Anyone have a guess on how much HP would be lost at 6 degrees of FALSE Knock retard on a 450 HP LT1 engine?

 

A whole bunch. Maybe over 40HP or so. When I had a knock problem and the scan master read 5 degress I could feel it. It was like driving into a head wind. When the PCM backs the timing out under WOT then kiss the power goodbye.

What is your compression ratio?
Do you have a good dyno tune?
Do you think it is false knock?

 

It might be just about as easy to guess what you are wearing when you are getting the knock. I would be concentrating more about how to correct it (knock module, tuning, etc.), rather than how much it is costing you.

 

I lost roughly 35 HP on a Mustang Chassis Dyno above 4500 RPM with knock retard of about 7-8 degrees. You may consider reducing your timing at WOT, since the PCM gives more timing than the program calls for (it's an optispark thing from what I have read). I set mine for 30 degrees at 95 and 100 KPA from 2800 RPM to redline. The data log showed a maximum of 34 degrees at the upper RPMs. That is where I made max power and tq. It seems like a drastic reduction over stock settings, but it worked for my car, the dyno doesn't lie.

 

Most likely the knock occurs at peak torque or VE. You can take out some timing in that area. Also depending on what the A/F ratio is in that area you can add some fuel.

On my L98 I'm running 27 degrees in the 4800 to 5200 rpm cell and then it increases up to 33 degrees of timing above 5600 rpm's. Also the A/F ratio in that cell is the richest with around a 12.7.

 

You can't really go by timing recommendations, you need to tune for it. I see you have heads/cam. My car only accepts ~20* advance at high map without knock, but makes good power. See sig.

BTW I was sure my knock was false, too, until I noticed the shiny little ***** on my spark plugs......I'd look for those with a good magnifying glass before being TOO sure it's false.

 

So if you have detonation or pre-ignition you will see shiny specs on the plug insulator?
Is this correct?

 

Appreciate the response, just got the engine together, 11.2-11.5 comp ratio, pcmforless tune (getting a dyno tune very soon!) I have gone the lt4 km route, clearanced the exhaust system the best i could. I am running 111 race gas to help rule out detonation. The valve train is loud, comp pro mags ect.

Its still pulling timing. I am way down on power right now. The car starts and runs/sounds great just dosent pull like it should. Im sure its false knock I am going to have it tuned out soon.

Will let you know what i find.

 

3 degrees is about 12 hp to 15 max depends I saw 9 10 when I was getting knock retard. Say about 20 hp

 

Not necessarily, but the converse is true - if you have little aluminum ***** on the plug, you do have detonation. Mine are truly tiny and hard for me to see without strong light and a magnifier.



Also, now that I have found and corrected my loose opti rotor screws, my random spark knock retard seems to be totally gone! BLMs still not all learned and no WOT yet due to fresh clutch, so results are not yet conclusive.