All Things Mk5 > Members Rides
White "Lion" Cupra - DSG converted track car
teo_parvu:
I've just spoke with my tuner who told me that he has 4 damaged Mahle motorsport pistons from different engines. They are not much better than BWJ semiforged Mahle and that he recommends JE but with service every 20k km.
Also he said that my engine should be ok for TTE480 without forged rods and pistons, and that I shouldn't worry. :scared:
In case of a failure most probably will be a piston, not a rod so there will be not much damage and that we can use 83mm pistons then. :surprised:
Told me that my problem now will be fueling and that I should get a 165 bar valve.
teo_parvu:
After some ... :thinking: I've decided to be on the safe side and order that kit from Bar-Tek containing:
Mahle forged pistons 83mm bore and 9:1 CR
Their own Bar-Tek I Beam light rods - they say up to 1000hp
ACL Motorsport Bearings
ARP 2000 3/8 inches Connection Bolts
I hope it's the right choice because this will be a big hole on the budget, I will have to do some honing for the new pistons and revise the top side of the engine too. I already had some misfire on my last run and I suspect a valve. I will have to open the cylinder head anyway.
teo_parvu:
Because I'll have to revise the cylinder head anyway, at least I'll do it right. I ordered the ARP 2.0 TFSI Head Stud Kit:
After 400+ bhp there is a risk of stretching the head bolts and lifting the top.
pudding:
Mahle are the best pistons available :happy2: I suspect if your tuner has seen bad ones, it was probably because of a bad tune, or other factors. I would take Wossner as a second choice and then Wiseco. I don't like JE. I've used them in the past and they were sloppy in the cylinders (bad piston slap when cold) and one of them scratched a bore in my VR6 and basically ended that block :doh:
I ran Wossner in my VR6 turbo for 60K miles with a lot of boost. After that mileage they were spotless, the coating was still on the skirts. Great pistons.
The OEM pistons are a special pressure casting with good quality material. They can take a lot of abuse but do give up eventually. The main advantage of 4032 and 2618 piston alloys is the material is denser than cast, so can handle heavier loads before cracking. Usually with aftermarket pistons, you will see a thicker top ring landing and reinforcements in the gudgeon pin area, which adds even more strength. And they are lighter :happy2: You won't go wrong with Mahle. They are OEM supplier to just about every high performance car maker out there :happy2:
ARP head bolts, great move! Get some ARP rod bolts as well, although they might come with the Bar-Tek kit? I do like Bar-Tek, again, you can't go wrong with those guys :happy2:
9:1 is a little low for the compression. You may find engine braking reduces, starting takes a little longer and off boost response suffers a little, but you may not notice these things in a race car :smiley: But the up side is you can run more boost safely and also make up the compression loss with more ignition timing :happy2:
teo_parvu:
Hey, really glad to read this. I'm happy then, I've made the right decision. VR6 turbo, WOOOW...better cars, better times :drool:
Was concern a bit about this operation, never rebuilt an engine, at least not the main block. The only repaired part was the cylinder head when the variator chain broke.
Got ARP rod bolts as well, you're right they come with the kit. :smiley:
I've spoke with Bartek Bartoszewicz from Bar-Tek, who, I must mention, is a really helpful guy, he is responding my emails within minutes even late in the evening. He said that 9:1 compression is when using their race gasket. I will use a new OEM gasket. Mahle PowerPak+ pistons are really 9.3:1, which I hope it's good.
These PowerPak Plus pistons for TFSI are forged from M142 alloy which combines the strength of 2618 and the oem behaviour of 4032. They are triple coated first with a phosphate dry film to protect the pin bores from galling. Next, MAHLE’s proprietary anti-friction Grafal is applied to the skirts. Finally, to withstand the higher cylinder temperatures and pressures, the top ring grooves are hard anodized to protect against micro-welding.
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