200Tdi: questions about EGT

[RRC200Tdi]

Hi guys,

I hope you are all doing well during these challenging days.

I first posted this in the Range Rover forum, but I believe it is more appropriate in the international forum since it directly involves a 200/300Tdi.

I am new to this forum, but have been a rover enthusiast for ages. My current rover is a 1989 range rover converted to a 200tdi. I have gone through an exhaustive process of tuning the FIP noting every change and recording the resulting data, both qualitative and quantitative. I would like to post my method soon, when I have a little bit of time, because maybe it will be useful to those who need to start over without any reference to the factory settings. My FIP was not original, as it was obviously from a 300Tdi with provisions for the EGR fitment. The anti-tamper collar and plug were previously removed and the diaphragm had already been adjusted and it was a bit of a dog. Anyway, I worked through a process to tune the FIP from scratch, based on the fundamentals of each adjustment and it seems to be running powerfully and efficiently without any smoke issues. Also, I set the FIP lift at 1.60 mm at TDC. If there is interest I will post my method.

As to my question of EGTs, it is well documented that ~730  C is a hard maximum for sustained temperatures in the 200/300Tdi, with some scattered anecdotes of people running much higher. The main factor for this limit is usually linked to damage to turbine vanes. My question is, does anyone have reliable knowledge about the safe limits of the other engine components, such as the head and pistons? I have an aftermarket Billet Hybrid Turbo Turbocharger CHRA, from Turbo Rebuild Ltd, for which they recommend a maximum safe limit of 850 C (1562 F) and I am wondering how much I can safely, if at all, push the rest of the engine beyond 730 C. Currently, my engine is pulling hard up to ~4000 RPM at 16 PSI of boost, but the EGTs rise quickly during hard acceleration and will easily exceed 1400 C on a steep incline . I know I can get a few more PSI out of the turbo (maximum recommended 22 PSI) which will reduce EGTs, but right now I am unwilling to go beyond 18 or 19 PSI, as I do not know the history of the engine or the condition of the head gasket. At the moment I can easily moderate the temps with my foot, and keep it between 1200 and 1350 when pushing it hard on the highway, especially while overtaking vehicles or climbing hills. I like having the extra power when I need it, but I also want to be able to keep my eyes on the road during those times rather than down on my poorly located gauge.  

I plan on refining the FIP settings to get the temps down a little more, but I hope to keep the level of performance where it currently is.

Thanks!

Jack

[cackshifter]

Do you really mean 1400 C? That seems extremely hot, around the melting point of steel. The Cummins folk reckon 1300F , 705 C is safe for them, and they seem quite adventurous. Some cars allow an overboost for a few seconds, presumably with extra fuelling, but controlled by the ECU, not something available with a wholly mechanical pump. I think 1400 C is flirting with disaster

 

[Ozzy50]

I’m guessing he means 1400F ?

[RRC200Tdi]

Yeah, sorry 1400 F 😬

 

 

[RRC200Tdi]

Quick update on the boost adjustment. I shortened the wastegate actuator rod by about 5 mm and threaded the the rod end and jam nut to very end of the threads as I was skeptical that the 200Tdi was going make much more boost (previously set at 16 PSI maxed out on the stock rod) given the CFM limitations of the engine and small turbo. Once the engine was at operating temperature I gave it a run on a freeway on-ramp and gently increased throttle in third gear up to wide open and watched the boost gauge shoot past 20 PSI (at the manifold) and before I could relax my foot hit it 24 PSI.  This little Billet Hybrid Turbo Turbocharger CHRA can really make some boost. I was hoping to see to what extent more boost was going to decrease EGTs, but I can't test it until I get my boost back down to safe levels. I will update as soon as I get another run in after I lengthen the wastegate actuator rod.

