Is lean uncorked AFR normal for turbo's?
Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
Is lean uncorked AFR normal for turbo's? Ever since I put these new heads on and fired up the car, with no other changes, it ran rich at idle, lean at full boost 14+PSI.
Well, today I took the car to meet my daughter at Panera Bread for lunch. I passed a car under 'some' boost (Not sure how much) and as I rounded in front of the passed car, I heard a distinctive 'Pop!' and the car started running poorly. I thought maybe it had popped off a coupler. I took a quick look at the Wide band and it said "19", "20" and "LEN" (for dead lean). I pulled over and took a look under the hood. Aha..the up pipe had popped off it's coupler just prior to the Blow off valve. I looked at it for a minute, musing over the fact that it had never came off that Bead rolled pipe before... Then I thought... "Hey...it's running like a non-turbo mode now. Like normally aspirated...why is it running so lean? Is the turbo *that* much of a restriction at ilde and Bryans tune compensates for that? Or is my intercooler stopped up?"
So.. my question for you guys is,... When/if you pull off your up-pipe, does it run lean?
Well, today I took the car to meet my daughter at Panera Bread for lunch. I passed a car under 'some' boost (Not sure how much) and as I rounded in front of the passed car, I heard a distinctive 'Pop!' and the car started running poorly. I thought maybe it had popped off a coupler. I took a quick look at the Wide band and it said "19", "20" and "LEN" (for dead lean). I pulled over and took a look under the hood. Aha..the up pipe had popped off it's coupler just prior to the Blow off valve. I looked at it for a minute, musing over the fact that it had never came off that Bead rolled pipe before... Then I thought... "Hey...it's running like a non-turbo mode now. Like normally aspirated...why is it running so lean? Is the turbo *that* much of a restriction at ilde and Bryans tune compensates for that? Or is my intercooler stopped up?"
So.. my question for you guys is,... When/if you pull off your up-pipe, does it run lean?
Ever since I put these new heads on and fired up the car, with no other changes, it ran rich at idle, lean at full boost 14+PSI.
Well, today I took the car to meet my daughter at Panera Bread for lunch. I passed a car under 'some' boost (Not sure how much) and as I rounded in front of the passed car, I heard a distinctive 'Pop!' and the car started running poorly. I thought maybe it had popped off a coupler. I took a quick look at the Wide band and it said "19", "20" and "LEN" (for dead lean). I pulled over and took a look under the hood. Aha..the up pipe had popped off it's coupler just prior to the Blow off valve. I looked at it for a minute, musing over the fact that it had never came off that Bead rolled pipe before... Then I thought... "Hey...it's running like a non-turbo mode now. Like normally aspirated...why is it running so lean? Is the turbo *that* much of a restriction at ilde and Bryans tune compensates for that? Or is my intercooler stopped up?"
So.. my question for you guys is,... When/if you pull off your up-pipe, does it run lean?
Well, today I took the car to meet my daughter at Panera Bread for lunch. I passed a car under 'some' boost (Not sure how much) and as I rounded in front of the passed car, I heard a distinctive 'Pop!' and the car started running poorly. I thought maybe it had popped off a coupler. I took a quick look at the Wide band and it said "19", "20" and "LEN" (for dead lean). I pulled over and took a look under the hood. Aha..the up pipe had popped off it's coupler just prior to the Blow off valve. I looked at it for a minute, musing over the fact that it had never came off that Bead rolled pipe before... Then I thought... "Hey...it's running like a non-turbo mode now. Like normally aspirated...why is it running so lean? Is the turbo *that* much of a restriction at ilde and Bryans tune compensates for that? Or is my intercooler stopped up?"
So.. my question for you guys is,... When/if you pull off your up-pipe, does it run lean?
Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
And with that in mind I'd already asked my tuner (Bryan Herter from PCM4less) and he said he couldn't think of why that would have anything to do with it.
