Welcome to cofee talk....................

After blowing up my first QR I went big and decided to tune to completly eliminate knock while getting as much HP as possible. Now what I did was log the knock sensor voltage in the EU. I have seen that while cruising it hovers arond 2.38V. When, what I think is knock, happens the voltage drops. 2.00V being OK, anything from 1.9-1.7 is mild to serious, anything below and you could be looking at a rod. I was just wondering if there was anyone who could shed some light on whether I am dead wrong or not. And if I am wrong, I see a whole bunch more HP in my future.

I am firm believer that any turbocharged QR in stock trim pushing 10+psi has it's days numbered without doing some sort of timing adjustment. Yes tuning has a major part in this and also the use of alky can hinder detination but IN MY OPINION (most times wrong) QR + 10+PSI = not good.

"Here's a topic talk among youselves." lol

I've logged countless hours and I'll agree.

If you can only get 91 octane, 8 psi w/ stock thermostats is (getting near) the danger zone in the summer.

I'm pushing 17* base timing running 93 octane, I'm at the ragged edge in summer at 9 psi. With base timing at 13* it'll run up closer to 12psi before I get worried, but the stock clutch is my saving grace. It's good at 9 psi, at 11 it'll slip. Lower temp thermostats are a big help. Putting in the JWT clutch gear sitting in my garage is on the list.

The knock sensor is weird, depending on the temp outside when you start it. the initial voltage will vary quite a bit. If it's knocking under load you'll hear it, that's the main reason my car's exhaust is so mellow.

W/ a 9:1 CR piston and cooler temp thermostats we tuned in well over 22-23* total timing WOT as the RPMs came up on Mike's car. Could have added in more but we we're already way above the stock timing tables, and timing wasn't netting returns on the dyno as we went up higher, so they got backed down a little. The only place I ran into real det issues was when tweaking timing in the 2400-3200 RPM range. It got so bad the car defaulted to the high det timing maps even when tuning to swith the car out of closed loop at lower RPMs and lower loads. I wonder how much of the timing sensativity in those RPM ranges is due to the variable intake cam timing (we didn't have access to the tables at that time to tune, but could log it).

Mike K. is pushing tons of timing in the project Spec V w/ 8.5:1 pistons and ?pump gas? (correct me if I'm wrong). I'll get you some data logs when I get home of how much total timing I'm pushing now under load in the dead of summer on 93 octane. I know I've seen over 20* (27ish maybe in the past) but I never took the time to compare ignition timing to cam timing when I was tweaking closed loop tuning to run timing up.

The closer you get to the max voltage on the MAF sensor you really start to get deminishing returns as far as power output goes per PSI you add in, one day I'll take the time to determine what variable is causing that, but not before i have a budget built backup motor ready.

You should try clamping MAF voltage .05 lower in increments and see where it starts to swing back into power and see what clamping lower does to cam and gnition timing.

My car is tuned on race gas only

Posted By Big J on 06-28-2009 09:10 PM
I've logged countless hours and I'll agree.

If you can only get 91 octane, 8 psi w/ stock thermostats is (getting near) the danger zone in the summer.

I can get 93 here but my first engine still went pop at 13psi. Granted It was my initiation into the tuning world and using an e-blue. So I'll take majority of the blame on that one.

Posted By Big J on 06-28-2009 09:10 PM
I'm pushing 17* base timing running 93 octane, I'm at the ragged edge in summer at 9 psi. With base timing at 13* it'll run up closer to 12psi before I get worried, but the stock clutch is my saving grace. It's good at 9 psi, at 11 it'll slip. Lower temp thermostats are a big help. Putting in the JWT clutch gear sitting in my garage is on the list.

I am pushing 17 base too with 8.5:1 compression pistons and the knock monitor still dips into the 1.6V area if I don't pull timing. Now I'm not sure if 1.6 volts is bad or not. I am just making an educated guess as too seeing knock on my SAFC and correlating(sp) it with the recorded value on the EU. By pulling timing I see knock go away on the SAFC and on the logged value in the EU.
(I don't have my O2 sensors plugged and I modifying the default map.)

Posted By Big J on 06-28-2009 09:10 PM
The knock sensor is weird, depending on the temp outside when you start it. the initial voltage will vary quite a bit. If it's knocking under load you'll hear it, that's the main reason my car's exhaust is so mellow.

My reading will also vary BUT as soon as the car warms up it hovers around 2.38v.

