Td5 wastegate

**OffTrack** · 12th February 2013, 08:19 PM

Originally Posted by bigkevg

Getting waaaaaay tooooo technical for me now

...no,I do understand but no practical experience in application to discuss the point

I just understand that standard D2s do manifolds from high egt when pushed. Increase by remap or boost MUST make this worse, so bigger intercooler is necessary to reduce or equalize the equation.

The update model may be sufficient...obviously it is better than standard, but aftermarket (quality one not cheap) intercooler should be even better.

On a 45degree day, going up that long steep hill, towing ......I'd rather be going with the traffic than holding it up....and not rooting my car at the same time

I think Dougals point is even small gains have a reciprocal benefit, a small decrease in egt equals better power and efficiency and is kinder on the motor.

So, I have bought the aftermarket cooler and will fit very soon. Rather spend a few extra dollars for what hopefully will be a better long term return

It's only money

....on to that Ashcroft stuff next Paul

I think what dougal is saying is that the increased air density you get from increasing boost reduces EGTs regardless of whether you have an intercooler upgrade or not. Adding a more efficient intercooler increases air density which further helps reduce EGTs.

So in a nutshell:

• increasing boost = lower EGTs
• adding more efficient intercooler = lower EGTs
• remapping = increased EGTs

cheers
Paul

**Dougal** · 13th February 2013, 05:55 AM

Originally Posted by OffTrack

I think what dougal is saying is that the increased air density you get from increasing boost reduces EGTs regardless of whether you have an intercooler upgrade or not. Adding a more efficient intercooler increases air density which further helps reduce EGTs.

So in a nutshell:

• increasing boost = lower EGTs
• adding more efficient intercooler = lower EGTs
• remapping = increased EGTs

cheers
Paul

That's exactly it.

BTW, lower EGT isn't always good. Your turbo is more efficient with higher exhuast temperatures. This has a direct effect on your fuel economy.

EGT's just need to be within safe limits, from there to push them lower needs more boost which takes power to generate.

**OffTrack** · 13th February 2013, 07:00 AM

Strangy has posted up some EGT comparisons with chip and intercooler here:

http://www.aulro.com/afvb/technical-...alive-i-c.html

This shows clearly how a chipped ECU substantially increases EGT's. Adding an intercooler drops the EGT, but when boost is upped to 1.4bar/20psi the temperature drop is larger than that caused by the intercooler.
Even with the performance I.C. EGT's are still higher than standard and the combination of chipped ECU and performance IC still results in excessively high EGT's unless boost is increased.

I've put Strangy's results into a table to make it clearer:

The temp drops listed are relative to the previous line, so the drop from boost increase is how much difference from chipped ecu + performance IC.

cheers
Paul

**Dougal** · 13th February 2013, 07:20 AM

All of those chips are making the engine run far too hot and rich.

They all need a lot more boost and intercooling to be safe. Especially under sustained load.

**OffTrack** · 13th February 2013, 08:02 AM

Originally Posted by Dougal

All of those chips are making the engine run far too hot and rich.

They all need a lot more boost and intercooling to be safe. Especially under sustained load.

It would be interesting to see what you could achieve by tuning for an optimal air:fuel ratio rather than tweaking things until the smoke is minimised.

I still need to get an EGT gauge, but will probably go for the PLX devices setup.
It's a modular system and perhaps a little ungainly as you need a sensor module and gauge for an operating system:

PLX SM-EGT | Exhaust Gas Temperature EGT

PLX DM-6 | Auto Meter Car Gauge

The big attraction is the ability to add in things like a wide band AFR module.
PLX SM-AFR | Wideband UEGO Air Fuel Sensor

You can log real time data using a PC interface so this would make it possible to fine tune the fuel mapping to suit the vehicle set up.

So many toys, so little spare cash.

cheers
Paul

**Dougal** · 13th February 2013, 08:20 AM

Originally Posted by OffTrack

It would be interesting to see what you could achieve by tuning for an optimal air:fuel ratio rather than tweaking things until the smoke is minimised.

cheers
Paul

That is the interesting thing Paul.
If they remap (no external tuning box) to a sane A/F ratio like 17:1 max (18:1 is really safe and clean), which can be easily done through the smoke map (aka air/fuel calibration table) then you can get maximum safe power throughout the operation range.
If you want more power, then pony up for a turbo upgrade and more boost.

Without more boost, any attempt at more power is just dangerous.

**Disco Muppet** · 13th February 2013, 10:07 AM

Originally Posted by OffTrack

So many toys, so little spare cash.

A familiar tale

**Disco Muppet** · 14th February 2013, 01:45 AM

So, if the turbo works better with higher EGTs and turning up the boost lowers them, does that mean the turbo is less efficient? or has to work harder?
Looks like it's time to get a EGT and boost gauge happening.

**Dougal** · 14th February 2013, 06:12 AM

Originally Posted by Disco Muppet

So, if the turbo works better with higher EGTs and turning up the boost lowers them, does that mean the turbo is less efficient? or has to work harder?
Looks like it's time to get a EGT and boost gauge happening.

Yes, as EGT drops the turbo requires more drive pressure to deliver boost. So it works the engine harder.
So once your EGT's are safe and your exhaust is running clean, there is no point in trying to push EGT lower as it will likely just cost power, torque and fuel economy.

**OffTrack** · 14th February 2013, 06:19 AM

I think the reason why higher exhaust temps help the Turbo perform better is to do with gas velocity. Gases become denser as they become cooler, so the pressure and velocity of the exhaust gases drops.

Ideally you want to keep the gases hot, without being excessive, so the energy in the exhaust gas is used to spin the turbo, rather than heating up the exhaust manifold and engine bay. This is the primary reason ceramic coating is used on performance manifolds - the coating on the inside of the runners helps stop heat leaching from the exhaust gas into the manifold. The fact that it reduces the tendency of the manifold to warp is a secondary benefit. If you were really keen you could also ceramic coat the exhaust side of the turbo.

I'd probably go for a Nanocom over a boost gauge TBH. Boost level is a "fun to watch" parameter but once the wastegate is set there isn't much point keeping an eye on it.

I finally got around to tweaking the wastegate last night. I haven't had a chance to really test that I have set it properly, but on a short backstreet blast the boost peaked at 1.255bar/18psi. It's certainly made the D2 feel a bit more zippy.

And after rereading the PLX Devices page the DM-6 gauge doesn't have pc logging. You have to fork out an extra $100+ for the OBDII gauges to get that feature.

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