Thanks for the insult. It's appreciated.
Thanks for the insult. It's appreciated.
Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
I purchased a used MAF Translator and hooked it up a little bit ago with the intentions of offseting the lean idle and cruise settings. But here's the 'lay of the land'...
Without the MAF Translator in use...
I introduce the MAF Translator into the circuit with it set to 'Base' of 5% lean.
I turn the MAF translator to %10 lean and restart the car...
I'm going to remove the MAF Translator and restart it and see if it's still only drifting down to 13.9.
Without the MAF Translator in use...
- Start the car (starts right up w/o hesitation) and turn on the wide band AFR gauge
- AFR starts at 14.7 and hovers there for a few seconds, the starts going to 14.6, 14.5, 14.3, etc till it's in the 13.9 range.
I introduce the MAF Translator into the circuit with it set to 'Base' of 5% lean.
- Start the car (starts right up with a 'little' hesitation) and turn on the wide band AFR gauge
- AFR starts at 14.7 and hovers there for a few seconds, then goes to 15.3
- I'm thinking "Nice!".... but then...
- The AFR goes to 15.2, 15.1, 15.0, etc until it goes to 12.9...WTH?
I turn the MAF translator to %10 lean and restart the car...
- Start the car (barely starts since I have to pedal it) and turn on the wide band AFR gauge
- AFR starts at 14.7 and hovers there for a few seconds, then goes to 15.9
- I'm thinking "Nice!" again.... but then...
- The AFR goes to 15.8, 15.7, 15.6, etc until it goes to 12.9 again. Damn!
I'm going to remove the MAF Translator and restart it and see if it's still only drifting down to 13.9.
Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
That's what I thought as well. I put my hand held Fuel Pressure gauge on and tested it at atmosphere. 43.5 psi... I put on the vacuum signal and then modulated the throttle. It was at 38.x at idle and modulated according to the use of the pedal.
I had to order the Hypertech handheld with it's much longer hose so I can put the gauge on the windshield and try a WOT. I'll get to that on Tuesday it looks like.
I had to order the Hypertech handheld with it's much longer hose so I can put the gauge on the windshield and try a WOT. I'll get to that on Tuesday it looks like.
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9 Second Club
Joined: Nov 2003
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From: Norn Iron
Your tuner thinks that the engine doesnt need re-tuned after fitting uprated parts, and that AFR's should be as they were before ??
Weird.
The only other obvious thing to check. Is has the installation of these new heads been carried out properly and by a competent person ?
ie, has something not been fitted properly which could cause bad running ?
Weird.
The only other obvious thing to check. Is has the installation of these new heads been carried out properly and by a competent person ?
ie, has something not been fitted properly which could cause bad running ?
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Verdad Gallardo Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
Yeah. I'm surprised that with no other changes other than the heads, the AFR has changed. And on both ends of the RPM spectrum. Bryans well known over here for his Forced Induction tunes. His initial tune for my car was spot on for a 93 octane daily driven street turbo car. I got a decent deal on these rare heads (only 50 pair made, I'm told) and thought I'd add them.
Your tuner thinks that the engine doesnt need re-tuned after fitting uprated parts, and that AFR's should be as they were before ??
Weird.
The only other obvious thing to check. Is has the installation of these new heads been carried out properly and by a competent person ?
ie, has something not been fitted properly which could cause bad running ?
Weird.
The only other obvious thing to check. Is has the installation of these new heads been carried out properly and by a competent person ?
ie, has something not been fitted properly which could cause bad running ?
9 Second Club
Joined: Nov 2003
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From: Norn Iron
Of course adding more airflow into the engine is going to affect AFR's If it wasnt going to make any difference, you would never need to re-tune for anything.
Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
This is what I don't understand. Why you keep hammering me dude. I ask the guy that SHOULD know and HE said he doesn't think it should have changed. I'm not the tuner. He is. I observed a condition, reported it to him. Asked him if he thought that was odd and he replied, "yes. that is odd". I wanted to pay him for a retune but he thought I must have a vacuum leak. I've checked it over and found none. I don't see how a vacuum leak could play into this anyway since the MAP is the same on both the old and new setups.
Before the head swap the car at cold idle (1,000 rpm) had -12 Manifold pressure. Now with the new heads, the cold idle (1,000 rpm) has -12 Manifold pressure.
Before the head swap the car at cold idle (1,000 rpm) had -12 Manifold pressure. Now with the new heads, the cold idle (1,000 rpm) has -12 Manifold pressure.
Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
The reason I switched heads was that the LT1 heads were pushing water at 12psi and above. I wanted some heads with thicker decks.
I had ported LT1 castings that had been upgraded to LT4 Valve sizes. The professional porting yielded I/E flows at .600 of 275/200. Good flows for an LT1 but pitiful in the LSx world, I know
I found a deal on some rare Canfields and bought them. The guy I bought them from said the Canfields were ported but all the ports looked 'as cast' to me. The valve guides weren't elipsed or smoothed at all. I bought them a couple of years ago thru the Classifieds on either this site or Camaroz28.com, can't remember.
The Canfields have (from what the seller stated)
CC = 58cc
Intake Valve size = 2.05
Exhaust Valve size = 1.60
Intake flow @ .600 = 270cfm
Exhaust flow @.600 = 200cfm
Intake port runner size = 200cc
There is damned little info on these particular heads. I even called Canfield themselves and talked to the owner and he couldn't tell me jack about them. He didn't have any data nor spec's on them whatsoever.
I know George Baxter ran 9.04 @ 155mph in his convertible Z28 LT1 with a set of these heads.
I had ported LT1 castings that had been upgraded to LT4 Valve sizes. The professional porting yielded I/E flows at .600 of 275/200. Good flows for an LT1 but pitiful in the LSx world, I know
I found a deal on some rare Canfields and bought them. The guy I bought them from said the Canfields were ported but all the ports looked 'as cast' to me. The valve guides weren't elipsed or smoothed at all. I bought them a couple of years ago thru the Classifieds on either this site or Camaroz28.com, can't remember.
The Canfields have (from what the seller stated)
CC = 58cc
Intake Valve size = 2.05
Exhaust Valve size = 1.60
Intake flow @ .600 = 270cfm
Exhaust flow @.600 = 200cfm
Intake port runner size = 200cc
There is damned little info on these particular heads. I even called Canfield themselves and talked to the owner and he couldn't tell me jack about them. He didn't have any data nor spec's on them whatsoever.
I know George Baxter ran 9.04 @ 155mph in his convertible Z28 LT1 with a set of these heads.
9 Second Club
Joined: Nov 2003
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From: Norn Iron
So if they arent, clearly there has been a problem during the installation. So you need to be looking for that. Who fitted the heads ?
Thread Starter
Joined: Feb 2003
Posts: 2,145
Likes: 133
From: East Chatham, New York
I installed these heads. Just like I installed the last 3 sets of heads on this car. Just like the other sets of heads I've replaced on other peoples LT1s in Houston.
I had the heads at the machinists, all valve guides inspected, valves lapped properly, spring height set to spec, brand new Beehive springs, locks and retainers. A .010 cleaning cut on the decks, brand new ARP 7/16" studs, brand new CC Ultra Pro mags, brand new LS7 Lifters, brand new ARP head bolts torqued in sequence to 65ft lbs. New FelPro 1074 head gaskets.
I had the heads at the machinists, all valve guides inspected, valves lapped properly, spring height set to spec, brand new Beehive springs, locks and retainers. A .010 cleaning cut on the decks, brand new ARP 7/16" studs, brand new CC Ultra Pro mags, brand new LS7 Lifters, brand new ARP head bolts torqued in sequence to 65ft lbs. New FelPro 1074 head gaskets.
