the motor is b20vtec, Stock. it is the low comp one


anyway I knoticed with 87 octane gas it makes a knocking sound at low rpm, like when I cruise 40 miles in hour in 5th gear a give it some gas...


So i used 91 octace and it does not do it anymore.. does anyone know what cause this? my comp is about 9:1.. i rather use 87 to save some spare change.. anyone knows where the noise can come fron.. valves, rods, bearings etc??

TIA

 

from dealer it calls for 93 octane

 

Your ignition is probably advanced to much. B20s run best with ignition retarted a degree or two when running on a vtec ecu.

 

i want to know is it the gas... like i said 91 octane it runs fine but, 87 it klunks in low rpm..

we only have 91 octane here, its the highest, they took 93 couple years ago..

 

I was running 87 for my b20vtec couple years ago. It knocked. I try 89 same ****. Try 91, the motor ran like a champ. You might try to retard the timing a little.

 

Its called detonation. Your fuel is igniting itself before the spark. Like stated in previous posts, retard your timing.

 

i know gas is sky rocket at the moment...im not trying to be a hard ***...but you got a better motor and that motor need it gas....i would try to maintain 91+ octane

 

I thought everyone knew as soon as u put in type of swap u should always use higher octane

since detonation occurs

but I guess I assumed

all swaps should be pump 91 or better if not kiss the life of the swap good bye
and u got a crvtec!!!!!

sorry but it is like buying a Benz and eating at Macdonalds....
just doesn't make sense

 

lets hope your sleeves didn't crack, it doesn't take much knock for them to give. Do a compression check asap.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by krazie1 &raquo;</TD></TR><TR><TD CLASS="quote">I thought everyone knew as soon as u put in type of swap u should always use higher octane

since detonation occurs

but I guess I assumed

all swaps should be pump 91 or better if not kiss the life of the swap good bye
and u got a crvtec!!!!!

sorry but it is like buying a Benz and eating at Macdonalds....
just doesn't make sense </TD></TR></TABLE> mines is low compression


i retareded the timming a bit.. not sure where at though, because i have no timming light.. mines broke.. so i pumped a few dollars worth of 87 gas to check.. the low rpm knock is gone... funny thig is vtec pops harder.

the reason why i pour 87 gas is because, i am a broke *** student; 87 octane i can buy a pack of smokes with a fill up. and this vtec head i added on cost more than i expected...

detonation; can some one explain how this happen, and what will it mess up. i am thinking valves; some one clue me in.

 

******* cheapass ITS CALLED PINGING!!!!!!!!!!!!!! THAT **** IS GONA BREAK...WHEN YOU HEAR DETONATION.....THAT MEANS ITS REAAAALLLLLY BAD...PUT SOME 93!!!!!

MY FRIEND PUT 89 IN MY B20VTEC ONCE I HAD TO DRAIN IT AND ADD 93

 

*sigh*

an eninge mixes air and fuel and ignites it with a spark. When the piston is traveling upward on its compression stroke, it reaches the top, and the spark plug "fires". The following explosion throws the piston down the cylinder. This force is what moves your vehicle foward. Detonation is when the fuel starts igniting by itself, like when the piston is only halfway up on its compression stroke. You can imagine how good this is for pistons and bearings, oh and cylinder walls. Come to think of it, its not good for anything. Quit smoking, fill it up with premium.

 

read this http://auto.howstuffworks.com/engine1.htm alot of the info there is real basic... but there is some good info buried in there. it might not actually cover knocking in there, but reading that and reading lsvtec's explaination of it will help you make sense of it.

also i like lsvtec's advice "Quit smoking, fill it up with premium."

 

You should def, quit the smokes, and spend the money on higher octane.

Either get stuck, walk to school while you smoke a pack, or just save $$ and be healthy. It's obvious that 87 is definately needed if you hear knock on 87 and not 93.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtecdamian &raquo;</TD></TR><TR><TD CLASS="quote">******* cheapass ITS CALLED PINGING!!!!!!!!!!!!!! THAT **** IS GONA BREAK...WHEN YOU HEAR DETONATION.....THAT MEANS ITS REAAAALLLLLY BAD...PUT SOME 93!!!!!

MY FRIEND PUT 89 IN MY B20VTEC ONCE I HAD TO DRAIN IT AND ADD 93</TD></TR></TABLE>

idiot, i did not say it was a ping... i can hear the difference between a knock and ping.. The only real reson why i pour 87 is my compression is low. if i had higher compression i would not pour 87. read first smartass..

i poured 87 because i read my motor did not need high octane.. so why waste the money if not need to... like i said earlier, the knock sound went away after i lowered the timming.. i just wanted to know why it happened in the first place.

now i just want to find out more about what causes it.. thanks lsvtec92 for the input...

as for smoking i tried mant times anyone who smoked for years will say they rather quit.. but i dont want to get into that topic..

 

no problem. But if you retarded your timing and the knocking noise went away, its probably ping buddy.

 

err umm man...you have a CRVTEC...you need high octane......it is a vtec motor now..if you have knocking......up your octane.....or dont drive it....why mess up a motor because you wanna mess up your lungs.....retard the timing...up the octane to 90...at least.....and quit trying to find other things wrong than the obvious

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by daidilus &raquo;</TD></TR><TR><TD CLASS="quote">err umm man...you have a CRVTEC...you need high octane......it is a vtec motor now..if you have knocking......up your octane.....or dont drive it....why mess up a motor because you wanna mess up your lungs.....retard the timing...up the octane to 90...at least.....and quit trying to find other things wrong than the obvious</TD></TR></TABLE>