Robert Posted August 23, 2009 Share Posted August 23, 2009 Hi, Im currently tuning my L24E turbo engine. Stock engine with a std turbo manifold, T04E turbo with .63 exhaust house, 3" exhaust and intercooler.. Now, when tune my cars (on road), I generally empty 2nd and 3rd to tune the high RPM range (datalog tuning).. But in later stages of the tuning, and when Im fine tuning the ignition map, I generally empty 2nd, 3rd, and if that works great I do it a couple of more times just for the extra data.. But what I found is that when I come to 3 gear for the second time, I get SEVERE knock! I did not put to much to it, but It does not look like its a timingAF issue.. So my question for the L experts is if there are any parts on the cyl head that get hot enough to cause severe knock in just a couple of hard runs? I didnt put to much time in tuning it away like I said, but retarding the timing didnt help much.. My next move is to connect the intake air temp sensor and see what that can tell me. If the temps rise enough, Ill try a air temp timing retard.. Oh, timing is currently 36 degrees at WOT (0), and ~8 degrees at ~24 PSI (260 KPA) where the knock takes place. Dont suggest the following: Spark plugs are cold. AFs are high 11s I have a intercooler Engine coolant is ~85 degrees C And for everything good in the world, dont come with "let a company do the tuning" stuff, lets stay on topic. Quote Link to comment Share on other sites More sharing options...
zcar? Posted August 23, 2009 Share Posted August 23, 2009 cyl #5 gets hot spots there is a thread about it. http://forums.hybridz.org/showthread.php?t=125186 good luck Quote Link to comment Share on other sites More sharing options...
Robert Posted August 23, 2009 Author Share Posted August 23, 2009 cyl #5 gets hot spots there is a thread about it. http://forums.hybridz.org/showthread.php?t=125186 good luck Great, thanks, I though the megasquirt (or me) was going insane Quote Link to comment Share on other sites More sharing options...
kolonelklink87 Posted August 23, 2009 Share Posted August 23, 2009 connecting that manifold air temp sensor is definately a good idea - you need to quantify your intake air temps to be able to know how effectively you are bringing them down. Then you can experiment with different combinations of exaust wrap and head sheilding intercooling etc. I'm running high comp on my l26 n/a and had ALOT of problems with det-moments... running like a dream now - insulate insulate insulate. Quote Link to comment Share on other sites More sharing options...
Robert Posted August 24, 2009 Author Share Posted August 24, 2009 connecting that manifold air temp sensor is definately a good idea - you need to quantify your intake air temps to be able to know how effectively you are bringing them down. Then you can experiment with different combinations of exaust wrap and head sheilding intercooling etc. I'm running high comp on my l26 n/a and had ALOT of problems with det-moments... running like a dream now - insulate insulate insulate. Hi, well actually you can get a long way without connecting it, the IAT temps dont get very high with an fairly efficient intercooler.. the reson I have not connected it yet is simply that Ive been a bit lazy But how can heat shielding and exhaust wraping help me? If you have some good tips and ideas there, Id love to hear them! This is car is built for track days, not drag races, so I need to get this knocking out of the way : Quote Link to comment Share on other sites More sharing options...
Robert Posted August 24, 2009 Author Share Posted August 24, 2009 Im reading myselfes to death in this "cyl5 thread". Someone should moderate it and add a conclution in the end... zzz Quote Link to comment Share on other sites More sharing options...
Robert Posted August 24, 2009 Author Share Posted August 24, 2009 So a note to myselfe and maybee others on the cooling issue: The musts or "DuÙH"s: Premium fuel, highest possible octane A cold thermostat or none at all <<-- Im thinking of removing the core in mine, leaving a "constant open high flow" thermostat. The easy mods: Water wetter -- http://www.summitracing.com/parts/RED-80204?autofilter=1&part=RED%252D80204&N=700+115&autoview=sku Higher pressure radiator cap Octane booster (expensive!) More advanced: RD28 water pump with large impeller Only for the extreme: Tap into the cyl heads #4 #5 #6 with seperate water lines to increase flow around #5 Reverse flow of the coolant Quote Link to comment Share on other sites More sharing options...
wigenOut-S30 Posted August 24, 2009 Share Posted August 24, 2009 From what I have found. A thermostat is needed. If you run with out one, the water doesn't stay in the block long enough to transfer the heat and then goes through the radiator too fast and doesn't cool correctly. What Octane fuel are you running when boosting 24psi? That seems like a awful lot of boost on pump gas if you are not running meth or some other type of injection. Quote Link to comment Share on other sites More sharing options...
