TurboSPFI Posted August 14, 2005 Share Posted August 14, 2005 Just wondering if anyone has like a spark map? needed to advance retard timing from the disty... when i had my timing tweaked, it feels like i have more low end power, but it also seems like i have gained it from the top end... the top end isnt has peppy as before and the low end is peppier... anyway i can meet it somewhere in the middle? it literally feels like im driving a diesel right now with all my power in the 1-3k rpm range.. Link to comment Share on other sites More sharing options...
NorthWet Posted August 14, 2005 Share Posted August 14, 2005 AFAIK, the ignition map is stored in the ECU, also AFAIK noone has "hacked" the ECU to develop different ROMs that would change the ignition and/or fuel maps. Link to comment Share on other sites More sharing options...
TurboSPFI Posted August 14, 2005 Author Share Posted August 14, 2005 maybe i worded something incorrectly, ill try again.. what does retarding/advancing do to my low end/top end? advance = more low end less top end? retard = less low end more top end? left = retard? right = advance? Link to comment Share on other sites More sharing options...
NorthWet Posted August 14, 2005 Share Posted August 14, 2005 Ignition timing does not add or subtract power. Proper timing optimizes power, while improper timing detracts from it. What you want is the PROPER amount of ignition advance for the engines current situation, and the manufacturer produces a "map" of what timing works OK for certain conditions of engine speed and load. This map is conservative, attempting to avoid detonation. A long winded way of saying that if you change the "base timing" (the tune-up timing spec), then it just shifts the map and you won't know what it will do unless you try it. To plant a seed of controversy: An "ideal" engine would require 0deg of ignition advance. Link to comment Share on other sites More sharing options...
TurboSPFI Posted August 14, 2005 Author Share Posted August 14, 2005 Lemme get back to you on this.. Link to comment Share on other sites More sharing options...
NorthWet Posted August 14, 2005 Share Posted August 14, 2005 BTW, I don't recall reading anything about how you are handling detonation issues with your turbo. Do you have anything that modifies spark timing (doubt it with an SPFI ECU), reduces boost pressure, or enriches or injects a suppressant? Link to comment Share on other sites More sharing options...
TurboSPFI Posted August 15, 2005 Author Share Posted August 15, 2005 Just wondering if anyone has like a spark map? needed to advance retard timing from the disty... Ok, I asked for a set of maps... BTW, I don't recall reading anything about how you are handling detonation issues with your turbo. Do you have anything that modifies spark timing (doubt it with an SPFI ECU), reduces boost pressure, or enriches or injects a suppressant? @ 8 psi it does fine, anything 11 psi or higher I quickly go lean.. Had a pretty nasty pinging issue at first that was cured by buying better gas. I think the 9.5:1 compression ratio definately helped make the headgaskets blow.. Oh, and theres no fuel cut that I've experienced.. There are no pressure switches under the hood (I think this is why I dont have boost cut, not sure yet) Link to comment Share on other sites More sharing options...
MorganM Posted August 15, 2005 Share Posted August 15, 2005 Nobody has the maps. Use the premapped system to your favor. As Northwet has said; you set the baste timing and ride the map to see how it works for you. Adjust base timing untill it behaves how you want it; optimized power but no predetination. Link to comment Share on other sites More sharing options...
NorthWet Posted August 15, 2005 Share Posted August 15, 2005 ... @ 8 psi it does fine, anything 11 psi or higher I quickly go lean.. Why do you believe that it is going lean? (Entirely possible, running around 50% more air mass...) If it is not really going lean, you might consider an intercooler to control detonation. And since it was not designed to be supercharged, I doubt that the ECU is set up to do any fuel cut. Link to comment Share on other sites More sharing options...
MorganM Posted August 15, 2005 Share Posted August 15, 2005 Why do you believe that it is going lean? The SPFI system can only compensate for so much added air mass. Just one little injector in the TB; I bet the MAF will read more air than the injector can even keep up with. I bet it screams with 8-10 PSI boost; does it need more? Nevermind... of course it needs more boost! Link to comment Share on other sites More sharing options...
TurboSPFI Posted August 15, 2005 Author Share Posted August 15, 2005 Umm.. on the lean subject, its simple, I have one injector, MPFI has 4. The MAF isnt effected... its stupid.. and.... i THOUGHT that the SPFI and MPFI computers were the same. Link to comment Share on other sites More sharing options...
NorthWet Posted August 15, 2005 Share Posted August 15, 2005 Umm.. on the lean subject, its simple, I have one injector, MPFI has 4... Many Detroit V8s only have one and they flow a lot more than my 4. Apples and oranges. If it were apples and apples, your car could only make, say 40-50HP, or WJMs could make 500 before worrying about injector capacity. ... The MAF isnt effected... its stupid... I believe that the implication was that the MAF is similar in flow capacity to the MPFI/Turbos and it could flow/meter more air than the SPFI injector could add fuel to. ...and.... i THOUGHT that the SPFI and MPFI computers were the same. They might be, but I haven't read anything that would indicate to me that they are. Your argument about one injector vs 4 would mitigate against them being the same: Different injector signal requirements, different mapping. I would try to avoid assuming it is lean unless you had some indication it was lean (sparkplugs, injector signal "maxed out", etc). Link to comment Share on other sites More sharing options...
ausubaru92 Posted August 16, 2005 Share Posted August 16, 2005 This is kinda a hijack, but I was told that i couldn't put a turbo on a NA mpfi because the ECU wouldn't allow for the extra fuel needed under boost and I would end up cooking my motor. Doesn't the ECU meter fuel proportional to MAF intake and use the o2 sensor to tweak the mixture? Sooooo TurboSPFI,..... How does your ECU handle the boost and allow the extra fuel???? Because if u can do it,... maybe there is hope for my NA compression - low boost motor yet:brow: End of Hijack Gannon Link to comment Share on other sites More sharing options...
