engine: B16A2, 84mm Bensen Sleeves, Peak Rods, CP Pistons, ACL Bearings, Cometic headgasket, GSR Cams, Superflow .5mm OS Valves, Head ported and poslished, Drag turbo kit, E-manage.

the car sounds perrrrrfect when you first fire it up cold... a little itty bit of pistol slap, but normal.

as the engine reaches temp and the oil thins out causing the pressure to come down to around 25ish at idle... well once its below 35 psi and warm it starts to make a knocking sound. sounds JUST like a rod knock. but its not. Also, if you raise the idle to 1000rpm, either the rev or the oil pressure from the rev causes the knock to go away. we can rev the hell out of the motor and it sounds perfect, this sound is just at idle below 1000 rpm.

just to play, we swapped out for some really thick oil to see if it had any effect. nope.

the block was originally built by earl... so since we did not originally build the bottom end we figured it to be wise to go ahead and do it ourselve. So we pull it all apart and measure measure measure. everything is in spec... rod end play on the crank is within service limits, the ACL bearings main and crank are just barely on the tight side of in spec... everything looks perfect even after over 3 hours of running with this damn sound.

so... its all mint looking... but just in case, i send the block out to another engine builder who has 4x the experience i do. he finds everything to be within spec and says it looks like its all breaking in perfect. WTF!!!

So we put it all together, and of course... it still knocks, REALLY BAD once the motor reaches operating temp. sounds just the same, as it should since nothing was changed. well, except a new headgasket since i dont reuse headgaskets.

sooooo... we decide to do a in-car head inspection. pull out the cams etc. everything looks perfect, no funny wear going on, everything seems mint. the valve clearance is still perfect from when we first set it.

So we are basically extremely pissed off that we cannot find the problem in our customers motor. some people we have showed it to said "ahh its fine run it on the dyno" but i say hell no. no engine is to make a sound like this and its not gonna start with this one. we have built countless motors and this is no piston slap that a noob worries about.

its somewhat embarassing to have to turn to others to try and find help like this, but really... its to the point where i just need this fixed so i can tune the car and get it on its way.

i am hoping that there is some kinda wierd thing in the b16 that i may not know about or what? i dunno, everything is all built by the book, with good tools, and experienced knowledable hands. i never had a problem like this in all the motors we done.

-charles

 

what about the oil pump? Is there a shitty aftermarket crank pulley? I would re-check the entire rotating assembly. Anything with as loud of a knock as you describe it has to tell on itself. Either that or its just a slight piston slap that gets louder as the oil thins out. You said yourself that it goes away after 1000rpm and whenever you rev it. Hell man it could go away after you break the motor in and the piston rings have time to stretch out and seal a little bit.

 

What about the lma's? Don't they work under hydrolic pressure in addtion to the springs inside? If you're oil pressure is way down and your losing volume to the turbo, perhaps you lmas don't have enough pressure? Just a thought.

Will b16 lma's handle gsr cams? How many miles were on the engine before the rebuild?

 

i really appreciate you guys reading that all and trying to help.

the oil pump is a brand new one from honda, and the crank pulley is factory, i dont build engines with solid crank pulleys.

its somewhat loud to be piston slap, and since it gets worse as the engine gets warm, i would kinda rule that out unless i should have reason to beleive otherwise.

the lost motion assembles we looked at today. They APPEAR to be fine, but I am considering popping them out and really investigating them.

The engine was just fine with the turbo before. it got rebuild because shortly after the turbo it cracked a piston ring land. the car had a great tune in it (very clean mid 11s:1), with the exception of the injectors running out of breath at redline at the lowest boost setting, hitting a 12.5:1 at redline... something we would have worked out if the owner knew it wasnt really resonable to take a 260fwhp stock b16 running a hair lean to redline in 5th gear a few times in a row... or so he says he was doin when it happened, i wasnt there.

but regardless... the motor is i beleive 45,000 miles old before the rebuild.

thanks

 

check the oil pump and crank pully....! i seen on the FmI thread a pic of what i think is your red eg that is turbo ?? if that was yours was that a spark racing intercooler?? what size?

 

think it would have anything to do with the floating wrist pins?

 

I had this same sound in my motor. Even after I rebuilt the bottom end it was there. It was the lma's. If u have not checked them more than looking at them I would do that first. I dunno how they could be worn that much with the milage u have on the motor in your shop but it is your best bet. A good way to check is all the ones I have worked on that do not make noise you press them down and there is no catchyness it just springs back up. My noisey ones catch and take a second to spring back up. I have also had alot of noise from using bigger 450 cc injectors but the lma's were the worst. Some times it would make u cringe when driving down crowded streets with the sounds echoing off the houses and other cars.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dyno Queen &raquo;</TD></TR><TR><TD CLASS="quote">think it would have anything to do with the floating wrist pins?</TD></TR></TABLE>

 

thats what it probably is, maybe not but thats my guess