maurice Posted March 8, 2012 Share Posted March 8, 2012 hi , I have found a simple way to increase the performance of the 250t and all other subarus , the crank cam belt timing sprocket is only made from mild steel and you can re-cut the keyway slot with a flat file to your advanced spec for your fuel ...and weld a blob on the key with a mig welder and file to suit and ovoid contact with the generator pullys and there you have it , instant horspower gains and improve fuel economy , yes you will have to lower the engine idle , I'm very happy to pass any help to those who need any help ...just be carfull filling , 2.5 mm to 3.5 mm max ...mines set at 2.5 mm advance get a spare sprocket and modify that one so you still have the orignal ...and reset your ecu and happy motoring Link to comment Share on other sites More sharing options...
danbennett2u Posted March 8, 2012 Share Posted March 8, 2012 Doesnt that only affect your valve timing not your fuel timing? I mean ignition timing... actually I dont know what I mean. I wouldnt call that simple either... at least not to me it isnt. Link to comment Share on other sites More sharing options...
WoodsWagon Posted March 8, 2012 Share Posted March 8, 2012 The crank and cam sensors read off those sprockets, so it advances the ignition timing as well. Link to comment Share on other sites More sharing options...
danbennett2u Posted March 8, 2012 Share Posted March 8, 2012 oh ok, I see. so you are changing your valve and ignition timing at the same time right? Link to comment Share on other sites More sharing options...
WoodsWagon Posted March 9, 2012 Share Posted March 9, 2012 Yeah, but advancing cams usually helps low end at the expense of top so it probably feels more punchy at low rpms. Link to comment Share on other sites More sharing options...
Ricearu Posted March 9, 2012 Share Posted March 9, 2012 unless I am doing full megasquirt, and race tune, I leave most of that stuff to the million dollar engineers at fuji heavy industries. I don't mind delta cams, but they aren't meant for everyone. there is lots of r&d in those cams too. Link to comment Share on other sites More sharing options...
maurice Posted March 9, 2012 Author Share Posted March 9, 2012 The crank and cam sensors read off those sprockets, so it advances the ignition timing as well. yes thats the idear , so the ecu still thinks nothing has happened , but the ignition timing is advanced to your setup Link to comment Share on other sites More sharing options...
maurice Posted March 9, 2012 Author Share Posted March 9, 2012 oh ok, I see. so you are changing your valve and ignition timing at the same time right? I put a new cambelt in for the quad cam engine at the same time , so the cams are set correct ...only changing the ignition timing Link to comment Share on other sites More sharing options...
Rooster2 Posted March 9, 2012 Share Posted March 9, 2012 Will advancing the timing affect passing smog testing? Link to comment Share on other sites More sharing options...
maurice Posted March 9, 2012 Author Share Posted March 9, 2012 Will advancing the timing affect passing smog testing? my car still has all its standard exhaust setup from behind the engine , so it should read less poluting carbon emitions with a improved flame speed in the combustion chambers ...the car gets off its arse without heaps of throtle down low and uptop Link to comment Share on other sites More sharing options...
Ricearu Posted March 9, 2012 Share Posted March 9, 2012 Will advancing the timing affect passing smog testing? I really don't mean to be a stick in the mud, but if it can pass emissions, have subaru known longevity, and all be fine and dandy, don't you think the engineers would have simply advanced the timing on the cams? hmmmm. let me know when you burn a hole in a piston, or burn a valve. the computer cannot tune out the advanced cam timing, and can only tune out so much advanced spark timing. Do you know what spark knock or lean burn condition is? both lean engines and super advanced timing make GOBS of power, til something fails. save this advice for hondatech. they make adjustable cam gears so anyone can break their honda engines. check ebay. Link to comment Share on other sites More sharing options...
bheinen74 Posted March 9, 2012 Share Posted March 9, 2012 I really don't mean to be a stick in the mud, but if it can pass emissions, have subaru known longevity, and all be fine and dandy, don't you think the engineers would have simply advanced the timing on the cams? hmmmm. let me know when you burn a hole in a piston, or burn a valve. the computer cannot tune out the advanced cam timing, and can only tune out so much advanced spark timing. Do you know what spark knock or lean burn condition is? both lean engines and super advanced timing make GOBS of power, til something fails. save this advice for hondatech. they make adjustable cam gears so anyone can break their honda engines. check ebay. true with everything you have said, including the Honda bits. Link to comment Share on other sites More sharing options...
maurice Posted March 13, 2012 Author Share Posted March 13, 2012 Yeah, but advancing cams usually helps low end at the expense of top so it probably feels more punchy at low rpms. my car drove like a pice of crap befor I changed the timing , so its hard to tell , if I lost any top end , and with changing the exhaust to that of a 1991 and repacing a faulty air meter 22680 AA160 , top end is still there , its just quicker to get there , and harder to keep at the speed limit with it wanting to go and go Link to comment Share on other sites More sharing options...
maurice Posted March 13, 2012 Author Share Posted March 13, 2012 true with everything you have said, including the Honda bits. ok I will keep everyone informed on my engine and how long it lasts for ...I have a spare cam sprocket that I'm retarding the camshaft key to keep the cam timing close to original spec as possible....and it too! is made from mild steel and can be filed by hand Link to comment Share on other sites More sharing options...
ivans imports Posted March 13, 2012 Share Posted March 13, 2012 iv'e seen offset ground cam pins somting to same efect not shure if it worked though. Link to comment Share on other sites More sharing options...
maurice Posted March 15, 2012 Author Share Posted March 15, 2012 iv'e seen offset ground cam pins somting to same efect not shure if it worked though. I can make my own pins and theres no point buying anything when the pin hole can be moved easy with a chainsaw file Link to comment Share on other sites More sharing options...
maurice Posted March 15, 2012 Author Share Posted March 15, 2012 true with everything you have said, including the Honda bits. one of the problems with electronic ignition systems is there is no way to adjust the timing to make up for poor feul quality ....and with old school , if you have highoctane fuel , you retard the timing and with low octane fuel you advance the timing ...but we dont have the same fuel as in Japan , what we have is not real fuel , its a cheap copy made to hit eveyone in the pocket $$$ and with ignition timing set for good fuel , our cars will only drink more to make up the power loss and give you very poor miles per gallon or klms per litre..... Link to comment Share on other sites More sharing options...
