5.3 88mm spoolup advice needed
Thread Starter
Teching In
Joined: Aug 2013
Posts: 23
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5.3 88mm spoolup advice needed Hi,
I'm having a major spoolup problem with the new combo. Basically I could lay a brick on the accelerator pedal and go watch some TV until it spools up
Forged 5.3, 317 heads, LS9 cam(8 deg retard for top end), custom 88mm turbo (111mm turbine, divided T6, 1.38AR). Glide with brake. E100 fuel.
Stepping on it will net me 3K rpm, 6 seconds later 3600 @ 1psi.
I have tried both worlds, lean+early and fat+retarded but no change.
I'm waging to degree the cam to 0 to see if there is any difference. DD shows only 10hp difference in spoolup area.
I'm having a major spoolup problem with the new combo. Basically I could lay a brick on the accelerator pedal and go watch some TV until it spools up
Forged 5.3, 317 heads, LS9 cam(8 deg retard for top end), custom 88mm turbo (111mm turbine, divided T6, 1.38AR). Glide with brake. E100 fuel.
Stepping on it will net me 3K rpm, 6 seconds later 3600 @ 1psi.
I have tried both worlds, lean+early and fat+retarded but no change.
I'm waging to degree the cam to 0 to see if there is any difference. DD shows only 10hp difference in spoolup area.
Pretty mismatched combo! The LS9 already has almost no bottom end. Then you retarded the crap out of it. Then your running too tight of a converter mixed with low compression and a huge turbo.
All that said hit it with a 100 shot on the brake until boost starts to build on it's own. Then shut the nitrous off. My nitrous was on for less than 2 seconds... It works really well. If a 100 shot doesn't work bump it to a 125-150. Your not on it long and a bottle lasts a long time this way.
All that said hit it with a 100 shot on the brake until boost starts to build on it's own. Then shut the nitrous off. My nitrous was on for less than 2 seconds... It works really well. If a 100 shot doesn't work bump it to a 125-150. Your not on it long and a bottle lasts a long time this way.
Thread Starter
Teching In
Joined: Aug 2013
Posts: 23
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I have shyed away from aftermarket cams since it is a reliability build not max effort. I really like the soft ramp rate of the LS9 cam so that is why it was chosen.
Basically, I see that with about 10% more power down low I should get the converter to flash 500rpm higher.
I have torn down the front end to get the cam degreed to 0 retard and if that is not enough then turbine housing swap or turbo swap to the old PT88 is next.
Basically, I see that with about 10% more power down low I should get the converter to flash 500rpm higher.
I have torn down the front end to get the cam degreed to 0 retard and if that is not enough then turbine housing swap or turbo swap to the old PT88 is next.
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just get a custom cam from martin @ tick, and have him grind it on a cam motion 8620 core....That is a super hard cam that should last a long time. LS9 cam sucks for a turbo setup. He doesn't use aggressive lobes either so it will be easy on the valve train.
Thread Starter
Teching In
Joined: Aug 2013
Posts: 23
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Converter is fresh 9" from Dusty speced for this combo.
It should go to 4K flash but it does not and the problem is not in the converter, rather my optimistic head flow numbers I gave him.
If there is 3000 @ -0.3psi when I floor it and 3600 1psi after 6 seconds then the converter should go where needed once I get 10-15% more power down low.
Cam swap is a little PITA, since I have prototype rev kit in it and need to take heads off for that.
It should go to 4K flash but it does not and the problem is not in the converter, rather my optimistic head flow numbers I gave him.
If there is 3000 @ -0.3psi when I floor it and 3600 1psi after 6 seconds then the converter should go where needed once I get 10-15% more power down low.
Cam swap is a little PITA, since I have prototype rev kit in it and need to take heads off for that.
Without a major combo revamp there is no easier solution. Hit it with a **** ton of nitrous until it comes up on the converter. Once it gets into 5-6psi, it will probably “light off” and make boost on its own. Shut the nitrous off at that point. That is by far the easiest/cheapest solution in your case. No amount of “tuning” is going to light that sucker off quickly with your combo IMO. Just went through something very similar with a tight converter, better suited cam, and smaller turbo on a 4.8.
If your 10-15% numbers are accurate. 50-60 hp worth of jetting should do it. I'd bet you need closer to 100.
If your 10-15% numbers are accurate. 50-60 hp worth of jetting should do it. I'd bet you need closer to 100.
Last edited by Forcefed86; Feb 24, 2015 at 05:00 PM.
The LS9 cam is for a supercharged app if I'm not mistaken. It's gonna be ground a little soft on the bottom end. If it wasn't, every wing nut that couldn't drive would be doing doughnuts every time they took off. Not on purpose. Lol! That being said, when you retard any cam 8 degrees, your dropping your dynamic compression goes in the basement and so does your bottom end. Hence, poor spool. I say put the cam straight up, an try it. Don't worry about losing top end power. Torque makes cars quick! Plus, not having to rev it to the moon will be easier on the engine.
around 740 with a 88mm on a 5.3. Need more info on the combo.
sounds like with the dropped compression of those 317 heads and the fact that you took all the power out of it by retarding the cam it just don't make any power out of boost. you don't have to retard that cam for topend you lost power everywhere retarding it that far .I have done some of that cam advancing/retarding and ive seen power in advancing but it is a few ft lbs and more than a few degrees from the suggested icl almost always takes power away somewhere in the power curve.
if the engine don't make power out of boost it don't make heat and exaust velocity and it won't spool . put the cam back where it goes or change it and it will be better. get it running stronger out of boost and it will spool. jmho.
if the engine don't make power out of boost it don't make heat and exaust velocity and it won't spool . put the cam back where it goes or change it and it will be better. get it running stronger out of boost and it will spool. jmho.