Also, I have been noticing a little puff of black smoke on a couple of occasions at around 2000-2500 RPM under hard acceleration. This happens sporadically and I am not sure what may be the cause of this. I wonder if it is a signal of a clogged injector(s) causing fuel to not properly atomize, which may also partly or fully explain my high EGTs. I have some nozzles coming, so I will soon rebuild my spare injectors and test this hypothesis. 

Cackshifter, thank you so much for your insight.  It is true that the maximum temperature that is usually referenced is 700 - 730 C, but it is normally associated with the limitations of the turbine vanes. Since I am using an aftermarket CHRA with uprated materials with a claimed maximum rating of 850 C, I am curious whether or not the other components, i.e., the pistons and head,  have similar temperature limitations, or if I have a little extra flexibility to run it a little hotter. It may be a moot point if my EGTs return to safe levels when I set the boost to 18 PSI or with an improved spray pattern with new injector nozzles.

-Jack

[cackshifter]

I think lowering the boost will increase your EGTs (unless accompanied by corresponding fuelling reduction) Your small puffs of black smoke might possibly be a slight misfire if not quite enough fuel is getting through, eg clogged filter, lift pump a bit lazy. The FIP likes a bit of positive pressure.  But saying it before some one else does, at this level of tune unless you know the condition of the engine, you may be applying the straw that will break the camel's back. If you have an oil pressure gauge that will give you an inkling as to the state of the bottom end, but for example on big ends the more they are worn the faster they wear. 

[RRC200Tdi]

13 hours ago, cackshifter said:

I think lowering the boost will increase your EGTs (unless accompanied by corresponding fuelling reduction) Your small puffs of black smoke might possibly be a slight misfire if not quite enough fuel is getting through, eg clogged filter, lift pump a bit lazy. The FIP likes a bit of positive pressure.  But saying it before some one else does, at this level of tune unless you know the condition of the engine, you may be applying the straw that will break the camel's back. If you have an oil pressure gauge that will give you an inkling as to the state of the bottom end, but for example on big ends the more they are worn the faster they wear. 

Thank you Cackshifter, that is a great point about boost and EGTs, which is why I was trying to increase boost from 16 to 18 PSI. Unfortunately I overshot 18 by 6 PSI or more 😱  It turns out I had shortened the actuator rod to the point of disabling the wastegate completely. Intriguing suggestions about the fuel pressure. I have only about 1000 miles on my current fuel filter, but it is five years old and may be impaired by algal growth. I couldn't be bothered to change it, but now it has me thinking...

Unfortunately it is true that the condition of both the bottom and top end of the engine is unknown to me. The importer I purchased the engine from claimed that it had 114,000 miles on the clock, so I took him at his word and hoped that it was in decent condition. I performed the conversion on a holiday to see my parents in the US and it was too short a time to strip it down and evaluate the condition. We were meant to be moving back to the US from Germany at that time so I had purchased the engine in advance, but plans changed and I had to swap it as quickly as possible to get the truck out of my parents driveway and back into storage before heading back to Germany. We returned to the US this year and I pulled the Range Rover from storage this past summer and have only just started to get it road worthy again, with loads of repairs, including overhauling the FIP seals, issues with the clutch slave cylinder (wrong one provided by the diesel engine importer), brakes, electromechanical gremlins, etc... Originally, when I did the conversion, I had planned to rebuild the bottom and top ends before putting the vehicle into regular service. Unfortunately, life is dynamic and I now need to use it as a daily driver for the near term and I do not have the facilities to perform any major repairs or overhauls. Challenging matters further, we now live in a valley in the foothills of the San Gabriel mountains of southern California leading to a commuting 'uphill both ways' scenario, with decent grades. My initial drives about town were nerve-racking ascents of these hills at 45-50 MPH, mashing the throttle in 4th with EGTs around 1100 F. After many iterative tuning adjustments, I had it cruising well at 70 plus on the flats and climbing the very same hills with moderate throttle at 65 MPH (2250 RPM) in 5th gear and EGTs between 1100 and 1200. If I mash the throttle the temps rise rapidly, but it has not been necessary to do so. With regard to engine oil pressure, it is about 62 PSI at idle when cold and 26 PSI at idle when at full operating temperature. When cruising at 65 MPH at 2250 RPM the gauge reads right around 35 PSI with EGTs at 900 F.  I replaced the alternator with a P38 unit so the RPM may be slightly off - I made some calculations to find the correct v-belt pulley diameter, but could have erred.

