The Toffinator Posted September 20, 2013 Share Posted September 20, 2013 (edited) This still confuses me like... i dont see how its not 9.1? I know i have a 5e and alamo based the 9.1 on a standard 5e with a 1.0mm gasket surely fitting a 1.4 will lower it to 8.?.?When i worked mine out with alamos specs and other guides ut came out to just over 9.1 so my ratio should be high 8s, higher than most peoples 8.5.1 Edited September 20, 2013 by The Toffinator Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 Tim @ TB, hes telling me these pistons are better for starlet engines, hes working out for me now what size head gasket im going to need by doing a bit of math Quote Link to post Share on other sites
AdamB Posted September 20, 2013 Share Posted September 20, 2013 This still confuses me like... i dont see how its not 9.1? I know i have a 5e and alamo based the 9.1 on a standard 5e with a 1.0mm gasket surely fitting a 1.4 will lower it to 8.?.?This is the thing I don't know what combustion chamber volume their using, Im sure I've heard before the FHE which they have in the states is different cylinder heads, but whats different I dont know.Here it is again.CR = (CV+CCV) / CCVCR = (379.25cc + 1mm gasket + 38cc chamber volume) / (1+38)CR = 10.72:1The gasket thickness doesn't change the CR a great deal.CR = (379.25 + 1.4+38)/ (1.4+38)CR= 10.62:1I agree that these engines are low compression and could do with bumping up a bit, but I wouldn't like to go over 9:1 tbh. Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 i just want to know which head gasket to use so lower my compression a bit so i can get my car set up on the stock ecu at .8 bar! Quote Link to post Share on other sites
AdamB Posted September 20, 2013 Share Posted September 20, 2013 You can do that now, but I expect the knock sensor to be working overtime. Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 even if the timing is slightly more retarded and using higher octane fuel? Quote Link to post Share on other sites
AdamB Posted September 20, 2013 Share Posted September 20, 2013 The best thing to do is to retard the timing using det cans. Using higher octane fuel isnt possible as I would expect nothing less than 98/99 ron fuel anyway. Other solutions I would consider in your shoes is either rectify the piston problem by getting the crown machined to increase the chamber volume or run a water/ meth injection system. Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 sorry, det cans? Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 (edited) you do realise the knock sensor in standard form doesn't actually do alot it doesn't detect little bits of knock and retard the timing. In standard form it almost acts like a fuse, that will blow when it detects large numbers and this throws the ecu into a safe mode. So don't feel its "working overtime" by adjusting the timing to suit because it just doesn't I do agree with adam that this engine should be setup with a proper ecu, but i also believe this on all starlets that reach there fuel cut level because this FPR, and fuel cut defender is just bodge tuning. I wouldn't take your current setup as bullet proof either as you said yourself you've cracked 3 pistons. I've been running 200bhp on my standard engine starlet for over 75,000miles now and its never missed a beat.....Why because its properly setup with a power fc ecu tuned for the modfications i have. But anyway back to the compression ratio. The wiesco pistons have a static compression ratio of 9.0:1 out the box calculated from a 1.0mm head gasket. Any increase from this size is going to lower the compression ratio. If my engine was to blow in its current 8.2:1 CR state (which by even turbocharged terms is very low) i would upgrade to a 9.0:1 setup and tune from there, this is going to give much better response off boost and a nicer smoother engine to drive and under 200bhp you won't have any issues. For example on the 3sgte engines we do under 400bhp we run those at 9.0:1 and the only reason we drop it above that is to give the block some stress relief because they are known to crack, which the 4e doesn't suffer from. Hell we even ran a 850bhp drag car at 10.0:1 at 2.2bar of boost on a gt4094 turbocharger and ran fine until it cracked the block. If the block was stronger this would have been as awesome setup. TimTB Developmentsps, det cans are a listening device that all mappers should use when mapping your car, this allows them to hear the early signs of detonation (pinking) and increase fuel or reduce the timing. Edited September 20, 2013 by TBDevelopments Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 thanks tim, did you calculate the gasket size in the end? didnt get a text back from you thats all Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 not yet, there is alot more to calculating CR that just punching in numbers. Really the parts want CC'ing to work out correctly. Bore and stroke we know. But the head gasket thickness is a variable But need to know head gasket bore (as there bigger than the 74mm piston bore)Need to know exactly the CC of the cylinder