scarybowtie

iTrader: (9)

Tell me what ypu guys think. Just had the car tuned again and something is a little off. I'll try and give you as much info as possible. 01 z28, m6, stock bottom end, AI 226 234 .600 .600 112lsa. Fresh 243 heads, pace setters, tsp xpipe bullet mufflers, ls6 intake, ported stock tb, stock maf with screen removed, tr55 plugs, msd wires, 10 bolt rear with 4.10s.
Tuner said there is a restriction somewhere because its still pulling 1-2the psi vacuum at wot. Any thoughts on the numbers? I'm not really concerned with racing the dyno, but what do you guys think of the vacuum issue? Suggestions? I thought my numbers were a little low. Thanks in advance - Josh

RoidedSS

that's roughly 470 crank horsepower on essentially a stock ls6 setup. figure an ls6 in a vette runs a claimed 405 hp at the crank, so you picked up 65 on a relatively small crank, longtubes, and a tune. I'm no tuner by any means so i'll keep my comments away from the thread in terms of trying to read the graph. Also, from the research I've done, the split in duration on that cam looks like it would be something to suit the ls3 heads better. Did AI suggest that cam, or anyone else?

Numbers don't seem too bad regardless though, and the torque looks curve looks nice and flat and 300 rwtq at 2500 rpms has to feel pretty good

also looks a little warm, but nothing too crazy.

redtan

iTrader: (5)

First of all, 1-2psi at WOT is pretty darn good. Also, vacuum at WOT is purely an intake restriction in front of the MAP sensor...which usually includes thorttle body, air tube, MAF and air filter. I would think a tuner would know that and be able to pinpoint exactly where the restriction is.

So given that your kPa reading is not really the problem of where your power is at, I would look elsewhere mainly the tune. Looking at the AFR, it seems to go all the way down to 12.0 at peak torque...which is a little excessive. My bet is the tune is slightly off.


But as you said I wouldn't worry too much about the power output as long as the tune is ok and the car pulls nicely.

disc0monkey

iTrader: (10)

since when do we use psi of vacuum and not inches of Hg? is this what the ecm displays the map readings?

scarybowtie

iTrader: (9)

Thanks for all the input guys. The tuner gave me the kpa reading but i don't remember what it was. I do not know much about tuning or those things. He pulled the lid and looked everything over and even did a pull with the airfilter out. He is a VERY reputable tuner in the area and said the tune was spot on but idk. I wonder how much power that vacuum restriction is leaving on the table?

redtan

iTrader: (5)

Ok my mistake. If it's 1-2 psi (or 7-14 kPa) then that's a pretty considerable restriction.

scarybowtie

iTrader: (9)

Yes 1-2 psi. What would be your first guess on which it is? Its got a lid, stock bellow, stock maf with screen removed, ported stock throttle body, and ls6 intake?

MikeWS6

Those numbers are fine. I wouldnt get caught up in the dyno wars around here since the numbers dont mean much at all.

scarybowtie

iTrader: (9)

Im not really concerned with the numbers Mike. I'm more interested in the vacuum the engine has at WOT that is most definately leaving power to be had

FASTFATBOY

iTrader: (23)

Those numbers are kinda low.

My LS1/LS6, LS1 bottom end with Mahle pistons and top end off a 2003 Z06(heads, cam, intake) made 385rwhp 379 tq.

Pacesetter long tubes and y pipe with SLP 2OTL, lid and free mods.

That car should be at 420rwhp.

thunderstruck507

iTrader: (18)

Has the airbox been opened up on the bottom or is it stock with a lid? If so, fix that (do a search on free ram air mod).

Never heard of a serious LSx tuner in Durant, does their shop do other work too?

scarybowtie

iTrader: (9)

420-430 is the numbers i have seen over and over with similar combos.

scarybowtie

iTrader: (9)

Yes sir the airbox has been opened up. And i have my car tuned at a large reputable shop in mckinney tx

FASTFATBOY

iTrader: (23)

The 4.10 gears is hurting the numbers some.

What length pushrods are in this engine? Did you mill the 243's any?

scarybowtie

iTrader: (9)

The heads were barely skimmed and 7.4 pushrods were used. That gave a touch over 2 1/2 rounds to 22 ft lbs if i remember right.
I made it to the track and it trapped 115, same as with the old cam, a bent valve, and weak springs...
still not sure why its making vacuum at wot