Guys I need some opinions on where or what to do from here. Story is this,

03 Z06 with
236/240 .601 .608 112 lsa
Ported Fast 92 from Vengeance
1 3/4 American Racing headers with high flow cats
Borla Stingers
Blackwing
Trickflow 215's milled to 59cc
Yella Terras
Nick Williams 92 mm TB

Cam only the car made 427/393

After the heads, ported fast, and TB the car made 478/409

Why no torque? I would have expected much more torque than this. Is the cam the issue? My goal was about about 475/435 so I am pretty disappointed in the low torque numbers. Any suggestions? The shop is scratching their heads a bit on this one so in the meantime I wanted to get some other opinions.

 

Which head gasket gm mls or cometic .040 ?

Do you have a graph? I'd like to see what kind of torque you make starting around 3000 rpms. Compression has a lot to do with torque on a 346, thats why I asked which headgasket you chose to use.

 

cam is partly responsible if motor in good health, but also cats.
First I would go with no cats into X into a LGM big 3 catback.

 

Post the graph.

Did it fall off at 6500?

 

Interested to see the graph as well. I had a similar situation.

Damian: I measured. I need 7.400". Your help has been invaluable.

 

Predator, if his compression is only 11 to 1 then those numbers are on par don't you think ?? If he's running the .040 cometic and the compression is higher then he's low. Thats just my opinion though.

Another question to the op, What rearend and what gears ? Stock or heavy duty?

 

Those are inline with my results with slightly smaller cam. Everything else about same.
Its only an LS1 how much torque do you expect ? No replacement for displacement

 

03 z06


Not trying to be picky, and I know it's the same displacement, but, it's still an LS6.

 

Thanks for the responses guys. GM headgasket (yeah should have went with a cometic but didn't) and stock rear end 3.42. Yeah we were thinking maybe I need to free up the exhaust a bit but honestly I was looking for close to 430 with those mods. I will post up the graph when I get home from work. On a side note I spoke with Vengeance and they said that it has to be the cam because I have the right parts to make more power. Idunno I might just not mess with it because it drives fine and after all makes good HP up top.

 

IMHO even if it is a LS6 once you change the heads and the cam, it basically becomes the same as any other LS1 with heads and a cam. After that the only real difference is the block and the block doesnt make any hp by itself. The runners on those heads are probably a little big to make big torque on a 346, AFR 205 might have had a better torque curve but the top end power might have not been as good. But like pred said, delete the cats if there not a must have where you are and try a better flowing catback.

 

No, nothing to do with the heads.
Cam specs could be teaked for more trq and as i mentionned the cats are a bit of a bottleneck. We are talking 14* overlap here, so cats will hinder proper scavenging and increase reversion (along with those cam specs).

 

id say pull it without the cats and see what it does,then think about cam.

 

The bump in compression from going with a .040 cometic vs the gm MLS will provide a better quench and should find some of the torque you are looking for in the process. Compression is your friend. Just ask Nick Williams about his 402 that when 100% done (porting intake, adding ewp) should be making 580+ rwhp and 510+ rwtq !! 12-1 compression on 98 octane. Per Nick retuning for 93 octane would lose about 10 rwhp. Still sick.

BTW, I am not saying pull the heads this second and spend a lot of money on a thinner gasket, just pointing out that is a place to look for the "missing" torque. Compression! Anyways if you have a headgasket issue in the future, it might be a good idea at that time to go cometics....JMO

 

i belive i would have went with the .040's to.

 

+1 on getting rid of those cats. And before you get too depressed over dyno numbers take it to the track and see what it really does.

 

+1 on this. your hp numbers are real strong and pretty much inline with other head cam cars. If you dont want to delete the cats, you could always run a cutout. That would pick you up some hidden hp and torque and you can still be stealth with the cats and a quiet exhaust.

 

Glad I could help my friend. Somebody had to come out and let people know about TF's and measuring pushrod length

To the OP, answer my question please. Does the car pull past 6500 on the graph or does it drop significantly?

 

Yes, dyno numbers are just bragging rights, the e.t.'s are the money maker.

 

was it a mustang dyno?

 

Here's the dyno graph. After talking with a few more people, I think it might be a combo of the cats, cam, and compression but mostly compression. Thanks for the input guys