head (these do change between engines,and even seen differences from one side of the engine to the other)Need to know exactly CC of the piston valve recessNeed to know exactly the piston face below the deck height from a dial gauge information I can't really get from just looking on the internet, race building involves doing this with equipment i have in the workshop. From that I can work you out some accurate numbers But they are designed with a 9.0:1 ratio at 1.0mm gasket. Last time i installed them this was about correct. so fitting the 1.4mm gasket you already have is going to bring it into the high 8's Personally i'd just get a proper ecu setup so it can all be setup correct and just keep them at 9.0:1. I'm going out on a limb here but i'm guessing you won't be exceeding more than 1.3bar on pump fuel anyway? TimTB Developments Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 i wont be exceeding 1.3 bar ever probably, its my daily I only planned on running it at 0.8 bar due to the stock ecu, a standalone + mapping is way out of my reach from a financial point of view at the moment, if i was to run a 1.9 gasket, roughly what would that bring the comp down to do you reckon? Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 i'm speaking my wiesco contact at the moment in america and trying to find out the manufacturing specifications used when they were built. From that i can work out a rough compression ratio and then change the gasket thickness around to get something. what i do need is a bore diameter from you of the head gasket your going to be using TimTB Developments Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 well the gasket will be an Athena, 1.4 or 1.9 havnt decided yet obviously down to working out what thickness I need Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 again mate should have said could have had a nice cometic one added to the piston order ;) Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 I wasnt really aware back then that Id be going through all of this, same goes with the rods really surely the gasket bore would be just over 75 by a guess? seeing as they fit the over sized pistons Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 not always mate, 3sgte for example are 86mm piston bore and the gaskets come in 88mm Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 thats why i said at a guess when you reckon youll know by for the thickness? just so i can let Idrees know about what gasket to send me cause ive sent my 1.2mm back to him today in exhange for a thicker one Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 ok going on some really rough numbers nere. guessing on alot of things Bore 74mmStroke 77.4mmHead Gasket - VariableHead Gasket Diameter 76mmPiston to Head Depression 0ccCombustion Chamber 39ccPiston Dome CC (set at 0cc because i don't know valve relief so this will give a lower reading once i know this) 1.0mm Gives 9.00:11.2mm Gives 8.83:11.4mm Gives 8.68:11.7mm Gives 8.45:11.9mm Gives 8.31:1 Remember these will drop once i know the CC of the piston dome and valve relief. like i said some really rough numbers TimTB Developments Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 read the text i sent you last, it has all the details of the pistons for the valve pockets etc Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 that was just machining specs of the angle of the valve cut etc doesn't really give me piston relief CC Personally i'd just go with the 9.0:1 and stick an emanage on there. If you've cracked 3 pistons on your old engine then there was something seriously something wrong with your setup. Like i said i've run my blitz K1 at 1.1bar at 200bhp for the last 70,000miles and its never missed a beat, this is because its all setup properly on bog standard engine internals. Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 the ringlands went, the engine had done 105k miles and had never been rebuilt, except having headgasket replacement but all else was standard, i was running .8 bar on it was ages, decided to turn it up to a bar and ran it for a few days and thats when it happened when i was flat out down the motorway at just over 140mph for about a minute lol Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 ringlands only normally go on these engines because of leaning out or detonation... This basically points to it not been setup up correctly i'm afraid buddy right i'm off to bed, have some fun with those numbers, you have my number if you need me Quote Link to post Share on other sites
EPnick22 Posted September 20, 2013 Author Share Posted September 20, 2013 im off to sleep too, could you let me know tomorrow if you find out which gasket is best for me please, wanna aim to be running as near to how it was before Quote Link to post Share on other sites
TBDevelopments Posted September 20, 2013 Share Posted September 20, 2013 numbers and thickness's on the first page mate. Valve relief won't make a huge different 0.1 point at most TimTB Developments Quote Link to post Share on other sites
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