Bigger exhaust fix for VNT Td5 with high gets?

[silverhammer]

Any comment on the value of a bigger free flow exhaust in reducing gets on my 03 D2auto would be appreciated. I've got a BAS VNT, bigger custom IC and map from Peter Bell BAS. Boost box also from Td5Alive. After over boosting still falsely registering, I bypassed the MAF from airbox successfully. Goes like a cut cat, great economy but big hills and towing really arabise the egts. Can moderate with right foot but would love to unleash the rest of the grunt when under load.

Maybe silicon hoses on IC input side too?

Cheers
Max

[Disco Muppet]

Sounds like an interesting combo :)
How high are we talking?

[justinc]

I'll give you a buzz tomorrow Max about the exhaust.:)

(This vehicle really IS a v8 eater DMuppet....:cool: you'd have to drive it to believe it. However it can quickly see 800 degrees with a tow load (2.5+ton) if you aren't watching...:D)

jc

[Disco Muppet]

Oh I can hear the howls and shrieks of the petrol heads already :twisted:
Mine will be too JC.
One day.....
Oh wait.
It already is :tease:

[justinc]

Oh I can hear the howls and shrieks of the petrol heads already :twisted:
Mine will be to JC.
One day.....
Oh wait.
It already is :tease:


yup, thats why i said it!:D

jc

[silverhammer]

As Justin says, (hiya Justine) an unloaded vehicle full bore 0-100km blast will see 750-780. Towing on level 450-550 at 90-95, big hills well I drive to control egts but would hit 800 at the top. Recovers very rapidly. I'm curiuos not concerned as JC has done all the work ;-) . Wonder why the exhaust mod is talked about when turbo outlet is the major constraint isn't it. I'm kinda with Justin's advice, ie why big pipe if turbo is smaller diameter. But I'll try anything if I can use my torque more on hills. Max

[goingbush]

I dont have VNT on my Td5 Defender but have all the other fruit, was getting high EGTs towing my van up hills, I don't want to go around Australia looking at the EGT gauge, so got onto Td5inside for a custom map for towing, Try no 1 was over boosting , a few more tweaks and Jose has got me a map thats perfect for my combo, EGT now refuses to go over 700 in 5th, tho I can push it over in 4th but thats fine. No black smoke, no over boosting, heaps low to midrange grunt, and without the Van goes like a cut cat, absolutely creams over any V8 Landy I've had. and fuel economy is leaving a smile on the dial !!

just saying , worth dropping Jose a line.

[strangy]

There has been some discussion on EGT's and exhausts somewhere around here about 12 months ago.
With the mods you have done I have no doubt you have been doing some careful reading.
Reduction of EGTs by using a bigger exhaust is subjective for many, however, it is worth noting that EGT's are a direct function of the combustion process.

As the design of domestic motor vehicle engines doesnt warrant the expense of monitoring the combustion process at all in most cases let alone, at a more accurate position such as the thermocouples in machinery such as aircraft and other specialised engines, an EGT monitor is the most effective and reliable means for the masses to use, but remembering it is exhaust gas temps being monitored at varying positions (i.e whever it fits) for determining critical combustion temps.

This has proven to be generally a reliable method of monitoring, however, it is monitoring the gas temperature post combustion after expansion and therfore cooling.
A drop of some 200deg C is common between probes pre and post turbo on the TD5 in std trim yet the combustion temps have not changed.
A bigger exhaust will not normally help lower your actual/true combustion temps and therfore EGT, but rather will significantly affect the gas temp experienced at the probe, unless your bigger exhaust allows the turbo to constantly produce more boost, therefore more/denser/cooler air charge you will not see lower combustion temps/ EGT.
Otherwise modifications post combustion will be an influence on the probe only and has led some to believe that the actual combustion process is now cooler, giving a false sense of safety margin and now happily peg the engine based on the modified reading at the probe.

The only way to have genuine cooler egt's is to provide cooler/denser air or less fuel for a given charge volume to lower the combustion temps.
Something you have already addressed with bigger IC and boost box.

The popular exhaust sellers claim the reduction of EGT's with their products as will a few here.
Increased performance due to free flow, turbo spool, cooler overall operating temps through the faster removal of hot gases are all benefits of the right sized sytem, but wont reduce the combustion temps.

cheers

[two up]

Any comment on the value of a bigger free flow exhaust in reducing gets on my 03 D2auto would be appreciated. I've got a BAS VNT, bigger custom IC and map from Peter Bell BAS. Boost box also from Td5Alive. After over boosting still falsely registering, I bypassed the MAF from airbox successfully. Goes like a cut cat, great economy but big hills and towing really arabise the egts. Can moderate with right foot but would love to unleash the rest of the grunt when under load.