Cackshifter, I heed and value your sound words of caution, but I have a genuine question. With respect, do you think running flat out in 4th gear with less fueling and less boost will lead to reduced wear and risk to the big end (as well as other components) as opposed to running it at lower RPM in 5th gear with more fueling and boost (at reasonable EGTs) when routinely climbing difficult hills? I do not wish to challenge you on this, I am sincerely curious. Do others have thoughts about this dilemma? 

To follow up on my last post, I lengthened the wastegate actuator rod about 4 mm and now level off at 18 - 19 PSI under maximum load in 4th and 5th gears. Taking Cackshifter's advice I also reduced overall fueling by adjusting the rear FIP screw (I refer to this as the overall-fueling screw rather than max fueling since it affects all aspects of fueling from idle to full boost) 1/8 of a turn CCW. These adjustments have led to maximum sustained EGTs at around 1380 -1400 degrees F (hypothetically, since I did not dare hold it at that high of a temperature for any length of time, but it seemed the rate of increase in temperature was approaching asymptotic beginning around 1300 F unlike before in which the rate of increase still appeared linear), and much more sensible EGTs, generally between 1000 and 1200 F, when modulating the pedal while climbing the hills around my area. I have turned the screw another 1/8 CCW, but have not yet tested it. I hope that these settings will be safe enough for the longevity of the engine and ancillaries. In sum, it appears that 18 - 19 PSI has brought the EGTs nearer to safe limits while also improving power. I am thinking that reducing the fueling a little further will drop maximum sustained EGTs below the critical temperature threshold of 1340 F, while returning similar power levels as to before I increased boost from 16 PSI to 18/19 PSI.

Sorry for the long post, I thought some context might be helpful!

-Jack

[reb78]

What intercooler are you running? Its my understanding that if you go OTT on the boost the intercooler cant cool the compressed air sufficiently so whilst you are under the impression you are putting more cool air in with higher boost, you aren't, its hotter and EGTs will suffer as a result. 

[RRC200Tdi]

1 hour ago, reb78 said:

What intercooler are you running? Its my understanding that if you go OTT on the boost the intercooler cant cool the compressed air sufficiently so whilst you are under the impression you are putting more cool air in with higher boost, you aren't, its hotter and EGTs will suffer as a result. 

Thank you, Reb78, that is an excellent point. I am no expert on this topic, but I have happened across a lot of discussions about the thermodynamics of turbos, intercoolers, and combustion as it relates to 200/300Tdis on the different forums, some very helpful and constructive and others a little less so, leaving me a bit uncertain. To answer your question, I am running a factory intercooler. I have considered upgrading, but have read posts suggesting that these engines and stock turbos really aren't capable of flowing enough CFM to increase air intake temperatures much above ambient after the charge is cooled through the intercooler. I have no empirical knowledge about this either way, but my results of lowered EGTs when raising boost from 16 - 18 PSI suggests I haven't yet crossed that threshold of increased boost leading to raised EGTs. That being said, this point is something to really weigh, and, as well, it does not necessarily mean that I wouldn't benefit from a larger intercooler.

 

[reb78]

Look up posts from @Daan on this. He did some testing with actual sensors and has some figures. My point was that I am not sure you can just keep upping boost assuming it will decrease egts or produce a better burn. There is a balance and the efficiency of the intercooler will likely come into that. 

