Is my exhaust system too restrictive for my 6.0L? :TECH ONLY:
10-28-2008, 01:48 PM
#42
Ok, no more tune talk, sorry if I whored up your thread just trying to help...If you notice your Manifold pressure, starts out solid then it slowly decreases over the run... All the logs I have seen, none of them do that, the manifold pressure usually peaks around peak tq... So that could indicate something is restricting the airflow and the load increases.... Look at some of your pre-6.0 logs and see if it is the same...
Is there a part number on the intake manifold somewhere that would prove or disprove if the intakes are different or the same?
10-28-2008, 05:17 PM
#43
How do I change this text
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I think the power falling off has nothing to do with the tune. AFR is AFR - matter how you get it (right or wrong) in the end if the AFR is on it's on. We can have this discussion another time about part throttle tuning with bad 02's and improper grounds, etc but I'm still not convinced the falling off power is in the tune. I've confirmed the TB was opening all the way, no air intake tube and the exhaust sounds like it's well up to the task. Unless a 4.8L intake manifold is different which I'm told it's not, it has to be in the cam timing or valve events, right?
LMFAO, thats nice.....
I didnt relize you have ran this without an intake, I find it interesting that it made less power without the intake tube... Also the fact the the map drops up top make me wonder about the throttle body?? 98 to 92 kpa is about the difference of 0 feet above sea level to 2000 feet....
How about this? Just lowwer your shift points?
10-28-2008, 05:30 PM
#44
If the intake manifold pressure drops some at higher RPM I'd think that it's because it doesn't flow enough air to feed the engine. Have you considered swapping over to something like a Fast or an LS6 intake manifold?
It does sound like your VE table is off a bit at higher RPM as well. If it was dialed in perfectly you would be able to hit your commanded AFR in the PE table instead of it going rich up top. I don't think it's the sole cause of the power dropping off though.
You cam is advanced 2 degrees. This lends itself well to making more torque down low, but your power will fall off sooner as well.
I think you are fighting against top end power with all three of these.
It does sound like your VE table is off a bit at higher RPM as well. If it was dialed in perfectly you would be able to hit your commanded AFR in the PE table instead of it going rich up top. I don't think it's the sole cause of the power dropping off though.
You cam is advanced 2 degrees. This lends itself well to making more torque down low, but your power will fall off sooner as well.
I think you are fighting against top end power with all three of these.
With the horrible gear spacing of the 5 speed you have to keep the revs up to keep it from bogging between gears. 
10-28-2008, 08:16 PM
#46
If the intake manifold pressure drops some at higher RPM I'd think that it's because it doesn't flow enough air to feed the engine. Have you considered swapping over to something like a Fast or an LS6 intake manifold?
It does sound like your VE table is off a bit at higher RPM as well. If it was dialed in perfectly you would be able to hit your commanded AFR in the PE table instead of it going rich up top. I don't think it's the sole cause of the power dropping off though.
You cam is advanced 2 degrees. This lends itself well to making more torque down low, but your power will fall off sooner as well.
I think you are fighting against top end power with all three of these.
It does sound like your VE table is off a bit at higher RPM as well. If it was dialed in perfectly you would be able to hit your commanded AFR in the PE table instead of it going rich up top. I don't think it's the sole cause of the power dropping off though.
You cam is advanced 2 degrees. This lends itself well to making more torque down low, but your power will fall off sooner as well.
I think you are fighting against top end power with all three of these.
This coming from the guy that originally said he should have gone with a 116? lol.
10-29-2008, 11:06 AM
#49
edit: what happened to his post right above mine?
Last edited by outlawz2004; 10-29-2008 at 11:24 AM.
10-29-2008, 01:00 PM
#50
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in case you are interested. with a 6 inch piece of flat iron you can make the stock truck engine cover fit.
I think I'm going to upgrade to the SSR 90mm TB and intake. I found a new take off for $200 then add a dr x on top and should have a nice setup for $400 or so. Although I could upgrade to the Weiand Street warrior setup. After all the screwing around though with relocation brackets, water pumps and hoses and wires for new injectors I'll have a headache and $800 out of my wallet. I have a new cam in mind along with the intake swap that I'd like to try. I'm thinking of a 224/224 .56x/.56x 110 LSA +4 degrees advance. This should keep a similar curve that I have now but carry on higher as well. Peak HP should be around 5800 or so and I should still retain my lowend torque. I think realistically a SSR 90mm intake is in order. It's the cheapest 90mm upgrade I'm going to be able to do, I'll put a SS engine cover on it and it should hide the junk underneath. What do you guys think?