How much knock is too much?
08-22-13, 05:06 PM
#1
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How much knock is too much?
My car runs fine but when I got it dyno'd at a non-rotary establishment (mainly LSX), they seemed alarmed that my knock was so high. I hit 189 today, should I be worried?
Also, just noticed today my 2nd turbo isn't boosting. Maybe just a loose vacuum line I hope.
Also, just noticed today my 2nd turbo isn't boosting. Maybe just a loose vacuum line I hope.
08-22-13, 05:11 PM
#2
and that seems like quite alot of knock , BUT the stock knock sensor isnt perfect any noise metal on metal vibrating action could cause that knock .
who tuned your car? if I were you just incase i'd get a tune with a safe timing map . and see if that makes a difference if not then its more then likely your sensor picking up interference .
08-22-13, 05:35 PM
#3
You need to know when the knock is happening and under what conditions. Also, you need a baseline knock reading for whats normal for your car, as all cars and sensors do not produce the same readings. With a number that high I would certainly invest some time into checking everything out before boosting any more. Once you have established whats normal for your car you should really only be concerned with knock under boost, any other readings are likely not true knock (loose parts, ect). For example my car rarely registers any knock readings in the 30's and when logging boost runs im typically in the single digits.
08-22-13, 05:43 PM
#4
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Thread Starter
Your temp was a little on the high side for only doing a couple dyno runs .
and that seems like quite alot of knock , BUT the stock knock sensor isnt perfect any noise metal on metal vibrating action could cause that knock .
who tuned your car? if I were you just incase i'd get a tune with a safe timing map . and see if that makes a difference if not then its more then likely your sensor picking up interference .
Apexi intake
HKS exhaust
RP hi-flow cat
Bonez DP
I was told by the seller I have a Koyo radiator as well
Last edited by 94RX7R2; 08-22-13 at 05:49 PM.
08-22-13, 06:42 PM
#7
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Must have a scaling thing or something. I've always tuned my cars for zero knock. Anything over 10 is like and oh **** moment on my old car.
Doesnt add up to me.
Jason
Doesnt add up to me.
Jason
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08-23-13, 02:42 PM
#9
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My car averages 70-80 knock. I've always been told that it is more of a warning when the knock is over the normal reading rather than just a high number. My car has always been around 70-80.
08-25-13, 11:34 AM
#11
Racing Rotary Since 1983
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i have found the stock OE knock sensor is to be respected. i tested 5 of them and they all generated the same reading.
as to how much knock....
it depends on where the knock happens. if the knock reading, say around 60, is in vacuum or just driving around, generally no problem as it is picking up something other than the combustion.
knock should drop to under 20 as you progress in boost. as the AI clicks on and the tune richens a bit along w less advance.
what should not happen:
knock rising while in boost.
if you experience rising knock in boost stop everything and fix the problem or you will be building another engine.
i have seen apex seals broken around one bar when the knock had a peak around 65.
howard
as to how much knock....
it depends on where the knock happens. if the knock reading, say around 60, is in vacuum or just driving around, generally no problem as it is picking up something other than the combustion.
knock should drop to under 20 as you progress in boost. as the AI clicks on and the tune richens a bit along w less advance.
what should not happen:
knock rising while in boost.
if you experience rising knock in boost stop everything and fix the problem or you will be building another engine.
i have seen apex seals broken around one bar when the knock had a peak around 65.
howard
08-25-13, 11:50 AM
#12
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Howard how is knock calculated by the ecu(the raw number spit out) vs a piston engine? My old car would wipe the mains out of a billet cranked stroker if under power i got more than 10 counts(bend the crank). Which leaves me confused on how knock is read/interpreted on a rotary here....
Jason
Jason
08-27-13, 01:34 AM
#13
It would probably also be beneficial for some members if we used the quantitive measurement for knock.
Not simply saying "My car has a knock value of 180." Because for the uninitiated, that could mean 180 elephants. And over what time scale period it occured.
EG 80 elephants over a period of 12 seconds.
Otherwise anyone could mistake it as an 80% knock value. percentage of what, I dont know. Or 80 knocks in 5 seconds.
Without knowing what the knock units are calibrated in, and over what period of time they occur, its pointless to ask if its too high. Its like saying my car has a power output of 80. 80 what?
Not simply saying "My car has a knock value of 180." Because for the uninitiated, that could mean 180 elephants. And over what time scale period it occured.
EG 80 elephants over a period of 12 seconds.
Otherwise anyone could mistake it as an 80% knock value. percentage of what, I dont know. Or 80 knocks in 5 seconds.
Without knowing what the knock units are calibrated in, and over what period of time they occur, its pointless to ask if its too high. Its like saying my car has a power output of 80. 80 what?
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