I know nitrous isn't technically forced induction, but that bigggg nitrous thread is in this section. So, anyway... I have a 93 civic... d16z6. I put a computerized nitrous system on it, which i have control over what size shot i throw at it. I was spraying a 55 shot, and prob at about 6500 rpm. All of a sudden the car started missing like a sob. I checked plugs, and found cyl #1 had the electrode cooked off. I had a friend crank it over, and cylinders #2,3, and 4 have quite a bit of compression, but cylinder # 1 has virtrually nothing. I know this is prob a hole in the piston, but I'm praying its not lol. Any one have any ideas? Other than a hole in the piston...???

 

I almost forgot to mention... the engine is dead stock, the tune on the car is stock, timing is backed off a few degrees, and i got lower heat plugs in it...

 

Bad exhaust valve.

 

compression's going somewhere, i reckon'.
do a leakdown test and figure out what's got a big gaping hole in it.
chances are probably an exhaust valve. i've seen lots of those fail with a big shot.
how's the pcv system functioning? excessive blowby? probably a piston.
etc etc etc on the testing.... you can figure it out.

 

i dunno about valve issues, i checked the clearance between the rockers and the valve stems, and they have clearance... wouldnt it be tight due to the stem coming up all the way? I mean with out the head of the valve being there, its kinda just being pulled up by the spring...?

 

will a d16 from a 96-00 civic work in a 92-95 civic?

 

Good call guys... its the exhaust valve... Pulled the head today, and its busted. No signs of scarring on the cylinder wall, or piston. Time to toss a valve in her and go spray some more hahah

 

It's always the exhaust valvesLOL!. Maybe your a little lean?. Stock valves should work with that shot.

 

I have a venom computerized system... its a dry shot, but controls the injectors to richen the mixture... Im not sure how lean it could really be... This thing is supposed to automaticly shut down if a lean condition is found... You dont think it has anything to do with spraying at a stock motor with 170k??

 

Def. possible but thats a small shot, usually melting things means lean. Got a picture of the valve?, is it burnt, bent, or broke?.
Loosing a ground strap will do any of those, once it gets stuck in the seat the valve will not seal and combustion gas comes out and torches it.
Happens more w/ stock valves, stainless will be a little more forgiving.

 

It honestly looks like its just broken. I did take pix, but their on my digital camera, locked in my tool box at work. So hopefully ill remember to bring it home tomorrow to upload the pix on here. You said loosing a ground strap could cause this? Any one's in particular? I'm not sure that i even know where they all are located. I know about the one on the p.s. and thats pretty much it lol. Do you think i'm gonna need a new valve seat, or do you think i could just lap the new one in without a problem? I was honestly only gonna replace the one that broke, considering the price of valves. 25*16=$400 just for the valves. Thats my price for honda, and i get them almost at cost... I think their like 35 or more if you don't have any connections. Its kinda senseless to replace all of them when i can get a re-built d16z head off ebay for $200

 

I've had just one valve seat replaced ,can be done if the seat is the only thing damaged.
It will need to be re-lapped and un-shrouded.
Can't tell you if the current seat can be re-lapped w/out pic.
Ferrea PN for stainless valves in a D16Z6 are, Intake:F1822P, Exhaust F1821P. I put that up because they cost as much as OEM.

 

un-shrouded?

 

When you grind the seat it lowers the valve, naturally.... You take away material... So typically a cut is done to restore the flow that might have been lost from raising the valve seat. Most machine shops do this and factor it in to the price of having a seat ground.

 

Yeah^^x2

 

exhaust valve

 

Word... Thanks for the help guys... I'm puttin her back together tonite... I'll let ya know how it goes

 

Car's all back together, runnin great. For some reason the intake sounds sooo loud. It's kinda odd...