Exhaust Exhaust for a 347???

V

vpap1

Member

Sep 21, 2009

109

2

19

Feb 25, 2013

#1

• Feb 25, 2013

• #1

OK current setup:

347 10:1 comp. track heat intake and 170 cc heads, 30# injectors, TFS 2 cam, 80 maf 75 TB,
BBK 1 5/8" short tube headers, into 2.5" non cat H pipe, into 2.5" flowmasters with no exaust pipes

made 351 RWHP at 5500 rpm

Upgrading the camshaft to a xfi236 ...and hoping with upgraded valve spring and retainers and headers with make in the 370's for RWHP at about 6100 rpm

question is:

1) Do I get a LT header with 2.5" collector and 2.5" x pipe and leave the 2.5" mufflers
2) LT Header with 3" collector, 3" x pipe and upgrade to 3" mac pro dumps
3)LT Header with 3" collector, 3" x pipe into a 2.5" reducer to the 2.5" flowmasters i currently have

Possibly adding spray later on for the strip...

What ya'll think?

V

 

MikeH686

Mine is only two inches though.

10 Year Member

Oct 11, 2011

2,843

1,753

184

Waldorf, MD

Feb 25, 2013

#2

• Feb 25, 2013

• #2

Dont do the third one it makes no sense to reduce back down to 2.5 im going 1 5/8 to a 3 inch collector to a 3 inch x pipe and 3 inch dumps

 

V

vpap1

Member

Sep 21, 2009

109

2

19

Feb 25, 2013

#3

• Feb 25, 2013

• #3

MikeH686 said:

Dont do the third one it makes no sense to reduce back down to 2.5 im going 1 5/8 to a 3 inch collector to a 3 inch x pipe and 3 inch dumps

Click to expand...

what do you have for power? @ what rpm? Thanks

 

MikeH686

Mine is only two inches though.

10 Year Member

Oct 11, 2011

2,843

1,753

184

Waldorf, MD

Feb 25, 2013

#4

• Feb 25, 2013

• #4

410 at 5700 rpm but that was on a carbed setup

 

clement

Founding Member

Feb 27, 2001

1,106

52

59

Oak Cliff

Feb 25, 2013

#5

• Feb 25, 2013

• #5

MikeH686 said:

Dont do the third one it makes no sense to reduce back down to 2.5 im going 1 5/8 to a 3 inch collector to a 3 inch x pipe and 3 inch dumps

Click to expand...

the further back the restriction is the less negative effect it will have because the gas cools back down the further it travels. its not ideal. full 3" would be ideal, either way i wouldnt run a chambered muffler like a mac or flowmaster. the dynomax race magnum should pick up .2-.3 in this combo.

 

V

vpap1

Member

Sep 21, 2009

109

2

19

Feb 26, 2013

#6

• Feb 26, 2013

• #6

who carries a 3" x pipe with flanges already welded on?

V

 

84Ttop

They make new pistons every day, so why worry?

5 Year Member

Jul 2, 2009

5,222

3,254

204

South Jersey

Feb 26, 2013

#7

• Feb 26, 2013

• #7

My suggestion is 1 3/4 long tubes w/3" collectors and some dynomax ultra flow mufflers

 

Reactions: MikeH686

MikeH686

Mine is only two inches though.

10 Year Member

Oct 11, 2011

2,843

1,753

184

Waldorf, MD

Feb 26, 2013

#8

• Feb 26, 2013

• #8

Bassani has a nice x pipe with ball and socket flanges

 

2000xp8

SN Certified Technician

Aug 8, 2003

8,016

1,613

194

NJ

Feb 27, 2013

#9

• Feb 27, 2013

• #9

My suggestion is to leave the exhaust the way it is and spend the money opening up the heads a bit which could possibly bring the power up around the 400 mark instead of 370.
I know plenty of people that make over 400rwhp on 347's with similar exhaust setups as to what you have now.

The guy i sold my entire 347 setup to, including my exhaust made 425rwhp and that combo was my extrude honed tw's ($750 for the extrude honing), rpII intake, custom cam, 1 5/8 mac shorties, offroad bassani x pipe, 30's 80mm pro m.
Literally i sold everything i had to fund my 4.6.

Buying all new exhaust parts is going to set you back quite a bit for what you are going to get. That money for sure would be better spent cnc'ing the wedges.