Robert Posted August 24, 2009 Author Share Posted August 24, 2009 From what I have found. A thermostat is needed. If you run with out one, the water doesn't stay in the block long enough to transfer the heat and then goes through the radiator too fast and doesn't cool correctly. What Octane fuel are you running when boosting 24psi? That seems like a awful lot of boost on pump gas if you are not running meth or some other type of injection. Hi, Yea I thought of that, but I figured if you remove everything and leave the metalplate in there as a "braeak", it should work as a fully open high flow thermostat.... ? Im running 98 RON, I think its about the same as 94 premium in the US? But with full ignition control, the octane dont matter to much, unless you have a bloody hot spot in the cylinder head Quote Link to comment Share on other sites More sharing options...
kolonelklink87 Posted August 24, 2009 Share Posted August 24, 2009 Hi, ...But how can heat shielding and exhaust wraping help me? If you have some good tips and ideas there, Id love to hear them!... : My point was that at this point you're assuming that your intake temps are fine because you're running an intercooler... however, without an IAT am i correct in thinking you don't have numerical confirmation of this assumption? because intercooling is not done *right* before the air enters the cylinders you can of course pick up heat prior to this point (which is where your engine cooling comes into play). The cooler your intake piping, manifold, runners and head the less the preheating on the air will be and the cooler it will be by the end of the compression stroke. This may not be necessary depending on what your IAT/MAT tells(i prefer to take temp inside the manifold) you but keeping the IAT down does have the added benefit of increasing air density per given pressure value thus adding power. If you have the opportunity to modify coolant flow to the head then go for it! I was merely attempting to point out that it is also very important to know what your intake temperature is doing. On a side note... 24psi seems quite serious. some background on the build? supporting headwork etc? -pete Quote Link to comment Share on other sites More sharing options...
Robert Posted August 24, 2009 Author Share Posted August 24, 2009 Well the thing is, this dont "feel" like IAT problems. they generally come on slow tracks, after several laps, or in very high temperatures. Here, the problems come after a couple of hard runs.. As if a plug is to warm or something.. The build: Stock L24E Megasqurt 440cc injectors Walbro pump Stock FPR, but modified rail for higher pressure and better flow Intercooler T04E turbo 300+ BHP (gut feeling) *edited* Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 24, 2009 Share Posted August 24, 2009 Premium fuel, highest possible octane A cold thermostat or none at all <<-- Im thinking of removing the core in mine, leaving a "constant open high flow" thermostat. I'd say flow restrictor at a minimum, but that is for continuous high-rpm usage, for street usage the variable flow capabilities of a thermostat are critical I would not run without one The easy mods: Water wetter -- http://www.summitracing.com/parts/RE...5&autoview=sku Higher pressure radiator cap Higher pressure cap should not be underestimated, it really helps, but beware of your under-dash hoses and heater core if you go to the extremes... Octane booster (expensive!) More advanced: RD28 water pump with large impeller LD28 Pump, I don't know if the RD series pump works, but in the #5 cooling thread it discusses the LD Pump, and they are scarce as hens' teeth Only for the extreme: Tap into the cyl heads #4 #5 #6 with seperate water lines to increase flow around #5 It is more to increase the flow in the slowest/lowest flowing portion of the head, and goes together with some other modifications, but as a standalone mod can help with lowering the affected combustion chamber cooling temperature... Reverse flow of the coolant some might call it extreme, some might call it 'common sense'---who puts the hottest coolant on the hottest part of the heat source? Putting cold water in there would seriously cool the head better, and help with cylinder taper and block warming during startup...as discussed... If you run hard, and then drop back and see AFR problems, I'd look at fuel pressure/fuel delivery issues first. The heat may be having some effect, but if it ran before and then you see AFR changes that says you got fuel delivery issues which need to be addressed. It's like a SBC Chevy that runs fine all around town when your dad drives it...but when you lock it in low and do 50, you notice surging over 35mph. Do some checking, find a clogged fuel filter! Fix it, and get a ticket for making those 85mph pulls in second to 'see if there is any other fuel delivery problems inherent in the system'... A plug being to warm may indeed be an issue, NGK 7's, or 8's should be in there, and for dyno runs and hard pulls for tuning 9's may not be out of the question! Burning a hole in the piston sucks, cold plugs only misfire when they foul. Hot ones do bad things... Quote Link to comment Share on other sites More sharing options...
