Boost and Knock Retard?
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 5,475
Likes: 718
From: Black Forest CO
Boost and Knock Retard?
I logged some data today using EFILive and found that I am once again getting some knock retard under boost. I am getting a maximum of 4.8 degrees and most all of the knock retard is well under that. I am running a maximum of 6.5 psi of boost.
Should I be striving for 0 knock retard or is that not realistic. I assumed that I needed to have 0 for my engine to live under boost. I am currently running 16-19 degrees of advance in the 4000 rpm plus range. I am using 91 octane Shell premium unleaded fuel which is the highest octane that is available here. I have plenty of fuel pressure under boost. My LTrims look good as they are mostly near 0 (except cell 22) and they are -4 under WOT.
Should I be concerned about this amount of KR and of so what should I do about it?
Thanks,
Mark
Should I be striving for 0 knock retard or is that not realistic. I assumed that I needed to have 0 for my engine to live under boost. I am currently running 16-19 degrees of advance in the 4000 rpm plus range. I am using 91 octane Shell premium unleaded fuel which is the highest octane that is available here. I have plenty of fuel pressure under boost. My LTrims look good as they are mostly near 0 (except cell 22) and they are -4 under WOT.
Should I be concerned about this amount of KR and of so what should I do about it?
Thanks,
Mark
Heel & Toe
Joined: Jul 2002
Posts: 22
Likes: 0
From: Maryville TN
Re: Boost and Knock Retard? (VortechC5)
With my Syclone I fight Knock every day. Definately need some higher octane fuel, you may want to consider running Xylene or Tolulene. What plugs are you running? I'd reccommend going a step colder, NGK TR6's. I ran them on my WS6 with nitrous. New plug wires, and change the fuel filter.
HTH, :seeya
[Modified by WS6Clint, 10:35 AM 6/17/2003]
HTH, :seeya
[Modified by WS6Clint, 10:35 AM 6/17/2003]
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 5,475
Likes: 718
From: Black Forest CO
Re: Boost and Knock Retard? (QuickSilver2002)
I am seeing the KR in second gear.
When looking at the EFILive data I am seeing up to 7 degrees of KR in the 4100 to 6100 rpm range.
When the worst of the knock is occurring the timing is in the 11.5 to 13.5 range.
My IATs are all in the 75-80 degree range. This is before the air is boosted. The Vortech kit does not relocate the IAT from the MAF housing to the intake tract after the aftercooler.
I didn't expect to see this much KR here at this altitude especially with as little timing as is dialed into the PCM. The air density at here at 7000 feet is way less than at sea level and I was hoping that would be more in my favor.
Thanks.
When looking at the EFILive data I am seeing up to 7 degrees of KR in the 4100 to 6100 rpm range.
When the worst of the knock is occurring the timing is in the 11.5 to 13.5 range.
My IATs are all in the 75-80 degree range. This is before the air is boosted. The Vortech kit does not relocate the IAT from the MAF housing to the intake tract after the aftercooler.
I didn't expect to see this much KR here at this altitude especially with as little timing as is dialed into the PCM. The air density at here at 7000 feet is way less than at sea level and I was hoping that would be more in my favor.
Thanks.
Le Mans Master
Joined: Apr 2000
Posts: 7,248
Likes: 0
Re: Boost and Knock Retard? (VortechC5)
Could be some bad gas, but I wouldn't count on it.
Which plugs and gap?
Relocating the IAT after the blower might be smart and I may do the same. Anyone have comments for the best location of the IAT on the Vortech kit after the blower?
Which plugs and gap?
Relocating the IAT after the blower might be smart and I may do the same. Anyone have comments for the best location of the IAT on the Vortech kit after the blower?
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 5,475
Likes: 718
From: Black Forest CO
Re: Boost and Knock Retard? (MelloYellow)
I am still running the stock plugs with the stock gap. The car only had 2000 miles on it when I put the blower on so I did not change them. They now have 3100 on them. I have a set of TR6s. Maybe I need to install them.
Steve01 relocated his IAT to the discharge side of the aftercooler. He emailed me some pictures and I'll be doing mine the same way. It looks like I'll be doing it soon too.
