Visceral

iTrader: (1)

Stats:
MTI hammer cam, LS6 ARE stage 3 heads, Grott LTs, Mufflex 4" catback, pulley, ported TB, LS6 intake, lid, etc....



I make the same power at 5500 as most 430 rwhp cars, but I peak at only 6000.

This is with full exhaust.

Im beginning to wonder if this 4" mufflex isnt as free flowing as I thought....
Stock tuning, btw.

MTI will dyno the car with an open exhaust in a couple days. That might tell us some things.

Thanks in advance...
Its good to have found where all the good tech posters went while I was doing other non car things the last few months.

Chris
(formerly TE-63 Syclone)
Now a C5 addict.

1madss

iTrader: (10)

Wow, your dyno looks almost just like mine. I have the MTI S2 heads and hammer cam and peaked at 408.7hp and 388.3 tq right about 6000. My car is going rich ~6K. That and my timing is not so great after 4K. What do your A/F and timing numbers look like. Also, any idea what that burble in the hp and tq lines are at 5-5.5K?

Mark

[ November 26, 2001: Message edited by: 1madss ]</p>

Jason99T/A

iTrader: (21)

On my heads/cam car, I went from 427rwhp to 442rwhp from just opening the cutout on my 3.5" Mufflex. I was not too happy with how the muffler performed, but it does sound SWEET! I think that could be part of your problem there.

www.thunderracing.com/jasondyno3.jpg
Jason

Mike Hoffpauir

You should auto tap the car to see whats going on too. I'm sure between the exhaust and a peek at knock, o2's and timing will sort you out =)

Pro Stock John

iTrader: (34)

4" Flowmaster muffler?

Keep us posted.

I have 4" mufflex, 3" orp, TTS longtubes and if you see a big gain I will run the car thru cutouts.

Jason so your best track runs are thru the cutout?

Jason99T/A

iTrader: (21)

[quote]Originally posted by Pro Stock John:
<strong>Jason so your best track runs are thru the cutout?</strong><hr></blockquote>

Yes, that would be correct. <img src="images/icons/smile.gif" border="0">

VINCE

iTrader: (1)

ARE Stage 3 heads? Is this a 346cu? What are the specs on the heads..?

jmX

Yes, 346ci. Stage 3 heads are everything stage 2's are, with a little "trick". Dunno what the deal is...Nick seems to not want to tell certain people the trick so I'll keep my mouth shut...visceral can tell if he wants. The heads have 2.08/1.60 valves.

VINCE

iTrader: (1)

You mean know one has beat him up for using such big valves. I just mentioned it and I rec'd a beating.. I am still going with the bigger valves.. Thanks JMX for the explanation..

jmX

No prob. I have the same sized valves as well...granted, my car has issues that are unresolved but I dont think its due to the large valves in the small bore.

VINCE

iTrader: (1)

Have you had that thing dyno'd yet JMX? I keep hearing about all the shrouding I am going to get from using the bigger valves on the 346ci..

Terry Burger

iTrader: (4)

I don't think the trick is working.. <img src="images/icons/wink.gif" border="0">

VINCE

iTrader: (1)

Do you guys think the problem could be shrouding? 2quick mentioned in another post that bigger valves in a 346ci could hurt performance and increase shrouding.. Can someone explain if this could be the case and if not why not..?

Crazyquik

Someone posted once they only lost 1 rwhp thru thier Mufflex, but they'd replaced the Flowmaster with a Borla XR1 or a 4" Dynomax I believe.

I want to say it was Rob Raymer but not sure.

Pro Stock John

iTrader: (34)

Tangent: 2.08/1.60 are big for a 3.900 bore engine.

I will try to source some cutouts for my car so I can compare at the track.

VINCE

iTrader: (1)

Pro that would be good. I would like to get more information..

SpeedDemon

[quote]Originally posted by vmoore:
<strong>Do you guys think the problem could be shrouding? 2quick mentioned in another post that bigger valves in a 346ci could hurt performance and increase shrouding.. Can someone explain if this could be the case and if not why not..?</strong><hr></blockquote>
I think you might be on to something here. <img src="images/icons/wink.gif" border="0"> <img src="images/icons/smile.gif" border="0">
My opinion is that a 2.080" intake valve coupled with a 3.900" bore is just WRONG! First off, my question would be why? There are too many heads out there that have 2.02" valves that are making AWESOME power... 425+ RWHP and some even more! A 2.055" intake valve is really too big for the stock bore also IMHO. Open the bore and dog will hunt! <img src="images/icons/smile.gif" border="0">

Crazyquik

[quote]Originally posted by Pro Stock John:
<strong>
I will try to source some cutouts for my car so I can compare at the track.</strong><hr></blockquote>

If you cant find some cutouts (dual ones in the Y pipe shouldn't be hard to do though) you could put a 3 bolt flange infront of the muffler to make it easily removable. No muffler restriction, save 20-25 lbs I guess too.

jmX

[quote]Originally posted by SpeedDemon:
First off, my question would be why? <hr></blockquote>

Well, my 2.08/1.60 heads made the same power as my 2.02/1.575 heads...same peak, same tq. If somebody was planning on doing a larger bore motor in the future, the larger valves will pay off.

[ November 27, 2001: Message edited by: jmX ]

[ November 27, 2001: Message edited by: jmX ]</p>

jmX

[quote]Originally posted by vmoore:
<strong>Do you guys think the problem could be shrouding? </strong><hr></blockquote>

It could be, but I think part of the "stage 3" trick was to reduce shrouding (if I recall correctly) so it may not be a key factor here.