mightyquickz28

iTrader: (8)

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?

98Z28CobraKiller

iTrader: (17)

You are hitting cells in the VE table that were never tuned.

AzShadow

rich at idle and lean under boost could be the fuel pressure reg..

stevieturbo

It would be very stupid to drive a car after changing heads and not having it re-tuned. That's just asking for a blown engine.

mightyquickz28

iTrader: (8)

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.

mightyquickz28

iTrader: (8)

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...

• 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.

mightyquickz28

iTrader: (8)

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.

stevieturbo

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 ?

mightyquickz28

iTrader: (8)

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.

stevieturbo

And that is exactly where you are wrong.

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.

mightyquickz28

iTrader: (8)

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.

98Z28CobraKiller

iTrader: (17)

Let's take one step back here. What heads did you remove and what heads did you put on?

mightyquickz28

iTrader: (8)

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.

stevieturbo

Then I'll repeat above. Assuming the head flow isnt much different to what you previously had, AFR's should be reasonable after the swap.
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 ?

mightyquickz28

iTrader: (8)

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.