trying to figure out what size boost pipe to go with

81.5 ls/vtec STOCK PORT GSR HEAD
garrett 60-1 .63 a/r
turbo elements standard manifold
38mm tial
greddy type s
3 inch downpipe (or would 4 inch be better, im gonna run open downpipe)
stealthmode oil lines
10:1 je's
eagle rods
balnced rotating assembly
buddy club spec 4s(anyones see a prob with these for boost?)

i was thinking 2.5 inch or would three inch be better? then i thought maybe the 3 inch will create lag

 

just go 2.5 thats what i run

 

whats your setup? i was think of the 3 inch because ill be at 10:1 with an equal length mani......any other suggestions would three inch be overkill?

 

if u tryin to get high 300 or over 400 whp i would go wit 3'' if not 2.5 is good

 

Thanks to Club Si for this next write up....original @
http://forums.clubsi.com/showf...47585

Your actual results may vary (ie when you add an IC) so just use my numbers as sort of a bench mark to compare different piping sizes. One thing you guys will notice is that none of the velocities goes above 304 MPH or 0.4 mach. According to Corky Bell, Maximum Boost pg 61, 304 MPH or 0.4 mach is the point at which airflow meets increased resistance (drag) and flow losses are experienced.

Anyways here are the numbers I came up with. The velocities are in miles per hour and mach, and the flow rates are in cfm. Measurements for the piping are in inches.

0.4 mach = 304 MPH

2" piping
1.57 x 2 = 3.14 sq in
300 cfm = 156 mph = 0.20 mach
400 cfm = 208 mph = 0.27 mach
500 cfm = 261 mph = 0.34 mach
585 cfm max = 304 mph = 0.40 mach


2.25" piping
3.9740625 sq in = 1.98703125 x 2
300 cfm = 123 mph = 0.16 mach
400 cfm = 164 mph = 0.21 mach
500 cfm = 205 mph = 0.26 mach
600 cfm = 247 mph = 0.32 mach
700 cfm = 288 mph = 0.37 mach
740 cfm max = 304 mph = 0.40 mach


2.5" piping
4.90625 sq in = 2.453125 x 2
300 cfm = 100 mph = 0.13 mach
400 cfm = 133 mph = 0.17 mach
500 cfm = 166 mph = 0.21 mach
600 cfm = 200 mph = 0.26 mach
700 cfm = 233 mph = 0.30 mach
800 cfm = 266 mph = 0.34 mach
900 cfm = 300 mph = 0.39 mach
913 cfm max = 304 mph = 0.40 mach


2.75" piping
5.9365625 sq in = 2.96828125 x 2
300 cfm = 82 mph = 0.10 mach
400 cfm = 110 mph = 0.14 mach
500 cfm = 137 mph = 0.17 mach
600 cfm = 165 mph = 0.21 mach
700 cfm = 192 mph = 0.25 mach
800 cfm = 220 mph = 0.28 mach
900 cfm = 248 mph = 0.32 mach
1000 cfm = 275 mph = 0.36 mach
1100 cfm max = 303 mph = 0.40 mach


3.0" piping
7.065 sq in = 3.5325 x 2
300 cfm = 69 mph = 0.09 mach
400 cfm = 92 mph = 0.12 mach
500 cfm = 115 mph = 0.15 mach
600 cfm = 138 mph = 0.18 mach
700 cfm = 162 mph = 0.21 mach
800 cfm = 185 mph = 0.24 mach
900 cfm = 208 mph = 0.27 mach
1000 cfm = 231 mph = 0.30 mach
1100 cfm = 254 cfm = 0.33 mach
1200 cfm = 277 mph = 0.36 mach
1300 cfm max= 301 mph = 0.39 mach

It looks like a lot of numbers and BS, but if you take the time to figure out where your turbo rates, you can justify using whatever size charge piping. Ideally, you want as much air speed as possible w/o incurring large amounts of resistance

 

whats boost pipe?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mikey3000 &raquo;</TD></TR><TR><TD CLASS="quote">whats boost pipe?</TD></TR></TABLE>

a pipe that boosts

 

awesome where do i get one? and will it work with vtec?

 

2.5 charge pipe, 3" exh 710 whp.

 

hahaha , you people are amusing

 

so i would asume 2.5 will be plenty for 3-400 whp, and a garrett 60-1?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93egallmotor &raquo;</TD></TR><TR><TD CLASS="quote">so i would asume 2.5 will be plenty for 3-400 whp, and a garrett 60-1?</TD></TR></TABLE>
Yes, you'll be fine with 2.5".

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93egallmotor &raquo;</TD></TR><TR><TD CLASS="quote">so i would asume 2.5 will be plenty for 3-400 whp, and a garrett 60-1?</TD></TR></TABLE>

i made 415 no problem with a 60-1 and 2.5" piping