Knock retard on #4 cylinder

[iTurbo]

I have my OTC scanner hooked up to my Shelby Lancer and the only time I see any knock retard is on #4 at WOT. I never see any KR on any other cylinder.

Car is Turbo II, 3" exhaust, +20s, MAP clamp, and 18 psi boost. I have the base ignition timing set to 14' BTDC, I'm going to try setting it back to 10' or 12' BTDC tomorrow. I'm just wondering why #4 is more prone to knock than the other cylinders.

[GLHSKEN]

#4 does not cool as well.

[iTurbo]

Is there anything I can do to address the problem without reducing the base timing across the board? Unfortunately 91 octane is the highest I can get around here. The wierd thing is sometimes it will retard timing on #4 only, sometimes not at all (18 psi). Could switching spark plugs help? I'm thinking of going from Autolite 63 to NGK BR9ES.

[GLHSKEN]

Go to RN3c's Chrimeny, They power a 2.5L 408 whp beast. they are all you need. Non-protruded tip same heat range as the RN9YC.

The other thing to do is the #4 cooling mod which provides fresh coolant to the #4 side of the cylinder head.

[SpoolinGLH]

Go to RN3c's Chrimeny, They power a 2.5L 408 whp beast. they are all you need. Non-protruded tip same heat range as the RN9YC.




Also NGK's BR9ES are awseme plugs as well.:thumb:

[GLHSKEN]

Not needed. Why spend the extra $$??? The champions are proven performers in high hp cars (gapped down to .025-.028). Just my opinion. Any car will run 13's... most plugs will be fine there... The acid test is turning up the wick

[SpoolinGLH]

LOL are you implying that i only run 13's?? Im hopin to hit high 11's this summer in my omni..(NO reason why it should once its tuned) Anywho, your talking about a 408hp animal that is NOT driven everyday. Thats why you want to spend the extra money. My engine seems to idle alot smoother now then when i had the champions in.Ngks have a recessed tip that is away from the heat which will keep knock down. Plus BR9ES's are two colder than you can even get in the champions. The only thing i dont like about NGK's is that there made in japan:rolleyes:

[GLHSKEN]

LOL.... Might not be driven daily, but it is fully capable of it.

The 13 wiseass crack was meant in general Kyle. Settle down ;) What's your best pass so far??

[SpoolinGLH]

LOL.... Might not be driven daily, but it is fully capable of it.

The 13 wiseass crack was meant in general Kyle. Settle down ;) What's your best pass so far??


Haha alright my BEST pass so far was in my sundance. 13.6 @102 Stock Head,2.5 exhaust,srt4 IC. The sundance is long gone now and i have my GLH..Here are some pics of it.. It will be running in about a week or so...(sorry to hijack the thread)

http://i50.photobucket.com/albums/f334/HollywoodFashionz/1c909781.jpg

http://i50.photobucket.com/albums/f334/HollywoodFashionz/8a9b9000.jpg

http://i50.photobucket.com/albums/f334/HollywoodFashionz/b9a7b02d.jpg

[GLHSKEN]

:) Go get 'em. You would be surprised at that 11 second barrior... Best wishes to success.

[SpoolinGLH]

Thanks man :thumb: I know it takes ALOT to break into 11's Hopin with alot of tuning,track time and Mr.Menegon's head that i can get there:eyebrows:

[GLHSKEN]

Thanks man :thumb: I know it takes ALOT to break into 11's Hopin with alot of tuning,track time and Mr.Menegon's head that i can get there:eyebrows:


There's the equalizer.. that head... Be ware.. it will be a thirsty machine at WOT with that..

BTW, question was answered.. so no HI JACKING of the thread has occured... :thumb:

[SpoolinGLH]

Yep, Im using a TU CAL, Paul said he has worked with menegons head before and pretty much had the fuel/timing curves down for it.... Hope he's right.

[bill2]

Is there anything I can do to address the problem without reducing the base timing across the board?

What are you coolant temps when you see the greatest amount of knock? If you can reduce your coolant operating temps by 10deg, it can reduce your engines octane needs by 1 point. Since its #4 your seeing the kr on, and thats the "hot spot", reducing your coolant temp could have an even greater effect than the just the 1pt relationship. I used a radiator fan controller and 180deg t-stat to accomplish operating coolant temp of 175 to 180, this worked very even with ambient temps into the 100's.

[iTurbo]

I installed the NGK BR9ES today. I checked base ignition timing before and after the plug change and it was 12' BTDC. Didn't notice much difference though, although it seemed to have less KR on #4, but still there. Before it was 4-5', now it's pulling 2-4' at WOT. Also, the KR is happening primarily at peak torque right when the engine sees full boost, and then disappears.

I think the next thing I'll try is reduce the base timing to 10' (for now), and then try to improve the cooling system efficiency. My coolant temps generally hover around 200' F when driving in town. The stock TII radiator doesn't seem all that great. I have a 180' thermostat with a small 1/16" hole drilled at 12 o'clock; other than that the cooling system is all stock. I will probably flush it, and install my spare TII radiator which looks like it's in a little better shape. I'm going to fill with 50/50 antifreeze/distilled water and a bottle of water wetter for good measure. I will look into the #4 coolant mod as well, but don't know a whole lot about it yet.

