SOMbitch

iTrader: (8)

Trying to figure out where my backup is. the LS2 403 made 487/456.

I don't think the backup is in the intake tract though I have no kpa numbers to back this up..

104mm FTP lid.
100mm TSP maf
92mm PTM TB
90 mm Vengeance ported fast.

Exhaust:
1 3/4 ARH headers
ARH 3" hi flow catted Y
Hooker CB

Incidentals...
Worked 220 TFS as cast heads (324 intake flow).
238/250 EPS cam (exhaust on Marine lobes)

Car runs great but peaks at 6k telling me there is a backup somewhere. It carries strong out to 6700. If it would peak at 6400ish I think it would be in the 520 range....

Thoughts???

ds98formula

iTrader: (3)

1 7/8 headers would help out.

Orange Juice

iTrader: (3)

Just the obvious but why marine lobes. Would a marine cam not be designed to run at a constant rpm with out worrying about peak power.

SOMbitch

iTrader: (8)

They are easy on the valvetrain and Geoff and Pat G have both run them with great success..

Z28Z06

iTrader: (2)

Try it without the cats.. just a thought.

BigBirdLS1

I'm betting that if you go from a y-pipe set up to a X or H pipe I'm betting that you will make more power. You could also get some cut-outs after the cats that would be your best bet. Although you could just get rid of the cats unless you want to keep them for some reason.

BrianSF-GA

I am peaking at 5700 and flat lining all the way to 6150 where the power slowly drops to 480 at 6700 with the 10-bolt. I am now running an S60 so I imagine my peak numbers are down under the 500 rwhp mark.

Are your numbers with the 10-bolt?

SOMbitch

iTrader: (8)

Yes 10 bolt thru a stalled 60e. Your tq. #'s are phenomenal

RPM WS6

iTrader: (3)

Would be interesting to see what that setup would do with 1-7/8" headers, and a 3" X-pipe with no cats and dumps at the axle. I think there would be noticeable gains by doing that, but it would be extremely loud. Maybe dual cutouts in the Y-pipe would be the answer, as someone mentioned above. I'd put the cutouts before the cats though, might as well get the most gain possibile from them if you're going to go that route. Bigger headers would probably help though.

DVS99TRANS

iTrader: (7)

What RPM WS6 said, cutouts. And you are also at the point where a 1-7/8" header will start to show itself.

01ssreda4

iTrader: (96)

Torque curve looks like she is a strong runner though....

BrianSF-GA

Love the torque ... mine makes 460 rwtq at 3500 and peaks at 4,750 with 497 rwtq. Like yours, alot of room under the torque curve makes for a strong motor. You are making good power with an A4 thru the cats. Unless you are looking for a dyno queen, you have a great running car. Track times will tell how well the car actually runs, but unless you are ready to part with the 10-bolt, you won't be able to hook it.

For comparisons with my 402 (technically a 403 as you refer to it), my intake flows 321.8 at .600.

NC98Z

iTrader: (1)

I think you ought to bring it to Nam this Sunday so we can find out!

SOMbitch

iTrader: (8)

LOL yeah I should but I just dumped money in the 10 bolt to keep it alive so I'm chicken All new bearings in the pumpkin + axles and axle bearings so not ready to put the Mickeys on just yet. My daughter has a bunch of stuff going on at church too.

Been gettin my racing fix on the Banshee at Busco Beach so haven't run the car in a long while...not a pass on this motor actually... I was gonna go to the North /South thing at Nam a couple weeks back but my Dad came to town so I hung out with him.

I will try to make it up there before it gets too hot. I have a buddy who runs his turbo Stang there about once a month so I will see when he is gonna hit it next and let you know...

Really been thinkin about some TD's since I found a Guy in Raleigh who can do some mandrel bend 3" stainless over the axle out the back......

CamaroSS27

iTrader: (6)

I think TSP new headers and different exhaust set up will get you above 500

2QUIK4U

iTrader: (7)

1 7/8 headers with TD's would probably get you over 500.

FiredUpZ28

I dont think its an issue of can you run that much power through cats - I'd only be worried about blowing them out and having to replace them.

SOMbitch

iTrader: (8)

They are metallic core so they won't blow out but I was thinking they are my restriction causing my early peak and costing me the additional 20-25rwhp that I would see at a 64-6500 peak.

If somebody else with a similar setup and cats was making 500+ and peaking later I would know to look somewhere else....

RPM WS6

iTrader: (3)

Well, the one thing you can be sure of is that they certainly aren't helping to make any power. The only positive purpose that cats specifically serve is if you live in an area where you need them for emissions. If you wanted them for sound reduction, you could always go with race bullets, which shouldn't really cost you any power at all.

Whatever gains you see from removing the cats would probably be doubled by going with bigger headers.

Z28Z06

iTrader: (2)

Just wondering if the rear was any quieter after putting in new bearings? Oh, and are you using Titanium valves in the heads, that might help the top end if the exhaust restriction is not getting you.