zRotary

Hey guys,



i am going crazy because i cant really lower my Knock - value.



3 Months ago, i had a RacingBeat FULL exhaust on my S5 Turbo. the Knock values were 45-55 during cruise, and around 20-25 WOT.

now my car is equipped with a 3" Corksport exhaust, and the Knock increased dramatically.. i dont know why.

during cruise i read 65-75 knock ( 22° BTDC, 12,3-13,1 AFR, -320mmHg),

WOT 40-55 knock (ca. 17° BTDC, 11,2 AFR, 0,80kg/cm²~~12psi)



My Knock Sensor ist at rotorhousing 1, if i plug it to rotorhousing 2, it reads only 1/2 of the knock: max 30 during cruise and 15-20 WOT.



I have tried many things, for example retarding my timing by up to 12° over the whole map (Test function) and enrich the mixture to 12,0 AFR during cruise and 10,2AFR WOT.. in BEST Case, it drops down knock by 2 - 4 lvls.. lol!



I also checked for loose bolts, covers etc. i also pulled out the power steering because it made some noise..





is there any chance to figure out TRUE knock??

its really horrible.. i CANT enjoy driving, because i am looking all the time to my knock lvls and AFRs..



ok here are the maps:



INJ-MAP







IGN Leading MAP





IGN SPLIT





The Ignition is almost BASE-Map, just 3-4° advanced in high RPM under boost, the cruise sector is untouched except for the split.



The Mods to the car are as follows:



Streetport,

Stock heat-range Plugs Platinum.

portmatched intake,

2nd throttlebody plates taken out,

Apexi Air filter,

Apexi 3Bar MAP Sensor,

Walbro 255 Fuel Pump

SARD 800ccm secondarys set on 0.20ms lagtime



like i said before.. i changed nothing but the exhaust, AND from mineral oil (Penzoil or Castrol GTX 20w50) to synthetic: Royal Purple 20w50.



under 12psi of pressure and WOT i get readings of 11,3-11,4 AFR, but my plugs are telling another story.. there are spots which are almost grey! especially the Lead-Plugs.

Before changing the exhaust system and Oil, it was all fine chocolate brown.

j9fd3s

was your racing beat exhaust the silver one? the older RB exhausts were 80mm, the silver ones are 70mm, also the y pipe on the silver system isnt as good. so if you had a silver one, switching to the corksport might increase flow



basically the knock sensor is a microphone, so louder exhaust might just raise knock...

zRotary

hey dude,



thats really interesting.. yes it was the stainless polished one! my old FC had the old-school black one, i sold it to a buddy and bought a newer modell.. but i really didnt know its only 70mm! WOW, i always thought it was a full 3" I.D. (76mm)!

Well then it makes sense.. the corksport is 80mm O.D. so ~ 76.I.D. and has less bends.. My AFR are OK now, it took a bit of tuning, i had to go MUCH richer compared to the racing-beat.



well, the corksport exhaust is EXTREMELY loud.. even in the engine bay, so it would be the reason for higher knock.. as i told before, my AFR are ok now, but the knock-value didnt drop, so mayb its really just the loud exhaust, well i hope so

j9fd3s

yeah the corksport is loud!

zRotary

I changed my Leading Sparkplugs from BUR9EQP to BR9EIX. i wanted to buy some BR10EIX but they werent available.



I have driven the plugs about 100miles now and pulled them out to check their faces.. the Leadings are near WHITE and the trailing are black like the night.



I dont really understand this. I modified my map to be very very rich + higher lag-time of the secondaries, so my fuel consumption is MUCH higher than with the racingbeat exhaust, but the leading spark plugs keep beeing grey/white. My ignition-timing is almost stock too, i cant imagine that i have to go more retarded than stock.. or should i?

Ranzo

Map seems fine to me. Maybe the new exhaust is flowing more and working for you. I have kind of quit looking at Knock numbers since mine sometimes go over 85 when revving in neutral. I have solid trans mounts and upgraded motor mounts though.

ArmyOfOne

@ zRotary... Nice to hear you have gotten everything together. Were you able to fix that leak at the rear of the engine?



Again sorry about the other night but by the time I was done talking to the wife you had already logged off. Well I should be back home in about 6 weeks, I look forward to hearing this beast we have built.



Laterz.

zRotary

Hey!! Nice hearing from you sarge



Well, yea i fixed that leak. Damn, that was an act lol, because it was my first time pulling the tranny out.. well, the next time, i am going to pull the engine and tranny together



I would post a Video, but the Video section doesnt allow me to make new topics.

zRotary

hey ranzo,



well i am going to quit looking at the knock also.. you just cant enjoy driving looking all the time on the knock-gauge. The car is running so smooth and powerfull, with no bogs or something like that, but the knock value just jumps around, that makes sick!

well, if i rev up my engine in neutral, i get readings up to 77 too i think its just the old engine which produces more noise than i "new" one.

i have not Solid motormounts, but the Mazdaspeed hardened ones. Whished i could use solid, but they arent available.

RobertWhite

a little offtopic, but how are the solid mounts vibration wise? My engine mounts are on the way out, and trying to decided between the mazdaspeed and solid mounts