EGT question

[BogMonster]

Has anybody with an EGT gauge on a 300Tdi ever measured the difference that fitting a big intercooler makes to the EGT (or the inlet air temp for that matter) at any given fuelling level?

Just curious... the thought process going through my head is "how much of the power comes from fuelling increase and how much from having more air" - yes I know the power only comes from the fuel but what I am thinking is something like as follows:

1 My current peak EGT when absolutely caning the ollocks off it up a hill is 609*

2 So if I increased the fuelling until the max was no more than 700 (below the 720 danger point)

3 And then added an intercooler and adjusted the fuelling so the max was again no more than 700

What would the difference in power output be between stages 2 and 3, compared to the difference between 1 and 2?

What would the likely drop in EGT be if I just added the big intercooler in stage 3 and didn't adjust the fuelling again?

Same question could be asked of what the difference would be if I added a bigger intercooler and adjusted the fuelling until the peak EGT was what it is at the moment - 609* - thereby putting no more thermal stress on the engine than the standard tune.

I know from past experience that fiddling with the pump gives huge improvements in power/torque and driveability (though at the risk of breaking your engine - I haven't a clue what the EGT was on the old 90, probably rather high, but I know it went a hell of a lot better!)

Thoughts.....?

[white90]

Stephen

mine achieved a Max EGT of 735 pre the new intercooler which dropped to 692 max after fitment

But the pump had been adjusted before the intercooler was fitted.

If I were to buy again I'd go to Brunel Performance for an intercooler their approach to design/build/useage was far more involved than simply fit from the shelf for a good friend with his 300TDI

Deano on here has one of thiers I believe.

[BogMonster]

Allisport was the preferred choice, don't know anything about this other bunch?

What sort of £££ are they?

Your temp observations pretty much support what I was thinking which is that the bigger intercooler can only drop the intake air temp a bit (not sure what the "heated post turbo" air temp is but say it is 100 deg C, you might get it down to 40 if you are lucky?)

So it isn't going to suddenly knock (say) 200 deg off the EGT. It suggests to me that if you are careful, you can probably get 80% of the power output without an intercooler, and do it for free

[white90]

the eng at Brunel worked for Mitsubushi ralliart team so I was told

he worked out the temp drop required across the intercooler then built it to that spec.

they have a web site and are no more expensive than the other ones available.

http://www.brunelperformance.co.uk/

[Lara]

The EGT is not really a good indicator of the power produced rather an indicator of combustion chamber burn condition.

If you have fuel timing too early or late then your EGT will be higher for the same power than a correctly timed engine, If your engine is running slightly over rich then the same occurs but on a much smaller scale, If you run an overly lean condition (as on most standard turbo diesels) you will see a reduction in EGT for the same power, Like all things you must be very careful in reading the wrong information from just a little information. Certainly an EGT of over 720 deg C will cause problems if held for any length of time, but it may be caused by a lot of things and rarely just too much power, Experiments have shown that on a well setup diesel you can use as much as 15 BAR boost pressures (if properly fueled and intercooled) and still not get an EGT of over 720-C. (The bottom will come out of most engines at this level though )

The long and the short of your question though is this, For a given boost pressure you will get more air into your engine if it is efficiently intercooled and thus you will be able to burn more fuel at the correct ratio and if timed correctly (just like spark ignition on a petrol engine) you will get more power while still within the safe limits of your engine.

Keep an eye on EGT by all means, as it WILL indicate when something is wrong but not necessarily that you are doing it correctly.

Intercooler question really depends on your inlet boost pressure and whether you live in the North (sorry) South pole, bellow .8 bar or in the ant-arctic, an intercooler is not really a benefit on a diesel, above this then it becomes more and more critical, Very hot air at 3 Bar boost un-intercooled will probably be only as dense as 1.5 Bar efficiently intercooled (I am not about to calculate this to make a point so don't ask) regardless of EGT, so if the question is power for given boost pressure then use an intercooler, remember that the harder the exhaust works to spin the turbo the slower the exhaust gas escapes so you get less power potential that way as well!

Hope this helps as I think I have written enough.

Lara.

[BogMonster]

15 bar....

bit optimistic for a 300 I think

I'm about as close to the antarctic as you are to the arctic

I think the essence of it is "stop being a stingy git and buy an intercooler"!

[will_warne]

Err, yes. Just shell out and buy a decent intercooler

Lara is perfectly right about the thremodynamics. Keeping the inlet temperature down means more air and less thermal loading. The only thing to watch with intercoolers is to fit one that has a low pressure drop. There's no point fitting a HUGE intercooler that cools the air right down but means most of the boost pressure is lost as you'll only loose performance.

[BogMonster]

The only thing to watch with intercoolers is to fit one that has a low pressure drop. There's no point fitting a HUGE intercooler that cools the air right down but means most of the boost pressure is lost as you'll only loose performance.

Erm

how do you find that out then? I've never seen figures quoted for that?

I suppose you can up the boost a bit to compensate, but the only easy place to measure boost (without drilling holes etc) is at the turbo. I remember in the Tdi tuning thread on LRE that Jon Roberts said something about drilling and tapping the manifold and putting the wastegate hose to that so it only opened when the manifold pressure got to 1 bar, I suppose that would be one way round it.

