jmX

I did this a couple years ago, totally stock exhaust, 393rwhp. TR227/224 with GTP heads. Its nice to see somebody do it on an F-body now though..without the benifit of dual exhaust!

Patrick G

iTrader: (14)

You would think this would benefit the setup, but my experience shows me the exhaust manifold to be the choke point and not the cats or y-pipe. On a previous 2000 F-Body, I gutted the cats on my 2000 WS6. This had the good cast iron manifolds and a cutout too. With stock cats, it made 476 rwhp on nitrous at 1100 psi bottle pressure. With gutted cats, it made exactly 476 rwhp (same bottle pressure) and the same torque. This proved to me that the exhaust manifolds were the choke point.

I even spoke with one of the guys at Mufflex who stated they've tried everything (high flow cats, larger y-pipes and Flowmaster merge collectors). The result? 0-2 rwhp gain.

On this current car (the one in this thread), we tried dropping the catback looking for some extra power. We made 0 more rwhp with open exhaust vs. closed. IMO, any improvements to the exhaust need to start with the manifolds first.

Flareside

Great post, thanks for sharing your info!

I've been running my LS1 with AFR205s and the GT2-3 cam along with stock exhaust manofolds and cats this year, and I really love the power increase. I just removed these parts since I'm trading in the C5 on a new C6, so my next motor project is in the planning stage. The one thing I don't like about my current setup is the valvetrain noise. Everything I read said that the small LPE grind would sound like stock, and it does at idle, but when the motor is running along at 1500 or 2000 rpms in the drive-thru or in a parking lot you can really hear the valvetrain. I've run it with the dual AFR springs, single Comp beehive springs, stock pushrods, and longer 7.425" Comp pushrods. The Comp spring/Comp pushrod combo is quietest, but not as quiet as stock. It bugs me enough that I'm thinking about keeping the stock cam in the new LS2, and just sticking with the AFR heads. Keep us posted on the valvetrain noise, I'd really like to know if it sounds different than stock in any situation.

CHRISPY

Great results Patrick

gollum

iTrader: (1)

There is no substitute for cubic inches other than nitrous.

The small 347 is limited because of its small size. Your combo with a 4.00" crank (383 ci) would make a lot more midrange torque.

Keith

This looks like one hell of a package for a truck too.

Congratulations on the results. Nice to see a well executed package!

Patrick G

iTrader: (14)

Yes, the package would work well on trucks too. The only thing Thunder Racing might change would be grinding the cam with a little more advance in it (for a lower power peak). I mean honestly, how many truck enthusiasts like to wind their motors out to 6800 rpm? LOL! The high air speed of the AFR heads make torque down low abundant while the docile manners of the 215/230 cam keep the mid-range and top end power nice too.

Christos

Hah! Not only are you the best head maker out there, you have no shame.

Man AFR all the way!

TT_Vert

iTrader: (12)

What was the compressed thickness of that gasket?

Thanks
dave

Patrick G

iTrader: (14)

.060"

TT_Vert

iTrader: (12)

wow thats quite a bit of quench.

Dave

eb02z06

iTrader: (18)

My heads are milled .040 and i run the cometic .040 compressed gasket as per AFR recomendations-now that's quench!

TT_Vert

iTrader: (12)

How far out of the hole was your piston?

Dave

Patrick G

iTrader: (14)

After we removed the carbon buildup on the pistons, they measured .008" out of the hole.

Racehead

That's very impressive Patrick, I can only imagine the tears that will be shed in any street encounter you might have Way to blaze a new path.

SIC LSX

iTrader: (10)

ok with these mods what do you think it should put down on a 6 speed car? longtubs & offroad y-pipe or cats I can do both, 90NW/90fast intake, slp lid, magnaflow catback and stock heads with right springs, and a tune threw HP tunners? thanx for your help

Kraest

iTrader: (3)

It would drive me completely insane knowing that I had another 50rwhp tied up in my car if I were to throw on some headers/exhaust.

I would have gone with a slightly bigger cam and ported LS6 heads with ported exhaust manifolds with a dyno-tune to get rid of the cam lope, but that's just me

Nice numbers

Mike

Patrick G

iTrader: (14)

Much bigger of a cam would have made the overlap unacceptable to work well with stock manifolds and still pass emissions. Ported LS6 heads would have been a step down from AFR 205s IMO because you'd lose too much air speed with ported LS6 heads. To match the air flow of the AFRs, you have to port the runners and bowl area too much. What you gain in flow, you lose in air speed. AFRs are better for this application. Ported exhaust manifolds are in the works...as are a ported FAST 90/90. Car was dyno tuned to the gnat's ***. There is no lope. Read the whole thread.

TT_Vert

iTrader: (12)

from what ive heard about this cam, it shouldnt lope even w/o a tune right?

Dave

Patrick G

iTrader: (14)

The cam will not lope once the car is warmed up, but because the 215 intake lobe has nearly the same lobe area as a TR 224 lobe, it will need some tuning to the VE tables to have superb cold start characteristics. Without tuning, it stumbles a little for the first 15 seconds, then runs fine. I slighltly modified the VE tables with HP tuners so it starts like stock when the motor's dead cold and the A/C is left on MAX. Any good tuner can do the same. Thunder has my files and can do a perfect mail order tune.