Posted By Big J on 06-28-2009 09:10 PM
W/ a 9:1 CR piston and cooler temp thermostats we tuned in well over 22-23* total timing WOT as the RPMs came up on Mike's car. Could have added in more but we we're already way above the stock timing tables, and timing wasn't netting returns on the dyno as we went up higher, so they got backed down a little. The only place I ran into real det issues was when tweaking timing in the 2400-3200 RPM range. It got so bad the car defaulted to the high det timing maps even when tuning to swith the car out of closed loop at lower RPMs and lower loads. I wonder how much of the timing sensativity in those RPM ranges is due to the variable intake cam timing (we didn't have access to the tables at that time to tune, but could log it).

I have my secondary thermo gutted. I have seen 25-27* timing WOT but that is at the ECU timing is still being pulled through the EU. At 20psi unter the torque curve (3600rmp-4700rpm) i am pulling ~14* to avoid what I THINK it Detination. I actually had to add some timining back between 4700-5200rpm because there was a HUGE HP loss there even at 11.5AFR.

Posted By Big J on 06-28-2009 09:10 PM
Mike K. is pushing tons of timing in the project Spec V w/ 8.5:1 pistons and ?pump gas? (correct me if I'm wrong). I'll get you some data logs when I get home of how much total timing I'm pushing now under load in the dead of summer on 93 octane. I know I've seen over 20* (27ish maybe in the past) but I never took the time to compare ignition timing to cam timing when I was tweaking closed loop tuning to run timing up.

The closer you get to the max voltage on the MAF sensor you really start to get deminishing returns as far as power output goes per PSI you add in, one day I'll take the time to determine what variable is causing that, but not before i have a budget built backup motor ready.

You should try clamping MAF voltage .05 lower in increments and see where it starts to swing back into power and see what clamping lower does to cam and gnition timing.

That would be cool. I'll send you some of my logs too if you want. Always nice to have another set of eyes to look at them. I am clamping my voltage at 4.5v and still seeing full ignition timing under WOT I think it was pimp and I that were comparing logs and after comparing his to mine the timing didn't change. I don't think MAF voltage have as much bearing on overall timing as we thought. Send me some logs and we'll compare notes

I watch the knock calibration screen on the SAFC matrix style, it doens't make sense to most people, but I know what the numbers mean. It's not so much a steady value that correlates to knock. It'll jump as soon as your foot goes in it, but it'll hold steady, that's pretty normal even if it's in the 300-380 range, it's the marked spikes or dips that are a concern. It gets audible in the 800-900 range, which I've only seen/heard once.

With the high piston speeds the motor loves timing except in the lower RPM ranges.

With your drop in compression, the stock timing tables, even at 17* base timing, are going to be fine at 20 psi. If you want to be safe, start at 13* base timing, add it back in 1* at a time.

I hear what you are saying but what scares me is that those dips and spikes are what I am tuning out. I've never heard it but the logs show something completly different.
Not sure what the "matrix style" SAFC values are but when I'm on it and the voltage goes from 2.4v steady to a 1.9v AND I verify with a knock reading from the SAFC, would assume that it is knock. Unless there is something wrong with my setup. The other explanation is a spark blow out or misfire, but adusting the timing removes the spikes. Sooooooo........?????....

J, do me a favor. If you could get some of Mike K.'s logs and send me one.....that would be awsome. I want to compare my engine logged values with his just for shits and giggles.
Thank mang.

ummmm...sp you're saying stock timing for a N/A motor is fine at 20 pounds of boost? LMAO stock timing tables are no where near fine at 20 psi unless you're running a super large super efficient turbo and IC in which case it wouldn't be efficient in terms of spool vs rpm.

I have seen 25-27* timing WOT but that is at the ECU timing is still being pulled through the EU. At 20psi unter the torque curve (3600rmp-4700rpm) i am pulling ~14* to avoid what I THINK it Detination. I actually had to add some timining back between 4700-5200rpm because there was a HUGE HP loss there even at 11.5AFR.

Pulling 14* in the lower RPM ranges is too much. You have to add timing in as RPMs go up so the pistons don't start to outrun the flame front. If you're running 25* timing and pulling 14* you end up with 11*, which is pretty low. You should be able to swing 16-17* total in the upper RPM ranges. The QR has high piston speeds. If you can make the same power at lower boost with more timing, it's win win. You swing back closer to a balanced intake to exhaust pressure, less time to spool the turbo because you're running lower boost, etc.

Posted By arby25 on 07-03-2009 05:06 AM
ummmm...sp you're saying stock timing for a N/A motor is fine at 20 pounds of boost? LMAO stock timing tables are no where near fine at 20 psi unless you're running a super large super efficient turbo and IC in which case it wouldn't be efficient in terms of spool vs rpm.

I'm wrong