Steve01 relocated his IAT to the discharge side of the aftercooler. He emailed me some pictures and I'll be doing mine the same way. It looks like I'll be doing it soon too.
Pro
Joined: Jan 2002
Posts: 741
Likes: 9
From: Rancho Cordova CA
Re: Boost and Knock Retard? (MelloYellow)
The most timing I have seen come out is 2 degrees with 91 octane. When I mix 100 octane with the 91 to get a 93 rate I see no timing being pulled. I have also found that the right octane booster will help as well. I will run my EFI live and post more info. :cheers:
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Pro
Joined: Jan 2002
Posts: 741
Likes: 9
From: Rancho Cordova CA
Re: Boost and Knock Retard? (MelloYellow)
I am using The Outlaw, Super concentrated octane booster. I comes in 32 OZ cans and I mix 1/2 can in each tank. I think it brings up the octane to maybe 92 or a little better. The race gas mix is best. I purchased a case from Kragen for $1.99 a can. They are blowing it out, I think because the cans are to big to use one per tank so you have to add it with a funnel.
My IAT temps are higher than I would like. 115 to 122 at 75 degree outside temp. I pushed it up to 6700RPM and over 10 lbs boost tonight. I could not get a good look at the boost gage as I was holding on with both hands. The MAP pegs the gage at 14.9 and goes flat until I let off.
RPM 6627
TP 99.6
MAF 12201
MAP 14.9
ADV 18.0
Knock 0
Load 100
VSS 79.5
MAF 56.6
AFR 8.31 Don't think is accurate
H02 B1s1 907 ?
H02 B2s1 885?
Let me know if you want the file.
:cheers:
My IAT temps are higher than I would like. 115 to 122 at 75 degree outside temp. I pushed it up to 6700RPM and over 10 lbs boost tonight. I could not get a good look at the boost gage as I was holding on with both hands. The MAP pegs the gage at 14.9 and goes flat until I let off.
RPM 6627
TP 99.6
MAF 12201
MAP 14.9
ADV 18.0
Knock 0
Load 100
VSS 79.5
MAF 56.6
AFR 8.31 Don't think is accurate
H02 B1s1 907 ?
H02 B2s1 885?
Let me know if you want the file.
:cheers:
Melting Slicks
Joined: Mar 2002
Posts: 2,931
Likes: 2
From: Tx
Re: Boost and Knock Retard? (Steve'01)
FYI, the stock MAP sensor/pcm can't read boost. The AFR you are seeing in the log is the commanded a/f ratio. This is what the computer thinks the resultant AF ratio will be based on the pulse width, rpm, and the MAF reading it is seeing (which is obviously not accurate since the MAF is maxed out).
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 5,475
Likes: 718
From: Black Forest CO
Re: Boost and Knock Retard? (Steve'01)
Steve01,
Thanks for logging some data. It's quite interesting. The IAT temps are just what I expected that they would be.
I noticed in your sig that your compression ratio is 8.5:1. I had forgotten that. Does the low rpm power seem soft at all with the compression that low?
If you could email me the file that would be great.
Thanks for logging some data. It's quite interesting. The IAT temps are just what I expected that they would be.
I noticed in your sig that your compression ratio is 8.5:1. I had forgotten that. Does the low rpm power seem soft at all with the compression that low?
If you could email me the file that would be great.
Team Owner
Joined: May 2000
Posts: 25,342
Likes: 222
From: Frisco, TX
Re: Boost and Knock Retard? (Steve'01)
I am using The Outlaw, Super concentrated octane booster. I comes in 32 OZ cans and I mix 1/2 can in each tank. I think it brings up the octane to maybe 92 or a little better. The race gas mix is best. . . .
Pro
Joined: Jan 2002
Posts: 741
Likes: 9
From: Rancho Cordova CA
Re: Boost and Knock Retard? (SteveL2)
Quicksilver2002- what do you recommend I do for the MAF maxing out. Is there a good aftermarket MAF out there for a 01.
SteveL2 – Prior to getting my ECM re-flashed the detonation was auditable, the knock sensor was pulling out 3 to 5 degrees at 5000RPM. I was not pushing the engine due to break in and tuning. I used a mix of 100 octane with 91 to bring it to 93 and the knock was gone. Using the octane booster I could still hear it but not as bad. I have not pushed the engine without the booster.
