EA81 SPFI mod question

[s'ko]

Ok so would you technically be able to say that an EA81 w/the EA82 SPFI intake is a EA82 SPFI motor for smog purposes.

 

I am thinking of doing the above mentioned mod and I won't be able to tell the smog ref that I put the SPFI intake manifold onto the EA81 b/c they have no benchmark to compare it to. They will be able to test it if I tell them that I have an EA82 SPFI though.

 

BW

[mikeshoup]

I guess you could. Just remember that the EA82 SPFI on an EA81 will run just slightly richer at WOT and perhaps idle since the EA81 flows air slightly less as efficiently as an EA82. That's the only thing I could see maybe causing problems.

 

But that's all a big if.

[GeneralDisorder]

I guess you could. Just remember that the EA82 SPFI on an EA81 will run just slightly richer at WOT and perhaps idle since the EA81 flows air slightly less as efficiently as an EA82. That's the only thing I could see maybe causing problems.

 

That shouldn't be a problem in practice - the SPFI computer figures fuel from the MAF and the O2 and will compensate for the reduced airflow of the EA81 heads. That's WHY the SPFI is so much more effecient than a carb - because it can and does modify the mixture on the fly depending on engine needs. That's also why you can mod any FI vehicle (to a point - turbo's are anothe story as most NA ECU's can't compensate for manifold pressure going positive) without really changing anything as there will always be some room in the software for changes in airflow. The ECU software is designed in this way largely to compensate for different altitudes and air density in different regions - thus eliminating the "high altitude kit" of the carb days. One ECU for all purposes. The slight differences of the EA81 amount largely to differences in compression and valve timing/size. I would be willing to bet that a port/polish, EA82 SPFI pistons, and a delta cam ground similar to the EA82's you would get near identical numbers across the board. As they sit stock the SPFI is certainly an upgrade on par with the Weber. That's been my experience.

 

GD