Turbo D

iTrader: (3)

Hey guys, Just looking for ideas on what the issue might be on my new combo Here is the combo
L33 5.3, 243 heads with a 227/235 .620 114 comp cam and pushrods and btr .660" springs, instaled on a 109 ICL
Twin 72/68mm turbo's with .81 housings
160lb injectors, ls1 intake, MS3 pro, br7ef plugs
E98 no intercooler
Glide with a PTC 9.5" converter with a 16-0 stator
3.55 gear, 275 pro 2550 lbs
Issue is the power it makes vs boost, the dyno we tune on is tight for power, but I'm not overly concerned about the power but the power vs boost as we raise it. On 5 lbs it makes 380rwhp, on 15lbs it makes 480rwhp and on 25lbs it makes 510rwhp, it will surge on 25lbs for part of the run because the motor isn't flowing the air and we are hitting the surge line. Could the cam be wrong? I don't have backpressure hooked up yet but I figured a q trim housing shouldnt choke out on half a 5.3l. I'm going to run it on friday on 15lbs and see what it does. Just looking to see if anyone has come across something like this and any idea in general. thanks

gametech

iTrader: (1)

I have a few concerns with that combo, but they are all tiny little things. The issue you have is huge. Even though I doubt the cam is ideal, I just don't see anything other than a major cold side leak doing that with a good tune. I guess if the tune was WAY off, it could do that, since E98 has quite the large tuning window, but your build leads me to believe this isn't your first rodeo. I'm guessing if you burned the converter down staying on the T brake too long you would already know it from the dyno graph, which could shed more light if posted.

Forcefed86

iTrader: (4)

That's a stinker I wanted those little turbos to work! I bought a set too.

I'd look a t your back pressure. I'd think that cam is fine as long as it was degree'd and you have low back pressure.

What were you running for timing? Did you log it and confirm it was at the commanded value? My defualt MAT/IAT table was setup goofy in the MS3 and was pulling a ton of timing as the charge temps went up.

What did charge temps look like?

Is your knock control disabled?

Might try....

Checking your cranking compression... (did you degree cam?)

Checking your converter slippage.

That converter seems loose for that combo, but shouldn't be causing that much of an issue. How high do you rev it? RPM drop on shift?

JoeNova

Are you.positive it'd an L33? Most people call every aluminum 5.3 an L33. If it's a gen 4, either cam or ignition timing is likely off by 6-9 degrees. The cranks were referenced differently.

Turbo D

iTrader: (3)

Its a true 24x L33, I've tdc'd it twice with 2 different pointers and verified base timing, the megalog shows the correct commanded timing. I'm going to check cranking compression. The converter is out of Chris Bishir's S10 he went 8.3@160 with it from what i've read. I'll calculate the slip thou just to be sure. duty cycle on the injectors is 68% on 20lbs of boost so it is using fuel.

Turbo D

iTrader: (3)

Cranking compression is 165psi at 3500' elevation. on 20lbs of boost, injector duty cycle is 68% at 6500rpm and 10.6afr on a gas scale on a 152lb injector.

one fast zo6

iTrader: (490)

What are the air temps?

Tomhames

iTrader: (3)

Any of that braided flex pipe (that could be internally collapsed) used on installation??

a05c

Do you have converter slip % data?

forcd ind

iTrader: (7)

Were the tires hooking on the dyno? the real test if you run it is weight vs MPH=HP
I once had a setup that didn't seem to produce results, one of the hoses was pulling out on boost, then going back in as boost went down, but if your actually reading the boost #'s, prob not the case.
Seems like you def enough parts to make power-the turbos seem big for twins on a 5.3, or am I way off, lol

Forcefed86

iTrader: (4)

So you verified TDC and IGN timing, but did you degree the cam to the card?

For reference, once I got my LC9 degreed, I was spitting out 200ish on all 8 @ 1300 FT. PIcked up around 12mph at the same boost level. (smaller cam though 212/212 @ 112 .565 lift)

roastin240

iTrader: (13)

Forcefed do you degree your cams with an aftermarket timing set or can you use an offset pin in the camshaft? If you have a factory timing set, then there is really no "degree'ing" and just is what it is right?

Forcefed86

iTrader: (4)

you can buy bushings for the oem cam gear bolt holes that will offset timing. In general thou yes, you need an adjustable timing set to change it. even if you dont have an adjustable set its a good idea to check the cam timing with a deegree wheel and ensure its within a degree or so of the cam card.

I dont think all of the Gen4 stuff has the odd ball crank keyway offsets. I just installed/degreed a cam on my LC9 5.3 with an OEM timing set and it was within a degree dot to dot. My last LC9 was 8-9* retarded dot to dot on a factory timing set. Same cam installed on a 4.8 crank was spot on dot to dot. Really just something that should always be checked.

etijsma

do you have a link for said bushings? Are the gen 4's the main ones that the degrees are off? I ask as I've seen it on here over and over again.

JoeNova

Yes, Gen 4s are the ones that have cam timing issues. Usually caused by the way the OEM stuff is referenced thanks to VVT.

svslow

I understand some have had issues with this, but is that only if you simply go dot-to-dot? If using the Gen 4 crank with an early 3 bolt cam sprocket, find true TDC and install the cam "straight up" would there still be an issue with the Gen 4 stuff?

Hopefully thank makes sense.

Forcefed86

iTrader: (4)

I’ve heard of several LS engines not making the power they should for no apparent reason, usually gen4 5.3’s. Most didn’t degree the cam and had low to lowish cranking compression. Very few of them ever degree the engine afterwards to verify and report back.

As far as I know I’m the only one that could confirm it was the crank keyway that was off by degreeing the same cam and timing set on another engine. I was able to “fix” the problem by degreeing the cam properly with no other changes, proven by back to back track visits. Was a night/day difference that could be heard as well as felt. The engine even fired more aggressively. I knew immediately it made a huge difference. Had a more raspy exhaust note common to higher compression engines. It revved much faster with crisp NA throttle response. (compared to how it was 8ish* retarded anyway)

Cam bushings example. I'm not sure what ID the bushing needs to be for the LS but these are what they look like. You drill your cam gear to match the OD of the bushing and press it in.

http://www.jegs.com/i/JEGS/555/20301...FZQ7gQod02oC2w

Turbo D

iTrader: (3)

I degreed the cam off the card, it's a 113+4 I installed it straight up, I have a comp hex adjust timing set so I can dial it in. I've degreed many cams so I know the deal. I'm going to run it this friday with the back pressure gauge, if it's high I might switch to a cam with less split like a 228/230 trick flow

Turbo D

iTrader: (3)

converter slip is 3.14% 6500rpm, 153mph, 3.50 gear, 89" roll out, 15.9% at 5000 rpm

Forcefed86

iTrader: (4)

There goes those ideas...

That cam isn't that different from the stage 2-3 LJMS cams. Plenty of guys running those making nice power.

So what kind of timing were you running at 20lbs? Charge temps?