NorthWet Posted August 16, 2005 Share Posted August 16, 2005 This is kinda a hijack, but I was told that i couldn't put a turbo on a NA mpfi because the ECU wouldn't allow for the extra fuel needed under boost and I would end up cooking my motor. Doesn't the ECU meter fuel proportional to MAF intake and use the o2 sensor to tweak the mixture? Sooooo TurboSPFI,..... How does your ECU handle the boost and allow the extra fuel???? Because if u can do it,... maybe there is hope for my NA compression - low boost motor yet:brow: End of Hijack Gannon Hi, Jack! The ECU while in closed-loop mode should continue to produce a proper mixture up to the limits of its injector(s) and its fuel mapping. The ECU in the turbo models uses a pressure switch to tell it that there is positive boost, at which time it goes open-loop and uses a fairly rich portion of the fuel map. I very much like the idea of boosting a NA engine. Not so much to produce monster mid-range torque, but to extend the torque curve beyond where it would normally fall off. Bye, Jack! Link to comment Share on other sites More sharing options...
TurboSPFI Posted August 16, 2005 Author Share Posted August 16, 2005 Many Detroit V8s only have one and they flow a lot more than my 4. Apples and oranges. If it were apples and apples, your car could only make, say 40-50HP, or WJMs could make 500 before worrying about injector capacity. True, this is basically the reason I decided to try to turbo an spfi setup. I have seen plenty of Chevy 350's that have TBI have a supercharger on them, with mild tuning, everything ran fine. I also figured, hey, if I dont have enough fuel, there are people adding auxilary injectors that are turned on at a certain pressure via pressure switches... I was told that i couldn't put a turbo on a NA mpfi because the ECU wouldn't allow for the extra fuel needed under boost and I would end up cooking my motor. Its not that, its the injector I believe. Just cant spray enough fuel to match say... 13 psi or whatever. Too much boost = too lean of a condition, which after a while will melt your pistons.. get yourself an A/F gauge and watch it like a hawk. There is enough fuel there for about 6 psi, @ 8, it starts leaning out toward the higher RPMS.. Doesn't the ECU meter fuel proportional to MAF intake and use the o2 sensor to tweak the mixture? Yup, extra boost = extra air... even coming out of the cylinder after ignition.. o2 sensor picks up that extra oxygen and increases the amount of fuel it delivers. Link to comment Share on other sites More sharing options...
TurboSPFI Posted August 16, 2005 Author Share Posted August 16, 2005 Grr, I just replied and the net messed up... I'll reply later. (LOL, I posted this and my reply came up.. stupid computer ) Link to comment Share on other sites More sharing options...
ausubaru92 Posted August 17, 2005 Share Posted August 17, 2005 Ok thanks, thats good info I was only planning low boost, say 5psi. What are your opinions on the cams,.. do you have turbo ones or do you use the spfi and suffer from 'blow-by' I assume there is nothing on a 89 MPFI ecu to tell it that it is under boost? Thanks guys Jack:rolleyes: (Gannon) Link to comment Share on other sites More sharing options...
MorganM Posted August 17, 2005 Share Posted August 17, 2005 It's not just the O2 sensor; O2 sensor isnt even recognized untill closed loop is initiated. It's a compilation of data from the MAF, TPS, O2 sensor, and water temp sensor that tells the ECU how much fuel to add. To answer your question; yes the SPFI system will compensate for the added air of a turbo. Upto a point however. As TurboSPFI has noted; thats about ... what... 10psi ? Since you got pinging at 11psi? 8psi sounds like a resonable way to keep reliable boost on an EA82 SPFI engine. Link to comment Share on other sites More sharing options...
TurboSPFI Posted August 17, 2005 Author Share Posted August 17, 2005 What are your opinions on the cams,.. do you have turbo ones or do you use the spfi and suffer from 'blow-by' stock everything... no blowby.. SPFI cams. It's not just the O2 sensor; O2 sensor isnt even recognized untill closed loop is initiated. It's a compilation of data from the MAF, TPS, O2 sensor, and water temp sensor that tells the ECU how much fuel to add. We're talking about closed loop here.. I could have explained open loop, closed loop, accel, decel or limp mode if I had to, but there was no need. 90% of your sensor values are based on the O2 sensor and the ECT sensor. I was only planning low boost, say 5psi. Ive been working with different size restrictions in the hose that leads from the boost to the wastegate... seems like 8 psi is what your going to get. Its not bad, just get ready to buy the expensive gas (wait.. that is bad lol) Link to comment Share on other sites More sharing options...
ausubaru92 Posted August 19, 2005 Share Posted August 19, 2005 I was under the impression that the turbo cams closed the exhaust valves earlier because scavanging of the cylinders wasn't nessaccery when there is boost. Therefore with NA cams in a boosted motor,.. part of the boost is pushed straight through the cylinder before the exhaust valve closes. Have you ever heard of this and is it of concern Probably not a concern though as you run yours with NA cams Say,.....what kind of turbo would spin up earlier and give me power in the lower part of my rev range,.. say,... 1500-4000 rpm (probably not possiabe but im hopeful.) Cheers All Gannon Link to comment Share on other sites More sharing options...
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