley on a turbo engine, you destroy oil pumps at a rapid rate. With a proper damper on the front, the oil pumps stop failing. Hypothesis: Torsional harmoncs are beating the oil pump up.

Now... what problems do the Audi fives have over 8000rpm with the oil pump? Hmm? I don't think this is an oil pump issue, I think it is a crank harmonics issue.

So, how much more RPM can you get with a stiffer, shorter stroke crank?

Dahlback was a fan of destroking engines for more power, hmm? Maybe this is why.

quattro wrote:
I have quite a few js coded engines. They are 2.0l, kjet 20v, 85kw

Yep, this is what my 80 quattro (Sparquattro) has in it.. 2.0l 115hp

Sorry Pete I didn't see your reply earlier.

Now... what problems do the Audi fives have over 8000rpm with the oil pump? Hmm? I don't think this is an oil pump issue, I think it is a crank harmonics issue.

The main issue with running the factory oil pump at higher RPMs is oil cavitation, not physical oil pump failure. At least I have not seen evidence of a pump failure due to RPM.

Anyone know what the rev limiter was set to on the S1? Of course they were running dry sump systems, but curious what they revved those motors to.

Okay, so it is cavitation eating the gears and not the gears shattering?

Cavitation can be fixed, or at least mitigated.

Noisy Cricket wrote:Okay, so it is cavitation eating the gears and not the gears shattering?

Cavitation can be fixed, or at least mitigated.

I think ed means its not a problem of pump component failure but more a problem of the volume and speed at which it pumps?

Cavitation is happening in the oil itself so basically the oil is getting aerated because of the speed of the pump I think.

Right... and you can help pump caviation to some degree by reducing restrictions on the inlet side of the pump, and in extreme cases by reprofiling the lobes slightly or allowing oil to bleed back to the inlet side of the gears... I have not had a 5cyl pump apart so I don't see what the pump flow problem is here specifically. I was under the assumption that the gears were being rattled apart, so I figured to just keep the RPM down and worry about other things. Keeping RPM down is also a cheap way to spec an engine

The 13B in my Mazda has had quite extensive work done to the inlet side of the oil system with respect to flow, and the pump has been altered, and a cross-channel bleed added... and I am using the smallest of the pumps Mazda made because Mazda increased capacity by adding width, and this makes cavitation more likely. Most people go with the bigger pump to solve top end oil pressure issues, I have long felt that this is a step backwards. My engine holds 90psi oil pressure from 4000rpm to 10,000rpm with none of the "high RPM pressure sag" that many people note with wet-sump rotaries.

Heck, even Mazda seems to have known this, when they increased oil pump capacity for the twin turbo FD, they redesigned the pump to have inlets on both ends instead of expecting it all to get pulled through one end like the previous designs. The RX-8 was reverted to the narrowest pump of the modern (pre-FD) type, despite/because of having the highest redline.