Patrick G

iTrader: (14)

I'm on my 5th LS1 project. I love the sound and the stealthy nature of running factory cast iron manifolds and cats, especially for a nice daily driver. I'd like to make 400+ rwhp naturally aspirated running the factory exhaust and dual/dual catback. Stock displacement too. I know it's doable, but I'm not sure how small of a cam I can get away with by doing it. Ported LS6 heads or 205cc AFR heads with LSX intake would be a must. A 224/224 cam would most likely do the trick along with the killer heads, but this cam also has lots of valve clatter due to its fast ramps. I don't want noisy valvetrain. ZO6 cams are quiet, but I'm not sure if they can get me to 400 rwhp without headers. Again, this is my car, so don't criticize me for running an oddball combination. Nobody said making 400+rwhp with factory exhaust and stock displacement was going to be easy. To me, that's part of the appeal.

InsomZ

iTrader: (1)

why are u so against headers? seems like LSX intake/afr head route to reach 400rwhp is alot more expensive then just getting some headers

Patrick G

iTrader: (14)

I'm not against headers in general. They make power. I've run headers in 3 of my 5 LS1 project cars. Problem is, headers make the car sound tinny, trashy, and non stock. I want this car to look and and sound stock (at a glace), but haul ***. Again, I have different goals for this car. I want great idle quality, good gas mileage, and low noise. My old 2000 WS6 ran 11.0s with factory exhaust and a 150 shot. Best car I ever had.

ccajun4real

iTrader: (29)

Get Kooks headers. They seem to be thicker and provide better exhaust flow stealth

Spl170s

iTrader: (8)

His post said no headers..........

99 Black Bird T/A

iTrader: (4)

Picked up a pair of extrude honed cast iron manifolds for my 3rd Gen before deciding to go with custom headers for it. The extrude honed manifolds were ~1/8 to 1/16 bigger in the primaries and collector than the stock manifolds I had to compare against.

I think going for 400+ with manifolds will have exhaust restriction. I think a traditional split with extra exhaust duration will help in your goal. The LPE GT2-3 cam is similar to the Z06 and has more punch but might still be on the small side 208/220 118.5 LSA. Maybe a scaled up version of something like that might be worth thinking about, TR old man cam or even a 224/228 etc

JS

iTrader: (4)

I'd go 218-224 560-565 114LSA
TEA or SAM (Your Boys) S1.5 (small runner hand ported and good flow to 570 lift)
LS6 int.
PTB
EWP
Good catback
Ported or E.honed stock manifolds
Rest of the basic boltons w/edit tuning
10-bolt 3.73's

I bet your close to 400RW threw a stick..
A4----------->forgetta bout it

Linear Velocity

iTrader: (1)

This is interesting because that was originally going to be my goal with my rebuild. Altough I was going to try and hit 400rwhp with an 02 LS6 Cam, Stage 1 heads, stock 01 cats/manifolds, and tuning. It was a stretch I know and I've since gone another route but I did do a lot of research on it. Patrick, an example would be Jason99TA. If I remember correctly, Jason hit 393 rwhp with a rebuilt motor (like mine), 02 LS6 cam, stock heads and Mac's with no cats. My rationale was that I would have heads instead of headers and I would hopefully be around same place he would be. I think an LPE GT-2 Cam or an MTI Stealth II cam would net the better power with a nice set of heads though. As far as the heads you can never go wrong with SAM, I would go for at least an 11:1 CR as bumping the CR will always help your hp. Another combo that seemed to work was mating an 02 LS6 cam with SLP 1.85 rockers, this increases the lift to just under .600; so if you had a nice set of stage 2 heads that peaked at a .600 lift it would allow them to breath to their potential. Speed Inc. did this on their Z06 (Stage 2 LS6 heads, stock LS6 cam, 1.85 rockers, longtubes) and made 420rwhp, so minus 20 rwhp or so for no headers you'd technically be right around there. I know a lot of this is bench dynoing so to speak and everyone's car is different but hope this helps.

