hey guys i just wanted to ask. i did a mini me swap on my car (d16y7/ d16y8 head) because it was cheaper than getting a d16y8 and i just wanted to ask if someone had any problems with the compression on the engine because i have about 215psi. all on board and it kind of pings. now i haven't checked the timing but i don't think that it's off, so my general question. does anyone know at what compression a 4 cylinder engine will start to ping at regular 87 pump gas??? or do i need to go higher octane with that compression???

 

I think you may have to run a higher octane gas if it pings.

 

so maybe just higher octane gas? maybe 89 or do i have to go with the 91??

 

91

 

With 215psi reading on a CR you're looking at 10:1 or a touch higher or so, generally speaking.

You REALLY, REALLY need to run premium gas, and quite possibly even retard your ignition timing a touch too once it gets hot outside.

 

I just saw you're from AZ - when it gets Arizona hot you will definately want premium fuel and retard the ignition timing some.

Just to be on the safe side have you checked your timing since finishing the engine?

You might have the distributor rolled too far advanced (back towards the firewall) or you might even have your timing belt off a tooth if it spark knocks really badly.

Try premium fuel and retarding the timing by rolling the distributor towards the nose of the vehicle. If premium fuel and retarding ignition doesn't work, then yor timing belt's probably off a tooth.

I built an 11:1CR SOHC and it pegged 250psi on a CR gauge, and it rarely ever spark knocked even in 100 degree humid GA heat on 93 octane premium fuel. I retarded the timing in the summer, then rolled it back during the rest of the year.

 

ok well now i retarded the timing a bit and most of the pinging ended but i still have some sometimes but i'm now running 89 octane so i'm gonna try the 91 now and see what happens. and yes it get pretty hot here in AZ.