Ever since the recent LS6 intake and cat delete. I have noticed that the power seems to level off at about 3k rpm. -odd for an LS1. I have a LOT of low end TQ, but it seems to stop pulling as hard about 3k rpm.

When I give it 1/2 to 3/4 throttle in 4th at about 2k rpm, the speedometer climbs like crazy. after about 3k rpm, it seems to level off.

Ideas? Since my LS1 Edit, I deleted my cats, EGR, AIR and added an LS6 intake. My last retune was also at 21k miles. She now has 40,400 miles.

That LS6 intake also added a LOT of TQ, but seemed to have increased slightly when I deleted my cats.

Well your finding all sorts of things wrong today aint ya.

Yeah... 40k and she's falling apart...

I hope not.

Make sure the TB is opening all the way and check for vacuum leaks.

^ yep... P+P'd SLP TB w/ Bump stop mod.

No vacuum leaks.. Deleted the AIR and plugged the hole for the extra vacuum line.

No way, thats still a new car. They dont let go that easily. I got 193K, and Ill take ya on anyday!

Really trying not to hijack but I've noticed the same thing after my LS6/header/exhaust install. Where is the extra vacuum line? I may have missed it. I actually don't recall plugging anything after I deleated the AIR/EGR.

Just because the TB is capable of opening all the way doesn't mean the throttle cable isn't in a bind and not opening it all the way.

2k? 3k?

The LS1 makes peak power closer to 6k. Why are you worried about low-end on an engine that doesn't even make peak torque until around 4200 rpm?

Mike

^ 2000. I'm not worried about the low end power... It's that lack of high end that confuses me.

My dyno graph shows my TQ peaks at about 4500. 320RWTQ at 2k rpm, but why does it feel like soo much more and so little at higher R's???

I'll have to do a WOT 4th gear run this weekend out in the desert. Going to try to get it re-dyno'd and re-tuned soon too.

There is a T in the back of the LS6 intake, next to the MAP sensor. You can remove the T if you delete the AIR system. One vacuum line goes to that air system 'diverter valve' type thing.

Change your fuel filter, clean you air filter. How old are the plugs etc etc.

I noticed it not pulling so hard up top a few months ago. I did the above and it felt like new again.

Only true way to tell if you're not pulling ok though would be to get a dyno run in somewhere.

Just checked out the dyno sheet and it looks great. Nice torque curve.


I don't see anything wrong with it. Take it to the track instead of trusting your ***-o-meter

I do need plugs. But I have to wait on new wires.. The Taylor ones were pulling out of the boot.

I know it sounds dumb, but the linear HP progression and absolute smoothness of the LSx may be tricking you. By all means, put it on the dyno again, or run it at the track, but those mods shouldn't have caused a drastic change in the powerband.