z28merica

What WHP/TQ does a 1996 z/28 M6 stock put down? Is 50hp or more a reasonable gain from headers, exhaust, cold air intake and tune? I would like to know if LT4 heads and intake manifold will drop right in? Including porting and polishing. If so, which headers are worth buying? Longtube or Short tubes? My goal is 350whp without ripping the interior out and all motor.

ahritchie

iTrader: (1)

Around 250-260 rwhp stock for 6spd. No, you won't gain 50hp with just the mods you mention, maybe if you added 1.6 roller rockers too. Honestly, don't bother with LT4 heads to get 350 rwhp, waste of $$ and better options out there (get your stock heads ported). Header choice depends on a couple things, obviously long tubes are best for maximum HP per $, BUT you also have to consider if emissions are an issue in your state, some places make it pretty much impossible to pass with longtubes, also if you lower the car, longtubes and the huge y pipe hang very low and will be dragging on everything; if either of those is going to be an issue, get Pacesetter mid-tubes, they are CARB legal and have excellent ground clearance, come with a y-pipe included, and cheaper. You will give up 10-15hp with mid-tubes vs longtubes. You could probably hit number that with just full bolt ons, good tune, and decent sized cam with untouched stock heads.

ahritchie

iTrader: (1)

LOL...I just noticed "San Diego", your getting mid-tubes buddy!

California is a **** state when it comes to these sorts of things ...ditto on the "decent sized cam", you'll need a baby cam instead.

93M6Formula

FWIW, my car put 281/323 bone stock. The only non stock thing was the muffler was cut off. Everything else stone stock. I would suspect it would have put down 275 with the muffler. After LT's, ram air, and a tune, I put down 294/334. Not a real amazing gain but it needed it none the less. This was on the same dyno also. And I have a 6-speed car.

Catmaigne

iTrader: (6)

CAI, long tubes, ORY without cats, a good 3" catback, and a cam with 220~230 duration. You also need all of the supporting mods to go with the cam (springs, 1.6 full roller rockers, hardened pushrods, etc). You could also add an electric water pump to eek a little more out of it.

Hotcam might fall short
XFI 466 is a little better
CC503 will definitely put you there
They get bigger from there... More than 220-230 for these:
XFI 467 is there and then some
Same with the CC306

Mind you, these are all with stock heads. You could also go with a custom grind but chances are that someone will spec you a cam with the duration of a 503, the lift of a XFI, but smaller LSA. Honestly, if 350rwhp is all you want then you'll do fine with a shelf cam. You could save some money and get one used from the classifieds for $150 because roller cams don't wear like flat tappets do. Just make sure there's no rust or score marks and you'll be fine, then use the money saved to buy other go fast parts.

ahritchie

iTrader: (1)

^Hardly any of those cams will fly in California, same for ORY You will need cats, CARB legal mids/shorty headers, a small baby cam known to pass emissions, and probably some ported heads or it will fall short of 350RWHP due to all the compromises for emissions, the plus side, it will make a solid 375+ RWHP if you choose the right porter for the heads; even with a baby cam.

Something along the lines of this:


Ai 214 / 220 - .517" / .517" - 112 LSA

A good choice for those who want no drivability sacrifice. Properly tuned this small grind will run and drive well with stock gearing & converter. Can be run on a 114-116° lobe separation for an idle that sounds stock. Easily passes emissions everywhere it has been tested.

96lt1m6

iTrader: (31)

Longtubes
2.5" X pipe,1ch.flows
1.6RR
160°
SLP lid
Madtuner tune
6Spd
4.10s
319Hp
336Tq
12.98/106mph at 3000'DA

z28merica

I was going to save up a bit and have it done right after smog since its for 2 years. I plan on moving back to Pennsylvania which doesn't have that.

Catmaigne

iTrader: (6)

Depends on the county you live in. There's smog where I am but getting stickers is never a problem because I have a few connects. It's not cheap but it beats getting inspected in COMMIEFORNIA.