Yeah, stock 317 heads as the OP said. I was just looking at some other people's setups and comparing to my own and I thought mine seemed a little small compared to some people that build 5.3's with a cam like mine.

But if you guys think I won't gain a whole lot by changing it out, I'll just leave it the way it is for now. Maybe someday if I'm looking to pull some more power out of this thing I'll consider optimizing it. Possibly a head upgrade in the future too to bump the compression a little. I'm pretty new to the performance building side of engines and cam selection got super confusing! Especially when reading about cam choice for boost, no websites or magazines seemed to agree on what and why, all different theories out there.

Thanks.

 

that's why you call an expert and have them do it for you... Erik at HKE would be my choice there but you'll have a lot of folks point you in a lot of directions in that department.

 

I wouldnt worry that it feels sluggish now... sounds like to built this thing to withstand 15# without even breaking a sweat. it will be a totally different animal once that falls into place.

 

Cool. And that was exactly the idea, build it to take whatever comes it's way. Ring gaps are opened, LS9 head gaskets, arp studs. It'll be good as far as strength is concerned.

 

Stock 4.8 and 5.3s only have 9.5 compression, so I wouldn't really see why 9.1 would make a big 408 sluggish. Also the stock 317s should hurt your top end some, but I would think it would be a low end tq monster with that small cam and small intake runners. Very interesting problem you are having!

Do you know how much timing was put into it during the tune?

 

My last time (only time) at the track the truck ran 15.58@92.9mph, so not too bad.

I have been tuning it myself all summer with HPTuners, big learning process with that! I'm really debating going to one of the well known guys around here once it's boosted, or just play it really safe for a while. Not sure on that yet, depends on how hard I can hit the books before then. I've been having a stupid idle surge issue all year that I've just dealt with.

Timing at WOT is around 21*. I do get occasional knock retard still but haven't dug into it a bunch. The motor definitely has torque and lacks on top end. I'm sure some of that is due to my bone stock exhaust with only a flowmaster.

Stock converter and 4l60e right now also but my 4l80e is ready to be installed and a 3,200 circle d converter is on the way. I should really start a build thread one of these days.

 

You ran 15s with the 402??? This is blowing my mind haha b/c stock 5.3s ext run 16s. I mean a cam, Lt, tune 5.3L will run 14s all day. Maybe one of these nice fellas on here will take a look at your logs/tune and see if there is anything major causing this sluggishness.

Hows the mid range power? Sorry for digging at ya, I have been thinking about changing my turbo route to a 370 forged rods/pistons with around 9.5 compression, and it will be dd for a few months on the N/A 370.

 

Thats not allot of timing for that setup, esp. for 9.1-1 comp. What fuel are you running when you are seeing KR? Are your Knock sensor settings stock? Try running better fuel to see what the KR does, sounds like false knock to me. Based on your ET @ MPH are you running a stock converter in the Trans?

 

Haha, yeah. Now you see my concern and the reason I started this thread. Something isn't quite right. I don't know whether it's just my crappy tuning or the fact that literally the only thing changed in the truck is the engine. Torque and mid range feel pretty good, I was thinking it was lacking on top end in part because of the exhaust. Still has cats, stock converter, etc. I didn't go too crazy on the tuning and beating on it this year because I know a lot would have to be changed next year and the transmission wasn't liking it.

I was kind of thinking it's false knock too, stock sensor settings. I just ran 87 octane to get me through the summer. The truck is parked for the year now until I get some more of my research done and get parts and start wrenching. It's just starting to snow up here and this truck has seen enough winters already if you know what I mean.

 

I would desensitize the knock sensors a little bit and get some timing in this thing. You should be running 26* at the very least if you run 93. Can you upload the tune and maybe a log of a WOT run?