1FastBrick

iTrader: (17)

Interesting... A friend of mine installed the exact same cam in a newly rebuilt LQ9.

Personally I was not impressed with it's performance. I thought it should perform a little better.

Any Chance you degreed this cam? It should pull just past 6k

03sierraslt

iTrader: (22)

It should pull past 5k no problem and not be laying over that fast.

making peak torque at 4600 there is no way power should peak 800rpm later unless there is a restriction, weak valve springs or no timing.

chubbza5

I agree that the cam should perform better than it currently is.

It's not degreed unless I made a mistake installing the timing set, but it's pretty simple to line up the dots. Gets 20mpg as well.

It's got brand new LS7 lifters, hardened BTR 7.4 pushrods feeding the BTR upgraded trunion rocker arms, pushing down on PAC 1218 springs. Stock valves, they got cleaned and lapped before reinstalling. Heads were hot tanked. MLS head gaskets.

Tuner said we were at 26 or 27 degrees of timing up top which doesn't seem like there's much on the table.

chubbza5

Come to think of it, I have a flowmaster 40 1 in 2 out muffler on it that's been on the truck since I got it. I have been noticing a rattle when I shut the door sometimes and there's a distinct rattle when I start the truck for a second or two from back there. Could it be a collapsed baffle in the muffler choking it off?

I am going to unbolt after the Y pipe, but it's wet today so I won't be able to tell if it makes a difference until it dries out.

madmann26

iTrader: (7)

The Flowmaster isn’t helping it breath.

Even though the 1218s are supposedly good to .600, you’re really close at .585. I wouldn’t be surprised if you’re getting valve float where the power starts to taper off.

What else is done? What’s the IDC of your injectors? What was the AFR?

706 heads have been proven to be the better head up to 6k RPMs. They would make your truck feel so much better everywhere.

chubbza5

I spoke with the guys at BTR and they said I should be fine with those springs, that .600 was their upper limit so while .585 is close it's not too much. I'm not an expert on springs so I took their advice. Is that what valve float looks like on a dyno?

IDC was ~65-70%, they're 52lb delphi injectors. AFR's were pretty stable, 12.5-12.8 or so with a sniffer in one of the exhausts. It did climb slightly towards top of the powerband but didn't go over 13. Made a tad more power being a bit richer (the first run was richest).

I can't think of any other relevant mods to mention. Trunion upgrade rockers from BTR, No EGR, 145A alternator, A/C was off as well as peripheral electronics. Driveshaft carrier bearing is new and shaft was balanced. I do hear a flappy sounds now that I listen closer in the video. I always thought that was just a 6.0 thing... looking closer at this muffler now. I may cut it apart after I get a new one just to see how it failed.

madmann26

iTrader: (7)

https://ls1tech.com/forums/dynamomet...they-suck.html

Plenty of reasons in that thread of why they’re called ChokeMasters.

03sierraslt

iTrader: (22)

Unbolt the exhaust and try again. Flowmasters suck unless your all stock and only care about sound.

68Formula

Looks like hp is peaking way down at ~5400rpm? Then something is choking it from about 5k up. With that cam and headers, the levelling off for power should begin at a higher rpm and the very peak should be well past 6000rpm. Could be you need an NNBS intake and TB, or upgrade the muffler (Borla, Magnaflow, or Dynomax), or a combination.

Edit: Just saw that you're running a Slowmaster. Dump the muffler and let rip as a quick test, and I bet you pick up quite a bit.

ZO6Ted

Yeah I was thinking exhaust or valve float possibly. Agree it should be making more.