Turbo 5.3 WAY down on power...HELP!
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From: Liberal land
Turbo 5.3 WAY down on power...HELP! My turbo 5.3 previously made 540 rwhp on 11 psi with no meth. Now I am running meth and 15 psi and I made 560 rwhp. Pathetic. The dyno graph was very questionable after 5200 RPM and it appeared to be a sure sign of valve float. Put in some BTR dual springs, hardened pushrods, and trunion upgrade, and after a data log the AFR was spot on still, meaning I picked up no more power. I don't know whats going on but a 5.3 @ 15 psi with my setup should be well into the 6xx rwhp mark.
Not sure what to look for next and I'm pretty upset about it. I'm wondering if maybe the timing chain or lifters could be the culprit, but it's a 38K mile motor so I have a very hard time believing either of those is worn out yet. Anybody that maybe has some experience, please help me out here. Set up is as follows..
-2005 5.3
-317 heads
-LS6 cam
-LS6 intake
-BTR dual valve springs
-BTR hardened pushrods
-BR7 plugs gapped at .026
-Tnetics T76 ball bearing w/ .96 hotside
-alky control methanol injection single 14 gph nozzle
-3.5" turbo back exhaust through bullet muffler
-viper spec T56 w/ textralia OZ700 clutch
This combo has roughly 4K miles on it over 3 years. If anymore info is needed, I can answer any questions. I have a bunch of data logs but nothing looks out of place. Boost holds steady in HPtuners at 202 kpa which is about 14.7 PSI. Timing is 14* across the charts, and AFR is 10.8-10.9 across the entire pull with no knock at all. It seems like it runs pretty well in all honesty, except for the lack of power. I'm at a loss here...
Not sure what to look for next and I'm pretty upset about it. I'm wondering if maybe the timing chain or lifters could be the culprit, but it's a 38K mile motor so I have a very hard time believing either of those is worn out yet. Anybody that maybe has some experience, please help me out here. Set up is as follows..
-2005 5.3
-317 heads
-LS6 cam
-LS6 intake
-BTR dual valve springs
-BTR hardened pushrods
-BR7 plugs gapped at .026
-Tnetics T76 ball bearing w/ .96 hotside
-alky control methanol injection single 14 gph nozzle
-3.5" turbo back exhaust through bullet muffler
-viper spec T56 w/ textralia OZ700 clutch
This combo has roughly 4K miles on it over 3 years. If anymore info is needed, I can answer any questions. I have a bunch of data logs but nothing looks out of place. Boost holds steady in HPtuners at 202 kpa which is about 14.7 PSI. Timing is 14* across the charts, and AFR is 10.8-10.9 across the entire pull with no knock at all. It seems like it runs pretty well in all honesty, except for the lack of power. I'm at a loss here...
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From: Liberal land
Worth a shot. Motor seems to run very well though. I've cracked ringlands before and I felt a noticeable skip at lower rpm.
Plugs always look perfect. Nice tanish color. No idea on lifter preload. Using 7.4" rods with a stock LS6 cam and lifters, so I would imagine it's what stock should be. Using a CX racing intercooler which doesn't seem to affect boost drop much at all. The AFR's are a bit rich but I don't think I'd pick up 50+ hp from leaning it out a bit.
Plugs always look perfect. Nice tanish color. No idea on lifter preload. Using 7.4" rods with a stock LS6 cam and lifters, so I would imagine it's what stock should be. Using a CX racing intercooler which doesn't seem to affect boost drop much at all. The AFR's are a bit rich but I don't think I'd pick up 50+ hp from leaning it out a bit.
How can you possibly know his pushrods are to short for his combo without measuring them... Every car is different and there are a lot of people with this same combo and doing just fine with 7.400 push rods.
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Correct but adding assumed measurements together is not always accurate, far from it in my experience. Ask any decent builder. There is only one correct way to determine pushrod length and that is measuring.
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From: Liberal land
100% meth. Feels faster for sure but it did gain 60 lbs ft over my last dyno...just not much power so it's hard to tell in the upper rpms. The runs were on 2 different dyno's, but both were dynojets. My brother's car was on each dyno and it made within a few HP on each, so I know they read very close.
Try a pull without the meth. If you have 93 then you shouldn't need it at that level. I would add a degree of timing and pull some fuel to get it into low 11s. Im pushing 17 psi on 93 pump gas with no meth on a stock bottom end 2000 5.3l and have had no issues for several thousand miles now. 726 rwhp. At 14 psi I was at 650.
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From: Liberal land
Try a pull without the meth. If you have 93 then you shouldn't need it at that level. I would add a degree of timing and pull some fuel to get it into low 11s. Im pushing 17 psi on 93 pump gas with no meth on a stock bottom end 2000 5.3l and have had no issues for several thousand miles now. 726 rwhp. At 14 psi I was at 650.
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It's a T56 car with a textralia clutch. The clutch slipping was a possibility to me but it only has 4K miles on it and it spins my 295 MT drag radials in 1st and 2nd with ease, so I wouldn't think that would be the issue. Just so many possible things it could be...wish there was a clear cut answer! Really thought the dual valve springs were going to solve it.
I normally would pick up 5 or so HP per degree of timing....seems excessive to gain that much but I guess it's worth a shot to add some and see how it feels. Easy enough anyways.
It's a T56 car with a textralia clutch. The clutch slipping was a possibility to me but it only has 4K miles on it and it spins my 295 MT drag radials in 1st and 2nd with ease, so I wouldn't think that would be the issue. Just so many possible things it could be...wish there was a clear cut answer! Really thought the dual valve springs were going to solve it.
It's a T56 car with a textralia clutch. The clutch slipping was a possibility to me but it only has 4K miles on it and it spins my 295 MT drag radials in 1st and 2nd with ease, so I wouldn't think that would be the issue. Just so many possible things it could be...wish there was a clear cut answer! Really thought the dual valve springs were going to solve it.
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Here is my .02. 317 heads on a 5.3=Dog. Several people to include myself have made tons of power with the junk 862 heads but everyone wants to run the 317's. I don't even run the 317's on a 6.0. 862 heads on a 6.0 gives it some compression and will run like a raped ape. So to me a 5.3 with 317's sounds about right as far as power goes. I just can't believe you will make any power at that low of boost and that rich an AFR with such low compression. When compression is low you make up for it by running more boost. Again, just my .02 cents.
Here is my .02. 317 heads on a 5.3=Dog. Several people to include myself have made tons of power with the junk 862 heads but everyone wants to run the 317's. I don't even run the 317's on a 6.0. 862 heads on a 6.0 gives it some compression and will run like a raped ape. So to me a 5.3 with 317's sounds about right as far as power goes. I just can't believe you will make any power at that low of boost and that rich an AFR with such low compression. When compression is low you make up for it by running more boost. Again, just my .02 cents.
