Ghettodeffender Posted October 3, 2012 Share Posted October 3, 2012 i'm building an l28 to run compression 10:1 with flat top pistons, basically the build will be this http://www.ebay.com/itm/Datsun-Z-240Z-260Z-280Z-ZX-P90-High-Compression-L28-Engine-Motor-Head-w-Warranty-/150906118714?pt=Motors_Car_Truck_Parts_Accessories&hash=item2322b4a23a&vxp=mtr with a MSA Schnieder cam with Lift(In/Ex): .480/.480. Duration(In/Ex): 274/274. do you think this engine will be able to run on pump gas without the dreaded ping ive been reading about, im hoping that with a cam of that duration it may prevent that but what is your thoughts? Also as a side note my Zed is 1977 so i have to pass the california smog test, do you think an engine of this build will have issues with that? Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 3, 2012 Share Posted October 3, 2012 Not a chance in hell it will pass smog. Quote Link to comment Share on other sites More sharing options...
Ghettodeffender Posted October 3, 2012 Author Share Posted October 3, 2012 well i'm not gunna tell the smog guy its got a cam...... so aside from that if i had the stock compression would it then? Quote Link to comment Share on other sites More sharing options...
PMC raceengines Posted October 3, 2012 Share Posted October 3, 2012 Its the cam that will make it fail Quote Link to comment Share on other sites More sharing options...
Lazeum Posted October 3, 2012 Share Posted October 3, 2012 I run this setup, you'll have to reduce timing to avoid ping (total was 30° on my setup). Most likely it would also affect the burn rate, making it even less prone to get SMOG passed. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 3, 2012 Share Posted October 3, 2012 You're much better off performance wise to the bump the CR a bit (to 9 to 1) and run at least 34 to 36 degrees of timing advance. And yes, you won't pass smog with that cam. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 3, 2012 Share Posted October 3, 2012 You're much better off performance wise to the bump the CR a bit (to 9 to 1) and run at least 34 to 36 degrees of timing advance. And yes, you won't pass smog with that cam. Yes!!! Especially in CA where the gas is crap. Take it from a guy who built a motor that was too hot and had to run ridiculously retarded timing to keep it from pinging or mix race gas to get the octane needed to run proper timing. There are a lot of ponies in that last few degrees of timing, and the extra point of compression isn't worth nearly as much. Quote Link to comment Share on other sites More sharing options...
Ghettodeffender Posted October 3, 2012 Author Share Posted October 3, 2012 ok sounds like ill probobally just run stock compression, too pass smog ill just putting in cats till it passes Quote Link to comment Share on other sites More sharing options...
johnc Posted October 3, 2012 Share Posted October 3, 2012 too pass smog ill just putting in cats till it passes That probably won't work. Read up why here: http://www.bearriverconverters.com/data/CatOpp.pdf Quote Link to comment Share on other sites More sharing options...
Ghettodeffender Posted October 3, 2012 Author Share Posted October 3, 2012 well my auto teacher has done it before, just kept adding cats till it passed and it did work Quote Link to comment Share on other sites More sharing options...
Ghettodeffender Posted October 3, 2012 Author Share Posted October 3, 2012 what about isoprpyl alchohol mixed in the withe gas 10:1 i believe Quote Link to comment Share on other sites More sharing options...
z-ya Posted October 3, 2012 Share Posted October 3, 2012 I am assuming that the best you can get at the pump in CA is 91? I agree with JohnC, run around 9:1 CR, and run more timing. Run flat tops with a P90 and 1mm gasket. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 3, 2012 Share Posted October 3, 2012 what about isoprpyl alchohol mixed in the withe gas 10:1 i believe C'mon dude. The smog techs are fully aware of those little games and they don't work. The BAR has implemented the STAR program that puts a lot more measurement and testing in place for techs and they are not going to risk their jobs when something as obvious as a dose of alcohol in the tank comes into their shop. Its getting difficult to cheat through a smog test with a legitimate smog tech. You might be able to find a tech that will fudge the test, but if you can find that tech, BAR can to and they have really stepped up their enforcement. Again, the few smog techs I know will not risk their job or business for someone trying to cheat through the smog inspection. Quote Link to comment Share on other sites More sharing options...
Ghettodeffender Posted October 3, 2012 Author Share Posted October 3, 2012 hmmm well anyone got any ideas on how to pass smog with this cam and stock compression? Quote Link to comment Share on other sites More sharing options...
rossman Posted October 3, 2012 Share Posted October 3, 2012 Move to a different state Quote Link to comment Share on other sites More sharing options...
z-ya Posted October 4, 2012 Share Posted October 4, 2012 hmmm well anyone got any ideas on how to pass smog with this cam and stock compression? Engine management running closed loop with wide band O2 and a catalytic converter. Quote Link to comment Share on other sites More sharing options...
duragg Posted October 5, 2012 Share Posted October 5, 2012 I ran my car with a similar setup through Arizona Emissions a total of 13 times and never got it to pass. I would get close on one measurement, and some other parameter would slip out. The kids at the DMV just LOVED it when I came and they took turns "driving" the Z. Then they enacted the Vintage Vehicle rule and I was exempted from smog. So the motor got rebuilt to mid-10 CR and with our crappy gas anymore I still run a mix of 100LL to keep it happy. Quote Link to comment Share on other sites More sharing options...
duragg Posted October 5, 2012 Share Posted October 5, 2012 (edited) dbl Edited October 5, 2012 by duragg Quote Link to comment Share on other sites More sharing options...
srgunz Posted October 5, 2012 Share Posted October 5, 2012 Here the county I live in we have to pass smog. The county my brother lives in 40 miles away does not require smog. I registered my Z in my brothers county using his address. But I still keep Z here with me. Its not a state wide requirement here only certain counties. I feel your pain. Quote Link to comment Share on other sites More sharing options...
Ghettodeffender Posted October 6, 2012 Author Share Posted October 6, 2012 so i talked to the guy whos rebuilding the engine, he builds about one of these a week so hes well versed in knowledge of these engines, the final build we decided is n42 head with the flat top pistons so the compression will be 10-1, he said i can run on pump gas of 91 with no issue, but with the cam and compression may have to advancethe timing a little. he said he has made builds likes these a few times and both worked well. Now i asked what are my chances of passing smog with this build, he said should be alright as long as my emissions equipment is working and my catalytic converter is fresh and new. so lets hope this is true, if not it looks like ill be buying a smog if you guys have any thoughts id love to hear them Quote Link to comment Share on other sites More sharing options...
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