Phil99vette

iTrader: (11)

There is a guy on the CF that just made 409rwhp/391rwtq with 2 mods....
AFR 205 cc heads
Halltech Stinger intake

TTopJohn

Any more info on this? I seem to recall Zed over on LS1.com dynoing an MMS head and cam package with stock manifolds and coming up with some 400ish horsepower numbers. But this was a few years back and I'm sure that post got lost in a server crash or something.

Jason 98 TA

iTrader: (4)

My wife's 3500 stall sleeper cam only car puts about 340rwhp to the ground. I think with some good heads 375 rwhp could be possible in a a4 converter car through stock manifolds & cats

TTopJohn

I think you may need to try that, in the name of science. Youve got the right idea with a stock manifolds car - it's all about putting the maximum amount of power in it while making it sound stock to the wife

eb02z06

iTrader: (18)

Hey Patrick I can totally see your viewpoint. My Z06 now makes 460RWHP and is as loud as a racecar-it was cool at first but I want stealth and total driveability. This is my daily driver so it's a little to obnoxious for daily driving. actually i'm in the midst of installing a smaller more streetable cam and installing the factory Ti exhaust-I figure I lose about 10 horse but gain a much more enjoyable daily driver. Anyway-400rwhp through cats and a tiny cam is very possible. A guy on the CF forum did a AFR head (on a Z06) swap only and made 410 at the wheels through the factory cats, manifolds, TB, Intake-he only had a aftermarket airbox. My car for example made 377 with just an airbox and ran 11.60@118 on et streets. Can the Z06 manifolds be adapted to work on f-bods? The Z06 maniflod almost looks like a shorty header and flow really good and so do the Z06 cats-plus the manifolds are cast iron and hold heat to really get the exhaust flowing. I personally think u can get more than 400 with a good set of heads, a more aggressive but quiet cam, fast intake and ported TB-I can see 425+. What about that old man grind u had. Keep us posted i would love to see your progress!

WAHUSKER

iTrader: (4)

I'd also suggest getting some Random Tech Cats & y-pipe. You will get a little deeper tone from the bigger y, but not the rasp of headers. And you'll let whatever cam, intake & heads you choose flow better, plus you'll pick ~20rwhp (or at lest I did with a pure stock motor....313 to 334)

CHRISPY

Yep I agree with above or just build a custom 2.5 inch Ypipe with 3 inch cats and FM reducer cones on either end of the cats. Very quiet and MUCH higher flow than stock. (about 500cfm more flow total) dual 2.5 into 3 inch FM collector would be nice too. Full 3 inch intermediate pipe into a SLP dual dual or similar.

Bad Habit Bird

iTrader: (12)

I had a setup similar to what you are talking about for awhile on my car. Stage 1 heads and a 228/232 cam through stock manifolds/cats and a stock WS6 catback. The car sounded nice and quiet and made 396rwhp

This was also with a stock lid and maf on the car.

narcszm

That's a decent size cam. I'm doing heads and 224/224 cam next week and keeping stock manifolds on the car; I'll let you know how it goes.

fasteddyss

iTrader: (1)

I am interested in going this route as well. I would like more power but not neccesarily with headers, I am looking at adding a cam(not sure which yet), ls6 intake and high flow catted y-pipe, and maybe heads.

Does anyone know if the 99 manifolds are better or worse than the newer ones??

Damian

iTrader: (89)

I've seen 415/390 through stock man and cats. TEA heads & TSP cam...

Patrick, I disagree with your statement. It is not the headers that make these cars sound like that. It is the lack of cats. Putting high flow cats on makes a WORLD of difference, and you still have the advantage with all of the sound.

Personally I think modding a bone stock motor internally is quite silly without proper intake and outake air flow. Cats will solve your problems. Run headers..

Patrick G

iTrader: (14)

'98-99 manifolds/cats are 5-10 rwhp worse than the '00 and newer versions.