Robert Posted August 24, 2009 Author Share Posted August 24, 2009 If you run hard, and then drop back and see AFR problems, I'd look at fuel pressure/fuel delivery issues first. The heat may be having some effect, but if it ran before and then you see AFR changes that says you got fuel delivery issues which need to be addressed. It's like a SBC Chevy that runs fine all around town when your dad drives it...but when you lock it in low and do 50, you notice surging over 35mph. Do some checking, find a clogged fuel filter! Fix it, and get a ticket for making those 85mph pulls in second to 'see if there is any other fuel delivery problems inherent in the system'... A plug being to warm may indeed be an issue, NGK 7's, or 8's should be in there, and for dyno runs and hard pulls for tuning 9's may not be out of the question! Burning a hole in the piston sucks, cold plugs only misfire when they foul. Hot ones do bad things... Thanks for the summary, lots of great info in a small place As for AFfuel delivery, I have no problems there anymore. As discussed in another thread, I maxed my injectors earlier, this got resolved with a "cowboy" increase of fuel pressure, and a new filter.. The plugs are Denso with NGK7 heat range. I used NGK 9s in teh beginning, but they where to cold, and I had to burn them clean every time I started the engine.. I am considering to put them back in now at this late stage of tuning, just to check. But I recall having the same problems in when they were in, but that was in the starting phase of tuning, so I never linked it to anything other then AFRtiming issues. Before any further tuning, a water wetter, no core thermostat and high pressure cap will be installed. Ill tell you how that worked for me! Quote Link to comment Share on other sites More sharing options...
Robert Posted August 24, 2009 Author Share Posted August 24, 2009 Premium fuel, highest possible octaneA cold thermostat or none at all <<-- Im thinking of removing the core in mine, leaving a "constant open high flow" thermostat. I'd say flow restrictor at a minimum, but that is for continuous high-rpm usage, for street usage the variable flow capabilities of a thermostat are critical I would not run without one If I remove the core, there will be a restrictor... This car is used on street as well, but Its built to outrun cars with many times the budget on the tracks, simply to show the Nissans superiority, and for fun, LOTS of fun! Nothings like a sleeper! Anyways, Ill see how a no core thermostat works, and get back to you. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 25, 2009 Share Posted August 25, 2009 If you're running over 10psi with a stock L24E you might be running out of octane if you run 93. Quote Link to comment Share on other sites More sharing options...
Robert Posted August 25, 2009 Author Share Posted August 25, 2009 If you're running over 10psi with a stock L24E you might be running out of octane if you run 93. But theres no knock until Ive emptied a few gears and made it hot and nice in the cylinders, so the octane is good until something, somewhere gets hot.. With good cooliong I could, If I for some stupid reason wanted to, run a lower octane, Id just need to lower the ignition timing. Oh, and remember 25PSI on a medium size turbo is not the same as on a large one. HP is not much over 300 BHP. I think. Heheh:) Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 25, 2009 Share Posted August 25, 2009 I would seriously consider drilling the extra coolant holes above#4, #5, and #6, and manifolding them to the thermostat housing, along with water wetter and a 165F thermostat. Quote Link to comment Share on other sites More sharing options...
dapiper Posted August 27, 2009 Share Posted August 27, 2009 There you go man. You may be running too small turbo for the boost level and it is heating the intake air and/or imposing too much back press and heating the exhaust. Look at your compresor map. Measure your turbine back press. You can open your exh to remove some back press. What is your exh back press? Quote Link to comment Share on other sites More sharing options...
Robert Posted August 27, 2009 Author Share Posted August 27, 2009 There you go man. You may be running too small turbo for the boost level and it is heating the intake air and/or imposing too much back press and heating the exhaust. Look at your compresor map. Measure your turbine back press. You can open your exh to remove some back press. What is your exh back press? Maybe. But after emptying the 3 gear second time (when knock comes), the pipes are`nt even beginning to glow.. So I dont think its that easy, and I wont be doing any pressure testing. Ive got a T3 .63 housing. Quote Link to comment Share on other sites More sharing options...
yetterben Posted August 27, 2009 Share Posted August 27, 2009 Put the damn iat on there. If you're to lazy to do that that than your to lazy for anything. Seriously dude you cant take advice and say that's not it if you have not tried it. After a few hard pulls under hood temps probably just increased 50 degrees or more. Quote Link to comment Share on other sites More sharing options...
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