Let the tinkering continue.....

[Greg Roles]

not big enough!!!

I've no idea off the top of my head, it's a Garrett VNT17. I assume you're talking exhaust?

[oracle1]

yes wondering about the change in diameter from turbo to 3.5 exhaust

[Greg Roles]

Ways off actually having to worry about specifics, much prep work to do yet, and the exhaust may just end up coming off a different turbo anyhoo. GT40 currently looking good.

[POLARBEAR666]

P-l-e-n-t-y of room. This is a nice exhaust, Miltek I believe.

Mine on the right is better. Chrome tips from VY commodore left hand side.

Secondly, you want to go from Big exhaust to small on turbo cars in order to maintain heat in the exhaust which causes the gases to flow faster, which reduces back pressure. As the gas cools it becomes more dense and needs less room. So you want to go down in size towards the end so that the gas stays reasonably hot and fast and sucks the gases out of the motor, rather than cooling in a HUGE pipe and slowing down.
Think of what happens when fast drivers are confronted with a slow driver in right hand lane and imagine that in your exhaust at the end.

Most WRC cars are 2.5" out the back fully heat wrapped etc

Also 3 inch turbo back exhausts support 500-600hp on turbo petrols... not sure about diesel but i bet 3 inch is plenty.

[Greg Roles]

hmmm, good points, I agree with the theory of that. You do have to factor in the diesels huge gas flows, and the fact I will build the exhaust to match what I end up doing to the other side PSI and power adder wise.....plenty of time to postulate given the expense of all that!!

[Greg Roles]

OK, back to reality, and what I can currently afford...I'm still messing with the intercooler spray controller, need to drive it in traffic and really get it hot to set it up right, the controller box works off a thermo-probe in the intercooler and decides when and how long to spray, which is very cool.

My Provent into the exhaust is working well, and to be honest, if it's not effectively getting burnt, it's hard to smell it in traffic at idle with all the windows down. Perhaps I'm just smoking out the guy behind, but when it was total loss, if the wind was blowing back towards the car, the smell was overpowering. Now it just seems like typical, healthy, traffic pollution. I'll still put it up higher in time, but to get to the bottom of the DPF area you really needs to drop the axle, which is right in the way. I think at delete time it'll happen!

My next experiment on my poor little car is to hobble the EGR circuit. I've contacted Wayne Schmidt from VW vortex who machines up the following O2 sensor adaptors, which effectively remove the lambda probe from the exhaust flow, so it basically misses the fact there's too much oxygen in the mix, and is happy that the EGR circuit is blocked, or hopefully, when totally removed. I understand it's function, and I'll be raising my NO emissions for the time being, but the next steps are all about forcing more air in, cooling the inlet charge even further, and then getting a custom tune to suit. All of which lower my EGT's and thus lower my NO emissions.

The adaptor would be easy to make, but given how many people use this guy's adaptor, and have no problems, for once I'll happily pay for an item over fabbing up my own. They cost $44 us shipped, and the next batch is a few weeks off being made, so perhaps a group buy if anyone else is interested. You would really need an EGT gauge like I now have to keep an eye on your turbo temps, as without EGR they are going to rise at max efforts.



I'll chuck this on, block the EGR and see what happens. If it works as expected, the next step will be to remove as much of the EGR circuit as possible ( I'm losing potential turbo spinning exhaust pressure afterall! ) and then to look into replacing the EGR mechanism and throttle flap in one move.

I like that groovy looking Allard EGR delete kit, but won't need it given the fact I'm replacing the entire inlet plumbing anyhow. The throttle flap is important at shutdown, and should a turbo ever go kapow, to prevent run away. I'm thinking that QTP 2.5" exhaust cutout I no longer need for my DPF bypass idea is looking good for a ignition controlled flap, for shutdown. Hmmmmm......

[250 downunder]

My muffler delete on wife's Golf Mk5 TDI. Just what every 60 year old grandmother needs! 2.5" straight out the back - no noticeable increase in noise levels but she claims much better response down low. Don't ask about the small black pipe entering just past the rear axle - it's a dummy!!

[Greg Roles]

Came up with a nice way to seal my Modshack in today, and have to save up for a carbon fibre kit from carbonmods.com. Thought about taking a scoop from the passenger Xennon washer garnish, which I reckon would look awesome, but FAR easier to stick with the stock inlet, and just seal it to the front of the modshack. If this turns out I may have a crack at some washer scoops, but that's a mission!

Next works in progress are the windscreen wash water level sensor kit, a turbo timer to run the radiator fans and my QTP throttle flap on ignition off, and a temp / wind switch to set off a Nascar brake duct blower to keep the engine bay air moving at the lights. Had a big chat with the old man on fathers day, handy he's an electronics guru, and we nutted out how to run all these ideas.





Jaycar here I come!

The temp probes are back in, one on top of the MAF sensor plug checking under bonnet temps, and the other oi now firmly wedged in the middle of my intercooler fins. Should be interesting, although it's hardly hot enough to get real, summer traffic temps.

[Greg Roles]

Interesting temp readings thus far.

My EGT's, at least post turbo are amazingly low. You need to drive for a while and be on boost to get it hot, and cruisy suburban driving see's my gauge, albeit chinese, showing 150 degrees or less. Intertesting how you need to drive to get it hot, and thus what you have to do to actually damage your turbo.

The same thing I noticed with my actual inlet temps pre and post intercooler are happening again with the underbody temps, and the intercooler itself to some extent. When you get the car up to operating temp and are driving along, temps stay about "ambient", but 2 mins at the lights see's the underbonnet rise 10-15 degrees even at this time of year. Give it a boot and get the intercooler temps up, and it takes a while for that to come back down. The intercooler really is a heatsink though, takes a bit to actually start getting hot, then a while to bleed that heat back off.

Underbonnet is scary. Park the car at the local store for 2 mins, and it's headed to well over 50 degrees under there. Come back to your car 3 hours later and it's still reading high 40's, and despite driving for a few minutes, quickly rises back up at the lights.

Once the engine, inlet, intercooler etc get's hot, it takes ages comparitively to get it back down, but don't get it hot in the first place, and the temps stay withing degrees of the MFD "ambient".

I believe any measure to stop things getting hot in the first place will give the greatest return, and if anyone has a open or unshielded pod of any sort in their engine bay, once you stop, that first lungfull on green is going to be amazingly hot, and you've just given up HP for sure.

[Preen59]

All very interesting. Have you thought about allowing the heat to escape more easily?? (Via the rear of the bonnet perhaps).

It's to some extent unavoidable that you will get heat sink, but you have to remove air to let more in, so the way i see it, if you allow more hot air to escape out the top at the back, you will allow more cool air in at the bottom in the front..

I've been enjoying reading your write ups. I think i'll probably go for a total loss crank case breather setup in the near future if it proves a viable option. I'm also thinking about removing the rear muffler box too (On the Caddy we're talking about here..).