Hey all,
My USDM B18C crapped out on me so I am looking to do a JDM swap. The swap will work fine, but my question is the ECU. Here in california we only have 91 octane fuel. The JDM runs 10.6:1 compression while the USDM is 10:1. If I use the USDM ECU, it will be giving enough fuel for the 10:1, and I don't know if it can adjust itself that much to compensate for the higher compression. If I use the JDM ECU, it will be tuned for the 10.6:1, but also for 100 octane fuel, so the timing curve might be too agressive for 91 octane. How do I go about this? Is my only option to get a hondata and just get it tuned? Who has experience with this? Thanks


oh, ya one more thing....do OBD-1 USDM ECUs look for the vtec pressure switch? becuse the JDM dont have that. Thanks

 

use the usdm P72. the jdm has a fuel map that is actually not as good as the usdm one. I dynoed my friends jdm gsr in his coupe and the usdm ecu was better by a bit. lot smoother in the rpm range. oh also if your jdm motor does not have the vtec pressure switch then swap out and use the usdm one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smart monkey &raquo;</TD></TR><TR><TD CLASS="quote">use the usdm P72. the jdm has a fuel map that is actually not as good as the usdm one. I dynoed my friends jdm gsr in his coupe and the usdm ecu was better by a bit. lot smoother in the rpm range. oh also if your jdm motor does not have the vtec pressure switch then swap out and use the usdm one.</TD></TR></TABLE>

did you back the timing off at all? im just worried the USDM cant compensate enough for the higher comp. ratio.

 

bump for an answer

 

get with jason (ih8ricerz) he live in cally and he rechipped me a p28 that works awsome now i know that the ecu does not control the butterflys but trust me when he gets done with it, it wont make a ****. im very happy with it and im still running a snail intake as well so..............its up to you and good luck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by saleensolution &raquo;</TD></TR><TR><TD CLASS="quote">get with jason (ih8ricerz) he live in cally and he rechipped me a p28 that works awsome now i know that the ecu does not control the butterflys but trust me when he gets done with it, it wont make a ****. im very happy with it and im still running a snail intake as well so..............its up to you and good luck</TD></TR></TABLE>

cant you just chip the p72 and still have the butterflys?

 

i did not have to back off timing at all. I am running it at 16 degrees. it is fine. I also have a P28 with IAB control that works better than the P72 also. that is what is in my friends car to date. yes you can also chip a P72 and retain IAB control

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smart monkey &raquo;</TD></TR><TR><TD CLASS="quote">i did not have to back off timing at all. I am running it at 16 degrees. it is fine. I also have a P28 with IAB control that works better than the P72 also. that is what is in my friends car to date. yes you can also chip a P72 and retain IAB control</TD></TR></TABLE>

alright, I will run the USDM p72 for thetime being. Did your friend get the p28 tuned? or just a program chip like skunk2 or mugen?

 

the P28 to P72 program is a program a friend of mine who does tuning made. it made better power over the P72 and smoothed out the lower rpm's. it was cool that he added IAB control. he also does them for H22 swaps.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smart monkey &raquo;</TD></TR><TR><TD CLASS="quote">use the usdm P72.</TD></TR></TABLE>

I would also agree with this. The 94-95 USDM P72 would be the perfect ECU to run on a stock GSR motor regardless of it being a JDM B18C. It will be fine for a stock GSR with bolt-ons. If you decide to cam it, bump up compression, switch to a single runner manifold, etc. then a chipped P28 would be a good choice.