Thread: 300 TDi Torque/Power Curves

Maybe if you spun a hiclone really fast it could help.

Pretty much any T28 turbo will work to compound the 300tdi. But the bigger exhaust housing the better. Set them for ~10psi and wind the original turbo wastegate in a bit. Should give you a solid 20psi by ~1800rpm in all conditions and even at high altitudes should provide 20psi by 2000rpm.
Can be wound up to over 30psi. But that would be asking for trouble unless you have a lot of supporting modifications.

The turbo I have used for my recent calcs is a bastard T25 with an odd turbine. It's close to useless for more performnace in the original application but close to perfect for this one.
Hopefully I'll get a chance to try it one day. I now have a 300tdi to play with.

Either setup will trump a VNT turbo for performance at all operating points. Not to mention reliability and cost.

I really don't think you'd want to exceed 20psi in a Tdi unless you O ring the head (even with a MLS head gasket) and I'd be worried about bore distortion and the bottom end too. It's only a cast crank and I have no idea how strong the rods are either.

Maybe an HS2.8 crank/rod assembly ?

Originally Posted by rick130

I really don't think you'd want to exceed 20psi in a Tdi unless you O ring the head (even with a MLS head gasket) and I'd be worried about bore distortion and the bottom end too. It's only a cast crank and I have no idea how strong the rods are either.

Maybe an HS2.8 crank/rod assembly ?

are they the same bore centres?

Originally Posted by rick130

I really don't think you'd want to exceed 20psi in a Tdi unless you O ring the head (even with a MLS head gasket) and I'd be worried about bore distortion and the bottom end too. It's only a cast crank and I have no idea how strong the rods are either.

Maybe an HS2.8 crank/rod assembly ?

The great thing about a compound set is you can run whatever max boost you want. But you get boost sooner, a wider operating range and excellent altitude compensation.
Except this turbo I may play which which is free-floating. I don't know if it'll drop enough boost just with the small turbo wastegate opening. Can always drop the fuel until it's safe.

I'm of the opinion that it's not boost that causes problems. It's the combination of boost, fuel and injection timing.
Retard the injection timing a little (or simply don't advance it from factory specs) and your peak combustion pressures drop significantly.

What's the story with these head bolts? John (Bush65) ran slightly more tension on his. Worryingly it looks like I may have a spare rattling around in the back of this vehicle. I could put it inside a steel sleeve and keep cranking up the torque until I measure permanent stretch.

Originally Posted by uninformed

are they the same bore centres?

Can you check next time you have yours apart?







Sorry, that was low.

Originally Posted by uninformed

are they the same bore centres?

Yep, and I'm pretty sure the 3.0l common rail version is the same.

Damned if I know how they punched that block out to 3.0l ?

Originally Posted by Dougal

Can you check next time you have yours apart?







Sorry, that was low.

Oooh, Serg has enough anxiety about that bloody engine now, don't start !

Originally Posted by Dougal

The great thing about a compound set is you can run whatever max boost you want. But you get boost sooner, a wider operating range and excellent altitude compensation.
Except this turbo I may play which which is free-floating. I don't know if it'll drop enough boost just with the small turbo wastegate opening. Can always drop the fuel until it's safe.

I'm of the opinion that it's not boost that causes problems. It's the combination of boost, fuel and injection timing.
Retard the injection timing a little (or simply don't advance it from factory specs) and your peak combustion pressures drop significantly.

What's the story with these head bolts? John (Bush65) ran slightly more tension on his. Worryingly it looks like I may have a spare rattling around in the back of this vehicle. I could put it inside a steel sleeve and keep cranking up the torque until I measure permanent stretch.

I think you're right it's more a combustion pressure issue, but they do run better with more advance, they need to rattle to go well !

John cranked a few extra degrees into his bolts.
They aren't TTY, although everyone thinks they are. I'll be using ARP bolt lube when I do my head, just to make things more consistent.
ARP will make a up a stud kit, but it costs $$$, and whilst I'm not as down on the Tdi as John, I think he's right when he said it starts to become the same as polishing a turd.