Texas_WS6

iTrader: (9)

Here is the tune if anyone cares to look it over.

98Z28CobraKiller

iTrader: (17)

In the front is the "correct" place for it.

Just looked at your tune. Get a quick log with the timing histogram on the tbrake in order to see what cylinder airmass you are at. From one column above to the 120 column and from 0 to 4000 RPM add 7* of timing. Then interpolate back to your 23* by 5200 and see how much higher you can bring up the stall. You will need to be able to get it over 3500 regardless of where the turbo is. Might need to get the converter loosened a little bit.

Shawn @ VA Speed

iTrader: (3)

I got to be honest with you-i believe those heads are really killing you.The big runner in the ls3's do not like to make low end tq-the tq is what helps spool-you need a 235-245 runner at the most.They would prob be fine in a frt mount.The 2 step will def help alot-we even use 3 steps on the race stuff.

bad6as

iTrader: (17)

even with a two step i cant build boost. rpm from 2500-4000 have the lnc 002

DrTurbo

iTrader: (3)

That stall RPM is way to low.....

MY99TAWS6

iTrader: (3)

Are you auto or stick..if stick you can use the antilag function that should help a lot.
If you are auto no idea what the heck is the problem . Unless your turbo spools up at like 5000 or higher rpm. then best to run small shot of nitrous.
That will spool it or maybe get a way higher stall converter.

Tiago

iTrader: (27)

I have the same problem, I going to probably add a shot of nitrous to get things moving.

buick_lsx

i have the same 2-step...my converter is only a 2800-3000 stall and at 2000rpm i get just 1 psi, and 2200rpm i get 2.4. Because of my rear brakes i cant hold the car any higher

good idea, i wish i could afford some n20 right now, but then id just run it all the way down the track and not just to get boost lol

jay_rich

iTrader: (8)

mine can see around 5-6psi on the brake no issues!
3600 stall convertor, seems loose as I can see like 4500 on the trans brake

Jay

Texas_WS6

iTrader: (9)

If I was possitive what my compression ratio was (-12 reverse dome, 70cc heads, 408) I would like to swap them out with my 02LS1 heads. I guess I could pick up some 6.0L heads. I will be ordering the 2 step this week. There is no dought this thing makes p*ssy torque down low. I do not understand what is going on with that. Maybe the builder (not a sponsor) f*cked them up when he ported them. He has done alot of different heads for me in the past, I would be suprised if he did. All he did was a symple $700 pocket clean up. They were flowing 318 right out of the box with no valve job, mild pocket clean up and a 3 angle valve job jumped them up to 340, but the intakes pulled them back down to 320ish so we stopped looking for more flow. I can not remember what he got the exhaust flowing to, but I know most of his work was in the exhaust trying to get the flow numbers were he wanted them as compaired to the intakes.

I think my biggest problem is in the week **** 408, something about it is not right.

Texas_WS6

iTrader: (9)

I am going to go out and play with it here in a bit. I will post up some scans and any tune changes. Circle D built the convertor to go to 3400ish on the tbrake. But if the engine is week, it will not get there anyway.

Texas_WS6

iTrader: (9)

Two things with the stall
1) Circle D built it to stall to 3400-3500ish on the tbrake with the 408. I do not think there is a problem with the stall, I think the 408 is symply a peice of **** and will not make any power NA, so it will not pull it up there.
2) I am sure the fluid I am running is reducing my stall rpm about 300-400 rpm, I am using John Deere Hyguard 20 as per the trans builders recomendations.

Before I pull the convertor and send it back to Circle D, I need to make sure the 408 is not the problem.

Do you remember talking to me about this turbo/ I first bought a PT76-GTS, then sold it and bought this GT088 from Beast. Ya'll hooked me up with the smaller PT T-4 turbine housing for it.

Texas_WS6

iTrader: (9)

I am running out of possabilities here. It is starting to look like in my mind the 408 is the issue. It has not preformed as advertised from day one when it was NA.