Tonight I will try some WOT runs when it's cooler out and the coolant temps are around 170-180' F and see if that has any effect on the KR on #4. Thanks for the ideas guys.

[iTurbo]

I tried some more WOT blasts tonight. Ambient temp was in the low 70s, charge temps in the 90s. As soon as my scanner was reading 160' coolant temps, I went to WOT. I'm still getting slight KR on #4, 1-2' which was just enough to make the 'knock active' parameter read 'yes' for a few short moments. I tried again with the coolant temps at about 180' and then 195' and got the same results.

I'm beginning to wonder how much my MAP clamp is affecting the KR. Since the MAP signal is 'clamped' at ~14.5 psi (ever-so-slightly below overboost threshold), the logic module is giving advance for that much boost, although I'm now pushing 18 psi in reality.

I'm going to put the base ignition timing at 10' BTDC tomorrow and see what I can do to improve the cooling system efficiency. I have removed *all* of the A/C components, but I need to seal off the radiator a little better than it is now so air is forced through the core instead of around it.

[iTurbo]

Ken, can you explain the #4 cooling mod, or is there a thread or web page on it already? I'm having a hard time coming up with anything trying to search for it. Sounds like this could be a real help for my car.

[iTurbo]

BTW Kyle that is an awesome Omni you have. I'm diggin the relocated battery;)

http://www.turbosedan.com/jerm/022004/101MSDCF/DSC00688.JPG

I have battery terminal covers on it now LOL, yikes!

[Pat]

You simply may be at your octane limit. 18 psi on 91 octane on a 2.5 seems like a lot to me, particularly if you're running a 2.2 cal. You're probably only seeing it on 4 because that is the cylinder on your motor that is most sensitive to detonation (hot spot, slightly leaner injector, plugs, etc).

At one point, I swapped heads on my GLHS and no matter what I did, I was always getting retard in #2. For some reason, that chamber was more prone to detonation than the others so I'd see retard there long before I'd see it in any other cylinders.

[GLHSKEN]

http://www.turbo-mopar.com/forums/showthread.php?t=995


FWIW, Warren hall has the same issue at peak torque with a 2.5L. He is running a 2.5 87 code cal.

[iTurbo]

My Shelby Lancer is 2.2L.

Although I do have a similar setup in my Omni GLH which is 2.5L with 2.5 SMEC and it doesn't seem to have this problem.

[SpoolinGLH]

BTW Kyle that is an awesome Omni you have. I'm diggin the relocated battery;)

http://www.turbosedan.com/jerm/022004/101MSDCF/DSC00688.JPG

I have battery terminal covers on it now LOL, yikes!


Thanks! I actually used your thread on td to give me some ideas. I wanted to get a stock mopar battery as well but the guy at the dodge dealership was no help.


Goodluck with KR, youll get it.

[iTurbo]

I just did some more WOT runs in the SL after resetting the base ignition timing to 10' BTDC. Ambient temp was about 75'F, charge temps at 125'F, and coolant temps were at 200'F. With 18 psi, I saw no KR whatsoever. I'm going to keep the timing and boost level where it is for now until I can improve the cooling system and get a wideband. 100 MPH sure comes up fast! 3rd gear is on the edge of loosing traction when full boost hits, and I have fully rebuilt suspension, new Z rated Kumho tires, poly bushings everywhere etc.

[turbo xtc]

are you boosting a log?the number four is the closest to the turbo and it gets the most air first i had a lot of knock for a while even burnt a piston so i relocated the fifth injector to the just above the throttle-body and i used a injector out of a bmw 535 the 535 has a 6 cylinder engine and the spray has a real nice wide conicle pattern and i'm using 27pphs with regular electronics for my laser xt the 2.5 will need more fuel then the 2.2 and as i have found out placement of the fifth injector means a lot.

[iTurbo]

It's '87 Turbo II, with the 2 piece blow-through intake. I'm still getting some slight KR on #4, although it's slight and disappears right away after peak torque. I deleted all the A/C, but forgot to reinstall the plastic shield that went over the A/C condensor. This was allowing air to bypass the radiator and go around it instead. I reinstalled it today so I'm hoping that will help somewhat.

Interestingly, my Omni GLH is getting slight KR at peak torque on primarily on cylinder #3. It seems to run a bit cooler than the Shelby Lancer which is surprising considering the NPR covers the entire radiator in a sandwhich configuration with about 1" gap between them. I sealed the gap on top with a piece of cardboard for now. I also put the NGK BR9ES plugs in the Omni today. Seemed to startup and idle great but I haven't driven it yet.

[Frank]

I would definently still do the number #4 coolant mod. You are close in my opinion in needing it. Just wait till we get into those good hot days. Its not to hard. :)


Frank

[iTurbo]

I'm going to look into doing that, and coolant system flush using distilled water and a bottle of water wetter to try to eliminate hot spots as much as possible.

I'm also thinking about moving the injectors around; i.e. swap out injectors #1 and #4 and see if the KR follows the injector just to rule that out.

[Frank]

Good call. An unbalanced injector is always good to verify.


Frank