[TrevHead62]

Well I lashed out and bought a S.S 3" Domin8tor exhaust with a hiflow cat and muffler. Here's hoping it will provide me with better performance and economy. I noticed the dump pipe has two tapping points for the EGT probe and the one that suits my thread is in the wrong spot... bugger. I'm worried that if I fit a reducing bush, the probe will not penetrate the exhaust stream the same amount as it is now and I'll end up seeing a bigger drop in EGTs than it really is. On the flip side, if I use the the one that matches, I'll have to butcher the heat shield. Decisions, decisions.
Either way, I'm looking forward to some nice gains in power, torque and fuel economy and I imagine I'll be back to square one with having to re-adjust the Dawes and needle valve.

 

[geeyoutoo]

Great, before you fit it get on a flat stretch of road and do some 80-100k ET's and 90-110k et's, you can lock the tranny on an auto, do that with what you have and then after you fit it go to the same stretch of road and do it again, this will give you a true indication of what actual gains you get. makes you feel good when you look at the stop watch and see a good gain. This is what I use as my cheap dyno after playing.

 

[South]

One is EGT and the other is AFR... furthest away is AFR.

 

[TrevHead62]

Thanks South, I'll be sure to use the one closest to the Turbo outlet flange. I don't think 5mm less probe is going to make much difference in the temps.
Thanks for the tip GuII. I have a testing section of road which has a few straight sections and lots of hills of different aspects. I've got EGT data pre NADS, Pre-EGR block etc along these roads so I'm going to run the tests again after fitting the new system.
With torque converter lockup in top gear she's just over 2000rpm at 100kph and the EGTs sit around 250 to 300. Boost varies between 7 and 10psi. If I reduce speed to around 95kph and the revs drop to less than 2000rpm, the EGT creeps up to 350 to 400 with boost about the same.
I'm hoping the new system will help EGTs in the 95 to 100 kph range.

 

[geeyoutoo]

When you fit the EGT, the senor needs to go as close to the centre of flow as possible to maintain accuracy.

 

[TrevHead62]

Wiil do. The quality looks pretty good so I assume the nut for EGT sensor has been welded on square!

 

[TrevHead62]

Fitted the 3" system today. A bit of mucking around refitting the EGT sensor (heatshield had to be cut more), a couple of adjustments to line it all up so there' would be no clashes, and a bit of bark off my knuckles ( I always seem to do that lol). it was all done in few hours.
Taking it for a spin, straight away I could tell the engine was breathing a lot better. EGTs are down by about 40 to 50 degC at cruising speeds of 90, 100 and 110 kph. I ended up opening the needle valve a quarter of a turn more to help smooth out the boost pressure when hits max (set to 16psi) when the tranny kicks back into third, e.g when starting to climb a hill). Under load, it has tendancy to drop sharply from 15/16 down to 10psi and continues to jump up and down like that a few times before settling down at 16. Opening the needle valve has helped a bit so I guess I'll be tweaking the needle valve a bit more as time goes on to get it right.
I have the VNT stop screwed in half a turn, do you think I might need to screw it in a tab more to help stop this boost bounce?