timing
fuel
confirm those are tip top and in perfect working order since car will still run just fine, but be lacking ALOT of power like you describe
then move back into convertor, send it back in. Did you order the the convertor with the CX stator or CCX stator? hard hit or soft hit stator if you dont know which stator type? those will make a difference too in overall performance
once all those options have been looked at and confirmed tip top, then move into engine internals, but only then, otherwise you may be wasting alot of time pulling engine and breaking them down for nothing-it's that simple. all of the items i described will hide themselves and make ou look elsewhere, and yes, car will run just fine, but performance lacking like you described.

having faulty timing, or faulty induction WILL make the convertor slip more...been there done that this year...now that i have carburator right, convertor slip dropped from 16% to 10%. still not perfect, but better. fact remains i have the wrong cam for the combo and possible head issues too with the throat area.....which brings up another very important question...were these heads worked on? hogged on? it's very very possible/plausible the heads are junk now and need repaired if somebody just went in there and started chewing away at them without flowing to moitor progress.

 

Eric Bradby ported the heads, for what they are they flow good. He got the cam too......we just talked and he is going to go over everything tommorow and thinks we need to moves the cam.

He does alot of fast LT1 cars and stockers, and we just copied another combo when we did mine.

 

Flow dont mean squat...proper air flow means everything and is one of the reasons i am having issues with my junk as well. the guy picked up 35cfm over what these 100% CNC'd heads did out of box....picked up flow at all point in the lift, but guess what, air flow is now screwed up since it's bottle necking in the throat area and causing too much turbulance and hurting it.

too many old school guys get caught up with more flow, more flow...it's not all in the flow, heads are a perfect example of less is more; more often than not, hence easily screwing up a set of heads by just grinding on them without checking certain spots across the port. The guy that voluntered to make mine right says he takes a minum of 5 readings across each port as he works, this way he can catch and fix anything that makes flow worse. not saying your guy ruined your heads, but i was'nt saying that about my guy either..and it happened...and the dude that did my engine builds alot of the outlaw super street S/C engines for that class...so i just assumed he knew his sheeot.

 

I was at the dyno the other day watching a friends 402 LSx on the rollers. Previously, the car did 480 rwhp with an A4. He now has a T56, Dana 60 rear, and 4.10 gears versus 3.42s and was wanting to see the power difference. First pass put down 412 rwhp! Car was smooth as silk and he had been driving it for QUITE A WHILE like this and noticed no driving issues except for it being kinda "soft" down low. A bunch of tuning wasn't helping much, so they started looking for problems.

Turns out, it was an MSD coil, therefore a completely dead cylinder! Changed it out for a stock one and BAM... 498 rwhp!

Ended up with 501 rwhp. So it was down ~90rwhp from a dead cylinder and was running smooth as silk!

 

Not saying that is your problem, just agreeing with others saying it can sometimes be unnoticeable!

 

A dead cylinder is noticeable to those who know their own setup. As stated the engine responds, sounds and feels different. I've never owned a LSx therefore I don't know... perhaps it's more difficult to find a dead cylinder because of its firing order.. dunno...

 

No clue. He drove it to the Fbody Gathering in Atlanta from NC which is about 4 hours and around town all the time and never noticed.

He said he never really got on it, either, so maybe that's why he couldn't notice the huge lack of power.

 

well the camshaft was 100% correct. everything else in the motor is dead on. No problems found there.

Talked to people about converter, sending the second one back to get checked out.

I have allready swapped all the igniton stuff once, wires, plugs, coil, msd box etc. etc. and it didn't do anything.

 

What does your map show when you go through the lights?

Again what is the a/f down the track? I know you asked about widebands before in the pcm section.

What did your ve tables end up showing for the higher hp rpm areas when you got the fueling right?

What fuel are you running in it?

You have made sure you're getting wot?

How do the plugs look?

I just find it really hard to believe that you have had multiple trannies and converters as well as ignitions in this thing and it has responded to NOTHING.

What kind of line pressure are you seeing in the trans? It could be slipping but with those rpm's you'd know pretty fast when the atf turned into baby ****. I vote converter if the engine stuff checks out and the trans is in order.

 

If I can get it back together and in tommorow I may try to dyno it this week, although I feel its a waste of money....and plan to run it again this weekend also. I also plan on a nice timing marker when I put it back together and locking out the DFI to 37* and seeing what it does. and I mean locking it 37 per a timing light.....

 

I see no problem with any of that, just wanted to make sure you werent running c16 or something.

12.4 is a little rich but at that level it is probably not hurting a thing.

Hook a hydrualic gauge up to the trans to monitor pressures, without good apply pressure a clutch will do nothing. Its just something else to verify. Should be in the 200-230psi range imo.

A dyno will not do you any good if the trans isnt putting the power down. The mph and your wideband tell you about all you need to know, your a/f is good, and the hp you're putting to the tire is not worth a diddle.

What gap are you running on the plugs? Verifying the timing with a light sounds like a good plan to me and should be worth a try. I was hoping your ve would be in a % so we could see what kind of wind you're moving at high rpm kind of a backdoor way to verify hp.

Sorry dude sounds like its probably your trans or converter as the doc said quite awhile ago.

Either that or god just hates you and reaches down special just to hold your car back .

 

This sounds very simliar to the problem I had with my turbo setup. Get it on the dyno and look at the datalogs closely to see if you are LOSING rpm at wot. Mine was doing that, and in the end would only drop about 50rpm(not noticable on the tach), but you could see it in the logs. My car on 8lbs should've been good for 10.80 at 128mph, but was pulling 12.0 at 110. It did make one good 1/8th mile pass when I first put it together, going 101mph in the 1/8th.

I replaced EVERYTHING ignition related, double checked the fuel side and replaced parts, swapped transmissions/converters, pcm's, tunes, everything....even went through my wiring harness WIRE BY WIRE checking it all.

Final straw was to replace the engine wiring harness completely, and I just got fed up with the car. I ended up pulling it out and sold the turbo kit, motor, etc.

I did find another thread on here where a guy had the same problem for 2 years and couldn't find it, even though he replaced everything. I wish I still had the page book marked.

 

the plugs are gapped at .035

I'm sending one of the converters back.

where do I hook a pressure gauge to on the trans? and where do I get one?

 

Did you retard the cam when you re-installed it? (second time). I'm at a loss if its not cam timing, if the FI is fine and the tranny is fine then thats the only thing that could rob that amount of power.

For bracket racing convertor slippage is a good thing for vehicle consistancy.

 

Sounds to me that the power is going out the exhaust. If it were the converter/trans and you were making decent power your rpms would shoot up fast and never come down at all between shifts. It would be almost like revving in neutral. Most likely you'd run out of RPM before the end of the 1/4. I say it is a pushrod/cam timing/timing/valvetrain issue. Ensure the installed height is correct on the springs and that the geometry is correct.

I am also wondering where you have the MAP located as a false reading from the MAP sensor could cause major tuning issues.

Good Luck,