looking for grunt !

[DBS404]

hi everyone
In readiness for the next job on my unimog, i would be interested in getting some feedback on improving the driveability under working conditions. Although i would like an increase in bhp to 140 or 150, im mostly interested in building toque, which in many instances is quite the opposite thinking of maxing out for horsepower.
I`ve found the posts in this section very enjoyable and would like to chat about pump and intercooler modifications for this purpose. I had thought about keeping the intercooler system volume to a minimum in order to aid building boost from idle, but im likely to experience sustained periods of boost whilst towing and mudplugging.
I have scoerd an intercooler and an inlet manifold from a 940 tic and wondered if i can do better bearing in mind i dont want to run any more than 20psi (adjustable) boost pressure. My engine was built with new head, bolts, pistons etc. Cheers, Brian

[Jason]

Brian,
a larger intercooler volume wont really have much effect on turbo lag, however the turbo itself will have much to do with it, along with fueling. If your looking to add about 40 to 50 hp (and the torque that will come with it) I would turn the pump up as explained in the performance sticky, and install your intercooler. I would stick with the stock turbo in your application, it spools very quickly and will give you the lower end and midrange power your looking for. Turn up the fuel untill your happy with the power, and run enough boost to clean up the smoke. I wouldn't really worry about how much boost your running, just run enough to use all the fuel your injecting. If your still pushing any black smoke under full boost, turn the boost up or back the fuel off slightly. With the pump mods, I would do the fuel pin grinding, but I wouldn't bother with the gov mod, I doubt your going to be screaming the engine up to 5k rpms very often. It wouldn't be worth the work of taking the pump apart in your application.

Jason

[Jason]

Forgot to mention, this is assuming you installed rebuilt injectors when you did your engine... Also, bump the timing to about 1.0mm.

Jason

[DBS404]

thanks for the advice jason - i was in need of the help as the vast majority of my performance work is with petrol engines so i`ll be happy to draw on your experience with these diesels - looks easy to do and this sounds like fun too! if i remember i had the injectors rebuilt with genuine bosch nozzles but had the turbo intercooler ones fitted as they were apparently larger than the D24T ones fitted originally. Pump timing was also to TIC spec, which was .95mm @ TDC. should have it done by april probably and hope to get some engine pics up by then. Its just occurred to my that the raised air intake i made might be a bit restrictive for my hot diesel, its 2.5" od pipe - what do you reckon ?

[DBS404]

oh, meant to ask you about running a fully synthetic oil in these engines, and what grade would i use. I couldnt find a synth. listing for these engines.

[Jason]

I like the Shell T-5 full synthetic 5w-40 oil. Other people have recomended Mobil 1 5w-30 as well. However, in my opinion using an oil that is rated for diesel use and has soot suspension properties is important. Castrol also makes a "turbo diesel" 5w-40 full synthetic oil. I have used the Shell because Wal-mart has it in gallon jugs for $19.50. I know a number of people who have run it in TDIs for hundreds of thousands of miles with great results. I will be changing over the the 5-40 after a few more break in miles on my engine.

Jason

[casioqv]

There's always Mobil 1 or Delvac 1 "Turbo Diesel Truck" 5w40. My personal preference is Amsoil Series 3000 5w30, but that's so expensive and hard to find that I usually use Mobil 1 instead. I change it every 15k miles because that's the interval I've personally confirmed in a D24T via oil analysis, but the oil was nowhere near needing to be changed at that point, and could almost certainly go much longer without any increase in engine wear. Intervals on fully synthetic shorter than 15k WILL needlessly increase metallic wear and reduce engine longevity (not to mention waste money). Contrary to popular belief, the rate of metallic engine wear (judged by change in oil metal concentrations/distance determined via regular oil analysis intervals) is highest when the oil is new, and continues to fall until at least 15k miles or so, and then very gradually rises again.

[Aidan]

Originally Posted by casioqv

There's always Mobil 1 or Delvac 1 "Turbo Diesel Truck" 5w40. My personal preference is Amsoil Series 3000 5w30, but that's so expensive and hard to find that I usually use Mobil 1 instead. I change it every 15k miles because that's the interval I've personally confirmed in a D24T via oil analysis, but the oil was nowhere near needing to be changed at that point, and could almost certainly go much longer without any increase in engine wear. Intervals on fully synthetic shorter than 15k WILL needlessly increase metallic wear and reduce engine longevity (not to mention waste money). Contrary to popular belief, the rate of metallic engine wear (judged by change in oil metal concentrations/distance determined via regular oil analysis intervals) is highest when the oil is new, and continues to fall until at least 15k miles or so, and then very gradually rises again.

Hi, firstly, please forgive what might seem an "attack" on your statement (which it certainly isn't, it's genuine curiosity) what you wrote seems very self contradictory. Essentially it translates as fresh clean oil causes more engine wear than dirty old oil, how can that be? I am assuming this information is based upon oil analysis which determines the metallic particle content of the oil. Is there not the possability that the analysis is being "corrupted" by the fact that when you put new oil in your engine, it will very quickly pick up the residue from the old oil (which obviosly will have a fair concentration of metallic particles) and thus give an artificially high particle content reading in the early stages of the oil's life. After this initial period most if not all of the old oil (and metallic particle's) have been absorbed by the new oil and subsequent analysis would show a lower rate of particle absorbtion (which would simply be particles from normal engine wear) giving the impression that older oil causes less wear. I would be very interested to see how the analysis would read if you took an engine of say 75k miles, totally strip it and get every last drop of old oil and residue out, put it back together (using the origional metalic components) and then perform the same analysis, I would be very suprised indeed if it still indicated an initially high wear rate with new oil. With all due respect to you, in 33 years as a mechanic this is the first time I'm ever come across a statement suggesting new oil causes more engine wear than old oil.

[Jason]

Every major diesel engine manufacturer I know of have an oil change interval recomendation, and a "severe duty" oil change recomendation, which is always shorter. I would classify my engine as severe duty since I run the crap out of it, and the fuel is turned up so soot contamination levels are higher than a stock tuned engine. I change mine every 5k miles, though I would push it farther if it was just a stock driver. I don't see how a shorter interval is going to increase engine wear... It will increase wear on your pocket book though I agree with that! I would also be interested to know how metal contamination in the oil is going to decrease over time from a higher point at the begining, as the engine is running and adding more wear particles to the oil. That is unless the filter is filtering it out, but then why would it be higher in the first place, when the fresh oil would have zero contamination?

Jason

[DBS404]

hi guys
thanks for the suggestions for oil choice, i`ll probably go 5w40 but the diesel variety for the extra detergents.
i was stumped by your oil analysis Casioqv, but here is a possible scenario. Aidens idea of initial contamination is spot on, you never get all the old oil out - the new oil can go black right after its filled and could account for the early contamination.
Secondly you may expect that to fall as the new filter gradually cleans up.
lastly ( and crucially ) as the filter reaches capacity and begins to choke , oil pressure starts to beat the filter bypass valve and recirculates the oil back into your engine ......this could account for the heavy initial contamination that you found also. Just a thought. there is no doubt that these synthetics will last for huge service intervals 18K + even, but these are for modern ecu controlled engines with common rail injection etc , not our `old` engines. even if the oil does last 15K best change your filters at least twice by then - oil and filters are cheap compared to fuel costs for worn engines and rebuilds. cheers brian