Merge collectors,,how big a choke

Crossbreed · 05-16-2013, 10:53 AM

Was wondering when is it beneficial to use a merge style collector, and how do you go about picking your choke point
Are pipemax type programs accurate as far as sizing and taper of cones,or do you error smaller to be safe?
Ive gotten some data from pipeamx but it seems the minimum choke is big in relation to some other combos ive seen
Combo is as follows

4.070 bore 6.2 liter
ALUMINUM HEADS AND BLOCK
4.0 stroke callies crank callies 6.125 h beam rods
wiseco dome piston 14.9 compression
1.2-1.2-3mm low tension backut ring package
GZ motorsports vacuum pump -12" or so for wet sump?
55 mm cam core
700"int-690" lift after lash
274*-280* at 050 in at 108
13.5 degree ls based 245cc runner tfs heads - cnc ported by TEA -and gone over a little by hand
these flow 360-285CFM at 650" lift ," lift or so
hollow stem 2.100 intake valve -stainless 1.6 exhaust
MAST 2 PIECE CNC'D CAST 2 PIECE MANIFOLD
Bigs `1050hp DOMINATOR on top of 1/2 SHEAR PLATE
1-7/8 headers TO- 3-1/2 EXH
2900 PD CAR
275 DRAG RADIAL
4.30 GEAR
TH 400
8IN CONVERTER(6200-6400 FLASH)
RACED IN DENVER AT 7500-9500 FT OF D/A IN NORMAL SUMMER CONDITIONS
PEAK, POWER RPM WANTED AT 7500 OR SO

My concern was also that the old collectors may be a touch big ,so i was thinking of reducing the collector size and going to a merge style is all
It has a 3-1/2 in collector now,so i was wondering if i go down to a 3" choke ,then back up to a 3-1/2" opening to the muffler would be ok,or if an even smaller choke size would work
I was told that at my elevation and power level ,that a 2.75 "or so choke size would be sufficient
PIPEMAX RECCOMENDS THIS
416ci from 5450 to 7950rpm
Diameter=1.933" to 2.058" Length=26.9 to 29.1"
--------2 step primary pipe specs--------
1st-1.933" length-13.5-14.6"long
2nd-2.058" length-13.5-14.6" long
--------3 step primary pipe specs--------
first step is the same as above first step
2nd-2.058" length-6.7-7.3" length
3rd-2.183" length-6.7-7.3" length

---------collector--------
Diameter-3.525" - 3.775" length- 15.1"
-------megaphone-------
3.025" taper to 4.025" 15.1" long

Best HP & Torque
26.9" length primary

Any opinions on this?
Thanks

jmcarter · 05-16-2013, 12:01 PM

I started to do some flow analysis when considering going to a merge collector but then called Mark Lelchook and was very happy with the results. Mark's expertise and workmanship is outstanding.

http://www.perfweldheaders.com/

Crossbreed · 05-16-2013, 03:41 PM

Im sure he knows more on the subject than i would forget,unfortunatly ill be the one building these as for the money they get,i could build a few sets myself and possibly learn something in the process(although im not very trainable lol)
thanks though

05-16-2013, 10:53 AM	#1
Crossbreed Junior Member Join Date: May 2013 Posts: 3 Likes: 0 Liked 0 Times in 0 Posts	Merge collectors,,how big a choke Was wondering when is it beneficial to use a merge style collector, and how do you go about picking your choke point Are pipemax type programs accurate as far as sizing and taper of cones,or do you error smaller to be safe? Ive gotten some data from pipeamx but it seems the minimum choke is big in relation to some other combos ive seen Combo is as follows 4.070 bore 6.2 liter ALUMINUM HEADS AND BLOCK 4.0 stroke callies crank callies 6.125 h beam rods wiseco dome piston 14.9 compression 1.2-1.2-3mm low tension backut ring package GZ motorsports vacuum pump -12" or so for wet sump? 55 mm cam core 700"int-690" lift after lash 274-280 at 050 in at 108 13.5 degree ls based 245cc runner tfs heads - cnc ported by TEA -and gone over a little by hand these flow 360-285CFM at 650" lift ," lift or so hollow stem 2.100 intake valve -stainless 1.6 exhaust MAST 2 PIECE CNC'D CAST 2 PIECE MANIFOLD Bigs `1050hp DOMINATOR on top of 1/2 SHEAR PLATE 1-7/8 headers TO- 3-1/2 EXH 2900 PD CAR 275 DRAG RADIAL 4.30 GEAR TH 400 8IN CONVERTER(6200-6400 FLASH) RACED IN DENVER AT 7500-9500 FT OF D/A IN NORMAL SUMMER CONDITIONS PEAK, POWER RPM WANTED AT 7500 OR SO My concern was also that the old collectors may be a touch big ,so i was thinking of reducing the collector size and going to a merge style is all It has a 3-1/2 in collector now,so i was wondering if i go down to a 3" choke ,then back up to a 3-1/2" opening to the muffler would be ok,or if an even smaller choke size would work I was told that at my elevation and power level ,that a 2.75 "or so choke size would be sufficient PIPEMAX RECCOMENDS THIS 416ci from 5450 to 7950rpm Diameter=1.933" to 2.058" Length=26.9 to 29.1" --------2 step primary pipe specs-------- 1st-1.933" length-13.5-14.6"long 2nd-2.058" length-13.5-14.6" long --------3 step primary pipe specs-------- first step is the same as above first step 2nd-2.058" length-6.7-7.3" length 3rd-2.183" length-6.7-7.3" length ---------collector-------- Diameter-3.525" - 3.775" length- 15.1" -------megaphone------- 3.025" taper to 4.025" 15.1" long Best HP & Torque 26.9" length primary Any opinions on this? Thanks

05-16-2013, 12:01 PM	#2
jmcarter VIP Member Join Date: Dec 2008 Location: Richmond Hill GA (and Port Ludlow WA) Posts: 4,295 Likes: 2,382 Liked 3,174 Times in 971 Posts	Re: Merge collectors,,how big a choke I started to do some flow analysis when considering going to a merge collector but then called Mark Lelchook and was very happy with the results. Mark's expertise and workmanship is outstanding. http://www.perfweldheaders.com/ __________________ Jim Carter 2340 Super Stock 2340 SST/2340 Stock Set another place at the table

05-16-2013, 03:41 PM	#3
Crossbreed Junior Member Join Date: May 2013 Posts: 3 Likes: 0 Liked 0 Times in 0 Posts	Re: Merge collectors,,how big a choke Im sure he knows more on the subject than i would forget,unfortunatly ill be the one building these as for the money they get,i could build a few sets myself and possibly learn something in the process(although im not very trainable lol) thanks though