300 tdi engine tweeks in a 101

[dangerous doug]

Not ignoring basic thermal dynamics at all, but in real world situations a bigger diameter exhaust 99% decreases turbo spool up times and EGT's.

We are talking about a 300tdi, it isnt a finely tuned race engine - by a very very long way.

What do you want out of your engine? more throttle response from idle, more top end or what?

Air filter postion and intake length make a HUGE difference and are easily modified.

I agree with this, the length and diameter of the pipe is more crucial on a NA engine where pressure wave scavenging is important, surely on a turbo car you need to get it out of the turbo as fast as possible as any restriction would choke up the turbine making work less efficiently and making it hotter

[Snagger]

But this is my point - bigger diameter pipes don't remove the exhaust gas faster, they do it slower. It's very simple thermodynamics. There is a diameter that gives the best compromise between exhaust gas pressure and velocity for a given mass of gas, and like I said, if you reduce the velocity, you increase the pressure. A tuned engine will shift a bit more gas than the standard version of that engine, so yes, a bigger pipe will help, but it doesn't shift a lot more gas, so you mustn't increase the diameter much either or you will suffer a performance penalty. The manufacturers don't chose exhaust diameters by accident.

[buff]

a VGT could help with the low down torque.

Ive been thinking about a VGT or VNT, nut have read that it could put strain on the bottom end. And that its not a fix for everything.

[hangover]

Ive been thinking about a VGT or VNT, nut have read that it could put strain on the bottom end. And that its not a fix for everything.

TDI bottom end is pretty stout , with a VNT you dont need to stress the motor as the turbo just adjusts to requirement.

[buff]

Finally bit the bullet and fitted a double thickness allisport inter cooler. Plumbed it all in and took it for a spin, it certainly pulled better, but felt gutless after half throttle. so i turned the fuel pin so the big step is now at the front of the pump, it was a little better. So i gave the fuel screw a turn and watched the EGT's go through the roof , currently turning it back a little at a time to see if it improves. Have standard 300tdi paper filter at present that's only a couple of months old . Not sure to try something like an ITG or Pipercross filter instead or go up to 3" on the exhaust diameter.