Maybe silicon hoses on IC input side too?

Cheers
Max

A bigger free flowing exhaust will help if your current one is restrictive, if it is standard it will restrict gas flow.

Also

Have a look at water/methanol injection, you will easily take 100-200 degrees out if configured properly.

[silverhammer]

Strangy
You've perfectly detailed my uninformed view re effect of exhaust on egt's.

Much appreciated previous post re fuel map mods by Td5alive. BAS guru Pete B may be my next step after JC has a look at it. Thanks to both posters
Max

[twr7cx]

I think your setup is pretty much similair to mine - BAS VNT, TD5 Alive/Alive Tuning intercooler and TD5 Inside ECU tune.

My exhaust system is the standard 2.5" pipe, but replaced all the cans with high flow Lukey Race Series straight through stainless steel mufflers. The previous owner also replaced the flexable joint on the down pipe with a proper 2.5" sized unit as the standard one is much smaller than the exhaust pipe causing a restriction.

Turbotecnics (the actual supplier of the VNT to BAS) only recommend a 2.5" for the BAS VNT.

Recently I got rid of my TD5 Alive/Alive Tuning Turbo Booster Box and Modified MAF and replaced them with a Dual Channel Turbo Booster Box from IRB Developments (took forever to organise and purchase). I now have no EGT issues, after installing it and manually tuning using my Nanocom, I can hit hills with the accelerator flat and my MadMan EMS alaram won't be beeping at my anymore due to the EGT.

In regards to my ECU tune Jose from TD5 Inside spent some time refining it for me based on the Nanocom reading I was sending back to him and it got better and better the more he worked on it.

[justfishing]

Hello
I have the same VNT and had a 2.5 inch exhaust which went great. I now have a S/S straight through 3 inch and in performance wise it does go better, lost a little bottom end but HUGE around 1900 + rpms I tow my boat and when I first did the exhaust it seemed as no difference bit once the boat was on wow didn't know it was there. It does spool quicker (it seems) and gives a wicked sound. I will make a more taped section at the manifold end next week and fit my EGT probe at the same time when I get home trying to get a little low end back. The reason why they say only 2.5 inch is so the turbo doesn't over spool. I am not gentle on my TD5 and never had a problem. Looking at a different air box have done the mod as in taking out the hyclone thing. I did try the bypass but lost performance due to not enough air though the MAF took it off, since made my own boost box never had a over boost again. I found the boost box that you have never worked at all.
Ian

[granno]

I have the 3" and found it great. Cant compare with 2-1/2 though as I went from stock to 3". I have my VNT but is off with the new manifold getting layered in good ceramic stuff.. I found it interesting that the outlet of the exhaust manifold was ~5mm smaller than the VNT inlet all the way around.. Is this normal??

I bought one of those "performance manifolds" from landrovertuning and spent 2 hrs on the die grinder smoothing out the very rough casting marks/daggs.

I am also installing a EGT gauge and was going to drill and tap into the EGR blank but will relocate. I assumed that there would be no difference from one end of the manifold to the other. Be an interesting experiment.

Here are some shots of the manifold (count the # H/T studs supplied)

The before and after smoothing out..

[TD50WA]

I have the 3" and found it great. Cant compare with 2-1/2 though as I went from stock to 3". I have my VNT but is off with the new manifold getting layered in good ceramic stuff.. I found it interesting that the outlet of the exhaust manifold was ~5mm smaller than the VNT inlet all the way around.. Is this normal??

I bought one of those "performance manifolds" from landrovertuning and spent 2 hrs on the die grinder smoothing out the very rough casting marks/daggs.

I am also installing a EGT gauge and was going to drill and tap into the EGR blank but will relocate. I assumed that there would be no difference from one end of the manifold to the other. Be an interesting experiment.

Here are some shots of the manifold (count the # H/T studs supplied)

The before and after smoothing out..

My egt has been drilled and tapped right in the middle on the collector in front of the turbo. Best place imo.

[Dougal]

On a completely mechanical engine it could help. But yours is EFI.

The ECU tune defines the air/fuel ratio under full load and yours is running too low (too much fuel, not enough air).
You need to go back to your tuner and get them to raise the smoke map to give it less fuel for the same air.

Then you can get your power back through more boost which will let you burn the same amount of fuel as before but with safer EGT.