Thread: 25 PSI boost on 300Tdi

Originally Posted by slug_burner

Would this baby get up to 25 psi? I note that there is a thread where one with these numbers was fitted to a TD5.

Yes. But it's significantly smaller than the turbos most are fitting. The ZD30 nissan which they bolt to only delivers 110kw. It's also quite expensive.

Originally Posted by slug_burner

Would this baby get up to 25 psi? I note that there is a thread where one with these numbers was fitted to a TD5.

It is a baby (I have a couple of them), that is why (52mm compressor impeller too small) it is not suitable for 25 psi.

With centrifugal compressors:
pressure is related to tip speed squared (function of exducer diameter and rpm),
air flow rate is related to inducer diameter,
efficiency is related to trim

Fitted to a 300Tdi engine, the GT2556V turbo is ok for around 22psi, GT2559V is ok for 25psi.

The GT2052V from a 3.0 litre Nissan is not going to be efficient at either of those boost pressures. It will produce more boost at low engine rpm, which would improve response for normal driving if you don't need better performance pulling a load at highway speeds.

BTW for Garrett GT series turbos, the first 2 numbers (following GT) give turbine family (small number = small turbine), last 2 numbers give compressor impeller diameter in mm, and V is for VGT/VNT type).

Stock 300Tdi turbo (T250-04) has a 54mm compressor impeller and is ok for 18psi, but Garrett did make improvements to their compressor impellers from T to GT series - improved again with the new GTX series to catch up with Borg Warner's extended tip technology.

Edit: Compressor efficiency tells how much heat is added to the air while compressing it. When the pressure increases to an inefficient range the temperature is increasing much more than air flow - what is happening with the impeller and air is similar to spinning tyres when traction is lost (no forward movement but engine power is converted to heat at the tyre contact).

Edit 2: Be aware, that turbo has a vacuum actuator that you would need to modified to operate on a 300Tdi, also lube fittings are completely different to 300Tdi, and it wont bolt to a 300tdi manifold. But don't let this stop you.

Originally Posted by Bush65

Stock 300Tdi turbo (T250-04) has a 54mm compressor impeller and is ok for 18psi, but Garrett did make improvements to their compressor impellers from T to GT series - improved again with the new GTX series to catch up with Borg Warner's extended tip technology.

Are you sure about the size of the stock turbo compressor John? Reason I ask is the 300tdi turbos I have seen apart looked significantly smaller than the 51mm compressor in my T25. But I haven't actually measured them.

What sort of power are you guys getting from the Disco TDi with the modified boost?

A few years ago coming up Tamworth range in Bro in laws Dico V8, a TDi passed us like we were standing still lol!

Ex mine worker here, patrols/Cruisers we used for surface vehicles, both too soft for underground, Kowari special build, were used underground, 3.9l Cummins 4cyl NA, 400nm+, toughest thing ive seen, only issues was breaking axles regularly, 3rd gear low in the Kowari was about equal to 1st low in Nissan or Toyota.

Cruisers we had, 70% aprox did gearboxes at around 130k, plenty of diff failures and transfer case lock-ups (vehicles used in 4x4 95% of the time)
Sold off at auction after 6mths, Patrols were generally trouble free although we did not have as many.

Managers had Disco V8s, only big issue with them was dust from rear door seals, but in saying that they were not used very often in rough conditions.

Originally Posted by Fish78

What sort of power are you guys getting from the Disco TDi with the modified boost?

A few years ago coming up Tamworth range in Bro in laws Dico V8, a TDi passed us like we were standing still lol!

Ex mine worker here, patrols/Cruisers we used for surface vehicles, both too soft for underground, Kowari special build, were used underground, 3.9l Cummins 4cyl NA, 400nm+, toughest thing ive seen, only issues was breaking axles regularly, 3rd gear low in the Kowari was about equal to 1st low in Nissan or Toyota.

Cruisers we had, 70% aprox did gearboxes at around 130k, plenty of diff failures and transfer case lock-ups (vehicles used in 4x4 95% of the time)
Sold off at auction after 6mths, Patrols were generally trouble free although we did not have as many.

Managers had Disco V8s, only big issue with them was dust from rear door seals, but in saying that they were not used very often in rough conditions.

The mines here use SMV driftrunners. Powered by perkins.

I just googled them, interesting vehicles, how do they go?.


The Kowari stuff was ok,rough as guts lol, but very tough.
Kowari Motors

Originally Posted by Fish78

I just googled them, interesting vehicles, how do they go?.


The Kowari stuff was ok,rough as guts lol, but very tough.
Kowari Motors

They seem very good, I've ridden on several but I'm not licensed to drive them. Very heavy and have massive axles underneath. Coil sprung and ride well for what they are.

Coil springs..gettin a bit technical mate, the Kowaris have massive leafpacks, i don think the guys that make them understand what watermelon size rocks make your back feel like when u hit them fairly hard lol, i would have almost killed for coils.