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  • Geat work Tommy. The AJT & D5252T are timed the same at 0.55.

    Its still too far advanced imo. As the revs increase, fuel and cylinder temps heat up you'll get ignition too early in the compession phase. Two stage injectors @ 1.54 have already lost half the fuel and fuel cooling delivery window.

    Look for another engine - you'll need it. I hope I'm wrong - genuinely.


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    • Originally posted by Activ8 View Post
      Geat work Tommy. The AJT & D5252T are timed the same at 0.55.

      Its still too far advanced imo. As the revs increase, fuel and cylinder temps heat up you'll get ignition too early in the compession phase. Two stage injectors @ 1.54 have already lost half the fuel and fuel cooling delivery window.

      Look for another engine - you'll need it. I hope I'm wrong - genuinely.


      Sent from my SM-G901F using Just T4s
      It was you that told me the Volvo was +0.8?!?!

      If it is too advanced I’ll know about it. Loads of mTdi’s are running at this stage. Read up on them, there’s info on 4 cylinder mTdi’s out there.

      This week will be getting to know it and tweaking stuff to get it perfect.


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      #vanlife

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      • Big smile on Tommy's face this morning

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        • Nice one mate! Sounds great to my untrained ear haha.

          But a major milestone all the same.

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          • I read out to you the Bosch settings for the Volvo 6 pot 2.4td with IC, that was 0.8 along with the other oldies. The LT 2.4td was 0.85. All the 5 pot TDI's are 0.55. I set mine to 0.50 this allows the minimum 5 degree ignition delay (because of the Euro standards for cetane in diesel fuel) it allows the maximum time for compression before fuel ignition.

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            Last edited by Activ8; 2 August 2020, 09:06 AM.

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            • Originally posted by Activ8 View Post
              I read out to you the Bosch settings for the Volvo 6 pot 2.4td with IC, that was 0.8 along with the other oldies. The LT 2.4td was 0.85. All the 5 pot TDI's are 0.55. I set mine to 0.50 this allows the minimum 5 degree ignition delay (because of the Euro standards for cetane in diesel fuel) it allows the maximum time for compression before fuel ignition.

              Sent from my SM-G901F using Just T4s


              Aahhhh okay. 6 pot. Got you. I’d be interested to understand more about the relationship between the pump sizing and the injector nozzles/break pressure point and how that effects things.


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              #vanlife

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              • Originally posted by Activ8 View Post
                Geat work Tommy. The AJT & D5252T are timed the same at 0.55.

                Its still too far advanced imo. As the revs increase, fuel and cylinder temps heat up you'll get ignition too early in the compession phase. Two stage injectors @ 1.54 have already lost half the fuel and fuel cooling delivery window.

                Look for another engine - you'll need it. I hope I'm wrong - genuinely.

                You are wrong, the theory and the practice do not tally. And I don't know why,

                When I've built mtdi pumps for the four pots, I've always set them at a baseline 1.2.

                If Tommy sets his pump to .55 it'll barely run and belch out white unburnt diesel smoke,

                It runs well with the timing he has and I don't think it is into diesel knock yet. I've been running too advanced pump for years on the TDs.

                Why the massive disparity between the two timing settings?

                My pump was at 55, I believe when you do a timing graph and drop into basic settings the ECU control drops out and you are essentially a mechanical pump. It still runs perfectly fine,.... Tommy's would not, it'll run like shit.

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                • It’s started first pip this morning. Almost instantly and without cold start. Slight puff of black on initial startup which is fine and it idled lovely. Put the front back on and took it out, I got 6psi so got back a swapped the turbo actuator spring for a stiffer one.

                  Not got 8psi but the BOV is set too weak so I need to adjust that now.

                  The van revs freely now and pulls very strong from not much above idle. Turbo has a bit of a leak between the core and the turbine housing. Not much but there’s smoke marks around the turbo. If needs be I’ll just sack the turbo off as I’m not fucking about with it anymore. I’ll think about this another day. Far to soon to make any decisions yet.

