I am total noob when it comes to engines and performance.

I have swapped my D15Y3 with D17A7 non vtec in Civic 2005. As you might know better that D17A7 is from Civic GX which is a CNG engine with 12.5:1 compression. We converted it to petrol, used injector rail, throttle body, transmission, ecu and headers of old engine D15Y3. We don't have O2 sensors in this model in our country, moreover ECU don't have knock sensor option.

Engine is in great shape and giving overall excellent performance, the only issue which I am facing is knocking. I am using 95 Octane, but still its knocking during quick acceleration. My mechanic is suggesting to retard the timing to fix knocking.

Experts, please suggest what are my options to fix the knocking problem and how we can get maximum power out of this engine.

 

For that compression ratio I think you need a higher octane. Closer to 105. No expert. Just do a search on the line and check for yourself.

 

I ran 93 in my 13.1 compression motor. never had any issues

 

Please suggest what I need to do to run it on 95 octane.

 

what a mess. pulling timing is your only option at this point along with trying a colder plug.

 

Mine is not even accepting 95 octane, plz suggest how I should tune it.

 

Already using 8 heat range NGK V power plugs.

 

you haven't 'converted' anything, just threw a bunch of gas parts on a CNG engine.

I would find some bigger injectors, something in the 240cc range. Also figure out what the timing looks like. Put a timing light on it and see where you are presently. I don't even know if timing can be adjusted at all since it's all ECU triggered.

what's the cam in a CNG engine look like compared to a gasoline engine?

is this something people in your area do? are there any locals you can ask for help? Here we just go for a K series since all our cars have the D17A already.

 

Thanks for your input.

We don't have this engine here, nobody ever seen this engine here, so unable to get any help. D17A7 is from US Civic GX, https://en.wikipedia.org/wiki/Honda_D_engine#D17A7

I found it in a junkyard, for $200, engine has only done almost 16000 miles, as mileage was written on a sticker pasted on engine, its almost like a brand new engine. It kicks harder than D17A2, not sure why, maybe due to high compression or condition of the engine. It also giving me very good fuel average almost 33mpg in city, hopefully will give more on highway.

Will replace injectors lets see if it works out.

 

Try some e85 or bump up the octane to see if it'll help

 

i don't know, you just can't expect to run a 12.5:1 compression engine with a bunch of parts taken off a lowly D15 gas engine. The D15 ECU expects prob 9.x:1 compression and 87 octane gas (or whatever the regular gas is over there). So you need bigger injectors for sure in hopes throwing more fuel will sustain the high compression. But in reality you want some kind of ignition timing control too. So start with the easy thing first and get good sized injectors.