Texas_WS6

iTrader: (9)

OK! I just got back from a little ride. This damn 408 might be a wimp off boost but holy **** batman! what a freaking beast under boost! DR Jeckel and Mr Hide kind of stuff! I got out on a peacefull rode and a pickup full of people were coming up behind me. They were already cruzin 50ish, I stood on the Tbrake, let her loose, once the boost came up, good buy slicks! Looked like James Bond with his smoke screen coming out of the car! I backed out of it (it was getting pretty squirrely) then stood back into it, she broke loose agai n at around 50-60mph! When I turned off, the pickup full of people went by honking with thumbs up and huge grins! You know they were like, what the F*&K! I haven't drove the car in over a month while doing the 4L80 swap. Man I am still shacking!!!! I freaking love that car!

Back to the lag issue: Here are three scans. First was a little warm up time, with one Tbrake launch, second was just a little driving, third was the full boost run. I have not looked at the scans yet. I am sure with the temp being almost 100 degrees today the VE will be way off, it was in the 60's when I was last tuning the VE. Also, the tune that was in it. Worked on a few things from last nights tune. Let me know what ya'll think.

Texas_WS6

iTrader: (9)

Oh, and here is the config I am using too.

Hmmm, It will not post up my config, Why?

Texas_WS6

iTrader: (9)

It is going way rich under boost. When I was tuning the VE at the track I was maxing out the 80's. On the way home I figured out the second fuel pump was not coming on. I corrected that and I have not been back to the track to correct the VE tables for the extra fuel yet. It is bottoming out my WB. I will be working on that lnext time I go to the track. The way she pulls under boost is so very scarry! No one in their right mind needs that kind of power on the street! Expecially me! HAHAHHAHA. I can not wait to work all my bugs out and get the boost up to 17psi! What a ride!!!

MY99TAWS6

iTrader: (3)

Sounds like fuel was an issue there. So maybe its all good now. Have have you got any dyno numbers yet. Mph is also a pretty good indicator of power. Et can be messed up by 60fts, etc.

98Z28CobraKiller

iTrader: (17)

I checked out your logs. You have 0 boost until 5500. That's NFG. Wont be fixing that thru the tune. Your fuel going rich is well beyond that point so it wont help this problem IMO. If the compression and leakdown check out, then you will need to look into making a drastic change or 2 in order to correct this.

Texas_WS6

iTrader: (9)

There you go, you have briliantly stated what I have been failing to state. What in the world is causing this? I have not done a leak down test, but I have done a few compression checks, as well as other things. I have been a professional industrial mechanic for 20 years now. There are no indications of a ring sealing issue, no blowby what so ever, no oil consumtion, no fowling plugs, no smoking, nothing. Compression does not look bad at 155. If need be I will get the tools to do a leak down test. I have pulled this engine twice looking for issues, I inspected everything multiple times. I checked the cam timing twice with the original NA cam. I personaly installed the new VTC cam, and triple checked the valve events. The ICL is set at 105. I have played with different pushrod lengths, double checked valve geometry. I checked for exhaust leaks, and cold air leaks until I am sick. Swapped manifolds thinking the low profile elbow was restricting the airflow. Tested waistgate and blowoff valves multiple times. Swapped the turbine housing from the original 1.08 to the .9?. Played with the timing, leaned the fuel out, richened it up. Pulled the 3500 convertor out (4L60) and had it rebuilt and loosened up. Switched to the 4L80 with a Tbrake.

Here are the facts as I know them.
1) The 408 NA first installed only ran 12.7 at 115mph, 4000lbs car. That shows a hp of about 425, at least 125hp less then what it was built to do.
2) The 408 is not making any low end power, NA or right before boost.
3) Nothing that has been changed has made any difference at all.
4) When the 408 was NA, I had EGT's on the engine. One on the drives side and the other on the passenger side. I could never get the EGT's over 999 degrees, and that would be at the end of the run. I leaned and leaned the fuel out until the time started falling off. added timing up to 22 degrees WOT, still the EGT's would not go over 1000 degrees.

This again tells me there is something not right with the 408, but what it is I have no idea.

I am open to any advise on this.

Texas_WS6

iTrader: (9)

I was not calling you out, I agree with you 100% on this, thats why I quoted you.