discomikey Posted February 13, 2012 Share Posted February 13, 2012 bear in mind that the temperatures are very low at the moment, that could amount to a big change as well due to bad aerodynamics combined with denser air. oil consumption is high to me as well. Daan dense air = good for a diesel engine Quote Link to comment Share on other sites More sharing options...
Daan Posted February 13, 2012 Share Posted February 13, 2012 dense air = good for a diesel engine correct, but: http://www.scientificamerican.com/article.cfm?id=why-is-the-fuel-economy-o daan Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted February 14, 2012 Share Posted February 14, 2012 srry thats what i meany Thanks that was what i was trying to say that thicker head gaskets would be required after a head skim But the valves are shut when the pistons are at the top, the combustion chamber IS IN THE PISTON as i said earlier. The gaskets are there to control the deck height because land rover couldnt make 2 engine blocks the same. I rebuilt the head on my 200 around 18 months ago, i took 7 thou off when it was skimmed and went from a 1.3mm gasket to a 1.1mm gasket. Quote Link to comment Share on other sites More sharing options...
discomikey Posted February 14, 2012 Share Posted February 14, 2012 valves are not always shut when the pistons are at the top. not on the exhaust stroke. valve overlap comes into play when actually both valves are open for a very small period of time, mainly to flush out any lingering exhaust and to help the initial flow (this one is not so important on turbocharged engines) into the cylinder. Quote Link to comment Share on other sites More sharing options...
Howitzer Posted February 15, 2012 Share Posted February 15, 2012 I did the pump tweak, set the boost to 10PSI and get no full throttle smoke and managed to run to the governor in top. I've not felt that it needed more power to be honest and it managed fine towing a combined total of about 4.5 to 5 tons. I realise this is incredibly dull mind you I wonder what the heat soak issues are like on them as the standard 200tdi intercooler is absolutely hopeless. My only gripe with the engine itself. When towing on long hills it will maintain speed (The long rise on the A1M to the A14) for a short while and then despite being an even gradient, will slowly start to struggle when keeping it in 5th. I also haven't noticed much difference in performance since fitting the rad muff (Only covered a few hundred miles mind you) when it is effectively blocking the intercooler off completely, so it turns into a pressure vessel more than a heat exchanger. I'm sure Perkins had one on the testbed out of a 200tdi Auto Discovery so i'll see if I can find out anything about what they did with the test results. When I re-fitted the 200tdi later on in life the large full width and height intercooler was far far too big for it and the response was hateful, like the propshafts were made of rubber. Dave! Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 15, 2012 Share Posted February 15, 2012 Have you measured the temperature of the air in and air out of the intercooler? How can you say the performance is 'abosutely hopeless'? Quote Link to comment Share on other sites More sharing options...
Howitzer Posted February 15, 2012 Share Posted February 15, 2012 Not measured the inlet and outlet no, but the symptoms are exactly the same as when I didn't set the chargecooler on the testbeds right, your power drops off as the boost temp rises. The fact it happily maintains the speed for a few hundred metres and then tails off until you are nearly flat to the floor. It could be pump related but imo it's heat soak. Dave! Quote Link to comment Share on other sites More sharing options...
SPendrey Posted February 15, 2012 Share Posted February 15, 2012 http://www.amazon.co.uk/SoundRacer-GH-SRV8-V8-Shelby-Cobra/dp/B0030IQK30/ref=sr_1_2?ie=UTF8&qid=1329312297&sr=8-2 These are still the best performance upgrade you can buy, although I was torn between V8, V10 or V12. Opted for V8 in the end. Quote Link to comment Share on other sites More sharing options...
RedLineMike Posted February 15, 2012 Share Posted February 15, 2012 I did the pump tweak, set the boost to 10PSI and get no full throttle smoke and managed to run to the governor in top. I've not felt that it needed more power to be honest and it managed fine towing a combined total of about 4.5 to 5 tons. I realise this is incredibly dull mind you I wonder what the heat soak issues are like on them as the standard 200tdi intercooler is absolutely hopeless. My only gripe with the engine itself. When towing on long hills it will maintain speed (The long rise on the A1M to the A14) for a short while and then despite being an even gradient, will slowly start to struggle when keeping it in 5th. I also haven't noticed much difference in performance since fitting the rad muff (Only covered a few hundred miles mind you) when it is effectively blocking the intercooler off completely, so it turns into a pressure vessel more than a heat exchanger. I'm sure Perkins had one on the testbed out of a 200tdi Auto Discovery so i'll see if I can find out anything about what they did with the test results. When I re-fitted the 200tdi later on in life the large full width and height intercooler was far far too big for it and the response was hateful, like the propshafts were made of rubber. Dave! 10psi? is it a 200 or a 300? 200 is 12psi standard & 300 is 14 psi standard Quote Link to comment Share on other sites More sharing options...
ajh Posted February 15, 2012 Author Share Posted February 15, 2012 Well, I managed to track down a compression gauge and.. yeah... front to back, 480, 490, 200, 490psi. So; tonight I'll check the valves and if needed pull the head to check the gasket/seats/worn bores. At least I have a direction now. Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted February 15, 2012 Share Posted February 15, 2012 valves are not always shut when the pistons are at the top. not on the exhaust stroke. valve overlap comes into play when actually both valves are open for a very small period of time, mainly to flush out any lingering exhaust and to help the initial flow (this one is not so important on turbocharged engines) into the cylinder. So, why do push rods and valves bend etc when timing belts break?? Quote Link to comment Share on other sites More sharing options...
elbekko Posted February 15, 2012 Share Posted February 15, 2012 Because the cam stops spinning, valves stay open, pistons keep going and hit the valves. Quote Link to comment Share on other sites More sharing options...
ajh Posted February 16, 2012 Author Share Posted February 16, 2012 Well, my problem isn't the clearances. I guess I need to remove the head and inspect the valves; my current assumption is one is damaged or the seat is carbonized. Quote Link to comment Share on other sites More sharing options...
ajh Posted February 16, 2012 Author Share Posted February 16, 2012 Well; now at least I know what the problem is. One of the valves on #3 has a crack across most of it's face. The others look like they could use a cleaning as well. Now the only question is, rebuild here or just find a used head? Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted February 16, 2012 Share Posted February 16, 2012 Because the cam stops spinning, valves stay open, pistons keep going and hit the valves. Which therefore means that during the normal 4stroke cycle on the tdi engines the exhaust valve cant be open when the piston is at the top of its stroke... Simple. Quote Link to comment Share on other sites More sharing options...
Landy-Novice Posted February 16, 2012 Share Posted February 16, 2012 no valves are open when the piston is a tdc. they close a few degrees before so they don't foul. Quote Link to comment Share on other sites More sharing options...
reb78 Posted February 16, 2012 Share Posted February 16, 2012 Well; now at least I know what the problem is. One of the valves on #3 has a crack across most of it's face. The others look like they could use a cleaning as well. Now the only question is, rebuild here or just find a used head? I would be tempted to re-build the one you have but do it thoroughly. I.e. pressure test etc first - to check if there is any other damage other than that visible on the valves. I'm sure trailerfitter has some videos on head re-builds. Have a look here: http://www.youtube.com/user/trailerfitter2?feature=mhee Quote Link to comment Share on other sites More sharing options...
discomikey Posted February 16, 2012 Share Posted February 16, 2012 So, why do push rods and valves bend etc when timing belts break?? the construction of the cam lobes define how much the valves are open at any given time. Valve overlap occurs when the exhaust valve is about halfway shut and the inlet valve is just opening and at the same rate. theyre never fully open together. Quote Link to comment Share on other sites More sharing options...
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