knock at low boost

[tttype]

Am having trouble with knock at rather low boost.
Can run 11 pounds ok, at 12# get knock.
On a full throttle run , knock starts a about a second into 2nd gear, timing about 22* at start , by top of second 19*, KR varies between .5 - 1.5 .
KR continues through 3rd gear.

Running 94 oct that has alc in it, diffferent brand 91 oct no change.
Friend w. similar setup can run 24# with meth inj on same 94 oct fuel.
So I was hoping to hit 15-17# before kr.

Signature states RX7 setup details.

Any ideas ?

 

[scot w.]

Not sure what the cause of the knock is but if you continue much farther running with that knock all the way into 3rd, You will be replacing the engine!

Did I read it correctly? You are adding Alky to the gas without a Alky kit?

SW.

 

[gczarny]

Am having trouble with knock at rather low boost.
Can run 11 pounds ok, at 12# get knock.
On a full throttle run , knock starts a about a second into 2nd gear, timing about 22* at start , by top of second 19*, KR varies between .5 - 1.5 .
KR continues through 3rd gear.

Running 94 oct that has alc in it, diffferent brand 91 oct no change.
Friend w. similar setup can run 24# with meth inj on same 94 oct fuel.
So I was hoping to hit 15-17# before kr.

Signature states RX7 setup details.

Any ideas ?

unless your boost gauge is way off getting knock at 12 psi is not octane problem so adding alky is NOT going to do anything ,maybe tune is very lean so check your fuel pump /pressure /regulator /filter or maybe is RPM related ? like motor mechanical rattle /knock ? rev the motor few times in park and see if you get any knock ,if so it's mechanical

 

[tttype]

94 oct fuel is alc enriched at refinery.

Boost gauge matches scan tool readings off 3 bar MAP, so that should be ok.

Fuel press goes up with boost.
Fuel press stays high throughout run, pump is new & has no problem keeping up.

Started tune at pig rich to be safe, got kr, thought was rich knock, so leaned out. Still get kr

Get no knock at 11psi, starts at 12psi.

From what had read about false knock, it peaks & disappears.
Like a downpipe hitting the frame. Knock shows & then gone.


This kr starts at same place each time & will continue as long as stay in throttle.

Will try reving in nuetral & look for knock.

Any other ideas ?

 

[kjizzle]

i'm having the exact same problem. i just swapped out the big turbo for the stocker to try to stop it, but that didn't help. tried checking fuel pres at WOT... that didn't help... its not a fuel problem for me, it knocks at low o2s, high o2s, with alky, no alky...

mine only really happens at high rpm... have you made any crazy changes (colder/hotter plugs, incorrect plug wires)... have you checked the coil pack?

 

[gczarny]

i'm having the exact same problem. i just swapped out the big turbo for the stocker to try to stop it, but that didn't help. tried checking fuel pres at WOT... that didn't help... its not a fuel problem for me, it knocks at low o2s, high o2s, with alky, no alky...

mine only really happens at high rpm... have you made any crazy changes (colder/hotter plugs, incorrect plug wires)... have you checked the coil pack?

I don't think going colder plug is going to do anything at this boost level , I think you have motor knock problem , it maybe something hitting something also ,false knock or .....real knock just NOT from fuel , rattle inside the motor , that's why I told you to rev it up to the max and whatch for knock , anything loose should show !