Ricearu Posted March 15, 2012 Share Posted March 15, 2012 you are wrong. to advance ignition timing, you must run high octane fuel to prevent detonation. The electronic (computer controlled) ignition advances itself as far as it can until detonation is detected. my old legacy had a bad knock sensor and ran like a dog. I thought I would be smart and install a 560k ohm resistor in place of it to get the power back, and with premium fuel, the first thing the computer did was advance the crap out of the timing and it ran like a scalded dog. It detonated like a bish too. I removed that thing real quick and bought a knock senso. The computer looks for detonation as a limit for ignition timing. this is all automatic, every drive cycle. I am not saying that you shouldn't experiment, but don't come on here and tell every open minded individual that they can squeeze power out of it by modifying it. the ignition timing is set by the crank position sensor, all you are doing is modifying the valve timing to lean the engine out. the computer cannot tune out your modifications, so if it takes your engine out then that is your own fault. Link to comment Share on other sites More sharing options...
maurice Posted March 17, 2012 Author Share Posted March 17, 2012 you are wrong. to advance ignition timing, you must run high octane fuel to prevent detonation. The electronic (computer controlled) ignition advances itself as far as it can until detonation is detected. my old legacy had a bad knock sensor and ran like a dog. I thought I would be smart and install a 560k ohm resistor in place of it to get the power back, and with premium fuel, the first thing the computer did was advance the crap out of the timing and it ran like a scalded dog. It detonated like a bish too. I removed that thing real quick and bought a knock senso. The computer looks for detonation as a limit for ignition timing. this is all automatic, every drive cycle. I am not saying that you shouldn't experiment, but don't come on here and tell every open minded individual that they can squeeze power out of it by modifying it. the ignition timing is set by the crank position sensor, all you are doing is modifying the valve timing to lean the engine out. the computer cannot tune out your modifications, so if it takes your engine out then that is your own fault. in my country we dont have highoctane fuel , its all crap , my cars running great , there's no nocking or anything , temps good , it good on fuel no no matter how much I stand on it ..I never said I was the top dog here , just if you have nothing to lose , it dosnt hurt to try something , my other car run for years on more advance than my latest one ..the old colin mcrae derek ringer car .....I'm only advancing the crank and not the camshaft , I know the difference ...what Im saying is this stuff can be moded with simple hand tools Link to comment Share on other sites More sharing options...
maurice Posted April 4, 2012 Author Share Posted April 4, 2012 just a wee note to update things , I'm still having good fuel savings of just over a third and every things fine Link to comment Share on other sites More sharing options...
Fairtax4me Posted April 4, 2012 Share Posted April 4, 2012 if you have highoctane fuel , you retard the timing and with low octane fuel you advance the timing Like Ricearu said, this is backwards. Advanced ignition timing requires higher octane fuel to prevent detonation. The change in cam shaft position compared to crankshaft position with this type of mod is minimal, only 1 or 2 degrees if that, but should increase power slightly in the mid to high rpm range. It's interesting though. I may try it sometime with my project legacy and try to compare some numbers with my scanner; stock vs modded crank sprocket. Link to comment Share on other sites More sharing options...
maurice Posted April 5, 2012 Author Share Posted April 5, 2012 Like Ricearu said, this is backwards. Advanced ignition timing requires higher octane fuel to prevent detonation. The change in cam shaft position compared to crankshaft position with this type of mod is minimal, only 1 or 2 degrees if that, but should increase power slightly in the mid to high rpm range. It's interesting though. I may try it sometime with my project legacy and try to compare some numbers with my scanner; stock vs modded crank sprocket. ....we all make misstakes , the petrol we have here , smells more like paint stripper and actone ,and has no lead , and you have to keep an eye on hoses that they havent melted....with the advance , the idle has to be lowered but the main one is the crank sprocket triggers and the number one cam triggers are in the right position so the computer thinks nothing has changed , the nock sensor takes care of to much advance and shows that is working .... Link to comment Share on other sites More sharing options...
Ricearu Posted April 6, 2012 Share Posted April 6, 2012 i may try it sometime myself, with a megasquirt project motor. Link to comment Share on other sites More sharing options...
Fairtax4me Posted April 6, 2012 Share Posted April 6, 2012 ....we all make misstakes , the petrol we have here , smells more like paint stripper and actone ,and has no lead , and you have to keep an eye on hoses that they havent melted....with the advance , the idle has to be lowered but the main one is the crank sprocket triggers and the number one cam triggers are in the right position so the computer thinks nothing has changed , the nock sensor takes care of to much advance and shows that is working .... I don't know of anywhere that still allows leaded gas in cars (maybe Cuba?). AvGas has it, but you can't just drive up and pour that in the tank. I know what you mean about gas smelling cheap these days. We get the 10% ethanol stuff here and it smells like rotgut corn liquor. Link to comment Share on other sites More sharing options...
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