Mark – I will send the file, let me know what you think.
[Modified by Steve'01, 8:49 PM 6/19/2003]
SteveL2 – Prior to getting my ECM re-flashed the detonation was auditable, the knock sensor was pulling out 3 to 5 degrees at 5000RPM. I was not pushing the engine due to break in and tuning. I used a mix of 100 octane with 91 to bring it to 93 and the knock was gone. Using the octane booster I could still hear it but not as bad. I have not pushed the engine without the booster.
Mark – I will send the file, let me know what you think.
[Modified by Steve'01, 8:49 PM 6/19/2003]
Pro
Joined: Jan 2002
Posts: 741
Likes: 9
From: Rancho Cordova CA
Re: Boost and Knock Retard? (SteveL2)
Almost forgot Mark, after my rebuild and the 8.5 compression I have not felt any loss of low RPM power. I think because of the headwork and the lightening and balancing of the engine components. Now the engine spins up very fast. This allows me to get to boost very quickly. Too quick sometimes, just spin tires. My gearing is 390 so that helps as well. I was about to change my gears to 342 prior to the belt problem to hopefully help traction. I am also looking at tubing and 335s to help. :cheers:
[Modified by Steve'01, 8:48 PM 6/19/2003]
[Modified by Steve'01, 8:48 PM 6/19/2003]
Melting Slicks
Joined: Mar 2002
Posts: 2,931
Likes: 2
From: Tx
Re: Boost and Knock Retard? (Steve'01)
Quicksilver2002- what do you recommend I do for the MAF maxing out. Is there a good aftermarket MAF out there for a 01.
Unfortunatly, there is not much you can do, besides going with an expensive aftermarket computer to control fuel and spark. I don't know of anyone that has a good ls1 recalibrated MAF setup for boost. It's not just the MAF that has limitations; the PCM also has a limited amount of airflow it will deal with. I think you could get around the PCM limitation by tricking it into thinking the airflow and injector flow was 1/2 the actual values, but I don't know of anyone who has done it.
I'm curious to know how LPE TTs get around this limitation. They may just deal with it like we do, but I'm not sure.
Racer
Joined: Sep 2000
Posts: 288
Likes: 2
From: Chicago IL ------
Cruise-In IV Veteran
Re: Boost and Knock Retard? (VortechC5)
I have a supercharged 99. Came back from a car show one day and had
no choice but to fill up with shell gas. Two days later couple of friends
wanted dyno our cars ran terrible. Didn't know what was wrong. Jeff
at Performance Tech center asked me about the gas. I told him I used
shell, he said there is your problem. Ran the gas out filled up with my mobil.
The car was back to normal. Shell was busted before, about saying its ninety
something octane and it wasn't. :mad
no choice but to fill up with shell gas. Two days later couple of friends
wanted dyno our cars ran terrible. Didn't know what was wrong. Jeff
at Performance Tech center asked me about the gas. I told him I used
shell, he said there is your problem. Ran the gas out filled up with my mobil.
The car was back to normal. Shell was busted before, about saying its ninety
something octane and it wasn't. :mad
Le Mans Master
Joined: Sep 2000
Posts: 6,976
Likes: 527
From: Clouds Over California
Re: Boost and Knock Retard? (Steve'01)
[QUOTE]Quicksilver2002- what do you recommend I do for the MAF maxing out. Is there a good aftermarket MAF out there for a 01.
You can use the older style MAF they do not peak like the 2001+ mafs or you can use a MAFT to trick the MAF and still deliver the fuel. You can also get bigger fuel injectors to compensate when the MAF does peak.
As for KR I would say you need to see Zero degrees KR at WOT...that is what you need to make the most hp. My ATI car made 12+lbs of boost and I had all of those issues tackled.
You can use the older style MAF they do not peak like the 2001+ mafs or you can use a MAFT to trick the MAF and still deliver the fuel. You can also get bigger fuel injectors to compensate when the MAF does peak.
As for KR I would say you need to see Zero degrees KR at WOT...that is what you need to make the most hp. My ATI car made 12+lbs of boost and I had all of those issues tackled.