Its not the diameter of the hole at the back of the turbo thats the restriction, its the total constriction of the stupid cast piece of crap thats the problem- with the bends put into it drop the diameter to about 1.5-2" total.gotoy wrote:A quote from Ferrit in another thread, transferred here.ferrit wrote:Dump Pipe:
The stock cast dump pipe off the back of the turbo is REALLY restrictive. As in taking a leaf blower and putting a garden hose adaptor on it levels of restrictive. It hinders the turbo flow, so it takes longer for the turbo to spool up and it doesnt spool up as low in the rev range. Theres a few options to fix it- EngTek make a dump pipe for a KZN130, but theyre asking $500+ for one now i believe, and its probably not suitable for your application- Surfs are all IFS and the off the shelf dump pipes are designed for that, not solid axles.
When I had the intercooler added a few weeks back I asked the shop to do the dump pipe too. This shop is more of a track car plac eand has recently gone into doing hilux, d-max type vehicles...just for some history.
When I collected the vehicle the dump pipe was still stock. The tuner's point was the output size of the turbo itself is too smal to warrant installing a 3" dump pipe. So he advised keeping the original dump pipe size as any bigger would not be benificial due to the turbo output size.
However, I always read on forums that the turbo dump pipe is an improvement.
This tuning shop has done hilux vigo and d-max dump pipes as the actual turbo outlet is big.
A friend on mine is checking his spare 1kz-te turbo so I can tell you the size soon, of the output hole.
Putting a 3" dump pipe and exhaust on it has made the 1KZ-TE in the hilux a hell of a lot more responsive than the apparently higher tuned 1KZ-TE in dads prado 90 series.