I recently swapped my D16y8 SOHC 2-stage VTEC in a '97 Civic EX Coupe for a 3-Stage JDM D15B VTEC. The only thing non-standard was the 104-tooth p2f timing belt. The timing marks lined up fine so I figured there wasn't a problem although everthing I've read online says that a 103-tooth belt is required. Acceleration/Power is great maybe better than my old engine until I reach 3.5 to 4,000 rpm. From that point until VTEC kicks in(about 5.5k rpm) acceleration/power sucks! Everything other than that seems great... that is the essence of my problem, though. This is almost exactly the reverse of the performance of my old engine. I have a hard time believing that the timing belt is the problem because all the timing marks line up perfecly but i am open to suggestions. This was a straight swap. No other modifications. There has to be something I'm leaving out. Does the ECU need to be modified? Are there other factors I'm leaving out? I need some help!

 

I dont get what you need help with, you put in a weaker engine and you have power loss?

 

My D16Y8 reportedly had 127 hp whereas the JDM D15B was reported to have 130 hp. During lower RPM acceleration I notice the power gain until about 3.5 to 4K RPM then experiences a significant decrease in acceleration/power until vtec takes over. Almost like it's being held back by something. I'm almost positive this isn't standard.

 

You put a smaller engine, and your not gonna feel those three horespowers

 

Thanks for all the expert advice!!!!!!!!! I found from another source what my problem is but THANKS to you guys that took the time out of your day to take a stab at answering my question. No further help required at this time.

 

so you mind posting the answer to the problem?

 

hello, well first of all. i have the same motor but opposite problem. i no power at lower rpm before vtec.. but when vtec hits.. its very good power.. and i know why this is happening.

well, for you situation. you should use the dual selenoid because one activites vtec at low rpm and another at high rpm. the only thing why your is not working is because. if you have the p2p ecu, the original ex ecu.. it will not activite the one vtec.. so you will either have one vtec either at low or high rpm...

The choices you have know is.. find the jdm 3 stage vtec and use the dual selenoid.. which is hard to find..

, you can also hook up the dual selenoid and connect the high rpm vtec to the ecu and buy a vtec controller to activiate the low rpm vtec to kick in.

or lastly.. you can use the replace the head to the y8 and use the one vtec selenoid. which is only 2 stage


and for me.. i am going to swap head to a y8 head.. havent done it yet but will soon.. i'll let you know how it goes ..


it took me over a year to see why my engine was acting like that too.. but know that i know why,.. i want to share my knowledge...


let me know how it goes

 

email me back for questions or comments because i usually dont go on here......

richardb0343@yahoo.com

 

He isnt coming back