                  I’m also interested in discovering the reasons behind the differences in timing between the Tdi and mTdi.

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                  Last edited by TommyP; 2 August 2020, 11:02 AM.
                  #vanlife

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                  • The timings I suggested were all turbo charged, LDA fitted, intercooler installed & derived settings from almost an identical engine but these obviously have low 120-135bar injector pressure settings as they were all old derived NA IDI engines.

                    I don't think Im right or wrong at this point in time, its a discussion to help the mTDI project along and all comments are written without any malice. We're all approaching the timing from different angles and experience which reads prety good if you were around a virtual table solving a problem!? Bosch spend and make billions out of this tech so its their lead I take.

                    The mechanicals are fixed - we all know this, as are the mechanical physics that make this engine run.

                    We know and many have experienced (including myself) theres a very very very fine balance regarding timing. The cold start timing difference/advance was 0.2mm on the 3 roller frankenpump that speaks volumes! Ive asked Tommy to check this now (4 roller frankenpump) just for clarity. Just 0.2mm adds enough advance to the pump/camplate to get it going. So why 0.99mm more advance than the ECU controlled version for the mTDI & 0.54mm more than an IDI?

                    The camplate rises from 0 to 2.49mm. Why 1.54mm to make it run sweet at tickover 800(?) to an unknown max or 'X' rpm. It WILL top out and cease injecting fuel at 2.48mm which will translate to an rpm limit.

                    Just thinking ...
                    The two break pressures of the Bosch injectors? Could try the two stage Stanadynes which deliver with a different mechanism? Bigger lift camplate but I doubt theres many options if any to choose from. Down size the pumphesd to 9 or 10mm? Lower the break pressures of the Volvo Bosch injectors. Originally they were 195bar 1st break. All food for thought!

                    All good fun and banter with the best people to get a result with!

                    Sent from my SM-G901F using Just T4s




                    Last edited by Activ8; 2 August 2020, 04:14 PM.

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                    • I changed for a stiffer spring in the BOV as that’s what’s holding it back now and got straight to 11psi. Going to dial in the adjuster on the top and drive again. Aiming for 14psi. Plus vat maybe.

                      As the boost is now going to be allowed to rise it most likely will mean I’ll have the actuator to play with again or maybe the pump. They all work together so setting it up won’t be an especially quick thing and involve a bit of time but it runs great now and it’s absolutely magnificent enough to go back into working service again.

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                      Last edited by TommyP; 2 August 2020, 02:13 PM.
                      #vanlife

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                      • Cold start advance is way more than 0.02 mm it's at lest ten times that.

                        The 55 timing setting is wrong for Tommy's engine, I don't know why it's wrong. Camplate or break pressures make no difference because it is all 2.5 standard parts.

                        Itll never reach 2.48 mm delivery with that pump head, demand will never be there.
                        Last edited by regcheeseman; 2 August 2020, 03:37 PM.

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                        • Originally posted by regcheeseman View Post
                          Cold start advance is way more than 0.02 mm it's at lest ten times that.

                          The 55 timing setting is wrong for Tommy's engine, I don't know why it's wrong. Camplate or break pressures make no difference because it is all 2.5 standard parts.

                          Itll never reach 2.48 mm delivery with that pump head, demand will never be there.
                          Yes my err its 0.2mm cold start. With timing tolerances on the IDI engines of 0.02mm.

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                          • I didn’t play about for too long with mine today as I had the old boy round with his to fine tune and that’s running great now. A super sweet 12psi, intercooled and LDA pump 2.4td.

                            Mine is currently 10psi and running nice. More power to come but I’ll play some more this week. Got plenty to do after work and hoping to get it all done before the weekend as I really need to concentrate on it’s paintwork.


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                            #vanlife

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                            • Tommy. How many teeth are on the 2.4 cam pulley and IP pulley?

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                              • Originally posted by Activ8 View Post
                                Tommy. How many teeth are on the 2.4 cam pulley and IP pulley?

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                                I honestly have no idea, why? What are you thinking?




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