Civic EG

Hi guys,

i have a d16a6 mini me (d16z6 head)

I had it rebuilt:
acl bearings (big ends and mains)
Micro polished crank
pm6 pistons standard
arp head bolts
skimmed head 0.8mm
d16a6 head gasket
standard head, cam etc

On first start up every morning i get very very loud piston slap, it sounds like a diesel for 10 mins until its warm 100% then its quiet on idle. when i accelerate between 1500 - 4000rpm (its limited to 4500rpm until its run in as im running aftermarket ecu) it still has a knocking sound or more of a sound like a lose washer is in there or something, then its quite again on idle.. this sound is there warm or cold.

first Q is piston slap bad?
what could the noise be under acceleration?

also my timing belt, tensioner and water pump are brand new, but the timing belt whines very loud!

ive done about 350miles so far on this engine with these noises.. unfortunately its my DD so i have to use it

Piston slap is more common on high mileage engines where the cylinder walls are worn. Once the piston warms up and the metal expands it should go away. A freshly built engine should absolutely not have piston slap.
The noise you are hearing at mid RPM's after the engine is warm sounds like pre-detonation (did you check the timing with a timing gun?) or Rod Knock (worn or wrong size bearings).

If you are hearing the timing belt whine, check the tension that it is not too tight, as that can shorten the life span.

Also since you have the head skimmed, your compression ratio is higher so you will need to use a higher octane fuel than before. Using to low of an octane for your setup will cause the knocking symptoms you described.

listen to teal! these noises you speak of are very not good

thx for the reply!
Mmm i wonder what it is then as it sounds like a truck in the mornings until it warms up. the block isnt new tho, it was just honed and not bored out. do u think the block is out of shape? will it cause any damage having this noise on start up? I did not check the timing as the tuner who installed the ecu and run-in map said he set the timing correctly. should i try retard the timing more? i unfortunately dont have a timing gun, ill try organise 1 this weekend.

I got told it could be lost motion assembly?

Ill check the tensioner this weekend, thx.. quite upset that i spend all this money and its all going to shit

oh im using 95 octane, pump gas.. the tuner set it to run rich until its run in, then it will go back for a dyno tune. ( if it runs rich, will it be ok in terms of detonation?)

As for how long this setup will last I don't know, but some race engines are built this way.and racers have benifited from this