Thread: TD5 High EGT - Intercooler vs 3 inch

Originally Posted by Kaaaiju

I went 3 inch exhaust and manaul version of the Allisport intercooler with was $980 landed last year and with my td5inside hybrid turbo and remap I get 650-700c quickly but drops down when I let off, the sensor is on the collector of the Allisport Manifold

I run 25-28psi but will upgraded head studs soon I'll go 2.0bar with the turbo and map

28 psi is essentially 2 bar anyway.

I've run 2.2 bar , but in all honesty it's beyond the flow capacity of the manifolds and head, the old law of diminishing returns rears its head!

And on most td5s, when you lift, the egt's drop really quickly, I can be at nearly 600 just before home, and a lift off and coast for the last few hundred metres will have it under 300

thanks guys, really appreciate the feedback.

sounds like a couple of things to check and replace.

at the end of the day with the intercooler change and possibly flex joint and bottom elbow of exhaust im really on only going to see 50c drop. which is better than nothing.

as always still keep driving by EGT gauge.

Pushing a turbo out of its efficiency island in search of extra pressure ratio result is more heat. Best not to generate that extra heat in the first place and if you do you will have to try and cool the air via a better charge cooler.

Gale Banks runs a Banks Power YouTube channel and has a video where he explains that the boost gauge is dead to him, it is air density that makes power not boost. Make sure you don’t push your turbo into an area of the map that drops efficiency meaning extra heat therefore lower charge density.

The size of the exhaust will effect when the turbo drive pressure will be greater than the boost. That is when the turbo is running out of legs. That is when the bigger exhaust and turbo will help.

I’d monitor the inlet temp after the charge cooler and try to drop the temp to increase the density of the charge. Done by more efficient cooler, maybe slightly less boost or bigger turbo and exhaust.

Driving by the EGT gauge is basically a manual form of derating the engine. Modern diesel management system do that for you. D2s don’t monitor EGTs, you have to do it yourself or modify the the parts of the system that provide best results in improving charge density not just boost.

I agree entirely, and I think as Gale once said, boost is only used to sell turbo's/super chargers to the Vehicle owner, after that, who ever does the tuning is only interested in aircharge figures, or whatever the term he used was.

Boost is essentially meaningless, it's a bit like selling tubs of water of unknown size, but insisting the purchaser should be happy to buy them sight unseen, as you have checked yourself and they are all full to the top...but how much is in the "full" container?

Unfortunately if you say you have a turbo that can do 1400 mg per stroke on a 5 cylinder 4 stroke revving at 3500 rpm, most owners wouldn't know what that meant, why should they?

But boost is easy to understand/compare against itself.
If I had a stock td5 running 19 or 20 psi, and I then found a turbo that could deliver 30 psi boost, that sounds impressive...but means nothing, other than I guess it can handle a pressure ratio of about 3!

this is a fascinating topic, but one that is over my head. I grew up on petrol engines, points and coil ignition, and an incredible array of carburettors. Wasn't bad with tuning twin or triple SUs, not so good with Webers. Understood advance curves. Did a bit of stuff with heavy diesels, GMs and Cat, but mostly repairs. My 300TDi and TD5 are the first diesel cars I have ever owned. I can work out the Bosch VE pump. But then I'm stumped. Is there a 101 type of thing to understanding maps? I don't expect to be tuning TD5s in five minutes, but I would like to have a handle on it.

DiscoTD5.com | Discovery 2 Td5 ECU Tech and Tuning read all you want and you can make your own maps

Originally Posted by Tins

this is a fascinating topic, but one that is over my head. I grew up on petrol engines, points and coil ignition, and an incredible array of carburettors. Wasn't bad with tuning twin or triple SUs, not so good with Webers. Understood advance curves. Did a bit of stuff with heavy diesels, GMs and Cat, but mostly repairs. My 300TDi and TD5 are the first diesel cars I have ever owned. I can work out the Bosch VE pump. But then I'm stumped. Is there a 101 type of thing to understanding maps? I don't expect to be tuning TD5s in five minutes, but I would like to have a handle on it.