Originally Posted by kinglt-1

The gears are not hurting much with that 4500 stall. The gears are just going to make the converter feel tighter. The stall will still flash the same rpm and net the same shift extension regardless of gear. The 26" tire will help due to less weight and rotating mass.

Imo you have added weight to the car which counter acts making more power going to a 4L80. I could see warranting such a trans upgrade in a 700whp+ car...not a H/C 346. I would look into valvetrain stability issues. What cam lobes, lifters, push rods, and valves? The Fast would definitely help. The cam looks fine but you could go bigger with that big stall.

Originally Posted by thunderstruck507

Seems your car runs really close to mine did with similar mods. Which is highly abnormal...usually a f body is a couple tenths and MPH quicker in the 1/4 with equal mods.

Do you have a dyno graph or have you tried other shift points? You could be overrevving it?

If not you might weigh it, could be heavier than you think.

The intake could help you a bit. I doubt a gear or bigger headers would net much gain. I would definitely agree the car is under performing a little.

Originally Posted by kinglt-1

in the OP it says "raceweight 3710lbs with me in it".

Originally Posted by thunderstruck507

But it was vague as to whether that was a guess or an actual weight. People often assume the weight of 4th gen Fbodies. I've seen them vary a ton...anywhere from ~3200lbs to ~3700 lbs.

Originally Posted by JDMC5

agree but the 4L60e can go to hell. I plan on spraying it and/ or boost in the future so i wanted to get the good trans and be done with it. There is controversy on just how much the 4L80 slows a car down so that is a little grey to me.

I still feel like the gears are hurting a tad. More gear means better 60 ft and longer time locked in 3rd gear. But yea 2-3 tenths tops.

Originally Posted by madmike9396

Your headers are sufficient imo. If your going 9 inch why not more gear ? 430 or 456 ?

Originally Posted by HCI2000SS

I agree even though the larger headers might gain a handful of hp, the current ones are sufficient enough for now, and certainly not the culprit here

Originally Posted by kinglt-1

Ahh well in that case the 4l80 is a good move...just a bit overkill for a H/C LS1.

Hmm I did not have to do anything with my fast and nw tb to get it to idle.

Just curious, What is your valve train setup?

Originally Posted by BrntWS6

I'm not saying that's what is wrong necessarily but from my own trial and error process with putting together several exhaust setups I know first hand what is left on the table. I would even look into 2", I know ls3's do well with them.

Here is my dyno b4 and after a header swap...both kooks and same dyno. Only change was 1 3/4 to 1 7/8".

20 rwhp 20rwtq

Originally Posted by BrntWS6

I'm not saying that's what is wrong necessarily but from my own trial and error process with putting together several exhaust setups I know first hand what is left on the table. I would even look into 2", I know ls3's do well with them.

Here is my dyno b4 and after a header swap...both kooks and same dyno. Only change was 1 3/4 to 1 7/8".

20 rwhp 20rwtq

Originally Posted by JDMC5

So im seriously considering 1 7/8" header. What are your thoughts on situations where people have lost power with them over the 1 3/4"?

Originally Posted by JDMC5

Hi guys I'm looking for opinions and experience on my combo and if I would benefit from a bigger cam. My power train setup when I ran 11.92@113 w/ 1.69 60ft was:

- SBE LS1
- PRC 243's which are CNC ported with stock valves and milled .030", measured ~60.5 cc combustion chambers
~300cfm @ .600" lift.
- Stock head gasket so compression should be about 11.1:1
- 228/230 .629"/.604" 112+2 cam
- PAC 1519 beehive springs
- LS6 intake/ ported stock throttle body/ 85mm maf/ 98mm lid/ gutted air box with K&N
- 1 3/4" long tubes with 4" cutout under the passenger rear seat
- MAF tuned to lambda .85/.88 (or 12.5/13.0 in gas terms) and 29-30 degrees
- E85
- 39 lbs injectors
- under drive pulley
- Built 4L80e with 245mm triple disk ~4500 stall. I foot brake to 3300 rpm then when I floor it rpms immediately shoot up to 4000 before the car starts to move and within 4 tenths 4500rpm before the curve slope decreases according to my hpt scans. I attached a pick to show what I mean.
- Stock rear end with 3.73 gear.
- 28" mickey thompsons
- race weight was approximately 3710 lbs with me in it.
- shifts were 6600-6800 rpm

11.92@113 w/ 1.69 60ft was with the converter unlocked and from what I can tell from my scans it would run about 11.8@115 with the converter locked in 3rd. Seems a little soft especially in the MPH considering weather was really good in MI October air. The car pulls pretty good especially out of the hole but feels like it pulls pretty linear with topend that is nothing to **** your pants about.

Over the winter, so far, I've added:

- Vengence ported fast 102, NW 102, 102 lid
- 60 lbs injectors
- SD tuned
- 26X11.5" mickey thompsons on 16" rims.

I'm expecting about 11.7@117 with the new setup and I plan on adding a 9" with 4.10's which should put me at 6600rpm@118 mph and should help get my 60 ft down a little. I still feel like 11.5's are still too slow for my mods. I was thinking something more aggressive like around 236/246 .650"/.650" might be a better idea since I'm at 4500rpm right off the line and never below 5500rpm after each shift. Plus, any low end I lose should be below 4500rpm not to mention a 4.10 should make up for that anyway. What do you guys think? Thanks for the read.

Oh don't mind the a/f ratio on the scan the wideband wasn't hooked up for this run.

Originally Posted by R6cowboy

The bolded print above was my first concern regarding your top end worries. That spring and cam combo possibly might be an issue (valve float) at approx. 6000+rpm. Of course there are many things that play a roll in valve train stability, but generally, about .600-.610 lift cam (give or take depending on other valve train components) maybe about the max lift for them springs. If you have stainless steel valves, I'd bet you have a little valve float going on at high rpm's.