[white90]

I fitted the boost gauge to the manifold and the boost is measured there is 21psi

at ther rear of the 300 manifold is a bolt you can remove and tap a thread into for the boost gauge tee piece.

I run this and have done for over a year.

Brunel would get my money if I ever purchased again.

the yellow jeep/Disco hybrid in the brunel gallery is my friends one

he cracked 2 manifolds prior to fitting the EGT gauge

[Turbocharger]

Tony - have you moved the wastegate sensing pipe to the inlet manifold too? My wastegate is turbo-sensed and the pressure is measured at the inlet, I usually see about 12psi there through the standard intercooler. It's not a big job to add another thermocouple so the EGT gauge could read inlet temperature too though... [eyes glaze over in deep thought]

[white90]

John

no I haven't it is still connected to the turbine housing.

the boost raises to 21psi holds until the wastegate opens

I avoid higher boost as I think the headgasket will complain if Pushed to hard

[Turbocharger]

1) Did you measure the boost pressure before you played with the turbo?

2) Did you set the boost to 21psi at the manifold, or set it to 21psi at the turbo and then replumb the gauge?

[white90]

15psi before adjustment

21psi set at manifold much more and you get into bleeding the boost as the wategate cannot close properly.

after that a call to Demon tweeks will be required for a bleed valve they do switchable ones from Turbosmart

[Turbocharger]

Was your pre-tweak 15psi at the manifold or the turbo? I'm trying to gauge the pressure drop across your intercooler - I see 12psi at the manifold and I'd guess 14psi (1.04 bar) at the turbo if it's all as LR intended. Boost fiddling is on my calendar after a bigger intercooler.

[white90]

all measurements were at the manifold.

raising boost does very little unless you add fuel I found after a lot of test drives

more air in more fuel in = Less mpg more power mine produsces it low down after pump alterations, ideal for climbs etc, still could be improved if I had the time/inclination.

fine line between useable low down and a slug on the motorway I guess

[Turbocharger]

all measurements were at the manifold.

raising boost does very little unless you add fuel I found after a lot of test drives

more air in more fuel in = Less mpg more power mine produsces it low down after pump alterations, ideal for climbs etc, still could be improved if I had the time/inclination.

Absolutely agree with you there. As anyone who's followed me will testify, I think I'm there with the fuel already, just need to fan the flames to actually make it burn (or turn it down a bit).

fine line between useable low down and a slug on the motorway I guess

I disagree there. It's not 'gearing', you can wind the smoke screw right in and make it peppy off-boost, or wind the max fuel screw and give it power on the motorway - it's not an either/or scenario.

Moving back on-topic(!) you can wind the fuel right up as I have and retain the standard intercooler. However, the intercooler heat-soaks and you can't sustainably keep the performance up or the temperatures down. This is something I've found as I've been developing my in-car performance widget - I was struggling to explain the spread of results I was seeing...

Spot the run that was performed (at higher revs only and) while the intercooler was still hot! That's a 10% drop in power. The other runs had over a minute with air running through the matrix - hence the next stage in keeping it all cool is on the way after I picked up a windscreen washer bottle/pump assy at Sodbury for a quid. Incidentally, the shape of the torque curve shows how badly the fuel setup is on my engine - I just can't get the air in to burn any more at low revs.

[white90]

well I now disagree too

re:

I disagree there. It's not 'gearing', you can wind the smoke screw right in and make it peppy off-boost, or wind the max fuel screw and give it power on the motorway - it's not an either/or scenario.

I never mentioned gearing

wind the max fuel screw just a tad and your EGT rockets/mpg plummets

this is from recent experience.

I run a fine balance of the star wheel and diaphram with the max fuel screw to get it how I like it.

and this with the Alisport stage1 intercooler(stage 2 wouldn't fit BTW)

[andylandy]

allisport have just made some temp test equipment and are putting a bowler wild cat on a rolling rd tomorrow this will feture in that mag called LRE so egt will be shown in some from of tech graph

the car has a tvg 2.8 and is doing next years paris dakar

the 2.8 runs hotter than a standard 300 tdi and we will soon find out the info will post when avalibile

i spoke to a guy at the three peaks and he had a EGT gauge fitted to his 300 tdi and it runs between 650-700 and when push hard to 750 but he doesnt like running this hot he had a standard 300 with a fan behind a standard intercooler

[will_warne]

Yes, the 2.8 does run hotter than the 300. I've had 680* out of mine (locked in 3rd, foot flat on the floor), that was after about 30 seconds on a steep hill, though. I've got a lot of work to do to try and improve airflow, though. At the moment the horn sits right in front of the I/C which isn't going to help.

A bit OT but what should I use to seal the gap between the rad and intercooler? At the moment there's a reasonable gap between them and it can't help my cooling.

[white90]

From: nr Abingdon, Oxfodshire

Will his made me laugh.

How about some chequer plate folded?

[will_warne]

From: nr Abingdon, Oxfodshire

Will his made me laugh.

How about some chequer plate folded?

Haha, its been like for a couple of months and on ones noticed until now (including me )

Hmm, no, it really needs to be something flexible to fill the gap but would stand the temperature..... I don't really want to RTV it as I'll nedd to get them appart at some point.