[RRC200Tdi]

Thank you, I will have a look at @Daan posts. I recall reading a thread about intercooler inlet/outlet temperature comparisons, but I can't remember who's post it was.  If I recall correctly, the results were recorded on an aftermarket full-width intercooler and outlet temperatures were largely independent of inlet temperatures. The outlet temperatures were consistent and low, and may have been close to ambient, but I do not remember ambient temperatures being reported, as I was really curious about them. I don't think there are any data on temperature delta on standard 200/300Tdi intercoolers that I have come across. Maybe someone here has them?

I am still hoping for some information about the material properties of the head and pistons if anyone has it, but it is less critical since my temps are more sane now 🙂

Thanks guys, for all of your helpful insights. I will update soon when I have a chance to do some test drives (my county is under full lockdown at the moment).

Stay well!

 

[RRC200Tdi]

Small update as I made an interesting discovery.

Earlier this week I finally adjusted the valve clearances on my 200Tdi. I have been meaning to do it for ages, but I lost my old feeler gauges and it took me awhile to remember to order some. When I did the work I didn't have enough daylight to try and measure the clearances as they were, but there was a lot of play with the the .20 mm gauge. Anyway, I set them all to .20 mm and I noticed that the power felt slightly improved, and of course quieter (although I added a 300Tdi engine cover at the same time). Not bad. Yesterday, I had to take a long drive to go collect an exposed-hinge cowl for the '89, hen's teeth these days, and I noticed my EGTs were holding at 1200 °F (~650 °C) on sustained pulls. That is about 180 °F below what I was seeing as a maximum before (only when I was being daring). It never occurred to me that setting the valve clearances would have an effect on EGTs, so I was quite surprised at this result.

Is this something that is commonly known? I have not come across valve clearance as a factor in my previous research of EGTs, but I suppose it could be possible. I am no expert on valve trains, but, to my logic, having too much gap between the rocker and the valve stem will lead to the valves not opening fully which will then result in less transfer of intake and exhaust gasses. Can anyone corroborate this? Maybe my situation was on the more extreme end because the gaps were so far out, but the noise wasn't that much worse before the adjustment so I have doubts that my experience was unique. 

The best result of this is that I was able to further increase overall fueling in the injector pump which did objectively improve power and performance while now having a maximum EGT of about 1340-ish °F during a sustained hill climb in 4th gear 🙂 

 

[Nonimouse]

18 hours ago, RRC200Tdi said:

Small update as I made an interesting discovery.

Earlier this week I finally adjusted the valve clearances on my 200Tdi. I have been meaning to do it for ages, but I lost my old feeler gauges and it took me awhile to remember to order some. When I did the work I didn't have enough daylight to try and measure the clearances as they were, but there was a lot of play with the the .20 mm gauge. Anyway, I set them all to .20 mm and I noticed that the power felt slightly improved, and of course quieter (although I added a 300Tdi engine cover at the same time). Not bad. Yesterday, I had to take a long drive to go collect an exposed-hinge cowl for the '89, hen's teeth these days, and I noticed my EGTs were holding at 1200 °F (~650 °C) on sustained pulls. That is about 180 °F below what I was seeing as a maximum before (only when I was being daring). It never occurred to me that setting the valve clearances would have an effect on EGTs, so I was quite surprised at this result.

Is this something that is commonly known? I have not come across valve clearance as a factor in my previous research of EGTs, but I suppose it could be possible. I am no expert on valve trains, but, to my logic, having too much gap between the rocker and the valve stem will lead to the valves not opening fully which will then result in less transfer of intake and exhaust gasses. Can anyone corroborate this? Maybe my situation was on the more extreme end because the gaps were so far out, but the noise wasn't that much worse before the adjustment so I have doubts that my experience was unique. 

The best result of this is that I was able to further increase overall fueling in the injector pump which did objectively improve power and performance while now having a maximum EGT of about 1340-ish °F during a sustained hill climb in 4th gear 🙂 

 

Justification for always setting the engine to 'Factory' prior to experimentation. Oil types and quality can effect the EGT's - it's that sort of engine!